CG hook on aero tows??

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)

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

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)

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

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

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)

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)

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.

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?

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