Compare/Contrast: CG hook on aerotow vs. CG hook on winch

[son_of_flubber]

I've been told (and witnessed) that aerotow on CG hook is initially difficult for someone who has trained for aerotow with a "nose hook" (aka hook-forward-of-CG). Suppose this CG-hook-newbie were to take winch tow training (with CG hook). Would the winch training reduce the initial difficulty of a CG hook aerotow?

Do the difficulties/danger of aerotow with CG hook go away completely with training and experience?

What sorts of misadventures are reasonably attributed to aerotow on CG hook?

I understand why CG hook is superior for winch tow. No need to rehash that explanation.

[Darryl Ramm]

On Thursday, May 24, 2012 7:54:00 PM UTC-7, son_of_flubber wrote:
> I've been told (and witnessed) that aerotow on CG hook is initially difficult for someone who has trained for aerotow with a "nose hook" (aka hook-forward-of-CG). Suppose this CG-hook-newbie were to take winch tow training (with CG hook). Would the winch training reduce the initial difficulty of a CG hook aerotow?
>
> Do the difficulties/danger of aerotow with CG hook go away completely with training and experience?
>
> What sorts of misadventures are reasonably attributed to aerotow on CG hook?
>
> I understand why CG hook is superior for winch tow. No need to rehash that explanation.

There is increased risk that come from the directional squirliness. Can you reduce this with training. Sure. Can you eliminate any risk, no. Can you reduce it enough to feel comfortable. Maybe, but that is a personal risk decision, not something somebody else can tell you. But I've seen a few departures to the weeds with folks aerotowing with a CG hook. The attention getting ones involve crosswinds and narrow strips and/or tall grass... ending in ground loops. That cross wind handling, need to be ready to quick release etc. should be things to look at with an instructor.

Its not clear what you are flying or where, but some flight manuals do prohibit aerotowing with a CG hook (e.g. my ASH-26E does).

Darryl

[Bill D]

On May 24, 8:54*pm, son_of_flubber > wrote:
> I've been told (and witnessed) that aerotow on CG hook is initially difficult for someone who has trained for aerotow with a "nose hook" (aka hook-forward-of-CG). *Suppose this CG-hook-newbie were to take winch tow training (with CG hook). *Would the winch training reduce the initial difficulty of a CG hook aerotow?
>
> Do the difficulties/danger of aerotow with CG hook go away completely with training and experience?
>
> What sorts of misadventures are reasonably attributed to aerotow on CG hook?
>
> I understand why CG hook is superior for winch tow. *No need to rehash that explanation.

Most glass two seat trainers (Grob, ASK-21, etc.) have both nose and
CG hooks so you can arrange to get some flight instruction in one aero
towing with the CG hook. Some countries prohibit aero tow with CG
hooks or require special training to do so. I can't say that 100% of
the dangers go away with training and experience but very nearly so.

I think winch training will improve any pilot - sometimes
substantially and not just with a CG hook.

For pilots trained on aero tow, the main danger with a CG hook is a
ground loop on the takeoff roll - a nose hook tends to keep the glider
rolling straight if a wing drops but the effect is small. If seen
many if not more ground loops with nose hooks.

A glider aero towing with a CG hook can easily climb above the tug
creating a very dangerous situation for the tug pilot but these upsets
happened primarily to pilots who had mostly winch experience and
little aero tow experience. It's as easy to stay in position behind
the tug but you have to be aware of the need to do so - you have to
really fly formation on the tug. The rope will not pull you back into
position.

[Eric Greenwell[_4_]]

On 5/24/2012 7:54 PM, son_of_flubber wrote:
> I've been told (and witnessed) that aerotow on CG hook is initially
> difficult for someone who has trained for aerotow with a "nose hook"
> (aka hook-forward-of-CG). Suppose this CG-hook-newbie were to take
> winch tow training (with CG hook). Would the winch training reduce
> the initial difficulty of a CG hook aerotow?

No, and I suggest it may make you worse at aerotowing, because you learn
to put the glider in a steep climb. "Kiting" on tow is a bad problem;
"kiting" during a winch launch is normal operation.

>
> Do the difficulties/danger of aerotow with CG hook go away completely
> with training and experience?

No, but you can significantly reduce the risks with training and experience.
>
> What sorts of misadventures are reasonably attributed to aerotow on
> CG hook?

The worst is the increased potential for the aforementioned kiting; the
rest tend to happen on the ground with a chance for damage, but not less
risk to people.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

[b4soaring]

On Friday, 25 May 2012 03:54:00 UTC+1, son_of_flubber wrote:
> I've been told (and witnessed) that aerotow on CG hook is initially difficult for someone who has trained for aerotow with a "nose hook" (aka hook-forward-of-CG). Suppose this CG-hook-newbie were to take winch tow training (with CG hook). Would the winch training reduce the initial difficulty of a CG hook aerotow?
>
> Do the difficulties/danger of aerotow with CG hook go away completely with training and experience?
>
> What sorts of misadventures are reasonably attributed to aerotow on CG hook?
>
> I understand why CG hook is superior for winch tow. No need to rehash that explanation.

Also, CG hooks can back release if you get a lot of slack in the rope. The manual may suggest a method for blocking the back release - make sure you remove it before winching.

[BruceGreeff]

In the spirit of embarrasing admissions here.

I transitioned to aerotow at around 300 flights. Only ever winch
launched for the first part of my career.

By then I was a happy and reasonably competent Std Cirrus driver. (no
nose hook) I found aerotow difficult to get right because of over
controlling the Grob Twin Astir - I was not used to the momentum in
those heavy wings, and we were towing on CG hook so that I would be used
to it when I transited to the Cirrus - and we wallowed all over the
place behind the tug. To the despair of my instructors who no doubt
started wondering how I had flown solo...
Trying to simultaneously transition to aerotow, on CG hook, with a
completely new class of glider to me - put me back at ab-initio
competence for a while.

To shorten a long and frustrating experience - the winch experience on
the CG hook was little help. In fact the winch training can impede
progress. If you can fly aerotow competently the CG hook makes it only a
little more difficult. The aircraft will not self correct nearly as much
as on nose hook, so sloppy flying will be rewarded with diverging
excursions.

Then the good news - to get back to your questions - as soon as the CFI
let me go fly my own nimble little Cirrus it all went a lot better.
There is no substitute for experience - on type, and yes training will
help. The control harmony of what you are flying will influence the
outcome and what really counts is experience with aerotow in general,
and experience with what you are flying. Specifically the ability to fly
very precisely, and experience on the type you plan to fly on the CG hook.

CG hook specific misadventures:
If you get too high - especially with some designs, there is danger of
kiteing.
On the ground run, crosswinds are much more of an issue. No correcting
force on the nose so the grass at the side of the runway exerts an
inexorable attraction. You have to be on top of lateral control all the
time and be prepared to release the moment if goes sideways. Lateral
diversions on the ground run that are recoverable on nose hook tow will
result in a ground loop on the CG hook.
If your mount has airbrakes behind the CG you can help with directional
stability at any point by cracking them open.
Nose up pitch - the CG hook is below the centreline, so jerks on the tow
rope will tend to rotate the nose up. Especially on a light high drag
single seater like a Ka8. (this is one way to go kiteing)

(PS: The Grob STILL flies like a pig on CG hook - just my biased
personal view.)



On 2012/05/25 4:54 AM, son_of_flubber wrote:
> I've been told (and witnessed) that aerotow on CG hook is initially difficult for someone who has trained for aerotow with a "nose hook" (aka hook-forward-of-CG). Suppose this CG-hook-newbie were to take winch tow training (with CG hook). Would the winch training reduce the initial difficulty of a CG hook aerotow?
>
> Do the difficulties/danger of aerotow with CG hook go away completely with training and experience?
>
> What sorts of misadventures are reasonably attributed to aerotow on CG hook?
>
> I understand why CG hook is superior for winch tow. No need to rehash that explanation.

--
Bruce Greeff
T59D #1771

[Tony V]

> CG hook specific misadventures:

> On the ground run, crosswinds are much more of an issue. No correcting
> force on the nose so the grass at the side of the runway exerts an
> inexorable attraction. You have to be on top of lateral control all the
> time and be prepared to release the moment if goes sideways. Lateral
> diversions on the ground run that are recoverable on nose hook tow will
> result in a ground loop on the CG hook.


Yes, to all of the above.

Plus, the glider type seems to make a difference. The Pegasus 101A that
I used to own a piece of always wanted to head for the weeds in any kind
of cross wind (and I've seen two others get damaged like that). OTOH,
the LS6-b that I now fly simply tracks straight under the same
conditions - no fuss.

Be sure that the glider is perfectly aligned before the take off roll on
a normal launch.

On an unassisted launch (read 'land out'), I put the down wingtip
slightly ahead, expecting the tip drag to straighten me out by the time
the wings level. How much of a lead depends on the surface type.

A nose hook is clearly superior for aero tow.

Tony "6N"

[Andy[_1_]]

On May 24, 7:54*pm, son_of_flubber > wrote:

> Do the difficulties/danger of aerotow with CG hook go away completely with training and experience?
>
> What sorts of misadventures are reasonably attributed to aerotow on CG hook?

It all depends on the glider. There is no generic answer.

To put my reply in context I have 456 aero tow launches with CG hook
in ASW19b and 243 aero tow launches with CG hook in ASW 28.

Neither glider has any issue at all with pitch stability or
directional control while in flight. The ASW 28 has no issues at all
with directional control on the the ground. However, the ASW 19b with
its small tail wheel could be tricky in moderate to strong cross winds
at the start of the takeoff roll. I have no way of knowing how much
better it would have been with a nose hook. With proper positioning
of the glider and with proper pilot technique I was able to make
takeoffs in any wind condition other gliders or pilots could handle.

Unless you are planning to fly a vintage glider that is prone to
kiting, and if you are competent at aerotow with a nose hook, the only
issues you are likely to experience with a CG hook are:

1. Risk of rope over-run and back release if the tug takes up slack
quickly. That's easily avoided by using the wheel brake.

2. Inadequate directional control at start of takeoff roll with cross
winds. This can be reduced by positioning the glider to compensate or
by using a wing runner who understands the problem and helps to keep
you straight.

The other side of the coin is that, as a tow pilot, I have been
subjected to moderate to severe abuse by pilots learning to fly the
Std Cirrus. As I said it depends on glider type and pilot skill
level.

A final data point - My ASW 28 has both a forward belly hook and a CG
hook. I choose to always use the CG hook for aerotow.

Andy (GY)

[Bill D]

On May 24, 10:18*pm, Eric Greenwell > wrote:
> On 5/24/2012 7:54 PM, son_of_flubber wrote:

> No, and I suggest it may make you worse at aerotowing, because you learn
> to put the glider in a steep climb. "Kiting" on tow is a bad problem;
> "kiting" during a winch launch is normal operation.

A pilot would have to be pretty stupid to let that happen. (Learning
is where you ADD knowledge - not replace what was already there.)
Learn winch launch - you WILL become a better pilot.

[Bill D]

On May 24, 11:05*pm, b4soaring > wrote:
> On Friday, 25 May 2012 03:54:00 UTC+1, son_of_flubber *wrote:

> Also, CG hooks can back release if you get a lot of slack in the rope. The manual may suggest a method for blocking the back release - make sure you remove it before winching.

If the CG hook is functioning properly (i.e. no weak springs), it
would take a LOT of slack to get a back release. So much so that
you'd be in front of the tug and probably want to release anyway.
Don't mess with the hook or you might make it malfunction completely.

Uncommanded releases are not a problem.

[T[_2_]]

On May 24, 7:54*pm, son_of_flubber > wrote:
> I've been told (and witnessed) that aerotow on CG hook is initially difficult for someone who has trained for aerotow with a "nose hook" (aka hook-forward-of-CG). *Suppose this CG-hook-newbie were to take winch tow training (with CG hook). *Would the winch training reduce the initial difficulty of a CG hook aerotow?
>
> Do the difficulties/danger of aerotow with CG hook go away completely with training and experience?
>
> What sorts of misadventures are reasonably attributed to aerotow on CG hook?
>
> I understand why CG hook is superior for winch tow. *No need to rehash that explanation.

Our primary trainer is an SGS 2-33A, with the low forward tow hook, it
likes to climb (kite) on tow and students learn to keep the nose down.
After solo they transition to the SGS 1-26D. After they are rated,
they transition to our Grob 103 on the nose hook. When they are ready
for single seat glass, we'll do a few tows in the Grob on the CG hook.

Big issue, on a CG hook the glider goes where it is pointed. No
assistance from rope tension on the nose to help keep you pointed on
the tow. We teach slack line recoveries to get the nose pointed at tow
before the line comes taught. That training transitions to tow with
the CG hook. Law of Primacy.

If on the ground, a wing goes down and you are pulled to the low wing
and can't correct, RELEASE!
If you are in the air and get wide in a turn on tow, get your nose
pointed back at tow. The glider will accelerate and faster means it
wants to climb. If you've ever been on water skis you'll understand.

T

[Kimmo Hytoenen]

>To put my reply in context I have 456 aero tow launches with CG
hook
>in ASW19b and 243 aero tow launches with CG hook in ASW 28.

Well, if you can manage ASW19b in aerotow using CG hook, you
should not have any problems with anyting else. I think that in
ASW19b the hook position is a typical compromise - works well
neither in winch or aerotow.

[ProfChrisReed]

I agree it's very type-specific. My first CG aerotow was an LS4 with a
tailskid on a gravel runway. 10 yds of furious pedal work and then it
all came together. On tow I could feel no difference from a nose hook
as the LS4 has perfect manners. My tailwheel Open Cirrus is even
easier, including launching (from short grass) with no wing runner and
the wing down.

I once aerotowed a K13 on the CG hook by accident - chatting to my
pupil and didn't notice the wrong hook was selected. No problem on the
ground run, but the offset CG hook meant that I had to fly the entire
tow with some rudder.

Other types may be harder to handle. An earlier poster said that only
a stupid pilot would allow kiting, but the BGA experiments some years
back demonstrated that stupidity would not be necessary. Take
something like a K8, which pitches up aggressively when there is a
strong pull on the rope. Add in strong thermals and a pilot who reacts
a second or two late (say low hours or out of currency) and kiting
goes out of control rapidly, leading to a tug upset.

Most UK clubs won't allow a light, high-wing glider to be aerotowed
off a CG hook (though experienced pilots might, or might not, be an
acceptable risk).

But a decent-handling glass glider should be perfectly manageable.
Directional instability on the ground run? Fix it with the rudder and,
if you can't, pull the bung. Perfectly safe enough. If you might hit
another glider or run off the field, even if you pull the release,
then you're launching from the wrong place.

[Markus Graeber]

On Friday, May 25, 2012 9:36:16 AM UTC-5, Bill D wrote:
> On May 24, 11:05*pm, b4soaring > wrote:
> > On Friday, 25 May 2012 03:54:00 UTC+1, son_of_flubber *wrote:
>
> > Also, CG hooks can back release if you get a lot of slack in the rope. The manual may suggest a method for blocking the back release - make sure you remove it before winching.
>
> If the CG hook is functioning properly (i.e. no weak springs), it
> would take a LOT of slack to get a back release. So much so that
> you'd be in front of the tug and probably want to release anyway.
> Don't mess with the hook or you might make it malfunction completely.
>
> Uncommanded releases are not a problem.

Actually they very well can be. I was piloting an IS-28B2 Twin Lark a couple of years ago behind a Super Cub during a 175 km transfer aerotow to another airport. We had to go over a pass and coming over the pass flew straight into serious rotor off a sharp mountain ridge bordering the valley we were entering.

Keeping the glider in position behind the super cub was a handful (a Twin Lark flies a bit like tank depending on what you are used to), I did end up getting some serious slack at one point while perfectly pointed at the cub. The cable bow reached back (the bow being to the left and almost level with the glider) to about where I was sitting in the front seat of the glider when I heard the "clonk" of the back release, the very moment I was starting to get worried it might just do that while remembering that the back release was not blocked...

The Twin Lark has a non-structural nose cone and the aerotow hook mounted just in front of the front rudder pedals. It is the same Tost hook as the CG hook installed and hence back releases unless you do something about it...

I could have grabbed the released cable if it hadn't been for the canopy, it was right next to me before I banked away to avoid potential damage. The bow was never a danger to the glider and never went anywhere near the wing tip or something else it could have caught onto, so the back release was completely unwarranted in this scenario.

An uneventful outlanding in unfamiliar terrain followed since we had plenty of altitude and I had a variety of fields to choose from but it was an all-nighter to get the trailer and crew there, load up the glider in the dark and get it to the destination airport through some serious mountain roads.

I made sure with a metal angle blocking any backwards movement of the hook rim that this would not happen again...

Markus Graeber

[Bill D]

On May 25, 7:20*pm, Markus Graeber > wrote:
> On Friday, May 25, 2012 9:36:16 AM UTC-5, Bill D wrote:
> > On May 24, 11:05*pm, b4soaring > wrote:
> > > On Friday, 25 May 2012 03:54:00 UTC+1, son_of_flubber *wrote:
>
> > > Also, CG hooks can back release if you get a lot of slack in the rope.. The manual may suggest a method for blocking the back release - make sure you remove it before winching.
>
> > If the CG hook is functioning properly (i.e. no weak springs), it
> > would take a LOT of slack to get a back release. *So much so that
> > you'd be in front of the tug and probably want to release anyway.
> > Don't mess with the hook or you might make it malfunction completely.
>
> > Uncommanded releases are not a problem.
>
> Actually they very well can be. I was piloting an IS-28B2 Twin Lark a couple of years ago behind a Super Cub during a 175 km transfer aerotow to another airport. We had to go over a pass and coming over the pass flew straight into serious rotor off a sharp mountain ridge bordering the valley we were entering.
>
> Keeping the glider in position behind the super cub was a handful (a Twin Lark flies a bit like tank depending on what you are used to), I did end up getting some serious slack at one point while perfectly pointed at the cub. The cable bow reached back (the bow being to the left and almost level with the glider) to about where I was sitting in the front seat of the glider when I heard the "clonk" of the back release, the very moment I was starting to get worried it might just do that while remembering that the back release was not blocked...
>
> The Twin Lark has a non-structural nose cone and the aerotow hook mounted just in front of the front rudder pedals. It is the same Tost hook as the CG hook installed and hence back releases unless you do something about it....
>
> I could have grabbed the released cable if it hadn't been for the canopy, it was right next to me before I banked away to avoid potential damage. The bow was never a danger to the glider and never went anywhere near the wing tip or something else it could have caught onto, so the back release was completely unwarranted in this scenario.
>
> An uneventful outlanding in unfamiliar terrain followed since we had plenty of altitude and I had a variety of fields to choose from but it was an all-nighter to get the trailer and crew there, load up the glider in the dark and get it to the destination airport through some serious mountain roads..
>
> I made sure with a metal angle blocking any backwards movement of the hook rim that this would not happen again...
>
> Markus Graeber

I used to own a Twin Lark equipped for serious wave and flew it in
some pretty darn turbulent Rocky mountain rotor. I never once got a
back release. I suspect you have weak springs in the hook or some
seriously draggy rope.

[Eric Greenwell[_4_]]

On 5/25/2012 7:31 AM, Bill D wrote:
> On May 24, 10:18 pm, Eric > wrote:
>> On 5/24/2012 7:54 PM, son_of_flubber wrote:
>
>> No, and I suggest it may make you worse at aerotowing, because you learn
>> to put the glider in a steep climb. "Kiting" on tow is a bad problem;
>> "kiting" during a winch launch is normal operation.
>
> A pilot would have to be pretty stupid to let that happen. (Learning
> is where you ADD knowledge - not replace what was already there.)
> Learn winch launch - you WILL become a better pilot.

Stupid, or poorly trained, or confused in an emergency. Still, I'm not
aware that learning winch launching in any way prepares you for aero
tow. The attitude and sight picture is entirely different, and you
aren't flying formation. I've done mostly aerotows and some auto tows,
and my experience was handling the glider took a different set of
skills. A notable difference is the auto launch was easier as long as
every thing went right - it took far less corrections compared to the
aero tow.

Learning to do winch launches so you are capable of doing winch launches
is an excellent reason, but I think it's a waste of time if your goal is
learning to do aerotow with a CG hook. The winch launch simply doesn't
challenge the pilot in the same way a CG hook aero tow does.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

[Don Johnstone[_4_]]

At 15:34 25 May 2012, T wrote:

>If on the ground, a wing goes down and you are pulled to the low wing
>and can't correct, RELEASE!

The above statement is probably the best advice you will ever receive, if I
was picky I would make it even shorter, "If on the ground, a wing goes
down, RELEASE!"
Several years ago the BGA in the UK recommended that the hand was on the
release at all times once the cable is attached (winch and aerotow). This
means that the pilot cannot give hand signals for the take up slack/all out
so the attachment of the cable is the indication that the pilot is ready
for launch. If the pilot wants to stop the launch he releases. In flapped
gliders I used a length of para cord attached to the release and looped
over my wrist.
I had reservations about this system but on balance it is the safest of the
alternatives, early release prevents a bad situation becoming a disaster.

[noel.wade]

To add to the chorus:

Any of the more-modern ships I've flown (70's glass/metal and newer)
seem to fly just fine on Aerotow with a CG hook. There are three
points to consider during the launch, in this order:

1) Wing position and cross-wind corrections. This has been covered by
others in the thread well-enough; but I'd like to emphasize that
starting with full downwind rudder helps a lot, at least in my
experience. And, as others have said: The best thing to do is watch
your first 50 feet of ground-roll. If it is going from bad to worse
yank the release and come to a controlled stop. In my experience with
auto-racing and flying, the worst situations always seem to happen
when something starts to go wrong and a person tries to "save it" (by
leaving their foot on the gas, or over-correcting, or whatever).
Don't try that - just call it off and try again.

2) On liftoff - as you get rolling try to use forward-stick and stick-
trim to get the tailwheel off the ground as soon as your rudder is
effective. That'll give you better steering control on the remainder
of takeoff *and* put the wing at a lower angle of attack (so you won't
jump/kite as quickly). Be prepared to add forward stick as you come
off the ground, and don't be shy about changing your trim multiple
times on the takeoff and aerotow. I'm not yet a CFIG but I've been
flying with a lot of new-to-XC pilots recently and I've noticed that a
LOT of them don't trim on aerotow, during thermalling, or in many
other phases of flight. Trim is your friend - the less you're pulling
or pushing on the stick, the better control-inputs you can provide for
roll & pitch excursions and the more relaxed you'll fly (making you
better able to feel and focus on other things).

3) Throughout the launch and aerotow - USE YOUR FEET! Aerotowing with
a CG hook means that you can pretty-much point the nose in any
direction you want. I actually view it as a nice "bonus" and prefer
towing with a CG hook for this reason (excepting the crosswind
difficulties during the beginning of the ground-roll). But I again
have found many newbies recently that don't think to use their feet on
aerotow. Its far easier to make small corrections with a bit of
rudder and slipping, than with big bank-angles on tow. Keep your feet
active and don't be shy about using some rudder (within reason) to
keep the glider behind the towplane and pointed in the direction you
want.

Just my $0.02,

--Noel
P.S. The back-release of the rope is a tricky thing on the ground in
my DG-300; like others I find a bit of wheelbrake while taking up
slack and just at the beginning of the roll is an effective "cure".

[Bill D]

On May 31, 7:05*pm, "noel.wade" > wrote:
> To add to the chorus:
>
> Any of the more-modern ships I've flown (70's glass/metal and newer)
> seem to fly just fine on Aerotow with a CG hook. *There are three
> points to consider during the launch, in this order:
>
> 1) Wing position and cross-wind corrections. *This has been covered by
> others in the thread well-enough; but I'd like to emphasize that
> starting with full downwind rudder helps a lot, at least in my
> experience. *And, as others have said: The best thing to do is watch
> your first 50 feet of ground-roll. *If it is going from bad to worse
> yank the release and come to a controlled stop. *In my experience with
> auto-racing and flying, the worst situations always seem to happen
> when something starts to go wrong and a person tries to "save it" (by
> leaving their foot on the gas, or over-correcting, or whatever).
> Don't try that - just call it off and try again.
>
> 2) On liftoff - as you get rolling try to use forward-stick and stick-
> trim to get the tailwheel off the ground as soon as your rudder is
> effective. *That'll give you better steering control on the remainder
> of takeoff *and* put the wing at a lower angle of attack (so you won't
> jump/kite as quickly). *Be prepared to add forward stick as you come
> off the ground, and don't be shy about changing your trim multiple
> times on the takeoff and aerotow. *I'm not yet a CFIG but I've been
> flying with a lot of new-to-XC pilots recently and I've noticed that a
> LOT of them don't trim on aerotow, during thermalling, or in many
> other phases of flight. *Trim is your friend - the less you're pulling
> or pushing on the stick, the better control-inputs you can provide for
> roll & pitch excursions and the more relaxed you'll fly (making you
> better able to feel and focus on other things).
>
> 3) Throughout the launch and aerotow - USE YOUR FEET! *Aerotowing with
> a CG hook means that you can pretty-much point the nose in any
> direction you want. *I actually view it as a nice "bonus" and prefer
> towing with a CG hook for this reason (excepting the crosswind
> difficulties during the beginning of the ground-roll). *But I again
> have found many newbies recently that don't think to use their feet on
> aerotow. *Its far easier to make small corrections with a bit of
> rudder and slipping, than with big bank-angles on tow. *Keep your feet
> active and don't be shy about using some rudder (within reason) to
> keep the glider behind the towplane and pointed in the direction you
> want.
>
> Just my $0.02,
>
> --Noel
> P.S. *The back-release of the rope is a tricky thing on the ground in
> my DG-300; like others I find a bit of wheelbrake while taking up
> slack and just at the beginning of the roll is an effective "cure".

I like your analytical approach. You'll make a great instructor.

[Mike the Strike]

I'm not sure that the advice to keep hold of the release on tow would be advisable in more turbulent environments (like Arizona) where unexpected glider movement could cause an unintended release.

Mike

[Squeaky]

To add to the chorus:

Just my $0.02,

--Noel
P.S. The back-release of the rope is a tricky thing on the ground in
my DG-300; like others I find a bit of wheelbrake while taking up
slack and just at the beginning of the roll is an effective "cure".

Not that I can claim to be an expert or know much, but in my Pilatus manual it mentions removing part of the Tost Release to allow for Winch launches --i.e. to allow a back release (I know my Pilatus is set for Aerotow and doesn;t back release with big slack...). If the part is not removed, there is no back release. Perhaps the different experiences in the same planes is tied to how their planes and the release mechanism were set up...

Just a WAG,
Squeak

[noel.wade]

On Jun 1, 8:59*am, Mike the Strike > wrote:
> I'm not sure that the advice to keep hold of the release on tow would be advisable in more turbulent environments (like Arizona) where unexpected glider movement could cause an unintended release.
>
> Mike

I've had the same thought, Mike.

When I take friends up for rides, I tell them to put their hand(s) on
their thigh(s). That way if they make any kind of reactionary grab,
they grip their leg and not an important control. I find that for
myself this technique works in turbulent conditions pretty well - keep
a hand on the thigh, preferrably near the release-handle. As part of
my pre-takeoff checklist, I practice reaching from my thigh to the
release a couple of times; so that I'm prepared in an emergency. Then
I put my hand back on my thigh. (Of course, my DG-300 makes this easy
by having the release-handle at the base of the panel, and I don't
have any flaps to deal with - so your mileage may vary).

--Noel

P.S. Bill - Thanks for the compliments! I appreciate the feedback
and comments that you and others have given on my various recent
postings. I'm still relatively new in the sport (just hit the 5 year
mark), and its nice to be able to pitch all these theories and ideas
and see everyone's different opinions and points of view. Its all
good food for thought.

[Ventus_a]

;815596']On 5/25/2012 7:31 AM, Bill D wrote:
On May 24, 10:18 pm, Eric wrote:
On 5/24/2012 7:54 PM, son_of_flubber wrote:

No, and I suggest it may make you worse at aerotowing, because you learn
to put the glider in a steep climb. "Kiting" on tow is a bad problem;
"kiting" during a winch launch is normal operation.

A pilot would have to be pretty stupid to let that happen. (Learning
is where you ADD knowledge - not replace what was already there.)
Learn winch launch - you WILL become a better pilot.

Stupid, or poorly trained, or confused in an emergency. Still, I'm not
aware that learning winch launching in any way prepares you for aero
tow. The attitude and sight picture is entirely different, and you
aren't flying formation. I've done mostly aerotows and some auto tows,
and my experience was handling the glider took a different set of
skills. A notable difference is the auto launch was easier as long as
every thing went right - it took far less corrections compared to the
aero tow.

Learning to do winch launches so you are capable of doing winch launches
is an excellent reason, but I think it's a waste of time if your goal is
learning to do aerotow with a CG hook. The winch launch simply doesn't
challenge the pilot in the same way a CG hook aero tow does.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

Agree. About the only thing winching could teach you, that you could take to aerotow, is a strong pull on the cable attached to the belly hook will tend to pitch the nose up.

With that small caveat I don't think that anything you learn from winch launching can prepare you for learning aerotow (tethered formation flying) from either a belly or a nose hook

Cheers
Colin

[Bill D]

On Jun 1, 1:04*pm, "noel.wade" > wrote:
> On Jun 1, 8:59*am, Mike the Strike > wrote:
>
> > I'm not sure that the advice to keep hold of the release on tow would be advisable in more turbulent environments (like Arizona) where unexpected glider movement could cause an unintended release.
>
> > Mike
>
> I've had the same thought, Mike.
>
> When I take friends up for rides, I tell them to put their hand(s) on
> their thigh(s). *That way if they make any kind of reactionary grab,
> they grip their leg and not an important control. *I find that for
> myself this technique works in turbulent conditions pretty well - keep
> a hand on the thigh, preferrably near the release-handle. *As part of
> my pre-takeoff checklist, I practice reaching from my thigh to the
> release a couple of times; so that I'm prepared in an emergency. *Then
> I put my hand back on my thigh. *(Of course, my DG-300 makes this easy
> by having the release-handle at the base of the panel, and I don't
> have any flaps to deal with - so your mileage may vary).
>
> --Noel
>
> P.S. *Bill - Thanks for the compliments! *I appreciate the feedback
> and comments that you and others have given on my various recent
> postings. *I'm still relatively new in the sport (just hit the 5 year
> mark), and its nice to be able to pitch all these theories and ideas
> and see everyone's different opinions and points of view. *Its all
> good food for thought.

I teach the heel of the left hand guarding the airbrake lever. That's
usually very close to the release knob. This covers two bases - open
spoiler on tow and quick release.

[dbrunone]

I transitioned from a nose-hook Blanik L-23 to my CG-hook LS1f, all on aerotow. To be honest, I don't think there is much difference on the CG hook, and I've taken off in some crosswind/gusty conditions. I'm not terribly experienced either. A buddy of mine has a CG hook on his Discus, and he had the same experience when he transitioned. Maybe some gliders are worse about weathervaning than others, but really I don't think it's as big a deal as people make it out to be.

[Andreas Maurer]

On Thu, 31 May 2012 18:05:10 -0700 (PDT), "noel.wade"
> wrote:



>2) On liftoff - as you get rolling try to use forward-stick and stick-
>trim to get the tailwheel off the ground as soon as your rudder is
>effective. That'll give you better steering control on the remainder
>of takeoff *and* put the wing at a lower angle of attack (so you won't
>jump/kite as quickly).

Hi Noel,

I have to admit that I regard this technique as bad airmanship. Really
bad airmanship (for example, an LS-6 will not lift off at all with
that technique). ;)

Let me explain:
I've often seen gliders roll behind the towplane for ages, balancing
on the main wheel, creating lots of rolling drag and bouncing all over
the place with each bump they hit. Usually lots of control deflections
to balance crosswind (a tail wheel in the air doesn't really help to
stabilize against a crosswind...), and often multiple touchdowns after
the first lift off due to PIO.

Sometimes I even see gliders with a pith attitude, effectively
creating negative lift until the pilot decides it's time to lift off.
Scary.


In my opinion it's so much easier to simply lift off with tail and
main wheel at the same time and let the glider float behind the tow
plane - once in the air, any glider is a lot easier to control, and in
my experience on grass strips the acceleration of the tow plane is
significantly better.

I fly from a 2000 ft grass strip where one really can see the
difference in the length of the takeoff run.
It doesn't make a huge difference with a light DG-300, but flying a
fully ballasted open class ship or a Duo Discus the correct technique
(liftoff at minimum speed) is usually the difference between the tow
plane being able to lift off or not (don't ask...).

One additional benefit: If the glider lifts off close to its minimum
speed, control authority of the elevator is less agressive, therefore
it's far less likely to overcontrol the glider and enter a PIO.




>Be prepared to add forward stick as you come
>off the ground, and don't be shy about changing your trim multiple
>times on the takeoff and aerotow.

I'm a little bit puzzled why one should mess with the trim during
aerotow.
By setting the elevator trim to the recommended position for aerotow
before launch (trim forward) you get a slight nose-down stick
pressure on all the (German built) gliders I've flown, which in my
opinion is extremely effective to prevent ballooning: The glider is a
lot more likely to descent behind the tow plane if you don't pay
attention for a moment. Better be too low behind the tow plane than
too high.

In my opinion messing with the trim during aerotow is not a good idea
for an inexperienced pilot - gliders with modern trim systems like the
DG-300 cannot be trimmed nose-down at all (as you have probably
noticed in your 300, it needs a significant stick push which isn't the
best idea if you want to keep your position behind the towplane).

Make one mistake, and you have a neutrally or even nose-up trimmed
glider - one further mistake and you might create brown pants in that
tow plane in front of you that is just disappearing under the nose of
your glider.



>3) Throughout the launch and aerotow - USE YOUR FEET!

Indeed. Always. And ignore that yaw string.

>But I again
>have found many newbies recently that don't think to use their feet on
>aerotow.

Clear case of bad training. One needs to learn to actively fly the
glider during an aerotow, otherwise problems are pre-programmed.




Best wishes
Andreas

[Don Johnstone[_4_]]

At 15:59 01 June 2012, Mike the Strike wrote:
>I'm not sure that the advice to keep hold of the release on tow would be
>advisable in more turbulent environments (like Arizona) where unexpected
>glider movement could cause an unintended release.
>
>Mike

Should have made it clear, it is only necessary to have your hand on the
release during the ground run and take off for both aerotow and winch
launch, once airborne and stable you can just keep your hand near the
release as normal. I use the looped paracord so I have some slack in the
sytem anyway.

[Dan Marotta]

All the concern about nose vs. CG release and the correcting force of the
nose release indicates, to me, poorly trained or lazy pilots. If you will
simply fly the aircraft and pay attention to your flight path, you'll find
that it makes no difference what type of release you have (unless you're
doing a ground launch).

Do some of you actually rely on the nose release to keep the nose aligned
rather than flying the aircraft?


"Andreas Maurer" > wrote in message
...
> On Thu, 31 May 2012 18:05:10 -0700 (PDT), "noel.wade"
> > wrote:
>
>
>
>>2) On liftoff - as you get rolling try to use forward-stick and stick-
>>trim to get the tailwheel off the ground as soon as your rudder is
>>effective. That'll give you better steering control on the remainder
>>of takeoff *and* put the wing at a lower angle of attack (so you won't
>>jump/kite as quickly).
>
> Hi Noel,
>
> I have to admit that I regard this technique as bad airmanship. Really
> bad airmanship (for example, an LS-6 will not lift off at all with
> that technique). ;)
>
> Let me explain:
> I've often seen gliders roll behind the towplane for ages, balancing
> on the main wheel, creating lots of rolling drag and bouncing all over
> the place with each bump they hit. Usually lots of control deflections
> to balance crosswind (a tail wheel in the air doesn't really help to
> stabilize against a crosswind...), and often multiple touchdowns after
> the first lift off due to PIO.
>
> Sometimes I even see gliders with a pith attitude, effectively
> creating negative lift until the pilot decides it's time to lift off.
> Scary.
>
>
> In my opinion it's so much easier to simply lift off with tail and
> main wheel at the same time and let the glider float behind the tow
> plane - once in the air, any glider is a lot easier to control, and in
> my experience on grass strips the acceleration of the tow plane is
> significantly better.
>
> I fly from a 2000 ft grass strip where one really can see the
> difference in the length of the takeoff run.
> It doesn't make a huge difference with a light DG-300, but flying a
> fully ballasted open class ship or a Duo Discus the correct technique
> (liftoff at minimum speed) is usually the difference between the tow
> plane being able to lift off or not (don't ask...).
>
> One additional benefit: If the glider lifts off close to its minimum
> speed, control authority of the elevator is less agressive, therefore
> it's far less likely to overcontrol the glider and enter a PIO.
>
>
>
>
>>Be prepared to add forward stick as you come
>>off the ground, and don't be shy about changing your trim multiple
>>times on the takeoff and aerotow.
>
> I'm a little bit puzzled why one should mess with the trim during
> aerotow.
> By setting the elevator trim to the recommended position for aerotow
> before launch (trim forward) you get a slight nose-down stick
> pressure on all the (German built) gliders I've flown, which in my
> opinion is extremely effective to prevent ballooning: The glider is a
> lot more likely to descent behind the tow plane if you don't pay
> attention for a moment. Better be too low behind the tow plane than
> too high.
>
> In my opinion messing with the trim during aerotow is not a good idea
> for an inexperienced pilot - gliders with modern trim systems like the
> DG-300 cannot be trimmed nose-down at all (as you have probably
> noticed in your 300, it needs a significant stick push which isn't the
> best idea if you want to keep your position behind the towplane).
>
> Make one mistake, and you have a neutrally or even nose-up trimmed
> glider - one further mistake and you might create brown pants in that
> tow plane in front of you that is just disappearing under the nose of
> your glider.
>
>
>
>>3) Throughout the launch and aerotow - USE YOUR FEET!
>
> Indeed. Always. And ignore that yaw string.
>
>>But I again
>>have found many newbies recently that don't think to use their feet on
>>aerotow.
>
> Clear case of bad training. One needs to learn to actively fly the
> glider during an aerotow, otherwise problems are pre-programmed.
>
>
>
>
> Best wishes
> Andreas

[Chris Nicholas[_2_]]

At 16:12 02 June 2012, Dan Marotta wrote:
>All the concern about nose vs. CG release and the correcting force of the

>nose release indicates, to me, poorly trained or lazy pilots. If you will

>simply fly the aircraft and pay attention to your flight path, you'll find

>that it makes no difference what type of release you have (unless you're
>doing a ground launch).

[snip]

The concern in the UK about towing on CG hook when a nose hook is available
came from tug pilot fatalities. The first, and most of the other, such
accidents happened with CG hooks, and one or more of the other factors,
which led to kiting, tug upset, and tug hitting the deck. As a result, the
BGA issued a poster listing the 6 factors most closely associated with
upsets, and advised having not more that two (IIRC) such factors on any one
launch.

More recently we started to have upsets again, so far fortunately without
fatality. Unable to find the original poster, we issued another which had
the following:
-------------------
Tug Upsets

These happen when the glider suddenly zooms above the tug, putting it into
a steep dive requiring considerable height to recover.

The BGA ran a successful campaign to end these fatalities to tug pilots,
but several years without incident now appear to have ended. This year
there have been two reported upsets and at least one other not reported.
Fortunately none resulted in crashes.

Six factors make upsets more likely:

 Lightweight, low wing-loading

 C of G hooks intended for winch launching

 Short ropes

 Inexperienced pilots

 Near aft C of G.

 Turbulent conditions

If two of these are present the danger becomes significant. More than
two should be considered unacceptable.

-----------------
Chris N

[Eric Greenwell[_4_]]

On 6/1/2012 5:11 PM, dbrunone wrote:
> I transitioned from a nose-hook Blanik L-23 to my CG-hook LS1f, all on
> aerotow. To be honest, I don't think there is much difference on the CG
> hook, and I've taken off in some crosswind/gusty conditions. I'm not
> terribly experienced either. A buddy of mine has a CG hook on his
> Discus, and he had the same experience when he transitioned. Maybe some
> gliders are worse about weathervaning than others, but really I don't
> think it's as big a deal as people make it out to be.

It may depend a great deal on the glider (some get aerodynamic control
sooner than others) and your launch conditions: if every launch uses an
experienced wing runner, a strong towplane, and the wind is always
straight down the runway, you will not notice much difference.

All the nose-hook gliders (primarily H301, ASH 26 E, and ASW20C) I've
flown were easier to aerotow than all the CG hook gliders (primarily
Ka6e, Std Cirrus, and ASW20C) I've flown. The ASW20C was a special case:
it came with a CG hook that I used for several years, then I had a nose
(actually, a "forward") hook installed. It was a noticeable and
significant improvement over the original CG hook.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

[Chris Nicholas[_2_]]

At 16:12 02 June 2012, Dan Marotta wrote:
>All the concern about nose vs. CG release and the correcting force of the

>nose release indicates, to me, poorly trained or lazy pilots. If you will

>simply fly the aircraft and pay attention to your flight path, you'll find

>that it makes no difference what type of release you have (unless you're
>doing a ground launch).

[snip]

The concern in the UK about towing on CG hook when a nose hook is available
came from tug pilot fatalities. The first, and most of the other, such
accidents happened with CG hooks, and one or more of the other factors,
which led to kiting, tug upset, and tug hitting the deck. As a result, the
BGA issued a poster listing the 6 factors most closely associated with
upsets, and advised having not more that two (IIRC) such factors on any one
launch.

More recently we started to have upsets again, so far fortunately without
fatality. Unable to find the original poster, we issued another which had
the following:
-------------------
Tug Upsets

These happen when the glider suddenly zooms above the tug, putting it into
a steep dive requiring considerable height to recover.

The BGA ran a successful campaign to end these fatalities to tug pilots,
but several years without incident now appear to have ended. This year
there have been two reported upsets and at least one other not reported.
Fortunately none resulted in crashes.

Six factors make upsets more likely:

 Lightweight, low wing-loading

 C of G hooks intended for winch launching

 Short ropes

 Inexperienced pilots

 Near aft C of G.

 Turbulent conditions

If two of these are present the danger becomes significant. More than
two should be considered unacceptable.

-----------------
Chris N

[Eric Greenwell[_4_]]

On 6/2/2012 9:12 AM, Dan Marotta wrote:
> All the concern about nose vs. CG release and the correcting force of
> the nose release indicates, to me, poorly trained or lazy pilots. If you
> will simply fly the aircraft and pay attention to your flight path,
> you'll find that it makes no difference what type of release you have
> (unless you're doing a ground launch).
>
> Do some of you actually rely on the nose release to keep the nose
> aligned rather than flying the aircraft?

I did in some conditions, such as cross winds and unassisted (no wing
runner) takeoffs. When the glider is moving slowly at the beginning of
the launch, there is no "flying" the glider - you are ballistic for a
length of time that depends on the wind and towplane acceleration.

Once aerodynamic control is available, then the differences between CG
and nose hooks are reduced, but in all the gliders I've flown, it was
still noticeable. How noticeable did depend on the glider type.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

[Chris Nicholas[_2_]]

At 16:12 02 June 2012, Dan Marotta wrote:
>All the concern about nose vs. CG release and the correcting force of the

>nose release indicates, to me, poorly trained or lazy pilots. If you will

>simply fly the aircraft and pay attention to your flight path, you'll find

>that it makes no difference what type of release you have (unless you're
>doing a ground launch).

[snip]

The concern in the UK about towing on CG hook when a nose hook is available
came from tug pilot fatalities. The first, and most of the other, such
accidents happened with CG hooks, and one or more of the other factors,
which led to kiting, tug upset, and tug hitting the deck. As a result, the
BGA issued a poster listing the 6 factors most closely associated with
upsets, and advised having not more that two (IIRC) such factors on any one
launch.

More recently we started to have upsets again, so far fortunately without
fatality. Unable to find the original poster, we issued another which had
the following:
-------------------
Tug Upsets

These happen when the glider suddenly zooms above the tug, putting it into
a steep dive requiring considerable height to recover.

The BGA ran a successful campaign to end these fatalities to tug pilots,
but several years without incident now appear to have ended. This year
there have been two reported upsets and at least one other not reported.
Fortunately none resulted in crashes.

Six factors make upsets more likely:

 Lightweight, low wing-loading

 C of G hooks intended for winch launching

 Short ropes

 Inexperienced pilots

 Near aft C of G.

 Turbulent conditions

If two of these are present the danger becomes significant. More than
two should be considered unacceptable.

-----------------
Chris N

[Chris Rollings[_2_]]

Given all the comments in the thread so far, I guess it's about time I gave
what follows another airing. It was written a few years ago in the
aftermath of a tow pilot fatality:

Whilst I was Chief Instructor at Booker Gliding Club, we conducted two
series of test on the phenomenon variously referred to as “Kiting�,
“Winch Launching behind the Tow-Plane� and “Sling-Shot Accident�,
one in 1978 and one in 1982; my memory of them is quite vivid.
Â*
Airplanes used were, for the first series, a Beagle Terrier (a side by
side, two place, high wing, tail-dragger), fitted with an Ottfur Glider
hook for towing (very similar to the Tost hook, dissimilar to the Schweizer
hook) with a 160 hp Lycoming engine; for the second series of tests a
PA18-180 with a Schweitzer hook was used. Gliders used were a Schleicher
Ka 8b and ASK 13. Tow rope initially used was a heavy (4000 lb breaking
strain) rope with a thinner rope weak link at the glider end (nominally 900
lb, but a well worn specimen could break at as little as 200 – 300 lbs
– laboratory tests, not opinion), the second series of test used the same
heavy duty rope with “Mity� links at each end, 1100 lbs at the
Tow-Plane end and 900 lbs at the Glider end – these links use metal shear
pins, one under load and a second unloaded, which takes over if the first
one fails. This eliminates failure due to fatigue and means that the links
always fail at close to their nominal load even after some time in service
– again laboratory tested, not just subjective opinion. Rope length was
around 180 feet in all cases.
Â*
I was the Glider Pilot on all tests; Tow-Plane Pilot was Verdun Luck (then
my deputy Chief Instructor) for the first series of tests and Brian
Spreckley (then Manager of Booker GC) for the second. The object of the
tests was to try to reproduce the “Kiting� under controlled
circumstances, with a view to developing a Tow-Plane release mechanism that
would automatically release the glider if it got dangerously high above the
Tow-Plane. All tests were conducted at about 4000 feet agl.
Â*
First test: Terrier Tow-Plane and ASK 13 on nose-hook. At about 4000 feet
I took the glider progressively higher above the tow-plane, eventually
reached about 100 feet above tow-plane (i.e. rope angle more than 45
degrees above horizontal). At about this point, the tow pilot, who had
been using progressively more back stick, ran out of back stick and the
Tow-Plane began to pitch nose down but not excessively violently. I
released at that point. It took a very positive control input on my part
to achieve the displacement, we both felt it was something unlikely to
occur accidentally, even with an inexperienced glider pilot, and there was
plenty of time for either party to release if it did occur.
Â*
Second test: Terrier Tow-Plane and ASK 13 on C of G hook. I pitched the
glider about 25 – 30 degrees nose up – the weak link broke immediately!
Tow pilot reported a sharp jerk, but no significant change to flight
path.
Â*
Third test: Terrier Tow-Plane, K 8b on C of G hook. I pitched the glider
about 25 degrees nose up. The glider continued to pitch up fairly rapidly
(as at the start of a winch launch) and substantial forward movement of the
stick only slightly slowed the rate of pitch. The glider achieved about 45
degrees nose up, speed increased rapidly from 55 knots to about 75 knots
and the glider was pulled back towards level flight (again as at the top of
a winch launch). I released at that point. The entire sequence of events
occupied a VERY short period of time (subsequently measured as 2 - 3
seconds). The Tow Pilot reported a marked deceleration and start of
pitching down which he attempted to contain by moving the stick back; this
was followed immediately by a very rapid pitch down accompanied by
significant negative “G�. The tow-plane finished up about 70 degrees
nose down and took about 400 feet to recover to level flight. We both
found the experience alarming, even undertaken deliberately at 4000 feet.
Our conclusion was that the combination of the initial pitch down and the
upward deflection of the elevator caused the horizontal stabilizer/elevator
combination to stall and the abrupt removal of the down-force it provided
caused the subsequent very rapid pitch-down and negative “G�.
Â*
Our first conclusion was that, in the event of this sequence occurring
accidentally as a result of an inadvertent pitch up by the glider pilot,
there was effectively no chance that either the glider pilot or tow-pilot
would recognise the problem and pull the release in the available time.
Â*
Attempts to produce a tow-plane hook that would release automatically were
unsuccessful for reasons that became apparent later.
Â*
These tests were repeated a few years later with a PA18 – 180 as the
tow-plane, Brian Spreckley flying it. The third test described above was
repeated and photographed from a chase plane using a 35 mm motor drive
camera on automatic (this took a frame every half second – video
camcorders of small size were not readily available then). The photo
sequence started with the glider in a slightly low normal tow position and
starting to pitch up, the second frame has the glider about 30 degrees nose
up and about 20 feet higher than previously in the third frame it is about
45 degrees nose up and has gained another 30 feet or so, the tow-plane is
already starting to pitch down, in the fourth frame the glider is about 100
feet higher than its original position and the climb is starting to
shallow, the tow-plane is about 50 degrees nose down, the final frame shows
the tow-plane about 70 degrees nose down and the glider almost back in
level flight , almost directly above it (that was about the point that I
pulled the release).
Â*
Sufficiently alarmed by events, Brian Spreckley had been trying to pull the
release in the tow-plane earlier and found that it would not operate until
my releasing at the glider end removed the tension from the rope.
Subsequent tests on the ground showed that the Schweizer hook fitted to the
tow-plane, whilst perfectly satisfactory under normal loads, was jammed
solid by the frictional loads when subject to a pull of around 700 lbs with
a slight upwards component – not something that a normal pre-flight check
would reveal.
Â*
We solved that problem on our tow-planes by replacing the bolt that the
hook latches onto with a small roller bearing. So far as I know, no one in
the UK has tested the Schweizer hook as fitted to a glider, but I would not
be surprised if it exhibited the same characteristics at high loads.
Â*
The photo sequence also showed that at no time was the glider at an angle
greater than 30 degrees above the tow-plane’s centre-line. However, of
course once the glider has pitched up, the wings generate considerable
extra lift and that extra lift provides extra load on the rope. With a
large, heavy glider it is easy to exceed weak link breaking strains and
with a lightweight machine the tension can easily rise to 700 lbs or so.
With that much load on the rope, quite a small upward angle provides enough
of a vertical component to produce the results described.
Â*
That of course is the reason that attempts to produce a hook that released
if a certain angle was exceeded were unsuccessful. The, quite small, angle
between the rope and the fuselage centreline needed to trigger the
“Kiting� when the glider is pitched significantly nose-up is not much
greater than the amount of out of position commonly experienced in
turbulent conditions. We did build an experimental hook and tried it, but,
set to an angle that prevented “Kiting� it occasionally dumped an
innocent glider in turbulence, and set to an angle that prevented that, it
didn’t prevent the “Kiting�. What was needed was a hook that
responded to the vertical component of the load, not the angle at which it
was applied, and that problem we decided was beyond us (at least in a form
robust and fool-proof enough to be attached to the rear end of a
tow-plane).
Â*
Our conclusions for preventing “Kiting� were:
Â*
Don’t aerotow gliders, especially lightweight, low wing-loading gliders,
on C of G hooks intended for winch launching (I think the JAR 22
requirement for nose hooks to be fitted to new gliders for aerotowing was
at least in part a result of these tests).
Â*
Don’t use short ropes. The speed at which things happen varies directly
with the length of the rope.
Â*
Don’t let inexperienced pilots fly at anywhere near aft C of G.
Â*
Don’t let inexperienced pilots fly solo in turbulent conditions.
Â*
Replace or modify all Schweizer hooks fitted to tow planes. (So far as I
know there are none on gliders in the UK, so that question never arose).
Â*
We did also modify our PA18’s so that instead of the release cable ending
at a floor-mounted lever, it went round a pulley where that lever used to
be, and then all the way up the side of the cockpit, anchored at the roof.
This meant that grabbing any point on the wire and pulling it in any
direction could operate the release; considerably easier than finding a
floor mounted lever when being subject to about minus two “G�. We
never regarded this modification as being likely to prevent a worst-case
scenario, because, as stated earlier, it was the opinion of all involved,
that in a real “Kiting� incident, there was no realistic hope that
either pilot would respond in time.


At 02:54 25 May 2012, son_of_flubber wrote:
>I've been told (and witnessed) that aerotow on CG hook is initially
>difficu=
>lt for someone who has trained for aerotow with a "nose hook" (aka
>hook-for=
>ward-of-CG). Suppose this CG-hook-newbie were to take winch tow training
>(=
>with CG hook). Would the winch training reduce the initial difficulty of
>a=
> CG hook aerotow?
>
>Do the difficulties/danger of aerotow with CG hook go away completely
with
>=
>training and experience?
>
>What sorts of misadventures are reasonably attributed to aerotow on CG
>hook=
>?
>
>I understand why CG hook is superior for winch tow. No need to rehash
>that=
> explanation.
>

[Steve Koerner]

I normally fly with aft CG. I have never had a kitting experience flying on a CG hook, but I have had occasion where holding full forward stick for a few seconds was necessary to hold attitude. That has happened only when the towplane was pulling me slower than I prefer.

This leads me to think that a preventive measure that perhaps every tow pilot should consider is to be vigilent in keeping the speed up on tow and especially in the first 500 feet (the death zone). At higher speed, the glider has more elevator authority to keep his nose down and the tug has more elevator authority to keep his nose up. Lifting forces on the elevator go as the square of airspeed, so a little extra airspeed can buy a lot of elevator authority.

Besides exacerbating the kiting scenario, slow towing at low altitude presents an entirely different and especially severe hazard to ballasted gliders.. That scenario has nearly killed me. Pulling the release is not an option when your glider is slow at 100 feet with the nose pointed up at 30 degrees in a full stall.

Keep the airspeed up tuggies.

[Dan Marotta]

A good post.

Some tow pilots strive to get into the air as quickly as possible since it's
easier to keep the tug straight in the air. This is not so nice for the
glider.

The last time I carried a full load of water, and with my CG aft of 90%, the
tug leapt into the air leaving me on the ground with full forward stick
trying to get the tail up. A few more knots would have made this an easy
tow.

When I'm towing, usually in a Pawnee these days, I simply guard the stick
during acceleration and let the tail come up by itself. Then, upon breaking
ground, fly in ground effect until reaching full tow speed for the glider's
weight. Haven't heard a complaint yet...


"Steve Koerner" > wrote in message
...
I normally fly with aft CG. I have never had a kitting experience flying on
a CG hook, but I have had occasion where holding full forward stick for a
few seconds was necessary to hold attitude. That has happened only when the
towplane was pulling me slower than I prefer.

This leads me to think that a preventive measure that perhaps every tow
pilot should consider is to be vigilent in keeping the speed up on tow and
especially in the first 500 feet (the death zone). At higher speed, the
glider has more elevator authority to keep his nose down and the tug has
more elevator authority to keep his nose up. Lifting forces on the elevator
go as the square of airspeed, so a little extra airspeed can buy a lot of
elevator authority.

Besides exacerbating the kiting scenario, slow towing at low altitude
presents an entirely different and especially severe hazard to ballasted
gliders. That scenario has nearly killed me. Pulling the release is not an
option when your glider is slow at 100 feet with the nose pointed up at 30
degrees in a full stall.

Keep the airspeed up tuggies.

[Dan Marotta]

Sounds to me like you're talking about aircraft limitations. I haven't yet
seen a case where the glider could safely takeoff with a nose hook but not
with a CG hook AND the tow pilot was willing to do the tow.

Your operation may vary but, where I fly, we have a 15 kt crosswind
component limit on the tow planes. I've towed and flown my CG hook equipped
LAK-17 with winds gusting up to 28 kts though the cross wind component was
under 15 kts. In these conditions, ground handling is the most difficult
aspect of the operation and we sometimes stand down simply because of the
risk of moving the tug.


"Eric Greenwell" > wrote in message
...
> On 6/2/2012 9:12 AM, Dan Marotta wrote:
>> All the concern about nose vs. CG release and the correcting force of
>> the nose release indicates, to me, poorly trained or lazy pilots. If you
>> will simply fly the aircraft and pay attention to your flight path,
>> you'll find that it makes no difference what type of release you have
>> (unless you're doing a ground launch).
>>
>> Do some of you actually rely on the nose release to keep the nose
>> aligned rather than flying the aircraft?
>
> I did in some conditions, such as cross winds and unassisted (no wing
> runner) takeoffs. When the glider is moving slowly at the beginning of the
> launch, there is no "flying" the glider - you are ballistic for a length
> of time that depends on the wind and towplane acceleration.
>
> Once aerodynamic control is available, then the differences between CG and
> nose hooks are reduced, but in all the gliders I've flown, it was still
> noticeable. How noticeable did depend on the glider type.
>
> --
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email
> me)

[noel.wade]

On Jun 1, 6:09*pm, Andreas Maurer > wrote:

> Let me explain:
> I've often seen gliders roll behind the towplane for ages, balancing
> on the main wheel, creating lots of rolling drag and bouncing all over
> the place with each bump they hit. Usually lots of control deflections
> to balance crosswind (a tail wheel in the air doesn't really help to
> stabilize against a crosswind...), and often multiple touchdowns after
> the first lift off due to PIO.

Andreas - Note that I said nothing about "pinning" the aircraft on the
ground. I simply said "get the tailwheel off the ground" - there's a
difference (albeit one I may not have clarified). You can get the
tailwheel off the ground (so the tail surfaces are more effective and
you can use the rudder to stay behind the towplane better), without
increasing your ground-roll by a huge margin.

I've seen plenty of people try to take off in a 2-point attitude with
the stick and/or trim back and when they jump in the air they quickly
get into a PIO because they have to shove the stick forward to prevent
kiting (and/or fight the back-pressure of a trim spring).

> creating negative lift until the pilot decides it's time to lift off.
> Scary.

Scary? Only if they prolong the takeoff to an unsafe degree.
Choosing when to take off is, IMHO, better than having the aircraft
jump into the air on the pilot and then the pilot is "behind" in
correcting and trying to chase the controls. But again, I was not
implying that people should keep the aircraft stuck to the ground -
just get the tailwheel off the ground so that you have better
directional control/authority.

> One additional benefit: If the glider lifts off close to its minimum
> speed, control authority of the elevator is less agressive, therefore
> it's far less likely to overcontrol the glider and enter a PIO.

The flipside of your argument is that at minimum control speed you are
also more likely to be upset and/or lose control in the event of a
thermal or wind gust. Where I fly, we sometimes hit 8-knot thermals
at the departure end of the runway. Hitting that with one wing at
minimum airspeed would really ruin your day (and probably the tugs, as
you roll and yank him with you). Plus, with less control-authority
you cannot prevent "weather-vaning" as easily. IMHO, what you want is
to take off in a reasonable amount of runway that yields a flying
airspeed that is sufficient for good control authority.

> I'm a little bit puzzled why one should mess with the trim during
> aerotow.
> By setting the elevator trim to the recommended position for aerotow
> before launch *(trim forward) you get a slight nose-down stick
> pressure on all the (German built) gliders I've flown, which in my
> opinion is extremely effective to prevent ballooning: The glider is a
> lot more likely to descent behind the tow plane if you don't pay
> attention for a moment. Better be too low behind the tow plane than
> too high.

....Because the factory-recommended trim setting does NOT account for
YOUR situation! It is a "book" value that doesn't account for your
weight, your CG, your aircraft's history of repairs or modifications,
etc. But most importantly: Because proper trim is always a good
idea. I know a lot of people are hesitant about this because they
think "wow, I'm so busy trying to keep position on-tow and look out
and manage the tow, why would I want to distract myself with trim?"
But they don't realize that part of the reason the workload is so high
is BECAUSE they're fighting the glider's trim! The truth is that
trimming properly lessens your workload and makes precision flying
easier. You should be able to (in a well-designed aircraft)
manipulate the trim without looking at it or taking your hands off the
primary flight controls. And you can feel the effects of the trim
change by the feedback on the stick - so if you make a couple of
incremental changes you can easily feel when you've got the trim set
properly (or close enough). Therefore adjusting the trim on-tow
should be relatively simple, and will result in a much better
experience (and with a lower work-load you can stay more alert to
traffic around you and emergency-preparedness as the tow progresses).

That nose-down moment IMHO is not good at all (and like all trim
settings, its highly dependent upon your current CG *and* your
airspeed). Why do I think a nose-down moment might not be good?
Springs are used for most glider control systems. Think about the way
a spring can bounce or oscillate, and think about your arm constantly
fighting that force. Isn't it clear how this can lead to PIOs and
over-controlling? Fighting a nose-down force may lead to PIOs just
like fighting a nose-up force can. Certainly the problem of kiting or
ballooning on initial takeoff is something to avoid; but I refer you
to my earlier comments in this message.

Bottom-line: The better you trim the aircraft in ALL phases of flight,
the better you'll fly. I may have only been doing this for a few
years; but the ONLY people I've had who fight me on this point are
people who've never used their trim all that much. Just last weekend
I mentored several budding XC pilots and almost all of them had a
horrible time making a consistent thermalling turn. Once I showed
them how to re-trim the aircraft once they'd established their bank-
angle and thermalling speed, all suddenly did MUCH better and remarked
on how much easier it was to thermal.
(Of course, then I had to remind them to watch their airspeed and re-
trim the aircraft as they rolled out of the turn... One step at a
time, I suppose! *chuckle*)

> DG-300 cannot be trimmed nose-down at all (as you have probably
> noticed in your 300, it needs a significant stick push which isn't the
> best idea if you want to keep your position behind the towplane).

Not true. I can hold the trim-release lever and apply a small amount
of forward force to the "trim indicator" (which is strong enough on my
ship to handle this load), while keeping the stick pushed to its
proper position to maintain attitude, and trim forward just fine.
Obviously this is not applicable to all aircraft; but I am pointing
out that the blanket statement is not, in fact, true.

BTW, you can also hold the trim release, briefly push the stick
forward while releasing the trim-lever, and then relax the stick aft
some. The nose will dip but if you practice this (NOT ON TOW) you can
get quite quick with the maneuver and the glider will only rise or
fall in relation to the tug by some 5 feet throughout the maneuver. I
do _not_ recommend this; but again just pointing out that its
possible. :-)

> Make one mistake, and you have a neutrally or even nose-up trimmed
> glider - one further mistake and you might create brown pants in that
> tow plane in front of you that is just disappearing under the nose of
> your glider.

Not sure I follow you... If you can keep pulling back on the stick to
offset your nose-down trim, why can't you keep pushing forward to
offset a nose-up trim? Either one is bad, and both can cause problems
if you leave tow position and don't correct for it. The glider
ballooning seems really bad and scary, but a seriously-low glider can
also cause the towplane to pitch up and stall or spin; its not like
one situation is "bad" and the other is "good". Both are bad!

Neutral trim on-tow and careful attention to tow-position should yield
the best tow.

> Clear case of bad training. One needs to learn to actively fly the
> glider during an aerotow, otherwise problems are pre-programmed.

Very true. But its not just training. Or rather, a lot of pilots get
complacent and don't think of themselves as needing "training" as they
age and gain experience. Bad habits form. Laziness happens. People
with nose-hooks can get used to always being pulled into position by
the tug; and subtly their rudder-use decreases over time. Then one
day they take a flight in a CG-hook aircraft and things get rough. :-P

Take care,

--Noel
P.S. If I were to summarize my typical aerotow (with my DG's CG-hook)
& my trim adjustments, here's how it goes:
1] I trim almost full-forward as part of my pre-takeoff check.
2] As the glider begins to roll, I keep wings level and try to track
behind the towplane.
3] As soon as the tail comes off the ground I give the trim-level a
quick squeeze & release (handy to do in the DG). This resets my trim
for a fairly flat attitude, giving me good rudder authority to track
behind the towplane.
(At my main airfield we have to stage off to the side of the runway
and begin the takeoff roll at an angle - rudder control is important
as we gently curve onto the runway and lift off flying down the
centerline)
4] As my airspeed climbs up about 5-10 knots above stall (around 40-45
knots in my DG), I apply a small amount of back-pressure to lift off
and fly in ground-effect as we continue to accelerate. I sometimes
give another quick squeeze-and-release on the trim, if I find that I'm
having to apply force on the stick to keep the plane flying or to keep
it from rising above the tug.
5] Then when the tug and I reach about 100 - 150 feet I re-trim one
more time as our airspeed approaches "normal" for the rest of the aero-
tow.
6] I may fiddle with the trim once more as we fly upwind and/or
crosswind; as the tug may retract flaps or otherwise change its speed
& attitude.
[Of Course, Your Mileage May Vary...]