CG hook on aero tows??

[Ted Wagner]

A few seconds into take-off roll today in a Pilatus B-4, while applying left stick to correct for a dipping right wing, the right wing suddenly dipped all the way into the ground. The glider lurched to the right, and a second or two later popped up into the air, a good 20 feet up and 30 or more feet out to the side. By that time I had full left rudder in addition to full left aileron, so the glider recovered rather quickly, and I was able to bring it to normal take-off position right about the time the tow plane started to climb. I was amazed he had maintained his heading directly down the runway. The winds were light and variable. It was my ninth flight on the B-4.

After landing, the tow pilot apologized, saying it was his fault -- something about the wake turbulence. But I'm still puzzled about what, if anything, he did wrong; it looked like a completely normally take-off roll to me.

I had thought that maybe a sudden tail wind had reversed the effective correction of my aileron deflection during take-off, causing the right wing to dip harder instead of leveling off. Does this make sense to anyone with more experience on an aircraft like the B-4?

Also, I'm curious to know how much the CG hook location on the B-4 contributed to the squirrelly sequence of events after the right wingtip hit the ground. How many 15+ meter gliders have CG-only hooks? Are such exciting events more commonplace with CG hooks?

Other than the wobbly tows, I'm loving the B-4, it's the first 15-meter single-seater ship I've flown, and the first with retractable gear...

~tw

[BTIZ]

CG vs Nose hooks.. the Nose hook will help pull the glider to center "some".. not much early in the run.. or resist a tendency to pull towards a dropped wing..

A dropped wing will create more drag on grass or gravel than on pavement.. a dropped "draggy" wing will cause more deviation from center with a CG hook. Large moment arm with no counter resistance. Consider a "crack the whip" effect like when water skiing.

As for the "tow pilots fault".. SOMETIMES.. a quick "Burst" application of power will create a spiraling propwash effect that as a tendency to drop a wing.. as opposed to a smooth increase in power.. where wing runner runs farther.. and slower for your ailerons to become effective.

Does not take much "tail wind" effect to decrease the effectiveness of controls.. a new owner of a Speed Astir learned that even 3knts was enough to make his rudder ineffective in the early stages of the take off.

A "loss of control" on takeoff resulting from a dropped wing and CG hook was evident in the launching accident at the Nationals a couple of summers ago at Tonopah NV. Wing heavy with water was dropped as power applied, down wing pulled the glider well off the runway where the wing then struck an airport maint worker.

Some gliders only have the CG hook, some only the nose.. and some both.. we mostly use the nose hook for the Grob 103, easier for the ground crew to get to. But we require those checking out in the LS-4 to have at least 3 rides with the Grob 103 (w/CFIG) using the CG hook.

BT
"Ted Wagner" > wrote in message news:pI1Kb.17587$7D3.9225@fed1read02...
A few seconds into take-off roll today in a Pilatus B-4, while applying left stick to correct for a dipping right wing, the right wing suddenly dipped all the way into the ground. The glider lurched to the right, and a second or two later popped up into the air, a good 20 feet up and 30 or more feet out to the side. By that time I had full left rudder in addition to full left aileron, so the glider recovered rather quickly, and I was able to bring it to normal take-off position right about the time the tow plane started to climb. I was amazed he had maintained his heading directly down the runway. The winds were light and variable. It was my ninth flight on the B-4.

After landing, the tow pilot apologized, saying it was his fault -- something about the wake turbulence. But I'm still puzzled about what, if anything, he did wrong; it looked like a completely normally take-off roll to me.

I had thought that maybe a sudden tail wind had reversed the effective correction of my aileron deflection during take-off, causing the right wing to dip harder instead of leveling off. Does this make sense to anyone with more experience on an aircraft like the B-4?

Also, I'm curious to know how much the CG hook location on the B-4 contributed to the squirrelly sequence of events after the right wingtip hit the ground. How many 15+ meter gliders have CG-only hooks? Are such exciting events more commonplace with CG hooks?

Other than the wobbly tows, I'm loving the B-4, it's the first 15-meter single-seater ship I've flown, and the first with retractable gear...

~tw

[Marc Ramsey]

Ted Wagner wrote:
> I had thought that maybe a sudden tail wind had reversed the effective
> correction of my aileron deflection during take-off, causing the right
> wing to dip harder instead of leveling off. Does this make sense to
> anyone with more experience on an aircraft like the B-4?

You had probably just barely reached flying speed. When you deflect an
aileron, it increases the effective angle of attack of that wing. The
tip probably stalled, and since the other wing was still flying, the tip
you were trying to pick up, instead dropped to the ground. The lesson
you should learn from this is that until you are at a reasonable speed
(i.e., able to pick up the tail and roll on the mainwheel), use opposite
rudder to pick up a dropping wing tip, not aileron...

Marc

[Bill Daniels]

"Ted Wagner" > wrote in message
news:pI1Kb.17587$7D3.9225@fed1read02...
A few seconds into take-off roll today in a Pilatus B-4, while applying left
stick to correct for a dipping right wing, the right wing suddenly dipped
all the way into the ground. The glider lurched to the right, and a second
or two later popped up into the air, a good 20 feet up and 30 or more feet
out to the side. By that time I had full left rudder in addition to full
left aileron, so the glider recovered rather quickly, and I was able to
bring it to normal take-off position right about the time the tow plane
started to climb. I was amazed he had maintained his heading directly down
the runway. The winds were light and variable. It was my ninth flight on
the B-4.

After landing, the tow pilot apologized, saying it was his fault --
something about the wake turbulence. But I'm still puzzled about what, if
anything, he did wrong; it looked like a completely normally take-off roll
to me.

I had thought that maybe a sudden tail wind had reversed the effective
correction of my aileron deflection during take-off, causing the right wing
to dip harder instead of leveling off. Does this make sense to anyone with
more experience on an aircraft like the B-4?

Also, I'm curious to know how much the CG hook location on the B-4
contributed to the squirrelly sequence of events after the right wingtip hit
the ground. How many 15+ meter gliders have CG-only hooks? Are such exciting
events more commonplace with CG hooks?

Other than the wobbly tows, I'm loving the B-4, it's the first 15-meter
single-seater ship I've flown, and the first with retractable gear...

~tw

It could have been a wake encounter. If there was a slight right crosswind,
the majority of the tug's prop blast would have drifted to the left and hit
the B-4's left wing, causing it to rise. I usually expect to encounter the
tug's wake after I have rolled about 2/3rds of the rope length. Sometimes
tuggies will advance the throttle more slowly in these conditions so as to
minimize the effect. That might be what your tug pilot was talking about.
I'm always ready to stuff in some fast downwind aileron at the wake
encounter.

As for the CG hook, well, it didn't help your situation. CG hooks aren't
much of a problem for airtow UNTIL you are way out of position and then
things can go really bad, really fast. I always remind myself before each
takeoff roll that this is a CG hook and to release if things start to go
bad. I won't accept a downwind takeoff with a CG hook.

I have done many training flights with pilots planning to fly a single
seater with a CG hook. The unfortunate result of many such flights is that
the trainee comes away thinking that airtow with a CG hook is no big thing.
It isn't a big thing -- until things get out of hand and most training
flights don't dare go there.

There's a BGA write-up on CG hooks and pitch-up incidents that should be
required reading for anyone contemplating airtow with a CG hook. Maybe one
of our British friends can provide a link to it.

Bill Daniels

[Andy Durbin]

"Ted Wagner" > wrote in message news:<pI1Kb.17587$7D3.9225@fed1read02>...
> A few seconds into take-off roll today in a Pilatus B-4, while applying
> left stick to correct for a dipping right wing, the right wing suddenly
> dipped all the way into the ground. The glider lurched to the right, and
> a second or two later popped up into the air, a good 20 feet up and 30
> or more feet out to the side.

>How many 15+ meter gliders have CG-only hooks? Are such
> exciting events more commonplace with CG hooks?
>
> Other than the wobbly tows, I'm loving the B-4, it's the first 15-meter
> single-seater ship I've flown, and the first with retractable gear...
>
> ~tw
>
> --

My 2 cents worth is that you should have used the 2 seconds to pull
the release before you left the ground. You may have been hit by a
thermal.

A cg hook will give less directional stability during the early part
of the takeoff roll, particulary in a cross wind, but should have no
influence on wing drop tendency.

I have flown the last 15 or so years with aerotow on a cg hook. My new
ASW-28 has forward and CG hooks but I have never used the forward
hook.

Andy (GY)

[Mike Borgelt]

On Sun, 4 Jan 2004 16:53:58 -0700, "Ted Wagner"
> wrote:

>A few seconds into take-off roll today in a Pilatus B-4, while applying left stick to correct for a dipping right wing, the right wing suddenly dipped all the way into the ground. The glider lurched to the right, and a second or two later popped up into the air, a good 20 feet up and 30 or more feet out to the side. By that time I had full left rudder in addition to full left aileron, so the glider recovered rather quickly, and I was able to bring it to normal take-off position right about the time the tow plane started to climb. I was amazed he had maintained his heading directly down the runway. The winds were light and variable. It was my ninth flight on the B-4.
>
>After landing, the tow pilot apologized, saying it was his fault -- something about the wake turbulence. But I'm still puzzled about what, if anything, he did wrong; it looked like a completely normally take-off roll to me.
>
>I had thought that maybe a sudden tail wind had reversed the effective correction of my aileron deflection during take-off, causing the right wing to dip harder instead of leveling off. Does this make sense to anyone with more experience on an aircraft like the B-4?
>
>Also, I'm curious to know how much the CG hook location on the B-4 contributed to the squirrelly sequence of events after the right wingtip hit the ground. How many 15+ meter gliders have CG-only hooks? Are such exciting events more commonplace with CG hooks?
>
>Other than the wobbly tows, I'm loving the B-4, it's the first 15-meter single-seater ship I've flown, and the first with retractable gear...
>
>~tw

How long was the rope?

Most of the towplane wake turbulence or whatever problems go away if
you use a 250 foot rope. Lots more time in the event of a pitch up and
less likely anyway due to lower energy in the wake turbulence.

I once saw three gliders damaged in one day at Waikerie(all unflyable
the next day) due to aero retrieves out of fields with short ropes and
nose hooks. Problem with a nose hook is that if things get out of hand
and you release they instantly get a lot worse.

Short ropes are deadly. It is the angle that counts. Longer rope =
smaller angle = recoverable situation. I find this so bleeding obvious
after observation, experience and thinking about it that if I was an
insurance company I'd refuse all claims for ground loops or towplane
upsets that used a shorter than 250 foot rope.

Anyway I gave up aerotowing and bought a TOP.

Mike Borgelt

[BTIZ]

we use a 200ft rope as standard.. we had 230ft ropes.. great for training..

160ft ropes really get your attention..

BT

"Mike Borgelt" > wrote in message
...
> On Sun, 4 Jan 2004 16:53:58 -0700, "Ted Wagner"
> > wrote:
>
> >A few seconds into take-off roll today in a Pilatus B-4, while applying
left stick to correct for a dipping right wing, the right wing suddenly
dipped all the way into the ground. The glider lurched to the right, and a
second or two later popped up into the air, a good 20 feet up and 30 or more
feet out to the side. By that time I had full left rudder in addition to
full left aileron, so the glider recovered rather quickly, and I was able to
bring it to normal take-off position right about the time the tow plane
started to climb. I was amazed he had maintained his heading directly down
the runway. The winds were light and variable. It was my ninth flight on
the B-4.
> >
> >After landing, the tow pilot apologized, saying it was his fault --
something about the wake turbulence. But I'm still puzzled about what, if
anything, he did wrong; it looked like a completely normally take-off roll
to me.
> >
> >I had thought that maybe a sudden tail wind had reversed the effective
correction of my aileron deflection during take-off, causing the right wing
to dip harder instead of leveling off. Does this make sense to anyone with
more experience on an aircraft like the B-4?
> >
> >Also, I'm curious to know how much the CG hook location on the B-4
contributed to the squirrelly sequence of events after the right wingtip hit
the ground. How many 15+ meter gliders have CG-only hooks? Are such exciting
events more commonplace with CG hooks?
> >
> >Other than the wobbly tows, I'm loving the B-4, it's the first 15-meter
single-seater ship I've flown, and the first with retractable gear...
> >
> >~tw
>
> How long was the rope?
>
> Most of the towplane wake turbulence or whatever problems go away if
> you use a 250 foot rope. Lots more time in the event of a pitch up and
> less likely anyway due to lower energy in the wake turbulence.
>
> I once saw three gliders damaged in one day at Waikerie(all unflyable
> the next day) due to aero retrieves out of fields with short ropes and
> nose hooks. Problem with a nose hook is that if things get out of hand
> and you release they instantly get a lot worse.
>
> Short ropes are deadly. It is the angle that counts. Longer rope =
> smaller angle = recoverable situation. I find this so bleeding obvious
> after observation, experience and thinking about it that if I was an
> insurance company I'd refuse all claims for ground loops or towplane
> upsets that used a shorter than 250 foot rope.
>
> Anyway I gave up aerotowing and bought a TOP.
>
> Mike Borgelt

[Peter Seddon]

"BTIZ" > wrote in message
news:HK7Kb.46875$m83.26542@fed1read01...
> we use a 200ft rope as standard.. we had 230ft ropes.. great for
training..
>
> 160ft ropes really get your attention..
>
> BT

The only bad take off I had in my Pilatus was at HusBos, it was downwind and
slightly cross, plus I was towed by a not very powerful Chipmonk. All other
takeoffs with our supercub are fine though these are all into wind as we
have three runways to play with. Its a great aircraft with few vices, and
can outclimb some newer glass ships.

Peter S

DLA
lakesgc.co.uk

[Ian Strachan]

In article >, Andy
Durbin > writes

snip

>I have flown the last 15 or so years with aerotow on a cg hook. My new
>ASW-28 has forward and CG hooks but I have never used the forward
>hook.

What you have been doing in your ASW-28 would not be allowed at Lasham
and many other clubs (or if I were towing you!). If you have a forward
hook (often called the air tow hook), at most gliding organisations with
which I have been associated, you must use it for air tows except for
well-controlled exercises to show the difference. A true CG hook
position is for winch launching.

Normally, if both hooks are fitted the rear one will be "really rear"
because the manufacturer will assume that it will only be used for winch
or auto-tow. What does it say in your flight manual?

If only one hook is fitted then it will be somewhat forward of the pure
"C of G" position because its location is a compromise for both air tow
and winch and it will be tested for both before the initial C of A is
given for the type.

The reason not to use a CG hook for air tows if a front hook is
available is not so much directional stability while on the ground, but
the potentially much more dangerous "tug upset" which can, and has,
killed tug pilots in the past.

I think that the tug pitch-upset situation has been extensively covered
before on this newsgroup. If the glider becomes high enough behind the
tug, the tow pilot pulls back on the stick to counter the nose-down
pitch and can run out of back-stick. The tug's tailplane (horizontal
stabilizer) can then stall, leading to a sharp and uncontrollable steep
nose-down pitch which, if near the ground (say 600 ft or less) is often
fatal for the tug pilot.

We have had such fatals in the UK at both Lasham, Dunstable and
elsewhere, hence the universal use of nose hooks for air towing where
such a hook is fitted to the glider.

There was even a debate within the BGA after the last UK fatal tug
upset, on whether gliders with only a CG hook should be allowed to be
air towed at all. The upshot was the present situation combined with
careful briefing and air tow practice concentrating on sitting close on
top of the tug slipstream and never getting high. Tug pilots watch the
rear-view mirror very carefully at and after takeoff and I am quite
willing to dump anyone who gets really high, particularly close to the
ground.

Finally, on rope length I agree with Mike Borgelt. The longer the rope
the easier an air tow is to fly in the glider. Last year I had a tow in
Poland in a Puchatz at their Zar mountain soaring centre on a VERY short
rope, and flying the tow was "very active". The field at Zar is a
respectable length so I do not know why they insist on using such short
ropes. The only reason for a short rope that I can think of is to tow
out of a VERY short field, and in my view even that is questionable, if
the field is THAT short it may not be safe to tow out of anyway.
Finally, Lasham make up air tow ropes to be 50m long (164 ft). From
memory, the BGA minimum tow rope length recommendation is 150 ft.

Andy, I really suggest that you start using your air tow (front) hook
when you take an air tow !

--
Ian Strachan
Lasham Tow Pilot

[Wojciech Scigala]

05-01-2004 06:46, BTIZ:

> we use a 200ft rope as standard.. we had 230ft ropes.. great for training..
> 160ft ropes really get your attention..
In Poland 200ft ropes are used for training, but pilots prefer shorter,
130ft ropes. For tows in very turbulent air (like tows for wave flying)
the ropes are even 60ft long.

Longer ropes gives more time for reaction to tug's turns, but shorter
ones are less springy, which makes easier to maintain steady speed
during tow. Especially if the tug is not so powerful.

--
Wojtus'.net __|__
FidoNet: 2:484/47 `--------o--------'

[W.J. \(Bill\) Dean \(U.K.\).]

There is an article in the archives of Gliding & Motorgliding International
on Aerotow "Upset" Accidents by Chris Rollings which may be found at:
http://www.glidingmagazine.com/ListFeatureArticleDtl.asp?id=327 .
All tug pilots, and glider pilots who launch by aerotow, should read this
article.

For the U.K. the B.G.A. give advice to be found in "Laws and Rules for
Glider Pilots" 14th edition June 2003 (cannot be read on-line):

Under "Recommended Practices":

RP12. The minimum length of aerowtow rope recommended is 150ft. However,
under special circumstances a short rope may be used. The operators'
attention is drawn to the following factors which may cumulatively
contribute to a hazardous situation:

(a) Low experience of glider and/or tug pilot
(b) Gliders fitted with C of G hook only
(c) Glider's C of G towards the aft limit
(d) Turbulent air in the take-off area
(e) Rough ground in the take-off area
(f) Significant cross-wind component.

RP13. After releasing the cable, the glider should turn away so that the
tug aircraft pilot can see clearly that the glider is free.

Under "Operational Regulations":

4.16 The sum of tows made by the tug pilot and the glider pilot, in their
respective capacities, shall not be less than six.

My own opinion is that if a forward aerotow hook is fitted it should always
be used for aerotowing. If the glider does not have an aerotow hook, but
can be fitted with one as a modification then this should be done if it is
to be launched by aerotow.

It is quite normal for tug pilots to refuse to launch a glider if the rope
is on the aft hook when an aerotow hook is available.

I cannot think of any circumstance when the use of the forward hook rather
than the aft one for aerotow launching could cause a problem.

The longer the rope the easier the flying is for the glider pilot (except
perhaps in violent rotor?). The 150 ft rope is a compromise between safety
and operational convenience which has been found to be satisfactory in
practice in the U.K.

The above BGA recommendations and my opinions are based on the assumption
that the glider pilot has been properly trained and checked for currency
etc. The requirements etc. are to be found in the BGA Instructors' Manual
(which is not available to be read on-line).

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.

>
> "Bill Daniels" > wrote in message
> hlink.net...
>
> <snip>
>
> There's a BGA write-up on CG hooks and pitch-up incidents that should be
> required reading for anyone contemplating airtow with a CG hook. Maybe
> one of our British friends can provide a link to it.
>
> Bill Daniels
>

[K.P. Termaat]

If I am well informed in Germany CG hooks are not allowed for airtow
anymore.
The exception is that if your glider does not have a nose hook, you may use
the CG hook provided that you can show that you made at least six airtows in
the last three month prior to this occasion (or wordings like this).

Karel, NL



"Ian Strachan" > schreef in bericht
...
> In article >, Andy
> Durbin > writes
>
> snip
>
> >I have flown the last 15 or so years with aerotow on a cg hook. My new
> >ASW-28 has forward and CG hooks but I have never used the forward
> >hook.
>
> What you have been doing in your ASW-28 would not be allowed at Lasham
> and many other clubs (or if I were towing you!). If you have a forward
> hook (often called the air tow hook), at most gliding organisations with
> which I have been associated, you must use it for air tows except for
> well-controlled exercises to show the difference. A true CG hook
> position is for winch launching.
>
> Normally, if both hooks are fitted the rear one will be "really rear"
> because the manufacturer will assume that it will only be used for winch
> or auto-tow. What does it say in your flight manual?
>
> If only one hook is fitted then it will be somewhat forward of the pure
> "C of G" position because its location is a compromise for both air tow
> and winch and it will be tested for both before the initial C of A is
> given for the type.
>
> The reason not to use a CG hook for air tows if a front hook is
> available is not so much directional stability while on the ground, but
> the potentially much more dangerous "tug upset" which can, and has,
> killed tug pilots in the past.
>
> I think that the tug pitch-upset situation has been extensively covered
> before on this newsgroup. If the glider becomes high enough behind the
> tug, the tow pilot pulls back on the stick to counter the nose-down
> pitch and can run out of back-stick. The tug's tailplane (horizontal
> stabilizer) can then stall, leading to a sharp and uncontrollable steep
> nose-down pitch which, if near the ground (say 600 ft or less) is often
> fatal for the tug pilot.
>
> We have had such fatals in the UK at both Lasham, Dunstable and
> elsewhere, hence the universal use of nose hooks for air towing where
> such a hook is fitted to the glider.
>
> There was even a debate within the BGA after the last UK fatal tug
> upset, on whether gliders with only a CG hook should be allowed to be
> air towed at all. The upshot was the present situation combined with
> careful briefing and air tow practice concentrating on sitting close on
> top of the tug slipstream and never getting high. Tug pilots watch the
> rear-view mirror very carefully at and after takeoff and I am quite
> willing to dump anyone who gets really high, particularly close to the
> ground.
>
> Finally, on rope length I agree with Mike Borgelt. The longer the rope
> the easier an air tow is to fly in the glider. Last year I had a tow in
> Poland in a Puchatz at their Zar mountain soaring centre on a VERY short
> rope, and flying the tow was "very active". The field at Zar is a
> respectable length so I do not know why they insist on using such short
> ropes. The only reason for a short rope that I can think of is to tow
> out of a VERY short field, and in my view even that is questionable, if
> the field is THAT short it may not be safe to tow out of anyway.
> Finally, Lasham make up air tow ropes to be 50m long (164 ft). From
> memory, the BGA minimum tow rope length recommendation is 150 ft.
>
> Andy, I really suggest that you start using your air tow (front) hook
> when you take an air tow !
>
> --
> Ian Strachan
> Lasham Tow Pilot
>
>

[Greg Arnold]

Ian Strachan wrote:

>
> Andy, I really suggest that you start using your air tow (front) hook
> when you take an air tow !

I presume you can have an upset incident even with a nosehook. Are
there any statistics that show the safety advantage of a nose hook
compared to a CG hook?

Greg Arnold
330 aerotows with CG hooks, and never any problems except when taking
off without a wing runner

[Andy Durbin]

Ian Strachan > wrote in message >

big snip, but all noted

> Andy, I really suggest that you start using your air tow (front) hook
> when you take an air tow !

I knew this would get a reply from someone. I am aware of the
conditions of the LBA certification for the ASW 28 and also aware that
BGA has prohibited, or discouraged, import of gliders that don't have
a forward hook for aerotow.

A Schleicher agent advised me not to buy the forward hook option. I
chose to have it fitted because I didn't want any risk that FAA would
grant an airworthiness certificate for aerotow. LBA certification
prohibits the use of CG hook for aerotow but I don't believe my FAA
experimental airworthiness certification has such a limitation.

I use the ASW 28 cg hook for 2 reasons:

1. With over 1500 hours in the ASW 19 I am very familiar with aero tow
with CG hooks. (the CG hook on both gliders is just forward of the
main wheel inside the gear doors)

2. The forward hook is a poor design which is difficult to hook up and
poorly sealed.


Andy (GY)

[Ian Strachan]

In article >, Andy
Durbin > writes

snip

>LBA certification
>prohibits the use of CG hook for aerotow

Does not that tell you something, then?

>1. With over 1500 hours in the ASW 19 I am very familiar with aero tow
>with CG hooks.

So I have no doubt also thought the glider pilots who got out of
position and killed the tug pilot.

Just do not come to my club and expect to tow on your aft hook, or
anywhere where I am towing. I would have thought where life-and-death
was concerned you could be a tad more humble about your undoubted
handling abilities. But perhaps unlike the rest of us, you never have
an off-day ......

--
Ian Strachan

[John Giddy]

"W.J. (Bill) Dean (U.K.)." > wrote in
message ...
| There is an article in the archives of Gliding &
Motorgliding International
| on Aerotow "Upset" Accidents by Chris Rollings which may
be found at:
|
http://www.glidingmagazine.com/ListFeatureArticleDtl.asp?id=327 .
| All tug pilots, and glider pilots who launch by aerotow,
should read this
| article.
|
| For the U.K. the B.G.A. give advice to be found in "Laws
and Rules for
| Glider Pilots" 14th edition June 2003 (cannot be read
on-line):
|
| Under "Recommended Practices":
|
| RP12. The minimum length of aerowtow rope recommended is
150ft. However,
| under special circumstances a short rope may be used.
The operators'
| attention is drawn to the following factors which may
cumulatively
| contribute to a hazardous situation:
|
| (a) Low experience of glider and/or tug pilot
| (b) Gliders fitted with C of G hook only
| (c) Glider's C of G towards the aft limit
| (d) Turbulent air in the take-off area
| (e) Rough ground in the take-off area
| (f) Significant cross-wind component.
|
| RP13. After releasing the cable, the glider should turn
away so that the
| tug aircraft pilot can see clearly that the glider is
free.
|
| Under "Operational Regulations":
|
| 4.16 The sum of tows made by the tug pilot and the
glider pilot, in their
| respective capacities, shall not be less than six.
|
| My own opinion is that if a forward aerotow hook is fitted
it should always
| be used for aerotowing. If the glider does not have an
aerotow hook, but
| can be fitted with one as a modification then this should
be done if it is
| to be launched by aerotow.
|
| It is quite normal for tug pilots to refuse to launch a
glider if the rope
| is on the aft hook when an aerotow hook is available.
|
| I cannot think of any circumstance when the use of the
forward hook rather
| than the aft one for aerotow launching could cause a
problem.
|
| The longer the rope the easier the flying is for the
glider pilot (except
| perhaps in violent rotor?). The 150 ft rope is a
compromise between safety
| and operational convenience which has been found to be
satisfactory in
| practice in the U.K.
|
| The above BGA recommendations and my opinions are based on
the assumption
| that the glider pilot has been properly trained and
checked for currency
| etc. The requirements etc. are to be found in the BGA
Instructors' Manual
| (which is not available to be read on-line).
|
| W.J. (Bill) Dean (U.K.).
| Remove "ic" to reply.

In Australia, all new gliders and any gliders which change
ownership must be fitted with a nose hook if aero tow is to
be used. C of A not valid otherwise.
John G.

[Eric Greenwell]

Andy Durbin wrote:

> I use the ASW 28 cg hook for 2 reasons:
>
> 1. With over 1500 hours in the ASW 19 I am very familiar with aero tow
> with CG hooks. (the CG hook on both gliders is just forward of the
> main wheel inside the gear doors)

I also had 1000+ hours on my ASW 20 CG hook (and another 600 on other
gliders) when I had a forward hook installed.
>
> 2. The forward hook is a poor design which is difficult to hook up

True, but I noticed each line person knew how to do it the second time
they hooked me up, and no one complained.

> and
> poorly sealed.

Not that bad, but I did spend an hour one day sealing against air
instrusion (for winter flying) when I had the seat pan out for an annual.

Why go to any trouble at all? I found the forward hook (about 1 to 2
feet back from the nose) was better in a crosswind, better if the wing
runner was clumsy, better if I got distracted on tow, better in rough
air, and I never ran over the tow rope, which happened once in a while
with the CG hook.

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Tom Seim]

> Finally, on rope length I agree with Mike Borgelt. The longer the rope
> the easier an air tow is to fly in the glider. Last year I had a tow in
> Poland in a Puchatz at their Zar mountain soaring centre on a VERY short
> rope, and flying the tow was "very active". The field at Zar is a
> respectable length so I do not know why they insist on using such short
> ropes. The only reason for a short rope that I can think of is to tow
> out of a VERY short field, and in my view even that is questionable, if
> the field is THAT short it may not be safe to tow out of anyway.
> Finally, Lasham make up air tow ropes to be 50m long (164 ft). From
> memory, the BGA minimum tow rope length recommendation is 150 ft.
>

I, too, have been towed by a short rope (10M!) in Poland; but only out
of a dirt field. Mind you, getting towed out of a soft dirt field is,
by itself, a new experience (in the States we would say "go get your
trailer", but in Poland, do as the Poles do. The tow pilot, who spoke
very little English, said "Rope OK?". I figured the guy had to have
his reasons, hopefully not to make me look silly, so I said: "Rope
OK". A short rope on a runway would be intimidating enough, but we are
talking about a soft plowed field! With the help of a bunch of Polish
children (they showed up every time I landed out) I positioned the
glider (Jantar Std III) on the hardest furrow in the field. After some
instruction by the tow pilot to the oldest child on how to hold the
wing (one hand in the back pocket) we were ready to go.
The tow plane was a 9 cylinder radial tail dragger Yak (lots of
power!). The first thing that happened was that one of the amin gear
dug in, causing the tow plane to veer that direction. Of course, I
followed (so much for the hard furrow theory. Then the other wheel
would dug in and we would go that direction. This ment that I would
bounce over from furrow to furrow. At the same time, my gear would dug
in, increasing tow tension until the gear pulled out. This would pull
me violently unto my nose, which would cause me to bounce back onto
the tail, which would bounce me back onto the nose and back onto the
tail. At the same time one of the wing tips would drag into the dirt.
At least 10 times I told myself this was just too intolerable and I
should release; but each time I said (to myslef) I would hang on for
just one more second, and if it didn't improve then I would release.
Throughout this whole experience our speed was increasing, which was
both good and bad. Good: we needed speed to fly. Bad: the jolts got
more violent. Finally, I saw the tow plane go airborne. This was great
except for one thing: I was still on the ground! Hanging on, I felt my
main clear the dirt. But I could hear (yes, hear), the tail dragging
through the ground. Then the noise stopped: I was airborne!
Once airborne you might think that your troubles were over: wrong! At
that distance you can see ever rivet of the tow plane. You are totally
concentrating on following every little movement of the tow plane,
especially the wing waggle (tow release). Because after they waggle
their wings they do a split-S to go after the next glider! Sure
enough, he waggled his wings and I released. Now, where is the
airfield (it has to be close, doesn't it)? The airfield is a square km
of grass, which happens to look like every other farm in the area! I
started looking for another field to land in. Then I spotted the
airfield, to my great relief.
BTW, why the short rope? Simple: on take off I always had clear
visibility; if the long rope had been used the dust from the prop wash
would have made me IFR.

[Ray Payne]

ASW 27B is only certificated for aerotow operation when the forward tow
release is used!

[Ray Payne]

ASW 27 flight manual 4.4.1.2. states,THE SAILPLANE IS ONLY CERTIFICATED FOR=20
AEROTOW OPERATION WHEN THE FORWARD TOW RELEASE IS USED, now i know we all us=
ed=20
to tow from belly hooks years ago, but think on , if you aerotow from the c/=
g=20
hook on ASWs with forward hooks you are flying an uncertified glider and may=
be=20
not be insured, big risk for a =A350,000 glider,and what about the tug pilot=
!

[Mike Borgelt]

So does any one have an actual list of tug upset accidents with
towplane type, glider type and circumstances?
Just off hand I can't remember any in Australia and yes even when you
use low tow the upset possibility exists after liftoff and before
transition to low tow.
We've had plenty of towplane/glider midairs which makes existence as
a tow pilot 10 times as likely to kill you as cropdusting per hour.

Mike Borgelt

[Andy Durbin]

Ian Strachan > wrote in message >...
> In article >, Andy
> Durbin > writes
>
> snip
>
> >LBA certification
> >prohibits the use of CG hook for aerotow
>
> Does not that tell you something, then?
>
> >1. With over 1500 hours in the ASW 19 I am very familiar with aero tow
> >with CG hooks.
>
> So I have no doubt also thought the glider pilots who got out of
> position and killed the tug pilot.


If you have data on those accidents I would be interested in seeing
it. I used to be a tug pilot (2 USA clubs and 1 UK club). The only
tug pilot fatalities I am familiar with that resulted from glider
being too high did not involve a cg hook.

>
> Just do not come to my club and expect to tow on your aft hook, or
> anywhere where I am towing. I would have thought where life-and-death
> was concerned you could be a tad more humble about your undoubted
> handling abilities. But perhaps unlike the rest of us, you never have
> an off-day ......

One of the reasons I included the forward hook in my order was the
slim chance that I would return to UK.


What should I do with my ASW 19? I had planned to transition my low
time wife to it but perhaps the risks are just too great. Is there an
approved forward hook modification?


Andy (GY)

[Andy Durbin]

Eric Greenwell > wrote in message >...

>I found the forward hook (about 1 to 2
> feet back from the nose) was better in a crosswind, better if the wing
> runner was clumsy, better if I got distracted on tow, better in rough
> air, and I never ran over the tow rope, which happened once in a while
> with the CG hook.

Thanks for that feedback. I'll try it next tow.

When you say it was better in those respects are you comparing your 26
on forward hook to your 26 on cg hook or with your 20 on cg hook.


Andy (GY)

[Andy Durbin]

Eric Greenwell > wrote in message >...

> I also had 1000+ hours on my ASW 20 CG hook (and another 600 on other
> gliders) when I had a forward hook installed.


Sorry, I read this too quickly before I posted the first reply. I now
realize that you modified your 20 and were not comparing with the 26.
Perhaps you could send me more info on the mod. I may want to do it
to my 19.


thanks


Andy (GY)

[Eric Greenwell]

Andy Durbin wrote:
> Eric Greenwell > wrote in message >...
>
>>I also had 1000+ hours on my ASW 20 CG hook (and another 600 on other
>>gliders) when I had a forward hook installed.
>
> Sorry, I read this too quickly before I posted the first reply. I now
> realize that you modified your 20 and were not comparing with the 26.
> Perhaps you could send me more info on the mod. I may want to do it
> to my 19.

When countries began requiring forward hooks for aero tow about 15 years
ago, Schleicher came out with retrofits for their gliders. I got the
pieces and instructions for doing this on my 20 from the Schleicher
dealer and had it installed. I assume the same is available for the 19.

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[W.J. \(Bill\) Dean \(U.K.\).]

There have been several fatal "aerotow upset" accidents in the U.K. where
it seems certain that towing on a hook intended for winch launching was a
factor.

These include:
Lasham new year 1963/4 Auster towing a Ka 6cr or Skylark 2 (I forget which),
Tug at Aboyne towing a Ka 6e,
Tugs (Super Cubs) towing K 18s at Portmoak and Dunstable (within a few
months of each other), this led to the tests by Chris Rollings, Verdun Luck
and Brian Spreckley at Booker see
http://www.glidingmagazine.com/ListFeatureArticleDtl.asp?id=327 .

Will that do, or how many others do you need?

Any glider which launches well on a cable using the aft launching hook, will
do the same behind a tug maybe killing the tug pilot in the process. If
you really think that the glider pilot can control or stop this process once
it starts, READ THE ARTICLE LINKED ABOVE; I suggest that the pilots who
conducted those tests were more experienced, more current and just plain
better than you.

To my certain knowledge it is possible to fit a forward hook for aerotow to
the ASW 15, 17, ASK 18, ASW 19, 20, and 22 and the Pegase; the ASK 21 and 23
and I think later types were fitted with it as standard. I don't know of
any examples of these in club (as distinct from private owner) use which
have not been modified.

I think you would be very wise to have your ASW 19 fitted with the approved
forward hook modification before your wife flies it on aerotow.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.

>
> "Andy Durbin" > wrote in message
> om...
>
> >
> > Ian Strachan > wrote in message
> > >...
> >
> > >
> > > In article >, Andy
> > > Durbin > writes
> > >
> > > <snip>
> > >
> > > LBA certification
> > > prohibits the use of CG hook for aerotow
> > >
> >
> > Does not that tell you something, then?
> >
> > >
> > > 1. With over 1500 hours in the ASW 19 I am very familiar with aero tow
> > > with CG hooks.
> > >
> >
> > So I have no doubt also thought the glider pilots who got out of
> > position and killed the tug pilot.
> >
>
> If you have data on those accidents I would be interested in seeing
> it. I used to be a tug pilot (2 USA clubs and 1 UK club). The only
> tug pilot fatalities I am familiar with that resulted from glider
> being too high did not involve a cg hook.
>
> >
> > Just do not come to my club and expect to tow on your aft hook, or
> > anywhere where I am towing. I would have thought where life-and-death
> > was concerned you could be a tad more humble about your undoubted
> > handling abilities. But perhaps unlike the rest of us, you never have
> > an off-day ......
> >
>
> One of the reasons I included the forward hook in my order was the
> slim chance that I would return to UK.
>
> What should I do with my ASW 19? I had planned to transition my low
> time wife to it but perhaps the risks are just too great. Is there an
> approved forward hook modification?
>
> Andy (GY)
>

[Mark James Boyd]

>In article >, Andy
>Durbin > writes
>
>>I have flown the last 15 or so years with aerotow on a cg hook. My new
>>ASW-28 has forward and CG hooks but I have never used the forward
>>hook.

First of all, if the manual says to not use the C.G. hook
for aerotow, I personally wouldn't try it, even once.
But that's just me.

Next, as a tow pilot, if I ever towed someone and found out
they used a CG hook not allowed by POH, I'd
have a lengthy discussion with the pilot. I'd explain why
I'm not interested in doing abnormal procedures without
being informed before the flight. I don't believe
I always must do everything recommended, but if I
decide not to, I MUST acknowledge that I am now a
test pilot, and have perhaps voided any insurance. I also
need to get the approval of anyone else put at greater risk
(a second pilot, the tug driver, etc.).

We had this happen when flying the Blanik L-13 without the
canopy. There was quite a bit of discussion and agreement
from all parties before doing this. In the end everything
worked out fine, but more importantly, everyone had input
and was comfortable that precautions and research had been
done. And boy was it FUN!

I would think glider CG might be an issue here.
In the past 15 years, you've flown using the CG hook of
a glider that has a certain CG and a certain, perhaps
fairly forward, loading. A new glider with a different
placement of the CG hook relative to the CG may
be a completely different ride. If you do try it, keep
meticulous records, and send a report to the manufacturer.
I bet they'd like to know, since maybe their test pilot
was too chicken to do it himself.

If you do decide to use the CG hook for an aerotow,
despite the voices here and the POH, at the very least
get the cooperation of the tow pilot, since it isn't just
you taking a risk. And if you can't find a towpilot to
agree, maybe that's a sign...

Another thought...is it possible to rig a towline in such a way
that it has TWO rings? So that one could release the nose
ring and then be on the belly ring? Could one then
launch (the super dangerous part) using the nose ring and
then release this and experiment using the belly ring up at
high altitude?

Hmmm...I guess not since they both release using the same
mechanism...but otherwise this seems to be a better way
to experiment than taking off on the CG hook.
I'd suspect that a factory test pilot who wanted to test both
hooks for aerotow might try something like this...with
two individual release knobs perhaps...

Of course all of this begs the question: if the glider
HAS a nose hook for aerotow, why not just use it? ;)
But that certainly wouldn't encourage a nice armchair
discussion, right?

[Martin Gregorie]

On 6 Jan 2004 05:38:04 -0800, (Andy Durbin)
wrote:

>What should I do with my ASW 19? I had planned to transition my low
>time wife to it but perhaps the risks are just too great. Is there an
>approved forward hook modification?
>
The only ones I've looked at in the UK (closely enough to count tow
hooks that is) have been fitted with both, so I'd always assumed that
was the norm.

Could there be a difference in factory spec between deliveries within
Europe and those to the US? That could make sense given the prevalence
of winching in Europe and its rarity on the US.


--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :

[Bob Kuykendall]

Some branches of this thread are starting to hot up. I call Godwin in four!

Bob K.

[Shawn Curry]

Bob Kuykendall wrote:
> Some branches of this thread are starting to hot up. I call Godwin in four!
>
> Bob K.
Yeah sure you would say that. What are you some kind of Naz....
He He Just kinding :-)

[John Galloway]

Our club lost a greatly respected, and still missed,
member in one of the accidents referred to in Bill
Dean's post. The visiting glider pilot 'winch launched'
on the aerotow run within the airfield with results
described in Chris Rolling's article.

I think that if that were to happen in the Scotland
now, and the glider involved had been towed by the
belly hook when a nose hook was available and mandated
for aerotow by the handbook, then manslaughter charges
would be inevitable - followed by civil action of the
part of the deceased's next of kin.

John Galloway

[Shawn Curry]

Shawn Curry wrote:

> Bob Kuykendall wrote:
>
>> Some branches of this thread are starting to hot up. I call Godwin in
>> four!
>>
>> Bob K.
>
> Yeah sure you would say that. What are you some kind of Naz....
> He He Just kinding :-)

Um, I mean kidding. The d and the n are sooo close, and my spell check
thinks "kinding" is a word.

[W.J. \(Bill\) Dean \(U.K.\).]

This is Double Dutch, a language I don't speak. Please give an English
translation.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.

>
> "Bob Kuykendall" > wrote in message
> om...
>
> Some branches of this thread are starting to hot up. I call Godwin in
> four!
>
> Bob K.
>

[John Giddy]

Mike,
There was a tug upset on takeoff in Tasmania a few years
ago. I don't remember the year, or other data. Sorry.
There must have been several in the more distant past to
cause GFA to mandate nose hooks for aero tow on new gliders
or those changing ownership. (Came in in the early 1980s I
think)
John G.

"Mike Borgelt" > wrote in
message ...
| So does any one have an actual list of tug upset accidents
with
| towplane type, glider type and circumstances?
| Just off hand I can't remember any in Australia and yes
even when you
| use low tow the upset possibility exists after liftoff and
before
| transition to low tow.
| We've had plenty of towplane/glider midairs which makes
existence as
| a tow pilot 10 times as likely to kill you as cropdusting
per hour.
|
| Mike Borgelt

[W.J. \(Bill\) Dean \(U.K.\).]

Schleicher used to fit what the customer wanted and was prepared to pay for.

I have seen an ASW 15 which had been delivered new to a club in France, and
later imported to the U.K., it had a forward hook for aerotow and no aft
hook for cable launching.

Many Schleicher single seaters were imported into the U.K. with only the aft
hook for cable launching, this hook was of course then used for aerotowing
as well.

When gliding in the U.K. had been alerted to the possible risks of
aerotowing using the aft cable launching hook, many privately owned gliders
were modified by fitting a forward aerotow hook, and I think this was
universal for club owned gliders.

Glasflugel with the Libelle got it right from the start by fitting both
hooks when it first appeared in 1965.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.

>
> "Martin Gregorie" > wrote in message
> ...
>
> >
> > On 6 Jan 2004 05:38:04 -0800, (Andy Durbin)
> > wrote:
> >
> > What should I do with my ASW 19? I had planned to transition my low
> > time wife to it but perhaps the risks are just too great. Is there an
> > approved forward hook modification?
> >
>
> The only ones I've looked at in the UK (closely enough to count tow
> hooks that is) have been fitted with both, so I'd always assumed that
> was the norm.
>
> Could there be a difference in factory spec between deliveries within
> Europe and those to the US? That could make sense given the prevalence
> of winching in Europe and its rarity on the US.
>
> martin@ : Martin Gregorie
> gregorie : Harlow, UK
> demon :
> co : Zappa fan & glider pilot
> uk :
>

[Andy Durbin]

"W.J. \(Bill\) Dean \(U.K.\)." > wrote in message >...

>If you really think that the glider pilot can control or stop this
process once
> it starts, READ THE ARTICLE LINKED ABOVE;

I don't think I ever suggested that, and I have read the article. My
reference to experience was related to the probability of the upset
happening not to the probability of recovering from it. BGA seems to
accept that allowing pilots to aerotow on CG hooks is an acceptable
risk if they have recent experience. I have recent experience, and by
flying the ASW 28 on the cg hook I maintained recent experience so I
could return to the ASW 19. Next season I'll use the forward hook.
After having this discusssion, not to do so would be tempting fate
more that I would like.

> I think you would be very wise to have your ASW 19 fitted with the approved
> forward hook modification before your wife flies it on aerotow.

I agree.


By now the original poster will probably have decided never to fly the
B4 again.


Andy (GY)

[Bill Daniels]

"W.J. (Bill) Dean (U.K.)." > wrote in message
...
> Schleicher used to fit what the customer wanted and was prepared to pay
for.
>
> I have seen an ASW 15 which had been delivered new to a club in France,
and
> later imported to the U.K., it had a forward hook for aerotow and no aft
> hook for cable launching.
>
> Many Schleicher single seaters were imported into the U.K. with only the
aft
> hook for cable launching, this hook was of course then used for aerotowing
> as well.
>
> When gliding in the U.K. had been alerted to the possible risks of
> aerotowing using the aft cable launching hook, many privately owned
gliders
> were modified by fitting a forward aerotow hook, and I think this was
> universal for club owned gliders.
>
> Glasflugel with the Libelle got it right from the start by fitting both
> hooks when it first appeared in 1965.
>
> W.J. (Bill) Dean (U.K.).
> Remove "ic" to reply.
>
> >
> > "Martin Gregorie" > wrote in message
> > ...
> >

Correct me if I'm wrong, but fatal tug upsets have happened even with nose
hooks and there is no CG hook only glider that can't be safely launched by
air tow - if flown a good pilot. Before we go overboard with the CG/nose
hook debate, lets place most of the blame for these accidents where it
belongs - on the glider pilot who can't fly a particular glider or launch
method safely.

Air tow with a CG hook requires more care than with a nose hook, but it can
be done safely if the glider pilot is properly trained and pays attention to
business.

In support of a tug pilot who insisted on pre-flight discussions, let me say
that this is a necessary part of the glider pilots training. I have always
had a pre-flight talk with the tuggie to let him (or her) know that, should
anything start to go amiss, the tug should release instantly. I then brief
my student that the safe "box" within which the glider must be flown is
smaller with a CG hook and that it will take more care to stay in that box.
Should he stray outside the box he should expect the tug to instantly
release the rope.

As an aside, while I read of pilots who have attempted a "winch" launch by
air tow, I have seen pilots accustomed to air tow simply fail to climb on
winch launches. From the back seat, I can easily imagine a cartoonists
thought bubble over the pilots head with a big question mark in it - as we
sail down the airfield at 2 meters AGL waiting for something to happen.

We all need to thoroughly think through what is about to happen as the rope
is attached to the glider.

Bill Daniels

[Andreas Maurer]

On Mon, 5 Jan 2004 21:58:53 +0000, Ian Strachan
> wrote:

>In article >, Andy
>Durbin > writes
>
>snip
>
>>LBA certification
>>prohibits the use of CG hook for aerotow
>
>Does not that tell you something, then?

Unfortunately the above is wrong.
LBA certification prohibits the use of the CG hook in these cases:

- no use of CG hook for aerotows of student pilots
- no use of the CG hook if a nose hook is available
- retro-fitting of nose hook NOT required.

- according to the Gliding Operation Handbook (SBO) of the German Aero
Club (DAeC) a pilot is required of doing at least three aerotows on a
nose hook before he can do aerotows on a glider equipped only with CG
hook.

....

Bye
Andreas

[Andreas Maurer]

On 6 Jan 2004 05:38:04 -0800, (Andy Durbin)
wrote:


>What should I do with my ASW 19? I had planned to transition my low
>time wife to it but perhaps the risks are just too great. Is there an
>approved forward hook modification?

Well... let me say it this way:

- if your wife has enough practice, she'll easily be able to do a safe
aerotow on the CG hook.
- in the begining of the year (with little practice), do a little
aerotow training on a nose hook ship (or even dual training)
- In my club there was not one situation in the last twenty years
where a glider climbed over the tow plane and lost sight. Not one.
Despite the fact that our DG-300 (40 hrs total required to fly it),
ASW-15/ASW-24 (70 hrs) and ASW-20 only had CG hooks.

The critical part is not the placement of the CG hook and the
resulting nose-up tendency - the problem is pilot training (this is
the cause why now these three aerotows on the nose hook are required).

Bye
Andreas

[Raphael Warshaw]

I've got a low serial number LAK-17a which came from the factory with only a
cg hook. Later, when a nosehook was made available in response to the LBA
directive, the factory stated that the nosehook could not be retrofitted.
So far, the only launch issue has been a tendency to drop a wing at the
start of the launch which I seem to have solved by starting the roll with
the flaps reflexed. Until seeing this thread, I hadn't given the hook
position much thought.

None of the tow pilots where I've flown have commented on it; in fact two
of them have flown the glider. I also don't recall any discussion about the
cg hook during the check-out when I flew a club Pilatus a few years ago.

There doesn't seem to be any unusual tendency for the ship to pitch up on
tow and it seems to follow the towplane reasonably well. I haven't towed
through serious rotor yet, but it seems to behave well on tow in rough
conditions.

How concerned should I be about this? I have no desire to harm a tow pilot
or myself, but I don't want to undertake a major modification to the ship if
it isn't necessary. Any other Lak-17a pilots out there with a cg hook and
an opinion?

Ray Warshaw
1LK



"Bill Daniels" > wrote in message
...
>
> "W.J. (Bill) Dean (U.K.)." > wrote in message
> ...
> > Schleicher used to fit what the customer wanted and was prepared to pay
> for.
> >
> > I have seen an ASW 15 which had been delivered new to a club in France,
> and
> > later imported to the U.K., it had a forward hook for aerotow and no aft
> > hook for cable launching.
> >
> > Many Schleicher single seaters were imported into the U.K. with only the
> aft
> > hook for cable launching, this hook was of course then used for
aerotowing
> > as well.
> >
> > When gliding in the U.K. had been alerted to the possible risks of
> > aerotowing using the aft cable launching hook, many privately owned
> glide
> > were modified by fitting a forward aerotow hook, and I think this was
> > universal for club owned gliders.
> >
> > Glasflugel with the Libelle got it right from the start by fitting both
> > hooks when it first appeared in 1965.
> >
> > W.J. (Bill) Dean (U.K.).
> > Remove "ic" to reply.
> >
> > >
> > > "Martin Gregorie" > wrote in message
> > > ...
> > >
>
> Correct me if I'm wrong, but fatal tug upsets have happened even with nose
> hooks and there is no CG hook only glider that can't be safely launched by
> air tow - if flown a good pilot. Before we go overboard with the CG/nose
> hook debate, lets place most of the blame for these accidents where it
> belongs - on the glider pilot who can't fly a particular glider or launch
> method safely.
>
> Air tow with a CG hook requires more care than with a nose hook, but it
can
> be done safely if the glider pilot is properly trained and pays attention
to
> business.
>
> In support of a tug pilot who insisted on pre-flight discussions, let me
say
> that this is a necessary part of the glider pilots training. I have
always
> had a pre-flight talk with the tuggie to let him (or her) know that,
should
> anything start to go amiss, the tug should release instantly. I then
brief
> my student that the safe "box" within which the glider must be flown is
> smaller with a CG hook and that it will take more care to stay in that
box.
> Should he stray outside the box he should expect the tug to instantly
> release the rope.
>
> As an aside, while I read of pilots who have attempted a "winch" launch by
> air tow, I have seen pilots accustomed to air tow simply fail to climb on
> winch launches. From the back seat, I can easily imagine a cartoonists
> thought bubble over the pilots head with a big question mark in it - as
we
> sail down the airfield at 2 meters AGL waiting for something to happen.
>
> We all need to thoroughly think through what is about to happen as the
rope
> is attached to the glider.
>
> Bill Daniels
>

[Andreas Maurer]

On 6 Jan 2004 12:41:34 -0700, (Mark James Boyd)
wrote:


>First of all, if the manual says to not use the C.G. hook
>for aerotow, I personally wouldn't try it, even once.
>But that's just me.

In the case of the 28 it's not a question of danger: Hundreds of 24's
(which has only a different wing, but identical fuselage, CG and tail)
are flying with CG hook only.

But what do you do with a glider like our ASW-27?
If only a CG hook is installed (yes, there are at least 150 27's
flying like this), it's fully certified for aerotow on the CG hook.
Since the new rules came out, all new 27's have a nose hook installed
and therefore this one MUST be used for aerotow.

Does the installed nose hook suddenly make the aerotow on the CG hook
dangerous?

(Consequence: Many owners of new 27's removed the nose hook).

The same goes for nearly all current gliders that were previously
built with only a CG hook and which are currently produced with a nose
hook.

>A new glider with a different
>placement of the CG hook relative to the CG may
>be a completely different ride. If you do try it, keep
>meticulous records, and send a report to the manufacturer.
>I bet they'd like to know, since maybe their test pilot
>was too chicken to do it himself.

If a CG hook is certified, the manufacturer has tested it for all
possible CG's.

>Another thought...is it possible to rig a towline in such a way
>that it has TWO rings? So that one could release the nose
>ring and then be on the belly ring? Could one then
>launch (the super dangerous part) using the nose ring and
>then release this and experiment using the belly ring up at
>high altitude?

Why would anyone do that?
The disadvantages of a nose hook is that it oftern creates significant
noise, draft, a little drag, costs money to build and to maintain.
Inflight it's nice to have.


>Of course all of this begs the question: if the glider
>HAS a nose hook for aerotow, why not just use it? ;)

See above.. :)
I admit that I've covered the nose hook with tape to get rid of the
noise and the draft when I was flying on very cold days - Schleicher
screwed up the design in my opinion.

An aerotow on the nose hook is probably less prone to pull the
towplane's tail up - but so far I have not seen one single accident
(!) statistic that could prove this point. I guess that by today
enough gliders with a nose hook should be in duty to see if the nose
hook really make a difference concerning accident rates.

The only information that I've seen so far is the Idaflieg flight test
that demonstrated that a gloder on a nose hook takes a lot more effort
and time to pull the tail of the tow plane up.

Bye
Andreas

[Andreas Maurer]

On 6 Jan 2004 08:21:29 GMT, Ray Payne >
wrote:

>ASW 27B is only certificated for aerotow operation when the forward tow
>release is used!

This is correct.
And an ASW-27 where no nose hook is installed is certified for aerotow
operation on the CG hook. :)

Bye
Andreas

[Stewart Kissel]

I got a question for any mate from OZ. IIRC low tows
are mandatory done there. So how does that work with
a CG hook?

[Chris OCallaghan]

Ted,

It's tough to say what the real cause of your upset was, but goodness
knows we're going to try.

Your tow pilot makes a good point, and one you should take to heart.
Before your next take off, note a physical feature on the runway where
the tow plane starts its take off roll. Most tow pilots apply full
power immediately. Since the tow plane is moving slowly at this point,
it is generating a good bit of turbulence that you are going to have
to negotiate at less than flying speed and probably well below a speed
where your controls will have anything close to full authority. Tail
draggers like the B4 are especially prone to upset at this point. As I
roll toward the tow plane start point, I try to anticipate the upset
(almost always a drop of the right wing) and catch it as it starts
rather than letting it catch me unawares.

The B4 has an especially strong elevator. If you get out of sorts, you
have to be extra careful not to over control. PIOs are common in the
model, especially during the first few aerotows.

[Mark James Boyd]

>On 6 Jan 2004 12:41:34 -0700, (Mark James Boyd)
>wrote:
>
>
>>First of all, if the manual says to not use the C.G. hook
>>for aerotow, I personally wouldn't try it, even once.
>>But that's just me.
>
>
>But what do you do with a glider like our ASW-27?
>If only a CG hook is installed (yes, there are at least 150 27's
>flying like this), it's fully certified for aerotow on the CG hook.
>Since the new rules came out, all new 27's have a nose hook installed
>and therefore this one MUST be used for aerotow.
>
>Does the installed nose hook suddenly make the aerotow on the CG hook
>dangerous?
>

OK, be prepared for me to completely change my tune. Are you guys
telling me the manual says that if it has only a CG hook, you can
aerotow with it, but if both hooks are present, the manual
prohibits aerotow on the CG hook for the ASW-27? And the
W&B limits and CG hook locations are identical for both
gliders?

If THIS is the case, a certainly can't argue with those
who see it as a simple paper shuffle. But I'd also say that in
this case a factory test pilot has surely flown that exact type of glider
with the CG hook in the exact position and flown it aerotow
that way. This means anyone who does it is NOT therefore a
test pilot.

Sounds like removing the nose hook just to "legally" aerotow
off the CG hook is a ridiculous paper shuffle hassle...
And yes, I did read the reasons why one might want to remove it.
Hmmm...so much for the manual, eh?

[Marc Ramsey]

I probably should resist the urge to jump in on this thread, but what
the heck. I've made several hundred aerotows using CG hook only
equipped gliders, and have had exactly 3 incidents which might have been
avoided with a nose hook. Two were my first flights in newly purchased
gliders, where I guessed wrong about the takeoff trim position, got
quite high on takeoff, but managed to recover with full forward stick.
The other time I got sideways early in the ground roll with half water,
released, and got stopped before going too far off the runway.

Being the skeptical sort, I went to the US National Transportation
Safety Board site, and did a query for all reports of accidents during
the past 20 years with the words "tow" and "glider" in them. This
yielded 280 hits. I eliminated those accidents that happened after safe
release, where there was a mechanical failure (disconnected controls,
etc.), where one of the pilots was likely to be impaired (heart attack,
etc.), or where the glider ran off the side of the runway early in the
takeoff roll. This left 17 accidents. Of those, 8 gliders (two
probably with CG hook, one more possible) had large pitch excursions on
takeoff, were released and subsequently crashed without damage to the
towplane.

That left 9 in which a glider high and out of position pulled up the
tail of the towplane causing it to crash. Of these, 3 very likely had
CG hooks (Std Cirrus, Open Cirrus, Ka-6E), 2 likely had nose hooks
(G103C and 1-26), and the remainder either the glider type was not
stated, or may have had either type of hook (Twin Astir).

The thing that struck me about these accidents was how many of them were
due to the pilot fiddling with an open canopy, or inadvertently deployed
spoilers. If the pilots simply payed attention to flying the aircraft,
most of the above would never have happened. The other thing that is
clear is that those freakin' Schweizer towplane hooks are a menace to
tow pilots, and *should* be banned.

These statistics don't suggest to me that we should prohibit aerotow of
CG hook only gliders in the US. A significant proportion of the single
seat gliders here only have CG hooks, as some of the European
manufacturers charged a fairly hefty premium to put in a nose hook until
recently (if they offered them at all), and, well, a lot of glider
pilots are kind of cheap.

As for the other side of the Atlantic, it would be interesting to see
some actual statistics...

Marc

[Andreas Maurer]

On 6 Jan 2004 20:01:17 -0700, (Mark James Boyd)
wrote:

>OK, be prepared for me to completely change my tune. Are you guys
>telling me the manual says that if it has only a CG hook, you can
>aerotow with it, but if both hooks are present, the manual
>prohibits aerotow on the CG hook for the ASW-27? And the
>W&B limits and CG hook locations are identical for both
>gliders?

Exactly.
The early 27's (as well as 24's, and probably all other glides that
are currently being produced in Germany) were only equipped with a CG
hook.
We retro-fitted one of our two DG-300's with a nose hook in order to
make it flyable for student pilots again who had been flying it safely
in aerotow the year before, but suddenly were forbidden to aerotow it
due to the new rules that demanded a nose hook for student pilots.


>Sounds like removing the nose hook just to "legally" aerotow
>off the CG hook is a ridiculous paper shuffle hassle...

More or less. If the nose hook was installed when the ship was
delivered, it must stay installed (yet some pilots seem to have found
an agreement with their inspector to remove the nose hook).

>And yes, I did read the reasons why one might want to remove it.
>Hmmm...so much for the manual, eh?

More or less.
The fact is undisputed that the nose hook indeed makes aerotows a
little easier and safer, therefore a nose hook definitely is an
improvement... but this does not mean that a CG hook per se is unsafe.

Bye
Andreas

[Eric Greenwell]

Marc Ramsey wrote:

> That left 9 in which a glider high and out of position pulled up the
> tail of the towplane causing it to crash. Of these, 3 very likely had
> CG hooks (Std Cirrus, Open Cirrus, Ka-6E), 2 likely had nose hooks
> (G103C and 1-26), and the remainder either the glider type was not
> stated, or may have had either type of hook (Twin Astir).

Very interesting numbers. Too bad we don't know what proportion of
launches are nose-hook or CG hook, then we could see if one was
over-represented.
>
> The thing that struck me about these accidents was how many of them were
> due to the pilot fiddling with an open canopy, or inadvertently deployed
> spoilers. If the pilots simply payed attention to flying the aircraft,
> most of the above would never have happened. The other thing that is
> clear is that those freakin' Schweizer towplane hooks are a menace to
> tow pilots, and *should* be banned.

Amen.

> These statistics don't suggest to me that we should prohibit aerotow of
> CG hook only gliders in the US. A significant proportion of the single
> seat gliders here only have CG hooks, as some of the European
> manufacturers charged a fairly hefty premium to put in a nose hook until
> recently (if they offered them at all), and, well, a lot of glider
> pilots are kind of cheap.

The US might have less trouble with CG hooks than a country where aero
tow isn't as common.

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Marc Ramsey]

Chris Rollings wrote:
> I am a staunch defender of anyone's right to risk his
> or her own life in pursuit of any goal they hold dear
> (including saving money). In launching on a C og G
> hook you are risking the tow-pilots life more than
> your own, and this I will not defend.

I personally prefer to fly aerotow with nose hooks, and both of the
gliders I now fly have them. But, I'm not convinced that anyone has
provided actual evidence of an observed safety issue with CG hooks.
Some numbers like these for, say, the past 20 years in the UK:

How many aerotow operations were there per year?
What percentage of aerotow operations used CG hooks?
How many aerotow upset accidents were there during that period?
What percentage of the aerotow upset accidents involved CG hooks?

If these figures aren't available, is the use of CG hooks being
discouraged based simply on the assumed lack of positive longitudinal
stability during aerotow?

Marc

[Ian Johnston]

On Wed, 7 Jan 2004 03:01:17 UTC, (Mark James
Boyd) wrote:

: Are you guys
: telling me the manual says that if it has only a CG hook, you can
: aerotow with it, but if both hooks are present, the manual
: prohibits aerotow on the CG hook for the ASW-27?

Under what circumstances would one tow with a CG hook when a nose hook
was available?

Ian
--

[Dave Martin]

At 09:18 07 January 2004, Marc Ramsey wrote:
>Chris Rollings wrote:
>> In launching on a C og G
>> hook you are risking the tow-pilots life more than
>> your own, and this I will not defend.
>
>> Marc Ramsey wrote
>> I personally prefer to fly aerotow with nose hooks,
>>and
>> both of the gliders I now fly have them. But, I'm
>>not
>> convinced that anyone has provided actual evidence
>>of an
>> observed safety issue with CG hooks.

>> Some numbers like these for, say, the past 20 years
>>in the UK:

>How many aerotow operations were there per year?
>What percentage of aerotow operations used CG hooks?
>How many aerotow upset accidents were there during
>that period?
>What percentage of the aerotow upset accidents involved
>CG hooks?
>
>If these figures aren't available, is the use of CG
>hooks being
>discouraged based simply on the assumed lack of positive
>longitudinal
>stability during aerotow?
>
>Marc

I hate to agree with Chris Rollings but he sums it
up quite well.

The questions posed by Marc Ramsey, difficult to obtain
that no one will even try, so they will not get answered.

Whatever we write here, I cannot see the owners of
C of G only aircraft rushing out to retrofit a nose
hook. Having towed on both, the worst being an Olympia
2B with only a C of G hook and a powerful tug, I prefer
the nose hook every time.

Some years ago, mid 1908’s I believe, the Australian
Gliding Association, following a number of tug upsets
produced a very graphic illustration showing the various
stages of a tug being upset by a glider on tow, wherever
the hook. It clearly and simply illustrated the difficulties
this caused the pilots at each end of the combination.


C of G hooks merely increase the likely hood of this
happening with an inattentive pilot.

The short answer is educating the pilots on the particular
hook to be used and hammering home the consequences
of inattention to all.

The Australian poster should be displayed at all gliding
sites.

To try to answer the question that started this thread,
the B4 pilots problems could be solved by asking the
tug to accelerate a little faster from the start, having
due regard to the problems this may cause. IE Things
may go wrong even quicker!

Dave

[K.P. Termaat]

Flying a Pik-20D some years ago I had to be very cautious in airtows because
the glider:
- had a large tendency of dropping the left wing at low speed (angle of
attack problem because of the large wheel and short fuselage)
- had a large tendency of dropping the right wing because of prop wash
- was quite unstable in pitch during the tow because of the quite backward
position of the CG hook, while no nose hooh available.
Nevertheless the towpilot and I survived very many tows without a serious
problem. However I would not go through this once more; just to risky that
something goes wrong.

After the Pik-20D I flew a DG800S 18m for about 10 years. Only a CG hook and
never a problem. Would do it again this way without hesitation.

Just recently we (my son and I) bought a Ventus-2cxT. Nice glider. My first
flight with it was on airtow. Used nosehook which we paid for seperately. No
tendency of dropping a wing. However very nervous on pitch during the tow.
Not a pleasure and was happy to release. I guess a novice would certainly
have had problems with it.

So one may say that each glider has its own way of being pulled into the
air. Being towed is certainly a safety issue. So I wonder why not everybody
concludes that for airtows nosehooks should be mandatory and CG hooks should
not be allowed. We are talking about money I guess. We spent many thousands
of euros on the glider itself and try to save some euros in not having a
nose hook installed and still like to take off in an airtow. To my humble
idea our lives and especially those of towpilots are to valuable to run an
additional risk of not using a nose hook in air tows.

Karel, NL



"W.J. (Bill) Dean (U.K.)." > schreef in bericht
...
> There have been several fatal "aerotow upset" accidents in the U.K. where
> it seems certain that towing on a hook intended for winch launching was a
> factor.
>
> These include:
> Lasham new year 1963/4 Auster towing a Ka 6cr or Skylark 2 (I forget
which),
> Tug at Aboyne towing a Ka 6e,
> Tugs (Super Cubs) towing K 18s at Portmoak and Dunstable (within a few
> months of each other), this led to the tests by Chris Rollings, Verdun
Luck
> and Brian Spreckley at Booker see
> http://www.glidingmagazine.com/ListFeatureArticleDtl.asp?id=327 .
>
> Will that do, or how many others do you need?
>
> Any glider which launches well on a cable using the aft launching hook,
will
> do the same behind a tug maybe killing the tug pilot in the process. If
> you really think that the glider pilot can control or stop this process
once
> it starts, READ THE ARTICLE LINKED ABOVE; I suggest that the pilots who
> conducted those tests were more experienced, more current and just plain
> better than you.
>
> To my certain knowledge it is possible to fit a forward hook for aerotow
to
> the ASW 15, 17, ASK 18, ASW 19, 20, and 22 and the Pegase; the ASK 21 and
23
> and I think later types were fitted with it as standard. I don't know of
> any examples of these in club (as distinct from private owner) use which
> have not been modified.
>
> I think you would be very wise to have your ASW 19 fitted with the
approved
> forward hook modification before your wife flies it on aerotow.
>
> W.J. (Bill) Dean (U.K.).
> Remove "ic" to reply.
>
> >
> > "Andy Durbin" > wrote in message
> > om...
> >
> > >
> > > Ian Strachan > wrote in message
> > > >...
> > >
> > > >
> > > > In article >, Andy
> > > > Durbin > writes
> > > >
> > > > <snip>
> > > >
> > > > LBA certification
> > > > prohibits the use of CG hook for aerotow
> > > >
> > >
> > > Does not that tell you something, then?
> > >
> > > >
> > > > 1. With over 1500 hours in the ASW 19 I am very familiar with aero
tow
> > > > with CG hooks.
> > > >
> > >
> > > So I have no doubt also thought the glider pilots who got out of
> > > position and killed the tug pilot.
> > >
> >
> > If you have data on those accidents I would be interested in seeing
> > it. I used to be a tug pilot (2 USA clubs and 1 UK club). The only
> > tug pilot fatalities I am familiar with that resulted from glider
> > being too high did not involve a cg hook.
> >
> > >
> > > Just do not come to my club and expect to tow on your aft hook, or
> > > anywhere where I am towing. I would have thought where
life-and-death
> > > was concerned you could be a tad more humble about your undoubted
> > > handling abilities. But perhaps unlike the rest of us, you never
have
> > > an off-day ......
> > >
> >
> > One of the reasons I included the forward hook in my order was the
> > slim chance that I would return to UK.
> >
> > What should I do with my ASW 19? I had planned to transition my low
> > time wife to it but perhaps the risks are just too great. Is there an
> > approved forward hook modification?
> >
> > Andy (GY)
> >
>
>
>

[Silent Flyer]

Chris Rollings > wrote in message
...

SNIP
> Let's look at the numbers. I will use the UK as an
> example, since I have a fairly accurate knowledge of
> the statistics there, but the pricipals are the same
> for any of the World's gliding nations.
SNIP

Chris

I learnt to fly at an all aerotow operation back in 1967 at the old
Leicestershire club at Rearsby. Training was on a Slingsby Capstan and
pupils were then sent solo in an Olympia 2b, (in my case after twenty seven
flights). These of course like virtually all gliders of that time had only
CoG hooks.

What do the accident statistics say when comparing that period with the
present day ?

Don Brown

[John Galloway]

Karel,

I think you may have paid the extra for the belly hook
not the nose hook. I am on the Schempp-Hirth waiting
list at present and when I enquired about the cost
of adding a nose hook I was told that all gliders had
the nose hook as standard and that the additional cost
option was for a belly hook. They would build a glider
with the belly hook only for no extra cost on special
request but it would be placarded as not certified
for aerotowing.

John Galloway

At 10:30 07 January 2004, K.P. Termaat wrote:
>Just recently we (my son and I) bought a Ventus-2cxT.
>Nice glider. My first
>flight with it was on airtow. Used nosehook which we
>paid for seperately. No
>tendency of dropping a wing. However very nervous on
>pitch during the tow.
>Not a pleasure and was happy to release. I guess a
>novice would certainly
>have had problems with it.
>
>So one may say that each glider has its own way of
>being pulled into the
>air. Being towed is certainly a safety issue. So I
>wonder why not everybody
>concludes that for airtows nosehooks should be mandatory
>and CG hooks should
>not be allowed. We are talking about money I guess.
>We spent many thousands
>of euros on the glider itself and try to save some
>euros in not having a
>nose hook installed and still like to take off in an
>airtow. To my humble
>idea our lives and especially those of towpilots are
>to valuable to run an
>additional risk of not using a nose hook in air tows.
>
>Karel, NL
>
>
>

[K.P. Termaat]

Yes John, you are right.
I looked through the papers and found that the belly hook is the option
indeed. So SH does it it in the right way and tries to convince pilots to
use the nose hook when on an airtow. Probably the LBA has forced them to do
so.

Karel, NL

"John Galloway" k>
schreef in bericht ...
> Karel,
>
> I think you may have paid the extra for the belly hook
> not the nose hook. I am on the Schempp-Hirth waiting
> list at present and when I enquired about the cost
> of adding a nose hook I was told that all gliders had
> the nose hook as standard and that the additional cost
> option was for a belly hook. They would build a glider
> with the belly hook only for no extra cost on special
> request but it would be placarded as not certified
> for aerotowing.
>
> John Galloway
>
> At 10:30 07 January 2004, K.P. Termaat wrote:
> >Just recently we (my son and I) bought a Ventus-2cxT.
> >Nice glider. My first
> >flight with it was on airtow. Used nosehook which we
> >paid for seperately. No
> >tendency of dropping a wing. However very nervous on
> >pitch during the tow.
> >Not a pleasure and was happy to release. I guess a
> >novice would certainly
> >have had problems with it.
> >
> >So one may say that each glider has its own way of
> >being pulled into the
> >air. Being towed is certainly a safety issue. So I
> >wonder why not everybody
> >concludes that for airtows nosehooks should be mandatory
> >and CG hooks should
> >not be allowed. We are talking about money I guess.
> >We spent many thousands
> >of euros on the glider itself and try to save some
> >euros in not having a
> >nose hook installed and still like to take off in an
> >airtow. To my humble
> >idea our lives and especially those of towpilots are
> >to valuable to run an
> >additional risk of not using a nose hook in air tows.
> >
> >Karel, NL
> >
> >
> >
>
>
>

[Chris OCallaghan]

Chris,

It's very hard to argue with your point of view. There is absolutely
no doubt that a nose hook should always be preferred to a cg hook
during aerotow for safety reasons. As you note, resistance to
regulatory change on this issue is based on cost. Retrofitting a
glider designed with only a cg hook will be high. And as is often the
case, a balance must be found between cost and improved safety. Which
gets to my point. You've offered an overview of why individual,
anecdotal experience should not be trusted, but you've given us
nothing quantitative to work with. Can you show that PIO related (as
opposed to control failure) aerotow take-off accidents involved a
disproportionate number of gliders with cg hooks? What is the current
ratio of such use among launched glider (not the whole fleet, but
those flying actively)? What is the cost of retrofitting an LS-4 or
Discus or other appropiate model?

I'll reemphasize that we're in agreement regarding the preference for
a nose hook, but if you are going to discount our collective
experiece, give us some real numbers.

[Andy Durbin]

Andreas Maurer > wrote in message >...
> On Mon, 5 Jan 2004 21:58:53 +0000, Ian Strachan
> > wrote:
>
> >In article >, Andy
> >Durbin > writes
> >
> >snip
> >
> >>LBA certification
> >>prohibits the use of CG hook for aerotow
> >
> >Does not that tell you something, then?
>
> Unfortunately the above is wrong.
> LBA certification prohibits the use of the CG hook in these cases:
>
> - no use of CG hook for aerotows of student pilots
> - no use of the CG hook if a nose hook is available
> - retro-fitting of nose hook NOT required.
>
> - according to the Gliding Operation Handbook (SBO) of the German Aero
> Club (DAeC) a pilot is required of doing at least three aerotows on a
> nose hook before he can do aerotows on a glider equipped only with CG
> hook.
>
> ...
>
> Bye
> Andreas


Hi Andreas,

The initial statement is correct because it was with reference to *my*
ASW 28 which I chose to have fitted with both books. (clause 2 of your
reply).

Andy (GY)

[Ian Strachan]

In article >, Andreas Maurer
> writes
>On 6 Jan 2004 08:21:29 GMT, Ray Payne >
>wrote:
>
>>ASW 27B is only certificated for aerotow operation when the forward tow
>>release is used!
>
>This is correct.
>And an ASW-27 where no nose hook is installed is certified for aerotow
>operation on the CG hook. :)

A point I made in an earlier contribution to this thread seems to be
being missed but I think is important. That is, where a glider has two
hooks, the rear hook can be placed close to the true C of G position.
With only one hook, the position will normally be somewhat forward of
the C of G position and will be a compromise rather than a true C of G
hook.

In other postings people talk generally about "CG hooks" without making
the above distinction, which could be critical to handling on the
launch. "Belly hook" might be a better term, and many will not be true C
of G positions unless a nose-hook is also fitted.

--------------------

In more detail:

<<Gliders with only one tow hook:>>

The hook will be under the belly rather than in the nose, so that it can
be used for both winch/auto tow AND air tow.

Test and certification. The hook will be tested for both wire and air
tow launches before the initial C of A is granted for the design.
Testing will be at a number of glider C of G positions, the most
critical being the aft CG case because it is the least longitudinally
stable.

The hook is unlikely to be aft enough to be strictly a "C of G"
position, so that natural longitudinal stability while on air tow is
maintained. This is rightly a certification requirement.

During a winch or auto tow launch, a positive pull force will be needed
to keep the right climb angle. With some gliders this pull force can be
quite high, but at least is safe in the sense that if the cable breaks,
the nose falls quickly as soon as back-pressure on the stick is relaxed.


<<Gliders with two tow hooks:>>

Front hook, for air tows. Straightforward. Better longitudinal
stability while on tow, more directional stability before takeoff. Less
tendency for a "tug upset". Better all round for air tow.

Winching on a nose-hook. One of my early clubs (RAF Swinderby, near
Lincoln, UK) had an old Cadet Mark 1 glider which only had a nose hook.
It also had no instruments! We used to winch launch it and were lucky
to get 600 feet. The back-pressure on the stick to get even this low
height, was considerable. How did we know that it was 600 ft? The CFI
borrowed an altimeter from the RAF Instrument Section and we carried it
in a pocket, consulting it when off the wire. Those were the days !

Rear hook.
Because there is a front hook, the rear hook can be placed close to the
true C of G position. That is, where the vector of the pull of the wire
during the main part of a winch or auto-tow passes close to the glider C
of G. This minimises the hard pull force otherwise necessary to climb on
a wire launch, and maximises the launch height.

Flight Manual and Testing. Such a hook may not be included in the
flight manual conditions for air tow and may not have been tested on air
tow during initial certification testing.

Back pressure during launch. During a winch launch there should be a
pull force, but not a large one.

At aft CG, little if any pull force may be needed on the winch and such
a condition can even be neutrally stable longitudinally (relax stick
pressure during the launch and the pitch angle hardly changes). Under
these conditions it is easy to climb too steeply and break the wire,
particularly with a heavy glider. Answer, look sideways at the angle
that a wing is cutting the horizon to judge pitch angle. At aft CG it
is easy to enter a spin, so careful handling is needed on cable break
recovery.

--
Ian Strachan
Lasham, UK

[Andy Durbin]

Chris Rollings > wrote in message >...
> Under JAR 22 (Glider Certification Rules), a glider
> is required to have postive (or at least neutral) longitudinal
> stability. Put simply, if you move the nose up (or
> down) a bit and then leave it alone, it should tend
> to move back towards where it started from, or at least
> stay where it is, not continue to pitch further up
> (or down).
>
> It is quite possible (easy in most cases) to learn
> to handle a glider that does not have this stability,
> but it requires CONSTANT vigilance on the part of the
> pilot. A failure in concentration of only one or two
> seconds can result in a massive divergence of the flight
> path with catastrophic consequences.

Both my ASW 19 and my ASW 28 exhibit positive pitch stability for
small disturbances when aero towed on the cg hook. Both gliders will
fly hands off on aerotow for several seconds and will return to the
trimmed pitch attitude following small upsets.

You tests on kiting used very large pitch upsets and they were
determined to be unrecoverable. Was any testing done to determine the
largest recoverable pitch upset?

Now that most gliders in UK have both aerotow and CG hooks, is there
any intention to repeat the test series to compare the characteristics
of the same glider with each hook?


Andy

[Eric Greenwell]

Todd Pattist wrote:

> Of course, despite those comments, we also experience too
> many towing accidents. The CG hook can be implicated in more
> than the kiting accidents, and I know several pilots who
> have purchased or retrofitted the nose hook after a loss of
> directional control during the initial roll on a CG hook
> aerotow launch.

That is exactly what prompted me to have a nose hook installed; I mean,
as long as it was in the shop anyway, getting the damage from the loss
of directional control fixed...

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Mark Zivley]

If someone can afford the cost of a new glider, it isn't going to break
them to pay for BOTH nose and CG hooks. I don't see why SH (or any
other manufacturer) would waste the time with "options" on this subject.
And it's good for re-sale since you never know where a glider may go next.

Mark

K.P. Termaat wrote:
> Yes John, you are right.
> I looked through the papers and found that the belly hook is the option
> indeed. So SH does it it in the right way and tries to convince pilots to
> use the nose hook when on an airtow. Probably the LBA has forced them to do
> so.
>
> Karel, NL
>
> "John Galloway" k>
> schreef in bericht ...
>
>>Karel,
>>
>>I think you may have paid the extra for the belly hook
>>not the nose hook. I am on the Schempp-Hirth waiting
>>list at present and when I enquired about the cost
>>of adding a nose hook I was told that all gliders had
>>the nose hook as standard and that the additional cost
>>option was for a belly hook. They would build a glider
>>with the belly hook only for no extra cost on special
>>request but it would be placarded as not certified
>>for aerotowing.
>>
>>John Galloway
>>
>>At 10:30 07 January 2004, K.P. Termaat wrote:
>>
>>>Just recently we (my son and I) bought a Ventus-2cxT.
>>>Nice glider. My first
>>>flight with it was on airtow. Used nosehook which we
>>>paid for seperately. No
>>>tendency of dropping a wing. However very nervous on
>>>pitch during the tow.
>>>Not a pleasure and was happy to release. I guess a
>>>novice would certainly
>>>have had problems with it.
>>>
>>>So one may say that each glider has its own way of
>>>being pulled into the
>>>air. Being towed is certainly a safety issue. So I
>>>wonder why not everybody
>>>concludes that for airtows nosehooks should be mandatory
>>>and CG hooks should
>>>not be allowed. We are talking about money I guess.
>>>We spent many thousands
>>>of euros on the glider itself and try to save some
>>>euros in not having a
>>>nose hook installed and still like to take off in an
>>>airtow. To my humble
>>>idea our lives and especially those of towpilots are
>>>to valuable to run an
>>>additional risk of not using a nose hook in air tows.
>>>
>>>Karel, NL
>>>
>>>
>>>
>>
>>
>>
>
>

[Bill Daniels]

I've noticed that, on many gliders, both the CG and nose hooks can produce
wind noise. I tape over the hook not in use to make it quiet and keep dirt
out of it.

Bill Daniels

"Mark Zivley" > wrote in message
m...
> If someone can afford the cost of a new glider, it isn't going to break
> them to pay for BOTH nose and CG hooks. I don't see why SH (or any
> other manufacturer) would waste the time with "options" on this subject.
> And it's good for re-sale since you never know where a glider may go
next.
>
> Mark
>
> K.P. Termaat wrote:
> > Yes John, you are right.
> > I looked through the papers and found that the belly hook is the option
> > indeed. So SH does it it in the right way and tries to convince pilots
to
> > use the nose hook when on an airtow. Probably the LBA has forced them to
do
> > so.
> >
> > Karel, NL
> >
> > "John Galloway" k>
> > schreef in bericht ...
> >
> >>Karel,
> >>
> >>I think you may have paid the extra for the belly hook
> >>not the nose hook. I am on the Schempp-Hirth waiting
> >>list at present and when I enquired about the cost
> >>of adding a nose hook I was told that all gliders had
> >>the nose hook as standard and that the additional cost
> >>option was for a belly hook. They would build a glider
> >>with the belly hook only for no extra cost on special
> >>request but it would be placarded as not certified
> >>for aerotowing.
> >>
> >>John Galloway
> >>
> >>At 10:30 07 January 2004, K.P. Termaat wrote:
> >>
> >>>Just recently we (my son and I) bought a Ventus-2cxT.
> >>>Nice glider. My first
> >>>flight with it was on airtow. Used nosehook which we
> >>>paid for seperately. No
> >>>tendency of dropping a wing. However very nervous on
> >>>pitch during the tow.
> >>>Not a pleasure and was happy to release. I guess a
> >>>novice would certainly
> >>>have had problems with it.
> >>>
> >>>So one may say that each glider has its own way of
> >>>being pulled into the
> >>>air. Being towed is certainly a safety issue. So I
> >>>wonder why not everybody
> >>>concludes that for airtows nosehooks should be mandatory
> >>>and CG hooks should
> >>>not be allowed. We are talking about money I guess.
> >>>We spent many thousands
> >>>of euros on the glider itself and try to save some
> >>>euros in not having a
> >>>nose hook installed and still like to take off in an
> >>>airtow. To my humble
> >>>idea our lives and especially those of towpilots are
> >>>to valuable to run an
> >>>additional risk of not using a nose hook in air tows.
> >>>
> >>>Karel, NL
> >>>
> >>>
> >>>
> >>
> >>
> >>
> >
> >
>

[Chris OCallaghan]

I just read the referenced article, and while its conclusions are
disturbing -- primarily the release failure of the tow plane's
Schweizer hook -- the experiment itself was not well conducted.

First and foremost, identical circumstances were not created to test
the difference between nose hook and cg hook. The K-13 with nose hook
was taken "progressively higher..." while the same aircraft with cg
hook was "pitched up."

As noted in an earlier post, I think all of us are in agreement that a
nose hook is (qualitatively) a safer proposition, but if you're going
to raise an alarm, it should be valid and proportionate.

Chris Rollings has presented us with a compelling demonstration of
what can happen during aerotow. The conclusions based on outcomes for
the two release types, since the maneuvers were not identical, has
been exptrapolated and are weighted to some degree by the knowledge
that the nose hook is preferred. A good next step would be to repeat
the experiment, this time putting emphasis on measuring the loads and
effects of identical maneuvers using a nose vs. cg hook.

In the absence of valid statistical or empirical evidence, it's hard
to determine just how critical this problem is. I think most of us are
willing to spend dollars on our well-being, but we'd like to know that
we are, in fact, purchasing something of value. If the record shows
that we're simply buying better handling as opposed to a measurable
increase in safety, then we are looking at a much different
proposition.

Point of reference, I only have a nose hook in my Ventus 2. I am
perfectly content to aerotow gliders with a cg hook if there is no
other choice. And frankly, I'd rather aerotow on a cg hook that winch
launch, which I consider an unreasonable comprimise to safety. It's
all a matter of what you're used to. No tow plane? let's unwind the
winch. But the risk to reward equation is becoming less attractive.

[Bob Kuykendall]

[Apologies if this is a double-post - Google seemed to have lost the
first one. This version is shorter and more to the point anyway.]

Earlier, Ian Strachan wrote:

> ... If only one hook is fitted then it
> will be somewhat forward of the pure
> "C of G" position because its location
> is a compromise for both air tow
> and winch and it will be tested for
> both before the initial C of A is
> given for the type.

From the perspective of an amateur sailplane developer:

That might have been true some time ago. However, increased demand for
better performance have made such compromises less tenable in the last
generation or two of sailplane.

The way I understand it, there are only two good locations for a tow
hitch: At the stagnation point on the nose of the glider, and aft of
the point of maximum thickness of the fuselage.

With the tow hitch buried in the nose vent at the stagnation point,
there is no particular disruption to the airflow, and you can
reasonably expect to get laminar flow over most of the forward
fuselage. At least, until the air encounters a disruption such as a
canopy separation line or passes the point of maximum thickness and
encounters an adverse pressure gradient.

With the to hitch located aft of the point of maximum thickness, the
airfow will already have tripped over into turbulent flow, and the
extra drag of that flow encountering the tow hitch will be minimal.

However, with the hitch located in the "compromise" area as Ian
suggests, it will almost certainly disrupt the laminar flow there, and
trip it over into draggier turbulent flow. Furthermore, the area of
turbulence will spread laterally at about a 7-degree angle aft of the
disruption. So you end up with a triangular patch of turbulent flow on
the belly with an included angle of about 14 degrees. That means extra
drag and poorer performance.

My own next glider will have a nose hook in the air vent duct at the
stagnation point on the nose of the glider, and a mounting location
for an optional CG hook that will be covered by the landing gear
doors.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24

[Greg Arnold]

Marc Ramsey wrote:


>
> If these figures aren't available, is the use of CG hooks being
> discouraged based simply on the assumed lack of positive longitudinal
> stability during aerotow?


Is the pull on a CG hook during aerotow ever great enough to have much
effect on the longitudinal stability of the glider? I have never
noticed such an effect, so I wonder if pilots who fly from a winch (very
quick acceleration and doubtless a significant effect on longitudinal
stability) are unfairly extrapolating their experience there to the
aerotow situation.

Doubtless a nose hook is better for aerotow, but I wonder if the alleged
advantages aren't being oversold by some posters to this thread.

[Bill Daniels]

"Chris OCallaghan" > wrote in message
om...

Snip-------------
> Point of reference, I only have a nose hook in my Ventus 2. I am
> perfectly content to aerotow gliders with a cg hook if there is no
> other choice. And frankly, I'd rather aerotow on a cg hook that winch
> launch, which I consider an unreasonable comprimise to safety. It's
> all a matter of what you're used to. No tow plane? let's unwind the
> winch. But the risk to reward equation is becoming less attractive.

Hmmm. After this harrowing discussion of the hazards of airtow, you would
think a winch might seem safer by comparison.

Bill Daniels
(Scared many times on airtow, but never on a winch.)

[Greg Arnold]

Greg Arnold wrote:

> Marc Ramsey wrote:
>
>
>>
>> If these figures aren't available, is the use of CG hooks being
>> discouraged based simply on the assumed lack of positive longitudinal
>> stability during aerotow?
>
>
>
> Is the pull on a CG hook during aerotow ever great enough to have much
> effect on the longitudinal stability of the glider? I have never
> noticed such an effect, so I wonder if pilots who fly from a winch (very
> quick acceleration and doubtless a significant effect on longitudinal
> stability) are unfairly extrapolating their experience there to the
> aerotow situation.
>
> Doubtless a nose hook is better for aerotow, but I wonder if the alleged
> advantages aren't being oversold by some posters to this thread.


Following up on my own post -- during aerotow, acceleration is greatest
at the beginning of the takeoff run, where airspeed is low. By the
time that airspeed gets to the point where the glider can fly,
acceleration is minimal. So the pull on the tow line shouldn't have
much effect on longitudinal stability when the glider is near takeoff speed.

I am sure that a glider with a CG hook will be inclined to climb more
steeply once it has a high angle of attack -- this is due to the pivot
point being further aft on the glider. However, in the initial stages
of going to that high angle of attack, does it matter whether the glider
has a CG hook or a nose hook? It is that initial stage that causes
problems on aerotow. Once a glider achieves a high angle of attack, the
towplane is well past the point of no return.

[Chris Nicholas]

I am not a sufficiently expert statistician to be certain, but I think
the UK data leads to two conclusions about tug upset fatal accidents:

1. There have been too few such fatalities - I think about 6-10 over 30
years - to draw conclusions with a high probablility of being certain of
the correlation - and I can't stipulate how "high" is high;

2. Notwithstanding 1. above, as far as I know 100 percent of UK tug
upset fatal accidents in the last 30 years happened with belly hooks. We
changed our procedures and recommendations before we could gather more
data and satisfy statistical pedants with some more fatalities which
might have improved the correlation calculations. Since the changes,
fatal tug upsets have almost entirely disappeared from the UK fatal
accident reports.

There have been tugging accidents other than upsets, with nose hooks as
well as belly hooks, but these do not affect such inferences as one can
draw from 1 and 2 above.

By the way, I fly mostly a Ka6E with a belly hook. I am very careful
not to kill my friends who tug, being all too well aware of the danger.
One of the changes was to alter our preferred tow position, as has been
referred to by others, to only just above the prop wash - termed the
"low High-tow" position, IIRC. Before the changes, we normally kept the
glider at or slightly above the tug height once established on tow.

Chris N.

[Andy Durbin]

Ian Strachan > wrote in message >...
>
> A point I made in an earlier contribution to this thread seems to be
> being missed but I think is important. That is, where a glider has two
> hooks, the rear hook can be placed close to the true C of G position.
> With only one hook, the position will normally be somewhat forward of
> the C of G position and will be a compromise rather than a true C of G
> hook.
>
> In other postings people talk generally about "CG hooks" without making
> the above distinction, which could be critical to handling on the
> launch. "Belly hook" might be a better term, and many will not be true C
> of G positions unless a nose-hook is also fitted.


In a previous posting I stated that the CG hook on my ASW 28, and the
only hook on my ASW 19, are in the same place. They are both just
forward of the main gear and inside the gear doors. I think they
would both be considered to be true CG hooks even though they are
forward of the CG.

My ASW 28 also has a forward belly hook. If I had a nose hook I would
never have used the cg hook on the ASW 28 for aerotow. Nose hooks,
like exposed CG hooks, are usually easy to hook up and easy to inspect
for proper closure. The same is NOT true for the forward belly hook
fitted on the ASW 28 because it is concealed by a very stiff slotted
plastic cover.

Andy (GY)

[John Galloway]

Chris,

Your wasting your breath in this thread - just listen
and learn from the wise ones.

John Galloway

At 19:30 07 January 2004, Chris Nicholas wrote:
>I am not a sufficiently expert statistician to be certain,
>but I think
>the UK data leads to two conclusions about tug upset
>fatal accidents:
>
>1. There have been too few such fatalities - I think
>about 6-10 over 30
>years - to draw conclusions with a high probablility
>of being certain of
>the correlation - and I can't stipulate how 'high'
>is high;
>
>2. Notwithstanding 1. above, as far as I know 100
>percent of UK tug
>upset fatal accidents in the last 30 years happened
>with belly hooks. We
>changed our procedures and recommendations before we
>could gather more
>data and satisfy statistical pedants with some more
>fatalities which
>might have improved the correlation calculations.
>Since the changes,
>fatal tug upsets have almost entirely disappeared from
>the UK fatal
>accident reports.
>
>There have been tugging accidents other than upsets,
>with nose hooks as
>well as belly hooks, but these do not affect such inferences
>as one can
>draw from 1 and 2 above.
>
>By the way, I fly mostly a Ka6E with a belly hook.
> I am very careful
>not to kill my friends who tug, being all too well
>aware of the danger.
>One of the changes was to alter our preferred tow position,
>as has been
>referred to by others, to only just above the prop
>wash - termed the
>'low High-tow' position, IIRC. Before the changes,
>we normally kept the
>glider at or slightly above the tug height once established
>on tow.
>
>Chris N.
>
>
>
>
>
>
>

[Ian Strachan]

In article >, Andy
Durbin > writes
>Ian Strachan > wrote in message
>...
>>
>> A point I made in an earlier contribution to this thread seems to be
>> being missed but I think is important. That is, where a glider has two
>> hooks, the rear hook can be placed close to the true C of G position.
>> With only one hook, the position will normally be somewhat forward of
>> the C of G position and will be a compromise rather than a true C of G
>> hook.
>>
>> In other postings people talk generally about "CG hooks" without making
>> the above distinction, which could be critical to handling on the
>> launch. "Belly hook" might be a better term, and many will not be true C
>> of G positions unless a nose-hook is also fitted.
>
>
>In a previous posting I stated that the CG hook on my ASW 28, and the
>only hook on my ASW 19, are in the same place. They are both just
>forward of the main gear and inside the gear doors. I think they
>would both be considered to be true CG hooks even though they are
>forward of the CG.

When you say that "the hook is forward of CG" you seem to imply a static
measurement.

The static on-the-ground measurement of where the glider GC is with
respect to the belly hook position is not what matters. It is what
happens on a launch (dynamic, not static conditions). What matters is
the angle-of-pull of the cable with respect to the centre of motion and
control effectiveness of the glider in that dynamic launch situation.

If you measure where the CG is statically, that is, on the ground, and
placed a tow hook directly underneath it, I think that you would find
the subsequent launch pretty unstable either on winch or air tow.

--
Ian Strachan
Lasham, UK

[Mike Borgelt]

On Tue, 6 Jan 2004 18:39:17 -0000, "W.J. \(Bill\) Dean \(U.K.\)."
> wrote:

>There have been several fatal "aerotow upset" accidents in the U.K. where
>it seems certain that towing on a hook intended for winch launching was a
>factor.
>
>These include:
>Lasham new year 1963/4 Auster towing a Ka 6cr or Skylark 2 (I forget which),
>Tug at Aboyne towing a Ka 6e,
>Tugs (Super Cubs) towing K 18s at Portmoak and Dunstable (within a few
>months of each other), this led to the tests by Chris Rollings, Verdun Luck
>and Brian Spreckley at Booker see
>http://www.glidingmagazine.com/ListFeatureArticleDtl.asp?id=327 .
>
>Will that do, or how many others do you need?

So that is 4 in 40 years.

I think we've managed to kill that many towplane pilots in Aus in the
last 15 in mid airs. At least one, maybe more would have had a good
chance of survival if he had had a parachute. Something that still
isn't required here.

The common link with the upsets mentioned seems to be high wing wooden
gliders of low wing loading with deep fuselages. These may be prone to
pitch up.

How long were the ropes in these situations?

Were there other circumstances that contributed?

Could they have been compensated for?
>
>Any glider which launches well on a cable using the aft launching hook, will
>do the same behind a tug maybe killing the tug pilot in the process. If
>you really think that the glider pilot can control or stop this process once
>it starts, READ THE ARTICLE LINKED ABOVE; I suggest that the pilots who
>conducted those tests were more experienced, more current and just plain
>better than you.

You are suggesting that on a winch launch with much higher loads in
the cable that these gliders are not controllable in pitch?
>
>To my certain knowledge it is possible to fit a forward hook for aerotow to
>the ASW 15, 17, ASK 18, ASW 19, 20, and 22 and the Pegase; the ASK 21 and 23
>and I think later types were fitted with it as standard. I don't know of
>any examples of these in club (as distinct from private owner) use which
>have not been modified.

I once owned an ASW20B. The GFA required the nose hook to be fitted.
The Scheicher factory job on this was pitiful. Nobody who bought
gliders from this batch of 6 put up with it. The releases were taken
out and glassed over. When finishing the area it became apparent that
the skin had been distorted by the additional release bulkheads.
I don't ever recall the 20B having the slightest tendency to pitch up
on aerotow on the belly release.

I have no aversion to properly engineered nose hooks like in
Glasflugel and Schempp gliders but poorly designed retrofits are a bad
idea particularly when no testing has been done on that particular
type to see if indeed the "solution" is effective or even necessary.

The BGA considers 150 foot ropes acceptable. I consider these
dangerously short, 200 feet is more like it with around 240 to 260
being much better.

Now consider this::

The world's politicians and bureaucrats are forever looking for ways
to meddle in our lives to keep themselves in jobs. If we place
requirements on our own operations (Like compulsory nose releases)that
are not firmly founded in proper testing and rational analysis we
weaken our case in resisting the idiot requirements that come in a
never ending stream from these people.

I've yet to meet anyone who has flown on a 250 foot rope who hasn't
admitted it was easier than on shorter ropes. When I aerotow I want to
go soaring for maybe several hours and maybe the enviroment on the
ground was stressful due to heat, humidity etc. I really don't need a
5 minute adrenaline thrill to begin a cross country. I would like
tows to be a non event. Longer ropes and tow pilots who don't try to
thermal or do other sudden manouevers all aid in this.

The scariest tow I ever had was in my Salto (with nose release) behind
a tow pilot who was not paying attention and who pulled back hard on
leaving the ground as we encountered a gust leaving me dangling low
from the end of the rope with decreasing airspeed. Followed by a hard
push just as I was climbing slowly back up into station(low tow)
leaving me very high followed by another hard pull which put me very
low again wherupon I released and did a 180 back to the strip.
Probably my shortest ever aerotow flight, closest to disaster and on
the 130 foot or so ropes that were fashionable at the time. I never
ever want to do this again. It was 30 years ago and I remember it
clearly.
A rope twice as long likely would have made this a non event.

The surprisingly easy tows were at Minden in an ASW20(belly release)
through the rotor behind a 182. Long rope, no problem at all.

Mike Borgelt

[Bob Kuykendall]

Earlier, Mark Zivley > wrote:

> If someone can afford the cost of
> a new glider, it isn't going to break
> them to pay for BOTH nose and CG hooks.
> I don't see why SH (or any other
> manufacturer) would waste the time with
> "options" on this subject...

The issue here isn't getting the buyer to pay for both hooks. It's
getting them to pay _more_ for them. That's where the profit margin
is. :)

A year or so ago, I had the experience of observing a friend select
and purchase a brand-new European racer. Just about everything that
wasn't absolutely required was optional. Even the canopy sliding
window was "optional."

With that experience in mind, I'd say that the factories play the
"option" game for the same reason that car dealers do it: It's a
relatively easy way to make the basic price tag look attractive, while
increasing the profit margin on the typical sale. It's not at all a
time-waster, except perhaps for the purchaser.

For all the relatively high prices the factories charge for new
sailplanes, they are still operating on relatively slender profit
margins. Even high-production types are pretty much hand-built by
skilled workers using some pretty expensive materials. It's hard to
fault them for getting all the market will bear, any way they
reasonably can.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24

[Bill Daniels]

"Mike Borgelt" > wrote in message

Snip------
> I don't ever recall the 20B having the slightest tendency to pitch up
> on aerotow on the belly release.
Snip------
>
> Mike Borgelt

Mike, I have flown a number of different gliders on air tow using a CG hook.
None of them had a tendency to pitch-up either. My Nimbus 2C tows just fine
with a CG hook. Airtow with a CG hook isn't a problem -- as long as the tow
is flown normally.

It is after the glider gets seriously out of position that the problems
arise. With a CG hook, it is easier to get out of position through pilot
inattention, and once there, the situation can very quickly become
unrecoverable. It is difficult to believe how fast things can go from
seeming normal to horribly wrong unless you have been there and done that.
It is so dangerous that no instructor would deliberately subject a tow
pilot, a student and himself to it just for training.

I encountered this once more than 40 years ago. I was a young student
pilot flying a glider known for it's challenging flight characteristics. At
the time, no weaklinks were required in the 200 foot, 9/16" nylon rope.
Note that I don't claim that this would not have happened anyway with a nose
hook, but it wouldn't have happened as easily.

I was inattentive, lulled into complacency by the smooth air. Instead of
watching the tug, I was watching the scenery. Sudden G forces woke me up as
the glider soared above the tug and to the right. Both the gliders and the
tug's releases jammed under the stress. The tug dove to the left and
pulled me it into the dive after it.

It was only because the aerodynamically clean glider could outdive the tug
that the rope went slack and both releases functioned simultaneously. We
both landed safely, but I bought beer for that tug pilot for several years
afterward. Had this occurred under 1000 feet, we both would have died. I
never looked at air tow the same way again.

The concern about airtow with CG hooks is for a condition that lies well
outside the experience of 99% of glider pilots. If you airtow with a CG
hook, keep in mind that a dragon lurks outside the normal airtow box. Don't
go there.

Bill Daniels

[Mike Borgelt]

On Wed, 7 Jan 2004 19:06:40 -0700, "Bill Daniels" >
wrote:


>The concern about airtow with CG hooks is for a condition that lies well
>outside the experience of 99% of glider pilots. If you airtow with a CG
>hook, keep in mind that a dragon lurks outside the normal airtow box. Don't
>go there.
>
>Bill Daniels


I completely agree Bill.

I'm a long rope fan because the normal box is larger. In fact I think
it is not a linear function of rope length as the first 100 feet of
rope is probably counts for little due to pilot/sailplane
perception/reaction times.

There are other dragons which have happened in Oz. Get too low on low
tow, put a large bow in the rope and have it catch in the aileron/wing
gap. Good reason to have a weak link at *both* ends of the rope.

Having once done a cross country tow in low tow on a 130 foot rope and
then discovered that the towplane exhaust system was about to fall off
makes me not a low tow fan.

I worry about the "we've required nose tow releases so we've fixed
that problem" thinking. The problem didn't get fixed because nobody
had the gumption to require a retrofit on ALL gliders. Politically
impossible because when the chips were down it would be impossible to
justify. Instead just stick the owners of new gliders with the cost
because if they are buying a new glider they can afford it.

The LBA/BGA/GFA/insert your civil aviation bureaucracy name here
bureaucracy get to feel good because they have "improved" safety and
can boast about this, most of the glider pilots don't care one way or
the other as they are unaffected and tow pilots are at just as much
risk as before as the fleet replacement only occurs slowly. Great!

Requiring longer ropes would have been cheaper and would give
immediate benefits but here we are still thinking 150 feet is
adequate. Wonderful.

Meanwhile we've had one mid air on tow in Oz. One side benefit of 250
foot ropes is that you do have time to look around while on tow
instead of maintaining station with all your attention.

Anybody who hasn't towed on a 250 foot rope I suggest you try it. It
took one tow in 1982 for me to be a convert.

Meanwhile realise as the tow pilot opens the throttle that you are
potentially less than a minute from proving that youve thought about
the low altitude tow emergency enough to carry it out successfully.
It could be a rope break, engine failure or getting out of station or
any one or more of quite a number of other things. Tom Knauff had a
good article about this that I saw in Gliding Kiwi.

Mike Borgelt

[Chris Rollings]

The Australian Poster Dave refers to was actually line
drawings of the photo's taken of the tests I described.

Chris Rollings

At 10:30 07 January 2004, Dave Martin wrote:
>At 09:18 07 January 2004, Marc Ramsey wrote:
>>Chris Rollings wrote:
>>> In launching on a C og G
>>> hook you are risking the tow-pilots life more than
>>> your own, and this I will not defend.
>>
>>> Marc Ramsey wrote
>>> I personally prefer to fly aerotow with nose hooks,
>>>and
>>> both of the gliders I now fly have them. But, I'm
>>>not
>>> convinced that anyone has provided actual evidence
>>>of an
>>> observed safety issue with CG hooks.
>
>>> Some numbers like these for, say, the past 20 years
>>>in the UK:
>
>>How many aerotow operations were there per year?
>>What percentage of aerotow operations used CG hooks?
>>How many aerotow upset accidents were there during
>>that period?
>>What percentage of the aerotow upset accidents involved
>>CG hooks?
>>
>>If these figures aren't available, is the use of CG
>>hooks being
>>discouraged based simply on the assumed lack of positive
>>longitudinal
>>stability during aerotow?
>>
>>Marc
>
>I hate to agree with Chris Rollings but he sums it
>up quite well.
>
>The questions posed by Marc Ramsey, difficult to obtain
>that no one will even try, so they will not get answered.
>
>Whatever we write here, I cannot see the owners of
>C of G only aircraft rushing out to retrofit a nose
>hook. Having towed on both, the worst being an Olympia
>2B with only a C of G hook and a powerful tug, I prefer
>the nose hook every time.
>
>Some years ago, mid 1908’s I believe, the Australian
>Gliding Association, following a number of tug upsets
>produced a very graphic illustration showing the various
>stages of a tug being upset by a glider on tow, wherever
>the hook. It clearly and simply illustrated the difficulties
>this caused the pilots at each end of the combination.
>
>
>C of G hooks merely increase the likely hood of this
>happening with an inattentive pilot.
>
>The short answer is educating the pilots on the particular
>hook to be used and hammering home the consequences
>of inattention to all.
>
>The Australian poster should be displayed at all gliding
>sites.
>
>To try to answer the question that started this thread,
>the B4 pilots problems could be solved by asking the
>tug to accelerate a little faster from the start, having
>due regard to the problems this may cause. IE Things
>may go wrong even quicker!
>
>Dave
>
>
>
>

[Chris Rollings]

The Capstan and Olypia 2 really have 'compromise' hooks,
halfway between nose hook and C of G hook. Not quite
so good for winch launching but not as wildly unstable
on aerotow as a true C of G hook.

Not sure about the accident statisics for those days,
my close involvement only began when I started work
at Booker in 1970 - certainly there were aerotow accidents
back then.

Chris Rollings

At 10:48 07 January 2004, Silent Flyer wrote:
>
>Chris Rollings wrote in message
...
>
>SNIP
>> Let's look at the numbers. I will use the UK as an
>> example, since I have a fairly accurate knowledge
>>of
>> the statistics there, but the pricipals are the same
>> for any of the World's gliding nations.
>SNIP
>
>Chris
>
>I learnt to fly at an all aerotow operation back in
>1967 at the old
>Leicestershire club at Rearsby. Training was on a Slingsby
>Capstan and
>pupils were then sent solo in an Olympia 2b, (in my
>case after twenty seven
>flights). These of course like virtually all gliders
>of that time had only
>CoG hooks.
>
> What do the accident statistics say when comparing
>that period with the
>present day ?
>
>Don Brown
>
>
>
>

[Chris Rollings]

Todd is right in every respect, at least one of the
aerotow upset fatals involved a largly winch launch
experienced pilot and the cicumstances he surmised.

Chris Rollings

At 15:06 07 January 2004, Todd Pattist wrote:
>Eric Greenwell wrote:
>
>>The US might have less trouble with CG hooks than a
>>country where aero
>>tow isn't as common.
>
>There are a couple of things that might make the U.S.
>experience a little different in view of our training
>and
>operating procedures and the different experience of
>our
>pilot base. Many/most U.S. pilots are unfamiliar with
>winch
>launching and are extremely uncomfortable with any
>kind of
>nose high attitude on launch. I have occasionally
>wondered
>if some 'kiting on tow' accidents might be related
>to the
>pilots control response in a situation that is dangerous
>for
>an aerotow, but not for a winch launch. Another potential
>difference is the prevalence of U.S. training in the
>venerable 2-33, which typically produces a very high
>nose up
>attitude as the roll commences and requires a strong
>forward
>stick to compensate.
>
>Of course, despite those comments, we also experience
>too
>many towing accidents. The CG hook can be implicated
>in more
>than the kiting accidents, and I know several pilots
>who
>have purchased or retrofitted the nose hook after a
>loss of
>directional control during the initial roll on a CG
>hook
>aerotow launch.
>Todd Pattist - 'WH' Ventus C
>(Remove DONTSPAMME from address to email reply.)
>

[Chris Rollings]

Yes the pull can be enough to affect stability, that
was what the test I descibed demonstrated.

Chris Rollings

At 18:36 07 January 2004, Greg Arnold wrote:
>Marc Ramsey wrote:
>
>
>>
>> If these figures aren't available, is the use of CG
>>hooks being
>> discouraged based simply on the assumed lack of positive
>>longitudinal
>> stability during aerotow?
>
>
>Is the pull on a CG hook during aerotow ever great
>enough to have much
>effect on the longitudinal stability of the glider?
> I have never
>noticed such an effect, so I wonder if pilots who fly
>from a winch (very
>quick acceleration and doubtless a significant effect
>on longitudinal
>stability) are unfairly extrapolating their experience
>there to the
>aerotow situation.
>
>Doubtless a nose hook is better for aerotow, but I
>wonder if the alleged
>advantages aren't being oversold by some posters to
>this thread.
>
>
>
>
>

[Chris Rollings]

The point is not 'does a Cof G hook cause a glider
to pitch up on tow'. The point is that if something
(an accidental pilot input, or a gust not corrected
for immediately because the pilot in momentarily distracted)
causes the glider to pitch up, will it carry on pitching
further up of its own accord, stay it the attitude
it has reached, or start to pitch back down of its
own accord? If the first of those three, how easy
is it to stop it pitching up? In the tests on the
Ka8, it seemed to me to be (almost?) impossible to
stop it, once the pitch angle exceeded about 30 degrees.


Don't know about most of the other types mentioned
in this thread. I've flown most of them, but even
I didn't include 'simulated tug upset whilst aerotowing
on C of G hook' in my normal type conversion exercises
- I think I would have found it hard to get a tow after
a while if I had.

Chris Rollings

At 00:00 08 January 2004, Mike Borgelt wrote:
>On Tue, 6 Jan 2004 18:39:17 -0000, 'W.J. \(Bill\) Dean
>\(U.K.\).'
> wrote:
>
>>There have been several fatal 'aerotow upset' accidents
>>in the U.K. where
>>it seems certain that towing on a hook intended for
>>winch launching was a
>>factor.
>>
>>These include:
>>Lasham new year 1963/4 Auster towing a Ka 6cr or Skylark
>>2 (I forget which),
>>Tug at Aboyne towing a Ka 6e,
>>Tugs (Super Cubs) towing K 18s at Portmoak and Dunstable
>>(within a few
>>months of each other), this led to the tests by Chris
>>Rollings, Verdun Luck
>>and Brian Spreckley at Booker see
>>http://www.glidingmagazine.com/ListFeatureArticleDtl.asp?id=327
>>.
>>
>>Will that do, or how many others do you need?
>
>So that is 4 in 40 years.
>
>I think we've managed to kill that many towplane pilots
>in Aus in the
>last 15 in mid airs. At least one, maybe more would
>have had a good
>chance of survival if he had had a parachute. Something
>that still
>isn't required here.
>
>The common link with the upsets mentioned seems to
>be high wing wooden
>gliders of low wing loading with deep fuselages. These
>may be prone to
>pitch up.
>
>How long were the ropes in these situations?
>
>Were there other circumstances that contributed?
>
>Could they have been compensated for?
>>
>>Any glider which launches well on a cable using the
>>aft launching hook, will
>>do the same behind a tug maybe killing the tug pilot
>>in the process. If
>>you really think that the glider pilot can control
>>or stop this process once
>>it starts, READ THE ARTICLE LINKED ABOVE; I suggest
>>that the pilots who
>>conducted those tests were more experienced, more current
>>and just plain
>>better than you.
>
>You are suggesting that on a winch launch with much
>higher loads in
>the cable that these gliders are not controllable in
>pitch?
>>
>>To my certain knowledge it is possible to fit a forward
>>hook for aerotow to
>>the ASW 15, 17, ASK 18, ASW 19, 20, and 22 and the
>>Pegase; the ASK 21 and 23
>>and I think later types were fitted with it as standard.
>> I don't know of
>>any examples of these in club (as distinct from private
>>owner) use which
>>have not been modified.
>
>I once owned an ASW20B. The GFA required the nose hook
>to be fitted.
>The Scheicher factory job on this was pitiful. Nobody
>who bought
>gliders from this batch of 6 put up with it. The releases
>were taken
>out and glassed over. When finishing the area it became
>apparent that
>the skin had been distorted by the additional release
>bulkheads.
>I don't ever recall the 20B having the slightest tendency
>to pitch up
>on aerotow on the belly release.
>
>I have no aversion to properly engineered nose hooks
>like in
>Glasflugel and Schempp gliders but poorly designed
>retrofits are a bad
>idea particularly when no testing has been done on
>that particular
>type to see if indeed the 'solution' is effective
>or even necessary.
>
>The BGA considers 150 foot ropes acceptable. I consider
>these
>dangerously short, 200 feet is more like it with around
>240 to 260
>being much better.
>
>Now consider this::
>
>The world's politicians and bureaucrats are forever
>looking for ways
>to meddle in our lives to keep themselves in jobs.
>If we place
>requirements on our own operations (Like compulsory
>nose releases)that
>are not firmly founded in proper testing and rational
>analysis we
>weaken our case in resisting the idiot requirements
>that come in a
>never ending stream from these people.
>
>I've yet to meet anyone who has flown on a 250 foot
>rope who hasn't
>admitted it was easier than on shorter ropes. When
>I aerotow I want to
>go soaring for maybe several hours and maybe the enviroment
>on the
>ground was stressful due to heat, humidity etc. I really
>don't need a
>5 minute adrenaline thrill to begin a cross country.
>I would like
>tows to be a non event. Longer ropes and tow pilots
>who don't try to
>thermal or do other sudden manouevers all aid in this.
>
>The scariest tow I ever had was in my Salto (with nose
>release) behind
>a tow pilot who was not paying attention and who pulled
>back hard on
>leaving the ground as we encountered a gust leaving
>me dangling low
>from the end of the rope with decreasing airspeed.
>Followed by a hard
>push just as I was climbing slowly back up into station(low
>tow)
>leaving me very high followed by another hard pull
>which put me very
>low again wherupon I released and did a 180 back to
>the strip.
>Probably my shortest ever aerotow flight, closest to
>disaster and on
>the 130 foot or so ropes that were fashionable at the
>time. I never
>ever want to do this again. It was 30 years ago and
>I remember it
>clearly.
>A rope twice as long likely would have made this a
>non event.
>
>The surprisingly easy tows were at Minden in an ASW20(belly
>release)
>through the rotor behind a 182. Long rope, no problem
>at all.
>
>Mike Borgelt
>

[W.J. \(Bill\) Dean \(U.K.\).]

A pilot might aerotow on an aft hook when a forward hook is fitted if:

a/ The forward hook is unserviceable,
b/ The forward hook is taped over:
to increase performance,
to reduce noise,
to reduce drafts.

I think that the tug pilot or the organisation providing the tow would be
fully justified in refusing to tow the pilot in any of these circumstances.

If there were to be an accident, there might be a problem in claiming on the
insurance, and any investigation is likely to be adversely critical, even if
the tow hook position was not a factor in the accident.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.

>
> "Ian Johnston" > wrote in message
> news:cCUlhtvFIYkV-pn2-LTEljpyteDPd@localhost...
>
> >
> > On Wed, 7 Jan 2004 03:01:17 UTC, (Mark James Boyd)
> > wrote:
> >
> > Are you guys telling me the manual says that if it has only a CG hook,
> > you can aerotow with it, but if both hooks are present, the manual
> > prohibits aerotow on the CG hook for the ASW-27?
> >
>
> Under what circumstances would one tow with a CG hook when a nose hook
> was available?
>
> Ian
>

[Andreas Maurer]

On 7 Jan 2004 09:53:55 -0800, (Chris
OCallaghan) wrote:

>A good next step would be to repeat
>the experiment, this time putting emphasis on measuring the loads and
>effects of identical maneuvers using a nose vs. cg hook.

This is exactly what has been done by the German LBA and DLR,
resulting in the regulations that a nose hook must be installed in any
newly produced glider.

This is the result paper of the experiments:

http://www.daec.de/se/faq/fschlepp/dlr.htm

(unfortunately only in German, I haven't found an English version yet)


>In the absence of valid statistical or empirical evidence, it's hard
>to determine just how critical this problem is.

http://www.daec.de/se/faq/fschlepp/unfallzahlen.htm

(number of accidents during winch launch and aerotow)

Not hard evidence... but the decrease in accident numbers in aerotow
is significant - maybe caused by the fact that more and more gliders
are equipped with nose hooks?


Bye
Andreas

[Ian Johnston]

On Thu, 8 Jan 2004 10:18:37 UTC, "W.J. \(Bill\) Dean \(U.K.\)."
> wrote:

: A pilot might aerotow on an aft hook when a forward hook is fitted if:
:
: a/ The forward hook is unserviceable,

That would be ruled out by my " ... is available"

: b/ The forward hook is taped over:
: to increase performance,
: to reduce noise,
: to reduce drafts.

And that would be sheer stupidity - the cause, I reckon, of 90% of all
gliding accidents.

: I think that the tug pilot or the organisation providing the tow would be
: fully justified in refusing to tow the pilot in any of these circumstances.

Agreed. Or to impose conditions. At my club, any visiting pilot who
wishes to tow with a belly hook has to take a check flight in a
two-seater, towed with the belly hook, before s/he may fly,
regardlessof experience or qualifications. But then, it's a club which
lost one of its tug pilots, elsewhere, to an upset.

: If there were to be an accident, there might be a problem in claiming on the
: insurance, and any investigation is likely to be adversely critical, even if
: the tow hook position was not a factor in the accident.

The latter point worries me a bit. Accident investigations should, I
think, concentrate on what happened and what mattered. They shouldn't
kae side swipes at things the investigator doesn't approve of, if they
are irrelevant. In fact, investigations generally shouldn't be
adversely critical. We can all do that when we see what the cause of
an accident were!

Ian

[Ian Johnston]

On Thu, 8 Jan 2004 10:16:04 UTC, Chris Rollings
> wrote:

: In the tests on the
: Ka8, it seemed to me to be (almost?) impossible to
: stop it, once the pitch angle exceeded about 30 degrees.

My Pirat does the rotation all by itself on a winch launch, regardless
of pilot input. I'd never even dream of aerotowing it with that hook.

Ian

PS The manual says it's fine to winch it with the nose hook!

--

[Martin Gregorie]

On Wed, 7 Jan 2004 23:29:16 +0000, Ian Strachan
> wrote:

>The static on-the-ground measurement of where the glider GC is with
>respect to the belly hook position is not what matters. It is what
>happens on a launch (dynamic, not static conditions). What matters is
>the angle-of-pull of the cable with respect to the centre of motion and
>control effectiveness of the glider in that dynamic launch situation.
>
>If you measure where the CG is statically, that is, on the ground, and
>placed a tow hook directly underneath it, I think that you would find
>the subsequent launch pretty unstable either on winch or air tow.

The best (static) procedure I know for correctly locating the tow hook
on a free flight model glider (launch for these is equivalent to winch
launch with the controls fixed for a minimum sink glide condition) is
to:

- locate the CG on the wing chord (A)
- draw the wing chord on the fuselage
- draw a perpendicular to the wing chord running through the CG
- a line through the tow hook and point A should slope forward
at an angle of 16 degrees from the perpendicular.

On most models that approximates to 18-20 degrees forward of a
vertical line through the CG. In other words, the optimum winch launch
hook position is in front of the CG by an amount that is related to
the vertical distance between wing and hook.

HTH

Martin

--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :

[Andreas Maurer]

On 8 Jan 2004 11:02:45 GMT, "Ian Johnston" >
wrote:

>My Pirat does the rotation all by itself on a winch launch, regardless
>of pilot input.

Does this mean that if you push the stick forward, you are unable to
stop the rotation (in other words - the pilot in a Pirat has no pitch
control during the winch launch)?

Hard to believe I have to admit.



Bye
Andreas

[Andreas Maurer]

On 8 Jan 2004 10:16:04 GMT, Chris Rollings
> wrote:

> will it carry on pitching
>further up of its own accord, stay it the attitude
>it has reached, or start to pitch back down of its
>own accord?

Check this (and use Babelfish for a rough translation - the sketches
should be self-explanatory even for non-German speakers).
http://www.daec.de/se/faq/fschlepp/dlr.htm






Bye
Andreas

[W.J. \(Bill\) Dean \(U.K.\).]

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.

>
> "Ian Johnston" > wrote in message
> news:cCUlhtvFIYkV-pn2-bKdumM0BMIOs@localhost...
>
> >
> > On Thu, 8 Jan 2004 10:18:37 UTC, "W.J. \(Bill\) Dean \(U.K.\)."
> > > wrote:
> >
> > A pilot might aerotow on an aft hook when a forward hook is fitted if:
> >
> > a/ The forward hook is unserviceable,
> >
>
> That would be ruled out by my " ... is available"
>

NO!

If the forward hook is unserviceable, then the glider is unserviceable for
aerotow.

Would you aerotow your Pirat on the aft hook if the forward hook is
unserviceable?

Would you winch launch a K21 on the forward hook (with no back release!) if
the aft hook is unserviceable? Would you do it if you could make the
forward hook back release? Would you wire launch any glider on the forward
hook (unless the C. of A. papers specifically allowed it) ?.

The glider has two hooks for a reason. If an apparently otherwise
identical glider has only one hook, that is a bad reason for assuming that
you can treat your glider hooks as interchangeable.

>
> >
> > b/ The forward hook is taped over:
> > to increase performance,
> > to reduce noise,
> > to reduce drafts.
> >
>
> And that would be sheer stupidity - the cause, I reckon, of 90% of all
> gliding accidents.
>

What seems stupidity to you may be a habit formed at a site where this has
become normal behaviour over the years.

>
> >
> > I think that the tug pilot or the organisation providing the tow would
> > be fully justified in refusing to tow the pilot in any of these
> > circumstances.
> >
>
> Agreed. Or to impose conditions. At my club, any visiting pilot who
> wishes to tow with a belly hook has to take a check flight in a
> two-seater, towed with the belly hook, before she/he may fly,
> regardless of experience or qualifications. But then, it's a club which
> lost one of its tug pilots, elsewhere, to an upset.
>
> >
> > If there were to be an accident, there might be a problem in claiming on
> > the insurance, and any investigation is likely to be adversely critical,
> > even if the tow hook position was not a factor in the accident.
> >
>
> The latter point worries me a bit. Accident investigations should, I
> think, concentrate on what happened and what mattered. They shouldn't
> take side swipes at things the investigator doesn't approve of, if they
> are irrelevant. In fact, investigations generally shouldn't be
> adversely critical. We can all do that when we see what the causes of
> an accident were!
>

It was meant to worry you.

Like it or not, accident investigators tend to enquire, notice and comment
on the whole operation and not just the immediate causes of the particular
accident. And some underwriters are always on the lookout for an excuse
not to pay.

Have you never visited a site, or noticed a particular pilot or syndicate,
and said to yourself "there is an accident waiting to happen" ? Accident
investigators look for this, as well as the particular factors directly
leading to an accident.

>
> Ian
>

[Cliff Hilty]

>'2. Notwithstanding 1. above, as far as I know 100
>percent of >UK tug upset fatal accidents in the last
>30 years happened >with belly hooks. We changed our
>procedures and >recommendations before we could gather
>more data and >satisfy statistical pedants with some
>more fatalities which >might have improved the correlation
>calculations. Since the >changes, fatal tug upsets have
>almost entirely disappeared >from the UK fatal accident
>reports.

Interesting thread! The only Accident that I have personal
knowledge of is one that happened at Turf Soaring in
95 and that particular one involved a SGS-2-33 and
a Pawnee 235 tow plane. The Student Gilder pilot saw
the tow plane go through a dust devil at about a 100-200
feet and when it hit him he was not prepared for it.
They were using a 200 foot rope and the tow plane was
fitted with SGS hook. Niether the tow pilot or the
glider pilot released and the rope broke 4 feet behind
the tow plane. But not before the tow plane was upset
enough not to be able to recover and he 'pancaked'
in to the ground killing himself. The glider pilot
was able to return to the field and land safely. Afterwards
they summarized that the towpilot could not have released
do to the forces on the release. Since then they have
redesigned andgotten FAA aproval to invert the SGS
hook and eliminate this problem. This happened with
a Nose hook and student pilot. I believe that the most
important factor in this disscussion is the lack of
experience not wether or not it is a nose or belly
or cg hook!

[Z Goudie]

Come on people, is the gliding world turning into a
nannie state?

As a glider pilot for some 40 odd (some very odd) years
and a tug pilot for 30 I can't believe some of this
drivel.

Launching of any description on any hook is not a problem
if the gowk at the back has had it properly drummed
into him to keep his hand on the release and thus be
able to throw the launch away instantly in the event
of a dropped wing or the tug disappearing from sight.

[Chris Nicholas]

Cliff Hilty wrote [snip] "This happened with a Nose hook and student
pilot. I believe that the most
important factor in this disscussion is the lack of experience not
wether or not it is a nose or belly
or cg hook!"
- - - - -

As Bill Dean wrote much earlier in this thread, the BGA recommendations
after a series of these accidents and the Chris Rollings etc. tests
included:

"The operators' attention is drawn to the following factors which may
cumulatively contribute to a hazardous situation:

(a) Low experience of glider and/or tug pilot
(b) Gliders fitted with C of G hook only
(c) Glider's C of G towards the aft limit
(d) Turbulent air in the take-off area
(e) Rough ground in the take-off area
(f) Significant cross-wind component."

Note, 6 factors, in addition to rope length, not just the hook position
issue. At the same time, there was a poster produced which no-one now
seems to have a copy of. My recollection of it was that it listed these
6 factors and said that if more than one or two were present, it would
be wise not to undertake such a flight. To think that there is just one
factor and any of the others can be any which way is asking for trouble.

I have no idea why people are still arguing about it. We have almost
eliminated tug upset accidents in the UK since this and the "Low
High-tow" standardisation, yet some people think the BGA should have
done nothing except change rope lengths and maybe not even that, some
people think it can't happen to them, and some people think we did no
more than mandate nose hooks when it was not in fact mandated in the UK,
just encouraged where possible.

Seems to me that if people want to go on risking lives in other
countries, feel free - and tell the tug pilots' families you don't mind
being sued, having read about and ignored the entire series of
recommendations that seem to have largely eliminated this type of
fatality where it was researched.

Chris N.

[Bill Daniels]

"Z Goudie" > wrote in message
...
> Come on people, is the gliding world turning into a
> nannie state?
>
> As a glider pilot for some 40 odd (some very odd) years
> and a tug pilot for 30 I can't believe some of this
> drivel.
>
> Launching of any description on any hook is not a problem
> if the gowk at the back has had it properly drummed
> into him to keep his hand on the release and thus be
> able to throw the launch away instantly in the event
> of a dropped wing or the tug disappearing from sight.
>
Agreed.

Bill Daniels

[Marc Ramsey]

"Chris Nicholas" > wrote...
> "The operators' attention is drawn to the following factors which may
> cumulatively contribute to a hazardous situation:
>
> (a) Low experience of glider and/or tug pilot
> (b) Gliders fitted with C of G hook only
> (c) Glider's C of G towards the aft limit
> (d) Turbulent air in the take-off area
> (e) Rough ground in the take-off area
> (f) Significant cross-wind component."
>
snip...
> Seems to me that if people want to go on risking lives in other
> countries, feel free - and tell the tug pilots' families you don't mind
> being sued, having read about and ignored the entire series of
> recommendations that seem to have largely eliminated this type of
> fatality where it was researched.

The length of this thread, and the bulk of the argument resulted from the
fact that some took one of the 6 points listed aboved (b) and made the
unequivocal statements to the effect that aerotowing with a CG hook was
dangerous and bordered on criminal. This is not, apparently, what the BGA
has said, it is simply the opinion of certain individuals.

I didn't notice anyone arguing that nose hooks aren't better for aerotowing,
the issue is whether CG hooks are sufficiently less safe than nose hooks
that we should flat out refuse to aerotow with them. For obvious reasons,
it is difficult to provide evidence based on actual accident data which
would justify the latter. We have, however, had at least 3 towplane upsets
here in the US that involved gliders with nosehooks, so eliminating CG hooks
most clearly will not eliminate towplane upsets and associated fatalities.

Here in the US, anyway, if we were to take a chunk of money to improve the
safety of aerotows, I'd say there is reasonable evidence that retrofitting a
bunch of gliders with nose hooks is not the most cost effective approach.
I' guess we would likely save a lot more tow (and glider) pilot lives, for
less money, if we (a) developed a safer alternative to the Schweizer tow
plane hook, (b) retrofitted swing open glider canopies with a spring loaded
positive latch, and (c) retrofitted gliders that have divebrakes that open
when unlocked, with a Piggot-style hook arrangement.

Marc

[Chris OCallaghan]

Would anyone be willing to translate and paraphrase this article? I
would be epecially appreciative of our effort.

Chris O'Callaghan

[Chris OCallaghan]

Andreas,

thanks for the link. I'll do my best to get it translated. We've some
willing German speakers at the club, but it's unlikely I'll see any of
them before March!

Cheers

[Ian Johnston]

Andreas Maurer > wrote in message >...
> On 8 Jan 2004 11:02:45 GMT, "Ian Johnston" >
> wrote:
>
> >My Pirat does the rotation all by itself on a winch launch, regardless
> >of pilot input.
>
> Does this mean that if you push the stick forward, you are unable to
> stop the rotation (in other words - the pilot in a Pirat has no pitch
> control during the winch launch)?

In my experience, yes, but only during the initial rotation, and it
only happens at a reasonable speed. In the climb it's fine. And a very
gentle initial acceleration avoids the earlier problems, mostly.

Ian

[Ian Johnston]

"W.J. \(Bill\) Dean \(U.K.\)." > wrote in message >...
> W.J. (Bill) Dean (U.K.).
> Remove "ic" to reply.
>
> >
> > "Ian Johnston" > wrote in message
> > news:cCUlhtvFIYkV-pn2-bKdumM0BMIOs@localhost...
> >
> > >
> > > On Thu, 8 Jan 2004 10:18:37 UTC, "W.J. \(Bill\) Dean \(U.K.\)."
> > > > wrote:
> > >
> > > A pilot might aerotow on an aft hook when a forward hook is fitted if:
> > >
> > > a/ The forward hook is unserviceable,
> > >
> >
> > That would be ruled out by my " ... is available"
> >
>
> NO!
>
> If the forward hook is unserviceable, then the glider is unserviceable for
> aerotow.

I'm not quite sure why you're contracdicting me when I'm agreeing with
you. The question I asked was: "Under what circumstances would one tow
with a CG hook when a nose hook was available?" An unserviceable hook
ain't available!

Mind you, if it was a type which was often aerotowed on a belly hook,
and if the pilot knew what s/he was in for, and had suitable
experience, then it wouldn't worry me greatly.

> Would you aerotow your Pirat on the aft hook if the forward hook is
> unserviceable?

No. For reasons I have outlined. And that's because of particular
properties of the Pirat belly hook.

> Would you winch launch a K21 on the forward hook (with no back release!) if
> the aft hook is unserviceable? Would you do it if you could make the
> forward hook back release? Would you wire launch any glider on the forward
> hook (unless the C. of A. papers specifically allowed it) ?.

I sense a little hostility here! I would not winch launch a K21 on the
nose hook, mainly because I am too busy beating my wife. And I haven't
winched the Pirat on the nose hook either, partly because I can't see
the point and partly because it doesn't have a back release.

> The glider has two hooks for a reason. If an apparently otherwise
> identical glider has only one hook, that is a bad reason for assuming that
> you can treat your glider hooks as interchangeable.

All assumptions are unreasonable. Deductions are fine!

> > And that would be sheer stupidity - the cause, I reckon, of 90% of all
> > gliding accidents.

> What seems stupidity to you may be a habit formed at a site where this has
> become normal behaviour over the years.

Indeed. Group stupidity appears in the blood-and-gore section of S&G
just as much as individual stupidity!

> Have you never visited a site, or noticed a particular pilot or syndicate,
> and said to yourself "there is an accident waiting to happen" ? Accident
> investigators look for this, as well as the particular factors directly
> leading to an accident.

True. There is one major gliding club in the UK midlands (it's not the
Midlands Gliding Club!) at which I will not fly because their attitude
to safety, on the one occasion I visited, was so sloppy as to be
almost unbelievable. And that was a couple of weeks after they'd
killed someone on the winch...

Ian

PS On rereading, let me make it clear: I am in favour of gliders
having nose hooks and I am in favour of using them for aerotows!

[Mike Borgelt]

On Thu, 8 Jan 2004 10:57:33 -0800, "Marc Ramsey"
> wrote:

>
>"Chris Nicholas" > wrote...
>> "The operators' attention is drawn to the following factors which may
>> cumulatively contribute to a hazardous situation:
>>
>> (a) Low experience of glider and/or tug pilot
>> (b) Gliders fitted with C of G hook only
>> (c) Glider's C of G towards the aft limit
>> (d) Turbulent air in the take-off area
>> (e) Rough ground in the take-off area
>> (f) Significant cross-wind component."
>>
>snip...
>> Seems to me that if people want to go on risking lives in other
>> countries, feel free - and tell the tug pilots' families you don't mind
>> being sued, having read about and ignored the entire series of
>> recommendations that seem to have largely eliminated this type of
>> fatality where it was researched.
>
>The length of this thread, and the bulk of the argument resulted from the
>fact that some took one of the 6 points listed aboved (b) and made the
>unequivocal statements to the effect that aerotowing with a CG hook was
>dangerous and bordered on criminal. This is not, apparently, what the BGA
>has said, it is simply the opinion of certain individuals.
>
>I didn't notice anyone arguing that nose hooks aren't better for aerotowing,
>the issue is whether CG hooks are sufficiently less safe than nose hooks
>that we should flat out refuse to aerotow with them. For obvious reasons,
>it is difficult to provide evidence based on actual accident data which
>would justify the latter. We have, however, had at least 3 towplane upsets
>here in the US that involved gliders with nosehooks, so eliminating CG hooks
>most clearly will not eliminate towplane upsets and associated fatalities.
>
>Here in the US, anyway, if we were to take a chunk of money to improve the
>safety of aerotows, I'd say there is reasonable evidence that retrofitting a
>bunch of gliders with nose hooks is not the most cost effective approach.
>I' guess we would likely save a lot more tow (and glider) pilot lives, for
>less money, if we (a) developed a safer alternative to the Schweizer tow
>plane hook, (b) retrofitted swing open glider canopies with a spring loaded
>positive latch, and (c) retrofitted gliders that have divebrakes that open
>when unlocked, with a Piggot-style hook arrangement.
>
>Marc
>

Spot on Marc.
a) Is already available.
b) Is problematical - there is a lot of friction in a Schempp canopy
latch which if the closing spring was powerful enough would likely
make the canopy difficult to open.
Whatever happened to pre takeoff checks?
c) Is a good idea and incredibly cheap to implement so worth doing
even if the benefit is slight.

It is the easiest thing in the world to spend someone else's money on
safety improvements. The aim must always be to spend it in the manner
where you get the most improvement for your dollar. Otherwise we are
open to uncontrolled cost increases for "improved safety" mostly based
on little more than conjecture.

Mike Borgelt

[Jack]

Now there's a piece of real valuable insight, Z. And we all know what would
happen if a frog had wings.

At least give us poor tuggies the ability to survive the (eventually)
inevitable tow with a "gowk" who has not received a proper "drumming".

A proper Tost hook, or at least an inverted Schweizer hook;
no CG hook aerotows when nose hook is available, and then only with glider
guiders of proven competence, is not too much to ask!

May we all continue to glide safely!



Jack
--------------

On 2004/01/08 09:36, in article ,
"Z Goudie" > wrote:

> Come on people, is the gliding world turning into a
> nannie state?
>
> As a glider pilot for some 40 odd (some very odd) years
> and a tug pilot for 30 I can't believe some of this
> drivel.
>
> Launching of any description on any hook is not a problem
> if the gowk at the back has had it properly drummed
> into him to keep his hand on the release and thus be
> able to throw the launch away instantly in the event
> of a dropped wing or the tug disappearing from sight.

[Eric Greenwell]

Mike Borgelt wrote:
>
> The LBA/BGA/GFA/insert your civil aviation bureaucracy name here
> bureaucracy get to feel good because they have "improved" safety and
> can boast about this, most of the glider pilots don't care one way or
> the other as they are unaffected and tow pilots are at just as much
> risk as before as the fleet replacement only occurs slowly. Great!

Even if you completely discount the risk of getting out of position,
there is still a benefit to the glider pilot: the first 100' or so until
the glider has good control is significantly better with nose hook. I've
seen ground accidents that would not have occurred (including mine) with
a nose hook. If you normally aerotow, I think it's cheap insurance to
get one with your new glider. It might be almost as good a value as a
retrofit, but because retrofit costs can vary so much, I can't be
dogmatic about it. It was a good value to retrofit my ASW 20 C.

>
> Requiring longer ropes would have been cheaper and would give
> immediate benefits but here we are still thinking 150 feet is
> adequate. Wonderful.

A longer rope won't aid the pilot in the first 100', when these ground
accidents usually develop.

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[E. A. Grens]

CG hooks on tow do not create a problem for competent pilots. It is only
necessary to fly the towed glider, as in close formation flying, without
depending on the tow hook to do a lot of the work for you. Of course, very
short tow ropes can make any tow difficult. Both my own glider, a Phoebus
A-1, and the DG-101 I frequently fly in my club, have only CG hooks. With
reasonable tow-rope length I have never found CG hooks to present any
problems. But, do keep the trim full down on take-off.

Ed

[Chris Rollings]

C of G hooks do not create a problem on tow - for anyone
who does not find himself with a significant degree
of pitch up (sorry can't give a figure in degrees,
it will vary according to type) relative to the tow-plane's
flight path.

I agree that competent pilots (whatever that means)
are less likely to find themselves in that position.
However, given that it takes less than 0.5 seconds
for the necessary amount of pitch up to occur, and
that pitch up can be caused by either a gust, an inadvertant
elevator input by the glider pilot, or an unexpected
attitude change by the tow-plane, I don't think anyone
is 'competent' enough to guarantee that it can never
happen to them.

Changing the subject just slightly; the use of 'low'
high tow, refered to several times in this thread,
does not really help because:

1. The 'few feet lower' position adds less than half
a second to the time the 'upset' takes (given a 'normal'
lenght rope of just under 200 feet); usually not enough
to make any difference to the outcome.

2. The slight upward angle of the force on the rope
increases the instability of the situation and means
that a slightly smaller pitch angle is needed to set
the whole thing off.

3. The close proximity to the tow-plane's prop wash,
and occasional indvertant excursions into it, may well
provide the trigger mechanism that causes the unwanted
pitch movement.

I will post no more on this subject until and unless
someone actually comes up with some new flight test
reports.

However, I am prepared to offer my services as an expert
witness, to the estate of any tow-pilot who is killed
in a 'tug upset' accident whilst towing a glider on
a C og G hook.

Chris Rollings

At 03:18 09 January 2004, E. A. Grens wrote:
>CG hooks on tow do not create a problem for competent
>pilots. It is only
>necessary to fly the towed glider, as in close formation
>flying, without
>depending on the tow hook to do a lot of the work for
>you. Of course, very
>short tow ropes can make any tow difficult. Both my
>own glider, a Phoebus
>A-1, and the DG-101 I frequently fly in my club, have
>only CG hooks. With
>reasonable tow-rope length I have never found CG hooks
>to present any
>problems. But, do keep the trim full down on take-off.
>
>Ed
>
>
>
>

[Andy Durbin]

Chris Nicholas > wrote in message >...

Chris you listed the following 6

>
> "The operators' attention is drawn to the following factors which may
> cumulatively contribute to a hazardous situation:
>
> (a) Low experience of glider and/or tug pilot
> (b) Gliders fitted with C of G hook only
> (c) Glider's C of G towards the aft limit
> (d) Turbulent air in the take-off area
> (e) Rough ground in the take-off area
> (f) Significant cross-wind component."

Then stated, almost as an aside,


> We have almost
> eliminated tug upset accidents in the UK since this and the "Low
> High-tow" standardisation,

I suspect that condition 7 may be more significant in reducing tug
upsets than any of the 6 in the primary list.

As a US instructor I have flown with many pilots that received their
initial training from other instructors. I have often been surprised
at the tow position taken by such pilots. I usually urge them to keep
lowering the tow position until they feel the wake, then to move just
high enough that the wake is not a factor. That tow position may be
10 or 15 ft lower than that initially used.

A pilot flying a high high tow has less time to react to a potential
upset than one flying the UK recommended low high tow. The fact that
US pilots seem to be trained to use high high tow may explain why tug
upsets continue to happen even when a nose or forward hook is used.


Andy (GY)

[Bill Daniels]

"Andy Durbin" > wrote in message
om...
> Chris Nicholas > wrote in message
>...
>
> Chris you listed the following 6
>
> >
> > "The operators' attention is drawn to the following factors which may
> > cumulatively contribute to a hazardous situation:
> >
> > (a) Low experience of glider and/or tug pilot
> > (b) Gliders fitted with C of G hook only
> > (c) Glider's C of G towards the aft limit
> > (d) Turbulent air in the take-off area
> > (e) Rough ground in the take-off area
> > (f) Significant cross-wind component."
>
> Then stated, almost as an aside,
>
>
> > We have almost
> > eliminated tug upset accidents in the UK since this and the "Low
> > High-tow" standardisation,
>
> I suspect that condition 7 may be more significant in reducing tug
> upsets than any of the 6 in the primary list.
>
> As a US instructor I have flown with many pilots that received their
> initial training from other instructors. I have often been surprised
> at the tow position taken by such pilots. I usually urge them to keep
> lowering the tow position until they feel the wake, then to move just
> high enough that the wake is not a factor. That tow position may be
> 10 or 15 ft lower than that initially used.
>
> A pilot flying a high high tow has less time to react to a potential
> upset than one flying the UK recommended low high tow. The fact that
> US pilots seem to be trained to use high high tow may explain why tug
> upsets continue to happen even when a nose or forward hook is used.
>
>
> Andy (GY)

I've seen the same thing, Andy.

Bill Daniels

[Andreas Maurer]

On 8 Jan 2004 11:37:23 -0800, (Chris
OCallaghan) wrote:

>thanks for the link. I'll do my best to get it translated. We've some
>willing German speakers at the club, but it's unlikely I'll see any of
>them before March!

I am pretty sure that there is an English version somewhere out
there... unfortunately I haven't found it yet...:(
Bye
Andreas

[Mark James Boyd]

>Mind you, if it was a type which was often aerotowed on a belly hook,
>and if the pilot knew what s/he was in for, and had suitable
>experience, then it wouldn't worry me greatly.

The same holds true for aerotowing an L-13 by the tail tie down.

I suppose it may be possible to install a tow release in the tail
or tie a towrope on the tail tie down, and then aerotow an L-13
tail first. If someone had tried this in a wind tunnel first,
and had lightning quick reflexes, and adjusted to a suitable
CG, perhaps he could reliably fly it on aerotow tail first, facing
rearward, and upon release, do a horizontal hammerhead type
manuever and then fly normally.

If you saw someone do this a dozen times, you might conclude
>and if the pilot knew what s/he was in for, and had suitable
>experience, then it wouldn't worry me greatly.

With the appropriate training, conditions, and experience,
one can fly an L-13 tail first, or fly the Wright flyer. This
is trivially true. Of more interest is the relative ease
of towing forward vs. rearward (front vs. CG hook) and the
associated things to be cautious about. :)

I'm waiting for someone to post that aerotowing with a CG hook is
easier and requires less training and experience than towing
with a nose hook. As yet I haven't seen this claim...

As usual, there have been several outstanding posts of firsthand
CG tow experiences, and I've been most appreciative for these...

[Mark James Boyd]

>"Z Goudie" > wrote in message
...
>> Come on people, is the gliding world turning into a
>> nannie state?
>>
>> As a glider pilot for some 40 odd (some very odd) years
>> and a tug pilot for 30 I can't believe some of this
>> drivel.
>>
>> Launching of any description on any hook is not a problem
>> if the gowk at the back has had it properly drummed
>> into him to keep his hand on the release and thus be
>> able to throw the launch away instantly in the event
>> of a dropped wing or the tug disappearing from sight.
>>
>Agreed.
>
>Bill Daniels
>

If anyone decides to modify their experimental glider to
be towed tail first on a tailhook, I guess we have two
volunteers to be the tow pilots... ;)

[Eric Greenwell]

Andy Durbin wrote:

> As a US instructor I have flown with many pilots that received their
> initial training from other instructors. I have often been surprised
> at the tow position taken by such pilots. I usually urge them to keep
> lowering the tow position until they feel the wake, then to move just
> high enough that the wake is not a factor. That tow position may be
> 10 or 15 ft lower than that initially used.

Where is the towplane, relative to the horizon?

> A pilot flying a high high tow has less time to react to a potential
> upset than one flying the UK recommended low high tow. The fact that
> US pilots seem to be trained to use high high tow may explain why tug
> upsets continue to happen even when a nose or forward hook is used.

10 or 15 feet doesn't sound like it would give much extra time, not like
the low tow position Australia uses.

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Ian Johnston]

"E. A. Grens" > wrote in message >...
> CG hooks on tow do not create a problem for competent pilots.

That's true, by definition: "A competent pilot is one for whom CG
hooks on tow do not cause problems." The trouble is - as my club has
found out - is that many pilots don't know whether or not they are
competent in this regard. We do some very wild towing in primary
rotor: even with a nose hook the tow can be a testing experience!

Ian

[Ian Johnston]

(Ian Johnston) wrote in message >...
>
> In my experience, yes, but only during the initial rotation, and it
> only happens at a reasonable speed. In the climb it's fine. And a very
> gentle initial acceleration avoids the earlier problems, mostly.

Sorry to follow up to myself but ...

The reson, I think, is that the Pirat has quite a high-set wing and a
belly hook as low as it can get. As a result, the lever arm, and
therefore upwards pitching moment from the winch cable about the wing
is relatively high compared to the typical glass glider with mid-set
wing and belly hook offset and up a bit. So with a good fast winch
launch, yes, this moment can overcome anything the elevator is trying
to do.

However, this is an intrinsically stable situation. As the cable angle
relative to the glider's longitudinal axis increases, the lever arm
reduces (by approximately 50% when the glider is 30 degree nose up and
the cable is 30 degrees down). So as the glider pitches up the effect
of the cable reduces, the effect of the elevator (all other things
being equal) stays the same and a point of equilibrium is reached. To
put it simply:

Nose down: winch pulls it up again.

Nose up: elevator pushes it down again

That, I think, is why a good winch launch - "it's like going up on
rails" is so easy and comfortable: the glider is much more stable in
pitch than it is in free flight. I'd expect this to be more marked as
the hook-wing distance increases.

I know, by the way, that I have omitted things like the effect of the
changing AoA on the lift and drag (secondary effects in this case, I
think) and the slingshot effect of a short rope and the relatively low
tow forces behind a tug.

Ian

[Robert John]

I don't think the positition of the horizon should
make any difference. In mountains it's irrelevant
and different tugs will climb at different rates -
a powerful tug will be more pitched up and adopt a
higher position relative to the horizon than a low
power one (relative to the thrust line, the prop-wash
and the best position of the glider just above the
prop-wash).
One of the advantages of being as low as possible is
not just the extra time that it takes to get to 'upset'
position (which is small) but the fact that you are
less likely to lose sight of the tug in the first place.
Once you can't see the tug, things can go wrong very
quickly.
I've flown in Australia with their low tow and whilst
I'm sure each method has its merits, I am personally
much more comfortable with the UK position, don't like
having to transition through the propwash at low level
and find that teaching a 'correct' position that looks
almost identical to the position on the ground before
All Out is easier too.
Rob

At 16:48 09 January 2004, Eric Greenwell wrote:
>Andy Durbin wrote:
>
>> As a US instructor I have flown with many pilots that
>>received their
>> initial training from other instructors. I have often
>>been surprised
>> at the tow position taken by such pilots. I usually
>>urge them to keep
>> lowering the tow position until they feel the wake,
>>then to move just
>> high enough that the wake is not a factor. That tow
>>position may be
>> 10 or 15 ft lower than that initially used.
>
>Where is the towplane, relative to the horizon?
>
>> A pilot flying a high high tow has less time to react
>>to a potential
>> upset than one flying the UK recommended low high
>>tow. The fact that
>> US pilots seem to be trained to use high high tow
>>may explain why tug
>> upsets continue to happen even when a nose or forward
>>hook is used.
>
>10 or 15 feet doesn't sound like it would give much
>extra time, not like
>the low tow position Australia uses.
>
>--
>-----
>change 'netto' to 'net' to email me directly
>
>Eric Greenwell
>Washington State
>USA
>
>

[Mark James Boyd]

In article >,
Ian Strachan > wrote:
>In article <3ffee053$1@darkstar>, Mark James Boyd >
>writes
>
>snip
>
>>If anyone decides to modify their experimental glider to
>>be towed tail first on a tailhook, I guess we have two
>>volunteers to be the tow pilots... ;)
>
>The main question is, in how many seconds would it be being towed
>tail-first ......
>
>Another question would be insurance, but we are in "reductio ad
>absurdum" land, here, aren't we?
>
>--
>Ian Strachan
>Lasham, UK

Ian,

Exactly right. So if we can all agree that "given the
appropriate level of experience and skill, a pilot can
fly any flyable aircraft in any conditions," we can avoid this
obvious truth and focus on the relative risks and
costs (including the cost of acquiring training and
experience).

[Eric Greenwell]

> The reson, I think, is that the Pirat has quite a high-set wing and a
> belly hook as low as it can get. As a result, the lever arm, and
> therefore upwards pitching moment from the winch cable about the wing
> is relatively high compared to the typical glass glider with mid-set
> wing and belly hook offset and up a bit. So with a good fast winch
> launch, yes, this moment can overcome anything the elevator is trying
> to do.
>
> However, this is an intrinsically stable situation. As the cable angle
> relative to the glider's longitudinal axis increases, the lever arm
> reduces (by approximately 50% when the glider is 30 degree nose up and
> the cable is 30 degrees down). So as the glider pitches up the effect
> of the cable reduces, the effect of the elevator (all other things
> being equal) stays the same and a point of equilibrium is reached. To
> put it simply:

I think you forgot to account for the increasing load that pitching up
produces. Sure, the lever arm is reduced, but the glider is at a higher
angle of attack, increasing it's lift. This increases the force much
more than the lever arm is reduced, and the pitch up continues.

This eventually stabilizes with the glider in the normal nose high
attitude of a winch launch, but this is not a good attitude for
aerotowing! For a nose hook, the lever arm is much less to begin with,
and a small pitch up reduces it to zero - quite a different situation.
--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Eric Greenwell]

Robert John wrote:

> I don't think the positition of the horizon should
> make any difference.

It's the position I typically use, so I'm trying to get an idea of how
different it is from what I normally do. Unfortunately, I can't go out
and experiment right now, with a foot of snow on the runway!

So, with a 180 hp Super Cub or Pawnee, say, is the tug canopy on the
horizon, the wing root, wheels, or maybe the tug is an entire "tug"
distance above the horizon?

> In mountains it's irrelevant
> and different tugs will climb at different rates -
> a powerful tug will be more pitched up and adopt a
> higher position relative to the horizon than a low
> power one (relative to the thrust line, the prop-wash
> and the best position of the glider just above the
> prop-wash).

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Tony Verhulst]

>As a US instructor I have flown with many pilots that
>received their
>initial training from other instructors. I have often
>been surprised
>at the tow position taken by such pilots. I usually
>urge them to keep
>lowering the tow position until they feel the wake,
>then to move just
>high enough that the wake is not a factor.

I also agree with Andy that the optimal tow location is just above the
wake. I like it because it's more efficient for the tow plane since less
up elevator is required to maintain proper airspeed. In the flat lands,
if the tug wings are on or above the horizon, you're too high, IMHO.

I've also been known to fly a little to the left on tow to give the tow
pilot's right leg a little rest.

Tony V.

[Ian Strachan]

In article <3ffee053$1@darkstar>, Mark James Boyd >
writes

snip

>If anyone decides to modify their experimental glider to
>be towed tail first on a tailhook, I guess we have two
>volunteers to be the tow pilots... ;)

The main question is, in how many seconds would it be being towed
tail-first ......

Another question would be insurance, but we are in "reductio ad
absurdum" land, here, aren't we?

--
Ian Strachan
Lasham, UK

[Andy Durbin]

Tony Verhulst > wrote in message >...


> In the flat lands,
> if the tug wings are on or above the horizon, you're too high, IMHO.


I think you got something reversed. The lower the glider goes, the
higher above the horizon the tug will appear to be. When I tow behind
a 235 Pawnee all the tug is above the horizon.


Andy

[BTIZ]

if you are towing that low out here in the summer time... you are going to
find yourself in the wake from time to time.. and being in the wake
increases the drag on the tow plane and reduces the climb rate and increases
the down pull, forcing the tow pilot to push on the stick..

we "train".. tow plane on the horizon.. granted there are hills/mountains
all around so the horizon is a "relative" term... keep all 3 wheels of the
tow on the same horizontal line.. the tail wheel between the mains.. works
just fine for the Pawnee 235

if you are low.. "to just above the wake".. it is more difficult for the tow
pilot to see you in the mirrors.. and he may think your going down to box
the wake. Also, with summer thermals.. the tow plane enters the thermal
200ft before the glider, and a 400fpm rate of climb jump to better than
1000fpm for the tow plane.. and you are in the wake.. granted.. in a couple
of seconds or so.. you'll be in the thermal and going up just as the tow
plane exits it and hits the sink

it's hard enough fighting the thermal drafts.. but to add an unplanned
excursion into the wake? a couple of those.. and at 2K AGL.. I'm off...

BT

"Robert John" > wrote in
message ...
> I don't think the positition of the horizon should
> make any difference. In mountains it's irrelevant
> and different tugs will climb at different rates -
> a powerful tug will be more pitched up and adopt a
> higher position relative to the horizon than a low
> power one (relative to the thrust line, the prop-wash
> and the best position of the glider just above the
> prop-wash).
> One of the advantages of being as low as possible is
> not just the extra time that it takes to get to 'upset'
> position (which is small) but the fact that you are
> less likely to lose sight of the tug in the first place.
> Once you can't see the tug, things can go wrong very
> quickly.
> I've flown in Australia with their low tow and whilst
> I'm sure each method has its merits, I am personally
> much more comfortable with the UK position, don't like
> having to transition through the propwash at low level
> and find that teaching a 'correct' position that looks
> almost identical to the position on the ground before
> All Out is easier too.
> Rob
>
> At 16:48 09 January 2004, Eric Greenwell wrote:
> >Andy Durbin wrote:
> >
> >> As a US instructor I have flown with many pilots that
> >>received their
> >> initial training from other instructors. I have often
> >>been surprised
> >> at the tow position taken by such pilots. I usually
> >>urge them to keep
> >> lowering the tow position until they feel the wake,
> >>then to move just
> >> high enough that the wake is not a factor. That tow
> >>position may be
> >> 10 or 15 ft lower than that initially used.
> >
> >Where is the towplane, relative to the horizon?
> >
> >> A pilot flying a high high tow has less time to react
> >>to a potential
> >> upset than one flying the UK recommended low high
> >>tow. The fact that
> >> US pilots seem to be trained to use high high tow
> >>may explain why tug
> >> upsets continue to happen even when a nose or forward
> >>hook is used.
> >
> >10 or 15 feet doesn't sound like it would give much
> >extra time, not like
> >the low tow position Australia uses.
> >
> >--
> >-----
> >change 'netto' to 'net' to email me directly
> >
> >Eric Greenwell
> >Washington State
> >USA
> >
> >
>
>
>

[Robert John]

With the supercubs and Robin DR400s at LGC the tug
wheels are generally on or a little above the horizon.
I wouldn't generally be so low as to be catching the
wake though in strong thermal conditions I can see
that you might. If I tow through a strong thermal
I'm going to release anyway!
Rob

At 18:00 09 January 2004, Eric Greenwell wrote:
>Robert John wrote:
>
>> I don't think the positition of the horizon should
>> make any difference.
>
>It's the position I typically use, so I'm trying to
>get an idea of how
>different it is from what I normally do. Unfortunately,
>I can't go out
>and experiment right now, with a foot of snow on the
>runway!
>
>So, with a 180 hp Super Cub or Pawnee, say, is the
>tug canopy on the
>horizon, the wing root, wheels, or maybe the tug is
>an entire 'tug'
>distance above the horizon?
>
>> In mountains it's irrelevant
>> and different tugs will climb at different rates -
>> a powerful tug will be more pitched up and adopt a
>> higher position relative to the horizon than a low
>> power one (relative to the thrust line, the prop-wash
>> and the best position of the glider just above the
>> prop-wash).
>
>--
>-----
>change 'netto' to 'net' to email me directly
>
>Eric Greenwell
>Washington State
>USA
>
>

[Ian Johnston]

Eric Greenwell > wrote in message >...

> I think you forgot to account for the increasing load that pitching up
> produces. Sure, the lever arm is reduced, but the glider is at a higher
> angle of attack, increasing it's lift. This increases the force much
> more than the lever arm is reduced, and the pitch up continues.

Good point. I have along train journey today, and will have a ponder
on this. I suspect the outcome will be along the lines of "the glider
has stick fixed stability in free flight anyway: the effect of the
added winch cable force is to increase this stability".

> This eventually stabilizes with the glider in the normal nose high
> attitude of a winch launch, but this is not a good attitude for
> aerotowing! For a nose hook, the lever arm is much less to begin with,
> and a small pitch up reduces it to zero - quite a different situation.

Agreed completely.

Ian

[Ian Johnston]

(Mark James Boyd) wrote in message news:<3ffede24$1@darkstar>...
> >Mind you, if it was a type which was often aerotowed on a belly hook,
> >and if the pilot knew what s/he was in for, and had suitable
> >experience, then it wouldn't worry me greatly.
>
> The same holds true for aerotowing an L-13 by the tail tie down.

What, if it was often done, and en experienced pilot tried doing it?

> If someone had tried this in a wind tunnel first,
> and had lightning quick reflexes, and adjusted to a suitable
> CG, perhaps he could reliably fly it on aerotow tail first, facing
> rearward, and upon release, do a horizontal hammerhead type
> manuever and then fly normally.

No s/he couldn't. The setup would be extremely unstable, both
dynamically and aerodynamically. That doesn't just mean it's
difficult: it simply can't be done.

> With the appropriate training, conditions, and experience,
> one can fly an L-13 tail first, or fly the Wright flyer. This
> is trivially true.

Sorry. It's trivially untrue. Not a terribly good basis for an
argument. Hint: look at the way the Flyer's elevator was hinged. Or
look at the relative angles of fore- and main-plane.

Ian

[Edward Downham]

I think it is interesting to look at what types of glider have been involved in
aerotow upsets in the past.

Most of the incidents/accidents cited here have been in older generation
gliders with low wingloadings and stalling speeds. They have a natural tendency
to want to rear up behind the tug and the aerotow is generally flown with quite
a large amount of forward stick, possibly outside the trim range.

Compare this with the later high wingloading glass gliders, especially when
flown fully ballasted. Unless the tug accelerates to 70Kts or so you are left
dangling below, trying to get out of the slipstream.

I find the most worrying thing about towing from a belly/winch hook is the
possibility of a back release at an awkward height. When I do a long tow I
disable the back release.

I find towing off the rear hook more comfortable in some gliders, as the nose
doesn't get dragged into the turn so much. I have a '27 and the nose hook is a
bit of an abortion so I don't use it unless I have to (slope, crosswinds etc.)

As a tug pilot I would be quite happy with someone in a modern glider behind
me, towing on the belly hook, as long as they were trained to aerotow properly
and paid attention to what they were doing. If in doubt, pull the release!

Anyone who has aerotowed in gliders from the 60's or before, using modern tugs
and their higher speeds, will know how 'on the limit' the whole thing feels and
what a relief it is to come off tow. Compare that to modern heavy machines
where you have a large margin of control.

To summarise my opinion: In modern gliders the hook position is almost
irrelevant when discussing the possibility of an aerotow upset - the main
factor is the competence of the guy on the back and how much concentration he
has on the task in hand.

[Mark James Boyd]

In article >,
Ian Johnston > wrote:
(Mark James Boyd) wrote
in message news:<3ffede24$1@darkstar>...
>

>> If someone had tried this in a wind tunnel first,
>> and had lightning quick reflexes, and adjusted to a suitable
>> CG, perhaps he could reliably fly it on aerotow tail first, facing
>> rearward, and upon release, do a horizontal hammerhead type
>> manuever and then fly normally.
>
>No s/he couldn't. The setup would be extremely unstable, both
>dynamically and aerodynamically. That doesn't just mean it's
>difficult: it simply can't be done.
>
>> With the appropriate training, conditions, and experience,
>> one can fly an L-13 tail first, or fly the Wright flyer. This
>> is trivially true.
>
>Sorry. It's trivially untrue. Not a terribly good basis for an
>argument. Hint: look at the way the Flyer's elevator was hinged. Or
>look at the relative angles of fore- and main-plane.
>
>Ian

Hmmm...for those of you who believe an aircraft which is dynamically,
statically, and otherwise aerodynamically unstable cannot be flown,

check out www.google.com

type in the words "X-15 dynamics of flight"

read chapter 7, including reference to Wright Flyer.

Those NASA folks can do some amazing things when they put
their minds and your dollars in action...

If you have enough time and $$$$'s, I believe you can
make very strange things fly. John Shelton is just one
example... ;P

The easiest "trivial" way to aerotow an L-13 by the
tail, which involves little aerodynamics at all,
is with a powerful helicopter. Or perhaps tow it on a
one foot rope behind a DC-10? Cmon, how about a little
imagination before baldly declaring something "impossible"? ;)

In the end I've enjoyed this thread, and the stories of
experienced pilots who have mentioned that towing from
a hook closer to CG simply takes more pilot attention,
quicker corrections, and has the potential for
ending up in an unusual attitude much faster. I was
a little surprised that nobody mentioned the importance
of setting trim correctly for loaded CG before takeoff.
This has been the source of some surprises at our club...

And for the rest of you...forgive me for diverging into the
adsurd at times. I find the extreme case sometimes provides
new insights and clearer pictures of the forces at work,
but for some readers it perhaps obscures and distracts from
the more practical issues. The X-15 and dynamically unstable
flying machines is quite a tangent from the original thread...

[Z Goudie]

At 14:18 11 January 2004, Edward Downham wrote:
>I think it is interesting to look at what types of
>glider have been involved in aerotow upsets in the
past.

I seem to remember a BGA poster which highlighted the
dangers of the combination of a CG hook, high wing
glider and a pilot who had little aerotowing experience.

The recommendation to tug-pilots and instructors was
not to let any more than two of these factors meet
on the same launch!

[Marc Ramsey]

Edward Downham wrote:
> I find the most worrying thing about towing from a belly/winch hook is the
> possibility of a back release at an awkward height. When I do a long tow I
> disable the back release.

As one who has had a back release 50 miles from home, over the desolate
terrain of central Nevada, just after sunset, I can relate to that!

Marc

[Peter Creswick]

I must say that I am a bit confused by all this discussion.
When I was trained back in the 70's, the rules were simple, nose tow for aerotow, belly tow for
winch, NO exceptions.
The reason for nose tow on aerotow was to keep the "line of forces" in as near as possible to a
straight line, ie, from the tug, the pull force is on the line, the force is applied to the glider
at the nose with the "projected line of force" being pretty much through the glider cg, and from a
yaw point of view, there was a continuous restoring couple since even if you got out of line a bit,
the resulting "side force" was applied far forward of the cg, and it was in the direction of the
required correction, ie, it was a "self restoring" force.
If on the other hand, you towed with the belly cg hook, the "line of force" was way below the cg,
and, worse still, it is virtually directly below the cg, with virtually no yaw restoring force
available, and under some conditions, can produce pitch control difficulties with hook way below cg,
which may be well below the aerodynamic centre, particularly on older high wing gliders with fairly
"deep" fuselages (ie, upright seating) compared to modern high performance gliders, which tend to
have mid or shoulder wings and reclining seating with shallow fuselage depth. In other words, if
you take a "side view" of the three positions, ie, hook, cg and aerodynamic centre, on the older
gliders, the distance hook to cg and the distance cg to aerodynamic centre is substantial, setting
up the possibility of significant "divergent pitch couples" under some conditions, often requiring
substantial forward stick on tow to control. These two distances are much reduced on modern
gliders, hence the possible "pitch couples" are reduced, hence the possible control problems are
reduced.
The second issue is "best towing speed" under "normal conditions". Older gliders tended to have
lower wing loading and lower min sink and best l/d speeds. Usually, a well designed glider has
minimum trim forces required at best l/d. The further you move from best l/d speed, faster or
slower, the more trim or stick force you need. Older gliders had fairly steep polars, modern
gliders have fairly flat polars. Thus the available speed range for towing with reasonable and safe
control characteristics is narrower for older gliders than modern ones.
Then there is the length of the tow rope to consider. A long rope reduces the workload on the
glider pilot substantially, since everything is far less "twitchy" and there is more time to correct
divergent trends as the tug goes through the edge of a thermal or turbulence or whatever. Short
ropes reduce reaction time and generate greater "relative tug / glider" station keeping
displacements, requiring faster and more positive corrections by the glider pilot to return to
position. We always used longish ropes, 150 to 200 feet. I can not understand why people want to
use short ropes. To me, anything under 100 feet is insane, just asking for trouble.
Now this bit is my own personal observation, but the best towing speed for older gliders always
seemed to me to be about 1.2 to 1.3 times best l/d speed, simply because of trim and control issues,
newer gliders say 1.2 to 1.4 best l/d.
For the sake of illustration only, lets create some numbers. Say old glider X has best l/d at
45KIAS, I found it towed best at 55 to 60 KIAS, no more. Say modern glider Y has best l/d at
55KIAS, I found it towed best faster, ie, around 65 to 75 KIAS. Note, that both the speed is
higher, and the speed range is greater, for the modern gliders.
This then puts the requirement back on the tug pilot, to tow at the appropriate speed(s) for the
glider he has on the rope at the time.
Unfortunately, I get the impression, that most tugs were/are operated to try and make the tow most
efficient for them, to reduce costs etc, which can create the situation where a powerful tug is
towing too fast for an old glider, which means that even if the tow is stable, the pilot may be
using a lot of stick just to stay there. If conditions are turbulent, he will have to be "on his
toes". If he is on a short rope as well, he will have to be "very toeie", and if he/she is a
relatively inexperienced pilot to boot, then perhaps the club secretary should start checking for
those insurance claim forms.
Under powered tugs trying to drag a fully ballasted open ship is another story, but I never actually
had that experience, so I will leave that issue alone.
In short, I think club CFI's and Tugmasters/captains need to give towing configurations a total
rethink, from first principles.

[Bruce Hoult]

In article <m6YKb.427104$J77.33562@fed1read07>,
Greg Arnold > wrote:

> Marc Ramsey wrote:
>
>
> >
> > If these figures aren't available, is the use of CG hooks being
> > discouraged based simply on the assumed lack of positive longitudinal
> > stability during aerotow?
>
>
> Is the pull on a CG hook during aerotow ever great enough to have much
> effect on the longitudinal stability of the glider? I have never
> noticed such an effect, so I wonder if pilots who fly from a winch (very
> quick acceleration and doubtless a significant effect on longitudinal
> stability) are unfairly extrapolating their experience there to the
> aerotow situation.
>
> Doubtless a nose hook is better for aerotow, but I wonder if the alleged
> advantages aren't being oversold by some posters to this thread.

I've done 36 aero-tow flights in an original model Janus with only a
CofG hook. It's hard to say wihtout being able to try it on a nose hook
but I think the feel-free flying tailplane is a *much* bigger issue with
it than the belly hook. I've noticed a pitch-up tendency as a slack
rope comes tight, but it's always been minor and easily allowed-for.

A couple of days ago I had an opportunity to do a winch launch in the
same model of Janus. Even with a powerful winch (far greater
acceleration than a tow plane), it was easy to hold the glider level
just after it became airborne, and it took positive action to go into
the climb.

I think my attitude towards aero-towing in the Janus is summed up by:

- it's not a problem if you're alert, and it hasn't been a problem even
when I haven't flown anything for 1 - 2 years and then fly the Janus
first-up.

- if it cost in the region of US$1k to put a nose hook on the Janus
then I'd probably think that it was worth doing as a form of insurance.

- I think I'm glad I'm not an instructor trying to teach aerotowing in
it :-)

All in all I think it's just one of those things that contribute to the
Janus providing a noticably higher piloting workload than, say, our Twin
Astirs, but all the same I'll fly it in preference any day of the week.

-- Bruce

[K.P. Termaat]

Some years ago I had a back release on the belly hook of my Pik-20D while
being towed in Gap Tallard France. I was still pretty low when it happened
over unlandable terrain in mountanous area (near the Petite Céuse). Luckily
enough I could just make it back to the airfield.
Since then I use a small piece of spongie rubber between the outer ring of
the Tost hook and the fuselage at the back side of the ring. In this way the
outer ring can still move backwards when necessary, but not very easily
anymore. I have had no back release problems since then. I use it also on my
later gliders.

Karel, NL

"Marc Ramsey" > schreef in bericht
m...
> Edward Downham wrote:
> > I find the most worrying thing about towing from a belly/winch hook is
the
> > possibility of a back release at an awkward height. When I do a long tow
I
> > disable the back release.
>
> As one who has had a back release 50 miles from home, over the desolate
> terrain of central Nevada, just after sunset, I can relate to that!
>
> Marc

[Tony Verhulst]

>>In the flat lands,
>>if the tug wings are on or above the horizon, you're too high, IMHO.
>
> I think you got something reversed. The lower the glider goes, the
> higher above the horizon the tug will appear to be.

I hate it when I do that. Yeah, I *meant* below the horizon. Thanks for
the catch.

Tony

[Tony Verhulst]

> we "train".. tow plane on the horizon.. granted there are hills/mountains
> all around so the horizon is a "relative" term...

I've also been on tow on really hazy says when there was no visible horizon.

> keep all 3 wheels of the
> tow on the same horizontal line.. the tail wheel between the mains.. works
> just fine for the Pawnee 235

Yup, reference to the tow plane, that's the ticket. Behind the Birddog,
I like to fly tow so that the horizontal stabilizor lines up where the
gear and wing struts join the fuselage.

Tony V.

[Chris Rowland]

On Mon, 12 Jan 2004 11:42:08 -0500, Tony Verhulst
> wrote:

>
>>>In the flat lands,
>>>if the tug wings are on or above the horizon, you're too high, IMHO.

What we teach in the UK is to keep the tug in the correct position on
the canopy, not a position on the horizon.

The position of the horizon changes depending on the terrain, the
position of the tug on the canopy doesn't seem to.

On the original subject I can add some experience.

Some years ago (mid 70s) I had a flight in a Ka6E on aerotow and got
slightly too high just after take off. I was surprised and alarmed to
discover I needed to put the stick on the front stop to start the
glider descending - slowly. A little higher or a bit of bad luck and
I could have joined the tug upset statistics.

This was with a CofG hook.
The tug was not powerful - an Auster.
It was one of my first flights on type.
I was a reasonably experienced pilot - 400-500 hours, Gold C,
Instructor, current on Aerotow.
Fine weather, light wind.

I still remember - nearly 30 years later - the feeling of helplessness
as I sat with the stick on the front stop, waiting for something to
happen - and yes, I was just about to release when it started going
down.

I'm not fanatic about this and I would launch on the CofG hook if
there was no alternative - or a good reason but if I was in charge of
a club that did aerotow all the club gliders would have nose hooks and
use them.

Chris Rowland