Tow Plane Upsets......

[Walt Connelly]

I have been towing for about two and a half years and have logged over 6,500 tows. Having recently experienced a couple of rather violent glider kiting incidents, one at about 300 feet AGL I decided to investigate the experiences of other tow pilots in these circumstances. I have spent several hours reading posts about gliders kiting and upsetting the tow plane, many of the posts deal with creating an automatic release that will recognize the actions of the glider and release without input from the tow pilot. Nice idea, some really creative approaches and the bottom line is anything can be done if you have enough money and can get the FAA to buy into it and give approval.

Lots of opinions and ideas as to why these things happen. Bottom line is that they do happen, they have resulted in loss of tow pilot lives and the causes are well known.

Of my two most recent experiences one was with a 67 year old licensed private pilot, glider only, no other pilot ratings who at 2000 feet tried to release, “slipped back in the seat pulling back on the stick and going vertical.” I took a stab at the release to no avail, the pressure was too great and I soon found myself at about 75 degrees nose down at full power. The natural instinct at this point is to pull back the power and try again to release. He managed to release before I could try for a second time and I recovered. If this has to happen to you, 2000 feet is a good place to be. My understanding is that this was his first tow in more than a year. Something to think about.

My second experience in the same week was with a 15 year old student on her 3rd solo pattern tow. At about 250 to 300 feet I started a turn from the downwind drift to the right. I felt a tug on my tail pulling my nose to the left. After a few seconds I tried again to turn to the right knowing that she was behind me to the right. Could not see her, no mirror on the right. (much easier if she was a little to the left) The second time the pull of my tail to the right and nose to the left was a bit more violent…..followed by a very hard tug of my tail UP and to the right. We could not have been much more than 300 feet when I found myself nose down and trying to release….again the pressure was too much to overcome and I needed to retard the throttle. Before I could make a second attempt at release I heard a loud BANG as the rope broke, I regained control and recovered just above the trees. (glad that I had made a pit stop before I started towing). She made it back to the field and didn’t seem at all concerned……I shall withhold my comments at this point.

I had to straighten out the Schweizer hook which was off to the right about 30 degrees before I could make the last 8 tows of the day.

While I have concerns with both of these pilots my major concern is that the difficulty of actuating the release when the glider kites is well documented. To make matters worse, the release in the tug I was flying, although a bit more manually accessible than the other two I fly requires that the pilot pull it back and push down to fully actuate the release. Not an easy thing to do under the circumstances. The other two release handles are down on the floor to the left and for someone of my height, sitting on a cushion and trying to grab the release is very difficult. It would seem to me that an easy fix would be to simply make a longer handle curved up so one could both see and feel for it in an emergency. A longer handle would also provide a bit more mechanical advantage although having read many of the posts I am not sure this would overcome the pressure on the Schweizer hook. Of course I hear all the noise about needing to apply for a 337 and get FAA approval….next I will need approval to put a cushion on the seat or to have an inspection after washing the airplane.

So, the fixes appear to be going to a Tost hook or inverting the Schweizer hook which I understand can be done with an available STC. In my case I would also like to see a more accessible release handle…would (or should) an STC be required for this? This would be the short term fix I would like to see. If the handle was made from the same stock as the current device, just a foot or so longer it would seem that this should be able to be done without a long drawn out approval process.

I love flying, enjoy the gliderport environment and people but I am NOT willing to give up my life. When the glider kites things happen very fast. Unless your hand is on the handle (not feasible in my circumstances) you will not be able to release before the pressure gets too great. If it happens much lower than I experience it will be lights out. So remember my glider pilot friends….fly well….the life you save might be your tow pilot.

Walt Connelly

[Charles Longley]

Hi Walt I am a tow pilot but don't have nearly as many tows. I do have a lot of total time and an A&P/IA.

I've given it a lot of thought and research. I won't tow with anything but a Tost tow hook for the exact reasons of your difficulty releasing. Of the three Pawnee's I tow with the releases are within easy reach from a normal seating position. I am adding a Tost hook to my personal Cub for tow pilot training . I intend to put the tow release within easy reach of my left hand near the throttle. There's a lot of leeway on where to put the release. An STC isn't really needed as installing a tow hook system is outlined in AC 43-13.

Just some of my thoughts. Hope they help.

[Dave Springford]

Walt,

Our Pawnees have Tost releases. Schweizer hooks were removed about 30 years ago after an upset accident. The release cable is within a few inches reach of the throttle lever.

The release cable runs along the floor near the flap handle to a pulley attached to the floor that turns the cable 90 degrees upwards and then it attaches to the bottom of the instrument panel directly in front of the throttle quadrant. Reach forward and pull the cable, the glider is gone.

Release handles mounted to the floor are an accident waiting to happen, as are Schweizer hooks. As you have now experienced!

[[email protected]]

On Sunday, April 23, 2017 at 8:43:12 PM UTC-4, Walt Connelly wrote:
> I have been towing for about two and a half years and have logged over
> 6,500 tows. Having recently experienced a couple of rather violent
> glider kiting incidents, one at about 300 feet AGL I decided to
> investigate the experiences of other tow pilots in these circumstances.
> I have spent several hours reading posts about gliders kiting and
> upsetting the tow plane, many of the posts deal with creating an
> automatic release that will recognize the actions of the glider and
> release without input from the tow pilot. Nice idea, some really
> creative approaches and the bottom line is anything can be done if you
> have enough money and can get the FAA to buy into it and give
> approval.
>
> Lots of opinions and ideas as to why these things happen. Bottom line
> is that they do happen, they have resulted in loss of tow pilot lives
> and the causes are well known.
>
> Of my two most recent experiences one was with a 67 year old licensed
> private pilot, glider only, no other pilot ratings who at 2000 feet
> tried to release, “slipped back in the seat pulling back on the stick
> and going vertical.� I took a stab at the release to no avail, the
> pressure was too great and I soon found myself at about 75 degrees nose
> down at full power. The natural instinct at this point is to pull back
> the power and try again to release. He managed to release before I
> could try for a second time and I recovered. If this has to happen to
> you, 2000 feet is a good place to be. My understanding is that this was
> his first tow in more than a year. Something to think about.
>
> My second experience in the same week was with a 15 year old student on
> her 3rd solo pattern tow. At about 250 to 300 feet I started a turn
> from the downwind drift to the right. I felt a tug on my tail pulling
> my nose to the left. After a few seconds I tried again to turn to the
> right knowing that she was behind me to the right. Could not see her,
> no mirror on the right. (much easier if she was a little to the left)
> The second time the pull of my tail to the right and nose to the left
> was a bit more violent…..followed by a very hard tug of my tail UP and
> to the right. We could not have been much more than 300 feet when I
> found myself nose down and trying to release….again the pressure was too
> much to overcome and I needed to retard the throttle. Before I could
> make a second attempt at release I heard a loud BANG as the rope broke,
> I regained control and recovered just above the trees. (glad that I had
> made a pit stop before I started towing). She made it back to the field
> and didn’t seem at all concerned……I shall withhold my comments at this
> point.
>
> I had to straighten out the Schweizer hook which was off to the right
> about 30 degrees before I could make the last 8 tows of the day.
>
> While I have concerns with both of these pilots my major concern is that
> the difficulty of actuating the release when the glider kites is well
> documented. To make matters worse, the release in the tug I was flying,
> although a bit more manually accessible than the other two I fly
> requires that the pilot pull it back and push down to fully actuate the
> release. Not an easy thing to do under the circumstances. The other
> two release handles are down on the floor to the left and for someone of
> my height, sitting on a cushion and trying to grab the release is very
> difficult. It would seem to me that an easy fix would be to simply make
> a longer handle curved up so one could both see and feel for it in an
> emergency. A longer handle would also provide a bit more mechanical
> advantage although having read many of the posts I am not sure this
> would overcome the pressure on the Schweizer hook. Of course I hear all
> the noise about needing to apply for a 337 and get FAA approval….next I
> will need approval to put a cushion on the seat or to have an inspection
> after washing the airplane.
>
> So, the fixes appear to be going to a Tost hook or inverting the
> Schweizer hook which I understand can be done with an available STC.
> In my case I would also like to see a more accessible release
> handle…would (or should) an STC be required for this? This would be
> the short term fix I would like to see. If the handle was made from the
> same stock as the current device, just a foot or so longer it would seem
> that this should be able to be done without a long drawn out approval
> process.
>
> I love flying, enjoy the gliderport environment and people but I am NOT
> willing to give up my life. When the glider kites things happen very
> fast. Unless your hand is on the handle (not feasible in my
> circumstances) you will not be able to release before the pressure gets
> too great. If it happens much lower than I experience it will be lights
> out. So remember my glider pilot friends….fly well….the life you save
> might be your tow pilot.
>
> Walt Connelly
>
>
>
>
> --
> Walt Connelly

[[email protected]]

Walt, I "feel your pain". It has been long reported that a Schweizer hook is difficult if not impossible to release under abnormal situations such as yours. A lot of tow pilots claim if that if the stick hits a stop, pull the release now! Another item I've always been acutely aware is the co-location of the flap handle and the release handle. Do you in a stressful time have the ability to grab the release NOW! Perhaps a Tee handle on a heavy cord in your lap would be quicker and provide more leverage. I like Dave's comment in favor of switching to Tost releases

[George Haeh]

It seems to require a dead towpilot before a club gets rid of Schweitzer
tow
hooks.

[Peter Whitehead]

A manual release system will never be suitable to stop the rapid pitch up caused in this situation. It happens too fast for a manual (actually a sensory-brain-muscle-manual) system, however good the manual system on the tug.

Glider CofG winch hooks are not really suitable for aero-towing, are they? Some of these gliders can't be controlled in pitch once the kiting starts. I have seen people leave their shoulder starts loose on areotowing, and that means the pilot can slide backwards - with hand held on the stick, so that moves too - on pitch-up. (Always use tight shoulder straps on launching, please).

I have lost two acquaintances, both gliding "greats" in such tug upsets. I would say banning the use of aero-towing using a CofG winch hook would be the safest bet to save lives, until an automatic system is available.I suspect this is something EASA and the FAA would sort very quickly ( the banning bit, not the automatic system). Sensors to measure pitch, rate rate of the tug, and also tug/rope angle and angular rate,suitably processed and actioned automatically could allow immediate release BEFORE the critical situation is reached - if we feel that we must continue to launch by aero-tow using CofG hooks.

A rule of nose hooks or "compromise" hooks only, meanwhile, would probably reduce the risk towards zero.

[Chris Rollings[_2_]]

I have posted what follows on a previous occasion but, given the posts in
this thread, I think it bears repeating.

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 10:06 24 April 2017, Peter Whitehead wrote:
>A manual release system will never be suitable to stop the rapid pitch up
>c=
>aused in this situation. It happens too fast for a manual (actually a
>senso=
>ry-brain-muscle-manual) system, however good the manual system on the
tug.
>
>Glider CofG winch hooks are not really suitable for aero-towing, are
they?
>=
>Some of these gliders can't be controlled in pitch once the kiting
starts.
>=
>I have seen people leave their shoulder starts loose on areotowing, and
>tha=
>t means the pilot can slide backwards - with hand held on the stick, so
>tha=
>t moves too - on pitch-up. (Always use tight shoulder straps on
launching,
>=
>please).=20
>
>I have lost two acquaintances, both gliding "greats" in such tug upsets.
I
>=
>would say banning the use of aero-towing using a CofG winch hook would be
>t=
>he safest bet to save lives, until an automatic system is available.I
>suspe=
>ct this is something EASA and the FAA would sort very quickly ( the
>banning=
> bit, not the automatic system). Sensors to measure pitch, rate rate of
>the=
> tug, and also tug/rope angle and angular rate,suitably processed and
>actio=
>ned automatically could allow immediate release BEFORE the critical
>situati=
>on is reached - if we feel that we must continue to launch by aero-tow
>usin=
>g CofG hooks.=20
>
>A rule of nose hooks or "compromise" hooks only, meanwhile, would
probably
>=
>reduce the risk towards zero.
>

[Walt Connelly]

Hi Walt I am a tow pilot but don't have nearly as many tows. I do have a lot of total time and an A&P/IA.

I've given it a lot of thought and research. I won't tow with anything but a Tost tow hook for the exact reasons of your difficulty releasing. Of the three Pawnee's I tow with the releases are within easy reach from a normal seating position. I am adding a Tost hook to my personal Cub for tow pilot training . I intend to put the tow release within easy reach of my left hand near the throttle. There's a lot of leeway on where to put the release. An STC isn't really needed as installing a tow hook system is outlined in AC 43-13.

Just some of my thoughts. Hope they help.

Thank you Charles.....this is the kind of response I am looking for especially from an A&P/IA.

Walt

[[email protected]]

In Australia we do low tow only with the aim of reducing tug upsets. It intuitively makes sense to me that kiting upsets are much more likely and much worse than 'diving' upsets (do these even happen?), and low tow offers much more time to react.
It's also much harder to lose sight of the tug, it's right there in your field of view.

On Monday, 24 April 2017 01:43:12 UTC+1, Walt Connelly wrote:
> I have been towing for about two and a half years and have logged over
> 6,500 tows. Having recently experienced a couple of rather violent
> glider kiting incidents, one at about 300 feet AGL I decided to
> investigate the experiences of other tow pilots in these circumstances.
> I have spent several hours reading posts about gliders kiting and
> upsetting the tow plane, many of the posts deal with creating an
> automatic release that will recognize the actions of the glider and
> release without input from the tow pilot. Nice idea, some really
> creative approaches and the bottom line is anything can be done if you
> have enough money and can get the FAA to buy into it and give
> approval.
>
> Lots of opinions and ideas as to why these things happen. Bottom line
> is that they do happen, they have resulted in loss of tow pilot lives
> and the causes are well known.
>
> Of my two most recent experiences one was with a 67 year old licensed
> private pilot, glider only, no other pilot ratings who at 2000 feet
> tried to release, “slipped back in the seat pulling back on the stick
> and going vertical.� I took a stab at the release to no avail, the
> pressure was too great and I soon found myself at about 75 degrees nose
> down at full power. The natural instinct at this point is to pull back
> the power and try again to release. He managed to release before I
> could try for a second time and I recovered. If this has to happen to
> you, 2000 feet is a good place to be. My understanding is that this was
> his first tow in more than a year. Something to think about.
>
> My second experience in the same week was with a 15 year old student on
> her 3rd solo pattern tow. At about 250 to 300 feet I started a turn
> from the downwind drift to the right. I felt a tug on my tail pulling
> my nose to the left. After a few seconds I tried again to turn to the
> right knowing that she was behind me to the right. Could not see her,
> no mirror on the right. (much easier if she was a little to the left)
> The second time the pull of my tail to the right and nose to the left
> was a bit more violent…..followed by a very hard tug of my tail UP and
> to the right. We could not have been much more than 300 feet when I
> found myself nose down and trying to release….again the pressure was too
> much to overcome and I needed to retard the throttle. Before I could
> make a second attempt at release I heard a loud BANG as the rope broke,
> I regained control and recovered just above the trees. (glad that I had
> made a pit stop before I started towing). She made it back to the field
> and didn’t seem at all concerned……I shall withhold my comments at this
> point.
>
> I had to straighten out the Schweizer hook which was off to the right
> about 30 degrees before I could make the last 8 tows of the day.
>
> While I have concerns with both of these pilots my major concern is that
> the difficulty of actuating the release when the glider kites is well
> documented. To make matters worse, the release in the tug I was flying,
> although a bit more manually accessible than the other two I fly
> requires that the pilot pull it back and push down to fully actuate the
> release. Not an easy thing to do under the circumstances. The other
> two release handles are down on the floor to the left and for someone of
> my height, sitting on a cushion and trying to grab the release is very
> difficult. It would seem to me that an easy fix would be to simply make
> a longer handle curved up so one could both see and feel for it in an
> emergency. A longer handle would also provide a bit more mechanical
> advantage although having read many of the posts I am not sure this
> would overcome the pressure on the Schweizer hook. Of course I hear all
> the noise about needing to apply for a 337 and get FAA approval….next I
> will need approval to put a cushion on the seat or to have an inspection
> after washing the airplane.
>
> So, the fixes appear to be going to a Tost hook or inverting the
> Schweizer hook which I understand can be done with an available STC.
> In my case I would also like to see a more accessible release
> handle…would (or should) an STC be required for this? This would be
> the short term fix I would like to see. If the handle was made from the
> same stock as the current device, just a foot or so longer it would seem
> that this should be able to be done without a long drawn out approval
> process.
>
> I love flying, enjoy the gliderport environment and people but I am NOT
> willing to give up my life. When the glider kites things happen very
> fast. Unless your hand is on the handle (not feasible in my
> circumstances) you will not be able to release before the pressure gets
> too great. If it happens much lower than I experience it will be lights
> out. So remember my glider pilot friends….fly well….the life you save
> might be your tow pilot.
>
> Walt Connelly
>
>
>
>
> --
> Walt Connelly

[Charlie M. (UH & 002 owner/pilot)]

Sounds great to me! In the US, high tow is predominate although low tow is taught.
Our club is one of 2(?) in the US that predominantly use low tow although we also teach high tow.
We have tested "going too low" and the towplane still has elevator available whereas going to high runs the towplane out of elevator.
If the glider pilot gets way out of position, the time difference is not much between the 2 tow types in my opinion.

Not trying to start a "conversation regarding which to use", just noting what we do. This can turn ugly fast, even worse than US contest rules discussions.......

PS, lost a friend during tow a couple decades ago while he was towing with a "known squirrel" on the glider end. The towplane was a L19 and went in from about 300' when the glider went too high in front of a couple dozen onlookers.
Not sure low tow would have helped.

[Chris Rollings[_2_]]

A large proportion of the tow-plane upsets, including most of the fatals,
happen very shortly after take-off, before there is an opportunity to get
into low tow. Also, descending into the prop-wash can be a trigger to the
momentary loss of control that leads to the upset, if the glider is on a C
of G hook.

At 12:05 24 April 2017, wrote:
>In Australia we do low tow only with the aim of reducing tug upsets. It
>int=
>uitively makes sense to me that kiting upsets are much more likely and
>much=
> worse than 'diving' upsets (do these even happen?), and low tow offers
>muc=
>h more time to react.
>It's also much harder to lose sight of the tug, it's right there in your
>fi=
>eld of view.
>
>On Monday, 24 April 2017 01:43:12 UTC+1, Walt Connelly wrote:
>> I have been towing for about two and a half years and have logged over
>> 6,500 tows. Having recently experienced a couple of rather violent
>> glider kiting incidents, one at about 300 feet AGL I decided to
>> investigate the experiences of other tow pilots in these
circumstances.=
>=20
>> I have spent several hours reading posts about gliders kiting and
>> upsetting the tow plane, many of the posts deal with creating an
>> automatic release that will recognize the actions of the glider and
>> release without input from the tow pilot. Nice idea, some really
>> creative approaches and the bottom line is anything can be done if you
>> have enough money and can get the FAA to buy into it and give
>> approval.
>>=20
>> Lots of opinions and ideas as to why these things happen. Bottom line
>> is that they do happen, they have resulted in loss of tow pilot lives
>> and the causes are well known.=20
>>=20
>> Of my two most recent experiences one was with a 67 year old licensed
>> private pilot, glider only, no other pilot ratings who at 2000 feet
>> tried to release, =E2=80=9Cslipped back in the seat pulling back on the
>s=
>tick
>> and going vertical.=E2=80=9D I took a stab at the release to no avail,
>t=
>he
>> pressure was too great and I soon found myself at about 75 degrees nose
>> down at full power. The natural instinct at this point is to pull back
>> the power and try again to release. He managed to release before I
>> could try for a second time and I recovered. If this has to happen to
>> you, 2000 feet is a good place to be. My understanding is that this
was
>> his first tow in more than a year. Something to think about. =20
>>=20
>> My second experience in the same week was with a 15 year old student on
>> her 3rd solo pattern tow. At about 250 to 300 feet I started a turn
>> from the downwind drift to the right. I felt a tug on my tail pulling
>> my nose to the left. After a few seconds I tried again to turn to the
>> right knowing that she was behind me to the right. Could not see her,
>> no mirror on the right. (much easier if she was a little to the left)
=20
>> The second time the pull of my tail to the right and nose to the left
>> was a bit more violent=E2=80=A6..followed by a very hard tug of my
tail
>=
> UP and
>> to the right. We could not have been much more than 300 feet when I
>> found myself nose down and trying to release=E2=80=A6.again the
pressure
>=
>was too
>> much to overcome and I needed to retard the throttle. Before I could
>> make a second attempt at release I heard a loud BANG as the rope broke,
>> I regained control and recovered just above the trees. (glad that I
had
>> made a pit stop before I started towing). She made it back to the
field
>> and didn=E2=80=99t seem at all concerned=E2=80=A6=E2=80=A6I shall
>withhol=
>d my comments at this
>> point. =20
>>=20
>> I had to straighten out the Schweizer hook which was off to the right
>> about 30 degrees before I could make the last 8 tows of the day.
>>=20
>> While I have concerns with both of these pilots my major concern is
that
>> the difficulty of actuating the release when the glider kites is well
>> documented. To make matters worse, the release in the tug I was
flying,
>> although a bit more manually accessible than the other two I fly
>> requires that the pilot pull it back and push down to fully actuate the
>> release. Not an easy thing to do under the circumstances. The other
>> two release handles are down on the floor to the left and for someone
of
>> my height, sitting on a cushion and trying to grab the release is very
>> difficult. It would seem to me that an easy fix would be to simply
make
>> a longer handle curved up so one could both see and feel for it in an
>> emergency. A longer handle would also provide a bit more mechanical
>> advantage although having read many of the posts I am not sure this
>> would overcome the pressure on the Schweizer hook. Of course I hear
all
>> the noise about needing to apply for a 337 and get FAA
>approval=E2=80=A6.=
>next I
>> will need approval to put a cushion on the seat or to have an
inspection
>> after washing the airplane. =20
>>=20
>> So, the fixes appear to be going to a Tost hook or inverting the
>> Schweizer hook which I understand can be done with an available STC.
=20
>> In my case I would also like to see a more accessible release
>> handle=E2=80=A6would (or should) an STC be required for this? This
>wou=
>ld be
>> the short term fix I would like to see. If the handle was made from
the
>> same stock as the current device, just a foot or so longer it would
seem
>> that this should be able to be done without a long drawn out approval
>> process. =20
>>=20
>> I love flying, enjoy the gliderport environment and people but I am NOT
>> willing to give up my life. When the glider kites things happen very
>> fast. Unless your hand is on the handle (not feasible in my
>> circumstances) you will not be able to release before the pressure gets
>> too great. If it happens much lower than I experience it will be
lights
>> out. So remember my glider pilot friends=E2=80=A6.fly
well=E2=80=A6.the
>=
>life you save
>> might be your tow pilot.
>>=20
>> Walt Connelly
>>=20
>>=20
>>=20
>>=20
>> --=20
>> Walt Connelly
>

[Bruce Hoult]

On Monday, April 24, 2017 at 3:45:05 PM UTC+3, Chris Rollings wrote:
> A large proportion of the tow-plane upsets, including most of the fatals,
> happen very shortly after take-off, before there is an opportunity to get
> into low tow. Also, descending into the prop-wash can be a trigger to the
> momentary loss of control that leads to the upset, if the glider is on a C
> of G hook.

Do these upsets *only* happen with a C of G hook?

I've done a fair bit of flying in a C of G hook Janus, including on days with wave and pretty bad rotor. Never had a problem.

Does an upset really happen because the glider pilot simply flies out of position? It seems unlikely to me. You need not only to be high but also with significant pull on the rope. All the times I've gotten high it's because the towplane suddenly ran into sink (of at least out of lift), and the result has been a slack rope, not the tight rope required for an upset. Simply maintaining station (even though high) until the slack starts to come out, and then descending back into position with a constant amount of bowing (i.e. low tension but not slack as such).

Without having actually been there myself, I suspect that upsets may be caused not by being out of position, but by having a slack rope suddenly come tight. With a C of G hook this causes a reasonably large nose up pitching moment which may not be able to be countered by the elevator. The glider can get significant angle of attack and lift and upwards and (as the angle increases) backwards acceleration. If you're towing at 68 knots (or more) with a stall speed of 40 knots then you can generate 3 G of acceleration. With 3 G of acceleration you've only got to get to 10 degrees nose up to tension the rope to half the glider's weight, 20 degrees nose up to put a full 1 G of force onto the rope, and 30 degrees for 1.5 times the glider's weight in tension.

The glider being out of position is most likely the very quick *result* of the glider going into winch launch mode, not the cause of it.

I can't see that low tow would make any significant difference to this. Slack being taken out violently (but not quite enough to break the rope) will have exactly the same effect as in high tow.

[Walt Connelly]

Walt,

Our Pawnees have Tost releases. Schweizer hooks were removed about 30 years ago after an upset accident. The release cable is within a few inches reach of the throttle lever.

The release cable runs along the floor near the flap handle to a pulley attached to the floor that turns the cable 90 degrees upwards and then it attaches to the bottom of the instrument panel directly in front of the throttle quadrant. Reach forward and pull the cable, the glider is gone.

Release handles mounted to the floor are an accident waiting to happen, as are Schweizer hooks. As you have now experienced!

Thank you for your input Dave....it is quite obvious that this problem is well known and that there are things that can (AND WILL) be done to mitigate the difficulty of releasing in an emergency. While nothing is fool proof our current situation is FOOLISH. Until you experience it, until you try to pull the handle it will not be obvious to you. It is now beyond obvious to me. The discussions going forward will be what we can do and why....NOT what we can't do. It CAN be corrected...It WILL be corrected. I love aerobatics, just not at 200-300 feet AGL in a non aerobatic airplane.

Walt

[Walt Connelly]

Walt, I "feel your pain". It has been long reported that a Schweizer hook is difficult if not impossible to release under abnormal situations such as yours. A lot of tow pilots claim if that if the stick hits a stop, pull the release now! Another item I've always been acutely aware is the co-location of the flap handle and the release handle. Do you in a stressful time have the ability to grab the release NOW! Perhaps a Tee handle on a heavy cord in your lap would be quicker and provide more leverage. I like Dave's comment in favor of switching to Tost releases

Wes,

There will be Tost hooks and release handle modifications post haste on all three of our tugs or I will commence my full retirement. There is NO logical reason why a longer handle cannot be fabricated and installed....FAA or NO FAA.

Walt

[Walt Connelly]

Sounds great to me! In the US, high tow is predominate although low tow is taught.
Our club is one of 2(?) in the US that predominantly use low tow although we also teach high tow.
We have tested "going too low" and the towplane still has elevator available whereas going to high runs the towplane out of elevator.
If the glider pilot gets way out of position, the time difference is not much between the 2 tow types in my opinion.

Not trying to start a "conversation regarding which to use", just noting what we do. This can turn ugly fast, even worse than US contest rules discussions.......

PS, lost a friend during tow a couple decades ago while he was towing with a "known squirrel" on the glider end. The towplane was a L19 and went in from about 300' when the glider went too high in front of a couple dozen onlookers.
Not sure low tow would have helped.

Charlie, a big part of the problem here were the squirrels but the inadequacy of the release in the tug is just as much my concern. I am a student of body language and facial expression and emotion. I do not believe some people should be allowed to fly, their head is not in it, they are mechanical, they are not seat of the pants, hard wired into the situation. In the future I will reserve the right to NOT tow someone.

Walt

[Roy B.]

Does anybody have actual experience or testing with the McFarlane product that uses a roller bearing instead of a mechanical connection between the latch and the finger? Again - I am looking for actual experience - not opinions.
See: http://www.mcfarlaneaviation.com/newsletters/march2007.htm
ROY

[Charlie M. (UH & 002 owner/pilot)]

"Time to get to low tow"?!?!
You're doing it wrong.

Towplane and glider start rolling, glider lifts off and stays a few feet off the ground in ground effect, towplane lifts off and climbs out, when sight picture looks correct, glider starts climbing.
The propwash is not really a factor since it has not quite come together yet with normal ropes, maybe felt a bit on rather short ropes. By the time the turbulence has come together, it's over the glider.

BTW, I am not an AandP or IA, just an ex CFIG, long time glider pilot with some power time.

As to a release with a roller, any roller is better than a sliding surface, although keeping it rolling while operating on grass or dirt may be an issue.
On a sliding type release, at least make sure the edges of the hook where it goes into the release are smooth, not mushroomed out. A flat file now and then to smooth it out helps this.
Also some lube on release cable guide rollers, inside guide tubes and release pivots helps out a bit.

[Papa3[_2_]]

As mentioned elsewhere in the thread, this topic comes up every few years. As I've posted in the past, I actually sat in a lab with John Campbell and built/tested a rig to measure release forces on the Schweizer release mounted on our PA-18 Supercub. We used various towropes, a simple protractor and a strain gauge.

I can't for the life of me find the handwritten notes and mimeographed (!!) handout that we created, but the conclusion is very clear.

- It only takes a fairly small amplitude kiting event to load up the Schweizer hook to a point where the release forces are significant. Don't quote me, but I believe the magic angle was less than 20 degrees above the longitudinal axis of the release hook with a relatively low load (100lbs IIRC)

- Beyond that point, the pilot in the towplane couldn't apply enough force on the release cable to effect a release. Compounding the problem is the fact that the routing of the release cable drastically reduced the effective force that was applied at the release point (cable bowed and routed around several pulleys). We had a separate version of the release we used for auto tows, and that one had a direct pull with a lever that actually worked under much higher loads.

Bottom line is that the towpilot was very unlikely to be able to release once the glider got significantly outside of normal tow envelope.

Erik Mann (P3)

On Sunday, April 23, 2017 at 8:43:12 PM UTC-4, Walt Connelly wrote:
> I have been towing for about two and a half years and have logged over
> 6,500 tows. Having recently experienced a couple of rather violent
> glider kiting incidents, one at about 300 feet AGL I decided to
> investigate the experiences of other tow pilots in these circumstances.
> I have spent several hours reading posts about gliders kiting and
> upsetting the tow plane, many of the posts deal with creating an
> automatic release that will recognize the actions of the glider and
> release without input from the tow pilot. Nice idea, some really
> creative approaches and the bottom line is anything can be done if you
> have enough money and can get the FAA to buy into it and give
> approval.
>
> Lots of opinions and ideas as to why these things happen. Bottom line
> is that they do happen, they have resulted in loss of tow pilot lives
> and the causes are well known.
>
> Of my two most recent experiences one was with a 67 year old licensed
> private pilot, glider only, no other pilot ratings who at 2000 feet
> tried to release, “slipped back in the seat pulling back on the stick
> and going vertical.� I took a stab at the release to no avail, the
> pressure was too great and I soon found myself at about 75 degrees nose
> down at full power. The natural instinct at this point is to pull back
> the power and try again to release. He managed to release before I
> could try for a second time and I recovered. If this has to happen to
> you, 2000 feet is a good place to be. My understanding is that this was
> his first tow in more than a year. Something to think about.
>
> My second experience in the same week was with a 15 year old student on
> her 3rd solo pattern tow. At about 250 to 300 feet I started a turn
> from the downwind drift to the right. I felt a tug on my tail pulling
> my nose to the left. After a few seconds I tried again to turn to the
> right knowing that she was behind me to the right. Could not see her,
> no mirror on the right. (much easier if she was a little to the left)
> The second time the pull of my tail to the right and nose to the left
> was a bit more violent…..followed by a very hard tug of my tail UP and
> to the right. We could not have been much more than 300 feet when I
> found myself nose down and trying to release….again the pressure was too
> much to overcome and I needed to retard the throttle. Before I could
> make a second attempt at release I heard a loud BANG as the rope broke,
> I regained control and recovered just above the trees. (glad that I had
> made a pit stop before I started towing). She made it back to the field
> and didn’t seem at all concerned……I shall withhold my comments at this
> point.
>
> I had to straighten out the Schweizer hook which was off to the right
> about 30 degrees before I could make the last 8 tows of the day.
>
> While I have concerns with both of these pilots my major concern is that
> the difficulty of actuating the release when the glider kites is well
> documented. To make matters worse, the release in the tug I was flying,
> although a bit more manually accessible than the other two I fly
> requires that the pilot pull it back and push down to fully actuate the
> release. Not an easy thing to do under the circumstances. The other
> two release handles are down on the floor to the left and for someone of
> my height, sitting on a cushion and trying to grab the release is very
> difficult. It would seem to me that an easy fix would be to simply make
> a longer handle curved up so one could both see and feel for it in an
> emergency. A longer handle would also provide a bit more mechanical
> advantage although having read many of the posts I am not sure this
> would overcome the pressure on the Schweizer hook. Of course I hear all
> the noise about needing to apply for a 337 and get FAA approval….next I
> will need approval to put a cushion on the seat or to have an inspection
> after washing the airplane.
>
> So, the fixes appear to be going to a Tost hook or inverting the
> Schweizer hook which I understand can be done with an available STC.
> In my case I would also like to see a more accessible release
> handle…would (or should) an STC be required for this? This would be
> the short term fix I would like to see. If the handle was made from the
> same stock as the current device, just a foot or so longer it would seem
> that this should be able to be done without a long drawn out approval
> process.
>
> I love flying, enjoy the gliderport environment and people but I am NOT
> willing to give up my life. When the glider kites things happen very
> fast. Unless your hand is on the handle (not feasible in my
> circumstances) you will not be able to release before the pressure gets
> too great. If it happens much lower than I experience it will be lights
> out. So remember my glider pilot friends….fly well….the life you save
> might be your tow pilot.
>
> Walt Connelly
>
>
>
>
> --
> Walt Connelly

[Walt Connelly]

It seems to require a dead towpilot before a club gets rid of Schweitzer
tow
hooks.

George, we are a commercial operation, not a club. BUT if there are not three Tost hooks ordered tomorrow when we open for business and arrangements made to properly position the release handle I will terminate my employment.

Walt

[Walt Connelly]

A manual release system will never be suitable to stop the rapid pitch up caused in this situation. It happens too fast for a manual (actually a sensory-brain-muscle-manual) system, however good the manual system on the tug.

Glider CofG winch hooks are not really suitable for aero-towing, are they? Some of these gliders can't be controlled in pitch once the kiting starts. I have seen people leave their shoulder starts loose on areotowing, and that means the pilot can slide backwards - with hand held on the stick, so that moves too - on pitch-up. (Always use tight shoulder straps on launching, please).

I have lost two acquaintances, both gliding "greats" in such tug upsets. I would say banning the use of aero-towing using a CofG winch hook would be the safest bet to save lives, until an automatic system is available.I suspect this is something EASA and the FAA would sort very quickly ( the banning bit, not the automatic system). Sensors to measure pitch, rate rate of the tug, and also tug/rope angle and angular rate,suitably processed and actioned automatically could allow immediate release BEFORE the critical situation is reached - if we feel that we must continue to launch by aero-tow using CofG hooks.

A rule of nose hooks or "compromise" hooks only, meanwhile, would probably reduce the risk towards zero.

Peter,

Both of these incidents were with nose releases not CG hooks. I've never really had a problem with a CG glider but I guess it could happen. Both of these incidents were due to extreme carlessness and or inexperience on the part of the glider pilot. My concern is with the inability to release at the critical moment. It will be my purpose to communicate this condition as broadly and relentlessly as possible. No commercial operation or club should be towing with a Schweizer hook or a release not immediately available to the tow pilot.

Walt

[Dan Marotta]

Well, I've only done about 4,700 tows, and I quit towing over a year
ago. My worst upset experience (Pawnee with Schweizer release) was when
an HP-14 kited high and outside of my turn. As I was yelling on the
radio and grabbing the release lever, he regained control (or so I
thought), turned inside of me and dived across my tail. The rope
wrapped around his wing, cutting it to the spar, and breaking the rope.
He went on to fly about 4 hours, discovering the damage after landing.
I vowed never to tow him again.

As I said, it's been over a year but, if I recall correctly, the
Schweizer release is mounted with a single vertical bolt so that it can
pivot left and right. And, at least on the Pawnee I last flew, if the
release was more than a few degrees off center, pulling the cable would
not open the release. It wasn't a matter of force, it just wouldn't
release if the cable was offset much off the center line of the release.

I agree: Replace Schweizer releases on tugs with Tost.

Dan, former tow pilot.

On 4/23/2017 3:09 PM, Walt Connelly wrote:
> I have been towing for about two and a half years and have logged over
> 6,500 tows. Having recently experienced a couple of rather violent
> glider kiting incidents, one at about 300 feet AGL I decided to
> investigate the experiences of other tow pilots in these circumstances.
> I have spent several hours reading posts about gliders kiting and
> upsetting the tow plane, many of the posts deal with creating an
> automatic release that will recognize the actions of the glider and
> release without input from the tow pilot. Nice idea, some really
> creative approaches and the bottom line is anything can be done if you
> have enough money and can get the FAA to buy into it and give
> approval.
>
> Lots of opinions and ideas as to why these things happen. Bottom line
> is that they do happen, they have resulted in loss of tow pilot lives
> and the causes are well known.
>
> Of my two most recent experiences one was with a 67 year old licensed
> private pilot, glider only, no other pilot ratings who at 2000 feet
> tried to release, “slipped back in the seat pulling back on the stick
> and going vertical.” I took a stab at the release to no avail, the
> pressure was too great and I soon found myself at about 75 degrees nose
> down at full power. The natural instinct at this point is to pull back
> the power and try again to release. He managed to release before I
> could try for a second time and I recovered. If this has to happen to
> you, 2000 feet is a good place to be. My understanding is that this was
> his first tow in more than a year. Something to think about.
>
> My second experience in the same week was with a 15 year old student on
> her 3rd solo pattern tow. At about 250 to 300 feet I started a turn
> from the downwind drift to the right. I felt a tug on my tail pulling
> my nose to the left. After a few seconds I tried again to turn to the
> right knowing that she was behind me to the right. Could not see her,
> no mirror on the right. (much easier if she was a little to the left)
> The second time the pull of my tail to the right and nose to the left
> was a bit more violent…..followed by a very hard tug of my tail UP and
> to the right. We could not have been much more than 300 feet when I
> found myself nose down and trying to release….again the pressure was too
> much to overcome and I needed to retard the throttle. Before I could
> make a second attempt at release I heard a loud BANG as the rope broke,
> I regained control and recovered just above the trees. (glad that I had
> made a pit stop before I started towing). She made it back to the field
> and didn’t seem at all concerned……I shall withhold my comments at this
> point.
>
> I had to straighten out the Schweizer hook which was off to the right
> about 30 degrees before I could make the last 8 tows of the day.
>
> While I have concerns with both of these pilots my major concern is that
> the difficulty of actuating the release when the glider kites is well
> documented. To make matters worse, the release in the tug I was flying,
> although a bit more manually accessible than the other two I fly
> requires that the pilot pull it back and push down to fully actuate the
> release. Not an easy thing to do under the circumstances. The other
> two release handles are down on the floor to the left and for someone of
> my height, sitting on a cushion and trying to grab the release is very
> difficult. It would seem to me that an easy fix would be to simply make
> a longer handle curved up so one could both see and feel for it in an
> emergency. A longer handle would also provide a bit more mechanical
> advantage although having read many of the posts I am not sure this
> would overcome the pressure on the Schweizer hook. Of course I hear all
> the noise about needing to apply for a 337 and get FAA approval….next I
> will need approval to put a cushion on the seat or to have an inspection
> after washing the airplane.
>
> So, the fixes appear to be going to a Tost hook or inverting the
> Schweizer hook which I understand can be done with an available STC.
> In my case I would also like to see a more accessible release
> handle…would (or should) an STC be required for this? This would be
> the short term fix I would like to see. If the handle was made from the
> same stock as the current device, just a foot or so longer it would seem
> that this should be able to be done without a long drawn out approval
> process.
>
> I love flying, enjoy the gliderport environment and people but I am NOT
> willing to give up my life. When the glider kites things happen very
> fast. Unless your hand is on the handle (not feasible in my
> circumstances) you will not be able to release before the pressure gets
> too great. If it happens much lower than I experience it will be lights
> out. So remember my glider pilot friends….fly well….the life you save
> might be your tow pilot.
>
> Walt Connelly
>
>
>
>

--
Dan, 5J

[Dan Marotta]

Ban CG hooks on air tow? How many gliders would be immediately
grounded? Six of my seven gliders had a CG hooks (only) and I never
kited. How about better training? And, BTW, shoulder straps, no matter
how loose (or not even worn), will not cause a pilot to slip AFT. The
seat back will prevent that. Of course the seat back could fail, or the
seat BELT could be too loose allowing the pilot to slide under the BELT
and that might cause him to pull back on the stick.

On 4/24/2017 4:06 AM, Peter Whitehead wrote:
> A manual release system will never be suitable to stop the rapid pitch up caused in this situation. It happens too fast for a manual (actually a sensory-brain-muscle-manual) system, however good the manual system on the tug.
>
> Glider CofG winch hooks are not really suitable for aero-towing, are they? Some of these gliders can't be controlled in pitch once the kiting starts. I have seen people leave their shoulder starts loose on areotowing, and that means the pilot can slide backwards - with hand held on the stick, so that moves too - on pitch-up. (Always use tight shoulder straps on launching, please).
>
> I have lost two acquaintances, both gliding "greats" in such tug upsets. I would say banning the use of aero-towing using a CofG winch hook would be the safest bet to save lives, until an automatic system is available.I suspect this is something EASA and the FAA would sort very quickly ( the banning bit, not the automatic system). Sensors to measure pitch, rate rate of the tug, and also tug/rope angle and angular rate,suitably processed and actioned automatically could allow immediate release BEFORE the critical situation is reached - if we feel that we must continue to launch by aero-tow using CofG hooks.
>
> A rule of nose hooks or "compromise" hooks only, meanwhile, would probably reduce the risk towards zero.

--
Dan, 5J

[Dan Marotta]

Good testing and great write-up!

While not intending to excuse the short comings of the Schweizer release
as a tow hook, I recall seeing one mounted to a ground launch vehicle
via a very robust hinge (something you'd see on a farm field gate). In
a kiting incident, the release would rotate upwards keeping it aligned
with the tow rope and making release possible. Of course, the final
mounting location of the release cable would have to be such that the
cable could still exert sufficient pull distance to effect the release.

On 4/24/2017 4:39 AM, Chris Rollings wrote:
> I have posted what follows on a previous occasion but, given the posts in
> this thread, I think it bears repeating.
>
> 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 10:06 24 April 2017, Peter Whitehead wrote:
>> A manual release system will never be suitable to stop the rapid pitch up
>> c=
>> aused in this situation. It happens too fast for a manual (actually a
>> senso=
>> ry-brain-muscle-manual) system, however good the manual system on the
> tug.
>> Glider CofG winch hooks are not really suitable for aero-towing, are
> they?
>> =
>> Some of these gliders can't be controlled in pitch once the kiting
> starts.
>> =
>> I have seen people leave their shoulder starts loose on areotowing, and
>> tha=
>> t means the pilot can slide backwards - with hand held on the stick, so
>> tha=
>> t moves too - on pitch-up. (Always use tight shoulder straps on
> launching,
>> =
>> please).=20
>>
>> I have lost two acquaintances, both gliding "greats" in such tug upsets.
> I
>> =
>> would say banning the use of aero-towing using a CofG winch hook would be
>> t=
>> he safest bet to save lives, until an automatic system is available.I
>> suspe=
>> ct this is something EASA and the FAA would sort very quickly ( the
>> banning=
>> bit, not the automatic system). Sensors to measure pitch, rate rate of
>> the=
>> tug, and also tug/rope angle and angular rate,suitably processed and
>> actio=
>> ned automatically could allow immediate release BEFORE the critical
>> situati=
>> on is reached - if we feel that we must continue to launch by aero-tow
>> usin=
>> g CofG hooks.=20
>>
>> A rule of nose hooks or "compromise" hooks only, meanwhile, would
> probably
>> =
>> reduce the risk towards zero.
>>

--
Dan, 5J

[Walt Connelly]

[QUOTE='Chris Rollings[_2_];944055']I have posted what follows on a previous occasion but, given the posts in
this thread, I think it bears repeating.

Chris,

Yours was one of the posts I paid the most attention to. I appreciate the approach you took to the problem and agree with your assessments although I think it's somewhat not feasible to eliminate aero tows to CG hook gliders. The vast majority of the high performance models I tow are CG but overall they are also being flown by the best pilots, never had big problem with one of them.

Short ropes, of course, bad idea but interestingly the rope on the student who kited low was a new rope and we make them longer to allow for repairs. This was not a problem in this instance.

These were largely inexperienced pilots, one student and one older gentleman who had not done an aerotow in quite some time. As I have noted earlier I will reserve the right to not tow someone for whatever reason. Having observed this older gentleman and had I known he hadn't done an aerotow in quite some time I would have insisted on some dual with an instructor.

Turbulence.....whlle there was some cross wind and we always have some thermals off the end of the runway it was not excessive, she flew two tows prior to the upset, she was not great but it was acceptable overall.

I agree with replacing all Schweizer hooks and this will be accomplished post haste with no argument or I will be gone.....

Release handle position....NO Question. These are things which I think should be on the FAA radar and under an AD note.

Thank you for your input, it greatly supports my position.

Walt

[Charles Longley]

I just looked. I don't think McFarlane sells that improved Schweitzer tow hook anymore. The Tost tow release is only $2,000. Well worth it in my opinion.

[kirk.stant]

The Pawnees at Turf Soaring had a 337 mod to invert the Schweizer releases. In theory that would work on a kiting situation, since the pull force would be on the fixed arm so the release arm would be free to move.

But that begs the question of the glider end - if a 1-26 or 2-33 kites, now HIS release is under tension, so HE can't release! A truly poor design, IMO.

Probably the best solution is the TOST internal reel with the guillotine - we checked ours on the ground (at rope replacement time) and even with relatively little tension on the rope (compared to a kiting glider), the guillotine (lever right in front of the throttle in the Pawnee) cut the rope like a piece of spaghetti. Actually surprised us how easy it was! And enough to convince us to install the same system on our other Pawnee, replacing the POS Schweizer release.

Kirk
66

[[email protected]]

I recently had a discussion with a CAP CFIG from Alaska that stated they actually tested the schewizer release on there tow plane at 45 degree angle up at 4000 pounds the release pressure on the handle was less than 25 lbs. Now I didn't get specifics as to method or condition of release. But it was his belief that it, as mentioned earlier in this thread, was more of a reaction time issue than ability. YRMV.

[[email protected]]

I have had the pleasure of taking tows behind Walt. He is best in show and a class act. I only have a few hundred tows in our club Pawnees and about 800tt in power and 50 in sailplanes so I'm no expert. What I do know is this: sailplane pilots are usually type-A and do a great job of rationalizing risk factors to themselves and others. Tost hook be damned, Walt- the variability in sailplane pilots at any club/commercial op will be a risk factor no modified release will solve for. It's a question of whether or not you are comfortable blocking out that idea or not. If I recall correctly, your past career is heavily analytical and clinical- I don't think this question is solvable that way.

[George Haeh]

The older, taller gliders were more problematic with CG hooks because the
hook was well below the actual CG. Some have a tendency to pitch up
excessively even on a winch.

I've taken aerotows on a CG hook in Pilatus, LS-4, ASW-20 and 27. None
harder than a nose hook in a Blanik.

The new designs are easier as long as the tow pilot gives you the
manufacturer recommended aerotow speed. One towpilot shorted me 10 kts
once too many times. I don't take tows from him any more as I got high
behind him twice and yanked.

The 27 with CG hook is lovely on aerotow, even through rotor. YMMV with
water and different CGs.

A nose hook is more work as you have to compensate for yaw and pitch
couples.

My question is which gliders with CG hooks are giving towpilots trouble?

Or is it a pilot problem?

[Walt Connelly]

I have had the pleasure of taking tows behind Walt. He is best in show and a class act. I only have a few hundred tows in our club Pawnees and about 800tt in power and 50 in sailplanes so I'm no expert. What I do know is this: sailplane pilots are usually type-A and do a great job of rationalizing risk factors to themselves and others. Tost hook be damned, Walt- the variability in sailplane pilots at any club/commercial op will be a risk factor no modified release will solve for. It's a question of whether or not you are comfortable blocking out that idea or not. If I recall correctly, your past career is heavily analytical and clinical- I don't think this question is solvable that way.

Rick,

I made a comment about the two pilots in question and you are right, there is a wide disparity among pilots relative to skill. A gentleman with obvious physical problems and a 15 year old student who never impressed me while she was dual are exactly the type you have to watch but if we only towed highly experienced pilots no one would get their license to gain that experience. That being said my analysis of the problem tells me that a Schweizer hook is inappropriate when we know the Tost will work under similar circumstances AND that the release handle MUST be immediately available to the tow pilot, not down on the floor or where one must bend and reach and feel for it and it must provide enough mechanical advantage to accomplish the job.

Learning that other clubs and facilities have changed to the Tost 30 years ago and that their handles are such that the pilot does not have to do Olympic class gymnastics to grab it concerns me. I realize that we can't pull things out of our asses today and rectify the problem immediately BUT I assure you things will be well underway today to correct my concerns OR I will be starting my second retirement a bit earlier than I had wanted to.

Walt

[Walt Connelly]

The older, taller gliders were more problematic with CG hooks because the
hook was well below the actual CG. Some have a tendency to pitch up
excessively even on a winch.

I've taken aerotows on a CG hook in Pilatus, LS-4, ASW-20 and 27. None
harder than a nose hook in a Blanik.

The new designs are easier as long as the tow pilot gives you the
manufacturer recommended aerotow speed. One towpilot shorted me 10 kts
once too many times. I don't take tows from him any more as I got high
behind him twice and yanked.

The 27 with CG hook is lovely on aerotow, even through rotor. YMMV with
water and different CGs.

A nose hook is more work as you have to compensate for yaw and pitch
couples.

My question is which gliders with CG hooks are giving towpilots trouble?

Or is it a pilot problem?

George, this was initially a pilot problem. A 15 year old student on her 3rd solo pattern tow and an older guy with obvious physical problems who had not taken an aero tow in a year or more are not the safest people to tow. That being said the next problem as previously stated is the Schweizer hook. It is well documented that under extreme pressure pulling the handle requires a herculean effort which I understand the a Tost conversion will correct. Then there is the question of the size and position of the release handle. It should be easily accessable and provide the necessary mechanical advantage. Someone mentioned reaction time. In one case I could see the belly of the glider in the mirror and I knew things were about to go bad but even if my hand was on the release at the time, by the time I knew I HAD to do it it would have been too late. It happened in the wink of an eye. The second time I could not see the glider as the student was out to the right and there is no mirror on the right side of the tow plane. There is ''NO ONE SIMPLE FIX."

Walt

[Roy B.]

The Tost Reel and guillotine system has its own set of issues and is itself controversial. My club used two of them for several years and later abandoned the system in favor of the straight Tost release.
If somebody wants details - start a different thread.
ROY

[Dan Marotta]

On 4/25/2017 5:18 AM, Walt Connelly wrote:

<snip>
....

AND that the release handle
MUST be immediately available to the tow pilot, not down on the floor or
where one must bend and reach and feel for it and it must provide enough
mechanical advantage to accomplish the job.

</snip>

It's been over a year but, IIRC, the release levers on the three tugs at
Sundance Aviation (Moriarty) are hinged at the floor with an
approximately 3-foot lever at about the same height as the throttle.
Easy to grab without looking and LOTS of mechanical advantage. Not
commenting at this time about the relative merits or each type of release.

[kirk.stant]

On Tuesday, April 25, 2017 at 9:03:34 AM UTC-5, Roy B. wrote:
> The Tost Reel and guillotine system has its own set of issues and is itself controversial. My club used two of them for several years and later abandoned the system in favor of the straight Tost release.
> If somebody wants details - start a different thread.
> ROY

Roy, would you PM me at kirk.stant at gmail.com? I'm curious about what problems you had with your Tost reel systems.

Cheers,

Kirk
66

[George Haeh]

We train boxing the wake, cannot release and slack rope recovery, and
expect
demonstration of some or all of these items on checkouts.

Hands up anybody who trains release when high on the towplane?

If students have never done this, how can we expect them to do it when
needed before or after license?

[Charlie M. (UH & 002 owner/pilot)]

I basically taught, "you lose sight of the towplane, you release". Yes, maybe a quick stab at the rudder will find the towplane again under your nose, then again, maybe not.

[George Haeh]

Yes, I know that's taught, but does anybody put the student high so that
release is required.

Just as with spins, there's a difference between being told what to do -
and
actually going into the situation.

[Charles Longley]

I am not a CFI. What would the risk be to doing that training? Particularly to the tow pilot?

[Jim White[_3_]]

At 03:16 26 April 2017, Charles Longley wrote:
>I am not a CFI. What would the risk be to doing that training?
Particularly
>to the tow pilot?
>
Maybe the answer is for the instructor to release whenever the student gets
high and it is safe to do so. The student may then get the message?

[Peter Whitehead]

Clearly some gliders are worse than others, and yes, better if in the hands of a good pilot. But even a moment's distraction can cause the good pilot to find himself/herself in a diverging and irrecoverable situation (kiting).. Whilst my suggestion to ground those gliders was slightly tongue in cheek, would that be preferable to continuing to see tug pilots "grounded" in a literal sense, with the miscreant sailing on unharmed?
The sustained force, mainly horizontal, from the rope really slows down the tug. 2-3 seconds of 700 lb force leaves the tug slow with a less effective elevator, and,as Chris Rollings noted, an elevator which may be stalled.
Sensor measuring sustained deceleration (not just a brief jerk/impulse) is maybe the measure best used to automatically jettison the rope at the tug end?

[Tango Whisky]

Le mercredi 26 avril 2017 03:45:04 UTC+2, George Haeh a écritÂ*:
> Yes, I know that's taught, but does anybody put the student high so that
> release is required.
>
> Just as with spins, there's a difference between being told what to do -
> and
> actually going into the situation.

Putting a student high so that a release is required would be plain stupid and reckless behaviour of an instructor.
Any exercise needs to be planned in a way that the student has some room for error, and that the instructor can recover the situation if the student finally fails to do so.
In a high position there is no such margin. There are situations which just can't be trained.

Bert
TW

[Justin Couch]

On Wednesday, 26 April 2017 18:11:04 UTC+10, Tango Whisky wrote:

> In a high position there is no such margin. There are situations which just can't be trained.

Can you kite in Condor or Silent Wings?

[Walt Connelly]

We train boxing the wake, cannot release and slack rope recovery, and
expect
demonstration of some or all of these items on checkouts.

Hands up anybody who trains release when high on the towplane?

If students have never done this, how can we expect them to do it when
needed before or after license?

Good point and it is obviously not part of any training syllabus of which I am aware. If done at altitude....2 or 3K feet and done only momentarily I feel it would be a reasonable thing to do BUT only with the towpilots knowledge that it is going to be done and with some kind of signal immediately before hand. I am confident I can get out of anything I can get into with sufficient altitude. Then again this would depend on the willingness and preparation of the tow pilot. JMHO.

Walt

[Tango Eight]

On Wednesday, April 26, 2017 at 4:11:04 AM UTC-4, Tango Whisky wrote:
> Le mercredi 26 avril 2017 03:45:04 UTC+2, George Haeh a écritÂ*:
> > Yes, I know that's taught, but does anybody put the student high so that
> > release is required.
> >
> > Just as with spins, there's a difference between being told what to do -
> > and
> > actually going into the situation.
>
> Putting a student high so that a release is required would be plain stupid and reckless behaviour of an instructor.
> Any exercise needs to be planned in a way that the student has some room for error, and that the instructor can recover the situation if the student finally fails to do so.
> In a high position there is no such margin. There are situations which just can't be trained.
>
> Bert
> TW

What can't be trained is the dangerous divergent situation. Agreed on all else.

-Evan / T8

[[email protected]]

On Wednesday, April 26, 2017 at 8:43:08 AM UTC-4, Walt Connelly wrote:
> George Haeh;944170 Wrote:
> > We train boxing the wake, cannot release and slack rope recovery, and
> > expect
> > demonstration of some or all of these items on checkouts.
> >
> > Hands up anybody who trains release when high on the towplane?
> >
> > If students have never done this, how can we expect them to do it when
> > needed before or after license?
>
> Good point and it is obviously not part of any training syllabus of
> which I am aware. If done at altitude....2 or 3K feet and done only
> momentarily I feel it would be a reasonable thing to do BUT only with
> the towpilots knowledge that it is going to be done and with some kind
> of signal immediately before hand. I am confident I can get out of
> anything I can get into with sufficient altitude. Then again this would
> depend on the willingness and preparation of the tow pilot. JMHO.
>
> Walt
>
>
>
>
> --
> Walt Connelly

This tow pilot will not agree to putting aircraft out of control at any altitude.
UH

[son_of_flubber]

On Wednesday, April 26, 2017 at 4:31:44 AM UTC-4, Justin Couch wrote:
> On Wednesday, 26 April 2017 18:11:04 UTC+10, Tango Whisky wrote:
>
> > In a high position there is no such margin. There are situations which just can't be trained.
>
> Can you kite in Condor or Silent Wings?

The ability to kite without the tug releasing automatically would be a great feature request for Condor_3. I'd also like to practice with a simulation of towing through wave related rotor. The first time that I recognized previously experienced Condor scenarios/sceneries in the real world, I was startled, 'that looks just like Condor'. Condor training would be beneficial..

In 2015 I ran the wing of a venerable_soaring_great who got trashed in rotor and broke the tow rope. Both pilots made it back to the airfield. Their account was harrowing. It can happen to anyone.

[Dan Marotta]

I was once air retrieving someone from an airport over 50 NM away from
Moriarty. We briefed thoroughly before takeoff that I would level off
and reduce power slowly at 10,000'. He later told me that, as I was
leveling off, he was looking inside the cockpit and missed it and lost
sight of me. He immediately released, which was great, but it was late
in the day and he did not have glide home. I told him to land and I
would give him another tow for free but he said he'd try for home. I
flew along with him looking for and guiding him to thermals. ...And he
beat me back to Moriarty. But he released immediately on losing sight
of me.

On 4/25/2017 7:40 PM, George Haeh wrote:
> Yes, I know that's taught, but does anybody put the student high so that
> release is required.
>
> Just as with spins, there's a difference between being told what to do -
> and
> actually going into the situation.
>

--
Dan, 5J

[Dan Marotta]

Just thinking of the physics here and remembering that the problem is
with the upward vector on the tow rope exerting so much force on the
Schweizer release that the tuggie can't release the rope. The following
assumes enough altitude to recover, not early in the tow.

Now, if the tug's tail gets pulled up sufficiently, the force vector on
the rope is more aligned with the longitudinal axis of the tug than the
vertical, thereby relieving the release of the upward (with respect to
the axis) force. Therefore the tug should be able to release as his
nose gets pointed towards the ground. Am I willing to prove this
theory? NO...

Also, if the glider is being pulled down via its CG release, the wing
should be fully stalled given the AoA of the wing in a (near) horizontal
descent with the fuselage level to the horizon. Application of rudder in
the glider should immediately induce a spin allowing the combination to
gently descend like a maple seed. Am I willing to prove this theory? NO...

And, when the tug hits the ground, the glider is free of the downward
pull of the rope and the resulting fire will generate a thermal allowing
the glider to climb away safely. Am I willing to prove this theory? NO...


On 4/26/2017 6:26 AM, Tango Eight wrote:
> On Wednesday, April 26, 2017 at 4:11:04 AM UTC-4, Tango Whisky wrote:
>> Le mercredi 26 avril 2017 03:45:04 UTC+2, George Haeh a écrit :
>>> Yes, I know that's taught, but does anybody put the student high so that
>>> release is required.
>>>
>>> Just as with spins, there's a difference between being told what to do -
>>> and
>>> actually going into the situation.
>> Putting a student high so that a release is required would be plain stupid and reckless behaviour of an instructor.
>> Any exercise needs to be planned in a way that the student has some room for error, and that the instructor can recover the situation if the student finally fails to do so.
>> In a high position there is no such margin. There are situations which just can't be trained.
>>
>> Bert
>> TW
> What can't be trained is the dangerous divergent situation. Agreed on all else.
>
> -Evan / T8

--
Dan, 5J

[Bob Kuykendall]

> This tow pilot will not agree to putting aircraft out of control at any altitude.
> UH

I can imagine that a severe kiting upset of the type under discussion could put a towplane uncomfortably close to its negative load factor limits. It might also expose the tug's tailplane to loads beyond those for which it was designed or tested.

--Bob K.

[George Haeh]

Well yes, we really don't want to go to extreme attitudes, nor do would
anybody half sane contemplate practicing getting high on the towplane until

approaching release altitude.

The idea is to build the muscle memory of releasing well before the
towpilot
has gotten to maximum up elevator.

We do want to give the towpilot adequate margin.

[Bob Kuykendall]

On Wednesday, April 26, 2017 at 10:30:05 AM UTC-7, George Haeh wrote:
> Well yes, we really don't want to go to extreme attitudes...

I definitely agree that we should teach recognition and remediation.

But I also think that the main point here is that a true kiting incident is a divergent condition such that, once established, can easily escalate at a rate beyond human control. So we have to be careful about how we teach it.

--Bob K.

[Jonathon May[_2_]]

At 17:49 26 April 2017, Bob Kuykendall wrote:
>On Wednesday, April 26, 2017 at 10:30:05 AM UTC-7, George Haeh wrote:
>> Well yes, we really don't want to go to extreme attitudes...
>
>I definitely agree that we should teach recognition and remediation.
>
>But I also think that the main point here is that a true kiting incident
is
>a divergent condition such that, once established, can easily escalate at
a
>rate beyond human control. So we have to be careful about how we teach
it.
>
>--Bob K.
>

I'm not a power/ tow pilot so this could be rubbish,but
Could an alarm be fitted at 90%back stick just to remind tug pilots just
how
much up elevator they are using to prevent gradually drifting into a
potential
dangerous situation from which there will be no escape.

[Bruce Hoult]

On Wednesday, April 26, 2017 at 8:50:01 PM UTC+3, Bob Kuykendall wrote:
> On Wednesday, April 26, 2017 at 10:30:05 AM UTC-7, George Haeh wrote:
> > Well yes, we really don't want to go to extreme attitudes...
>
> I definitely agree that we should teach recognition and remediation.
>
> But I also think that the main point here is that a true kiting incident is a divergent condition such that, once established, can easily escalate at a rate beyond human control. So we have to be careful about how we teach it.

I would like to know what happens if you have a 1000+ ft aerotow rope and cause the glider to "winch launch" behind the tug.

I have a hunch that very very bad things start to happen long before there's any significant upward angle on the rope. Such as the tug virtually stopping mid air and stalling/falling.

[[email protected]]

On Wednesday, April 26, 2017 at 2:45:05 PM UTC-4, Jonathon May wrote:
> At 17:49 26 April 2017, Bob Kuykendall wrote:
> >On Wednesday, April 26, 2017 at 10:30:05 AM UTC-7, George Haeh wrote:
> >> Well yes, we really don't want to go to extreme attitudes...
> >
> >I definitely agree that we should teach recognition and remediation.
> >
> >But I also think that the main point here is that a true kiting incident
> is
> >a divergent condition such that, once established, can easily escalate at
> a
> >rate beyond human control. So we have to be careful about how we teach
> it.
> >
> >--Bob K.
> >
>
> I'm not a power/ tow pilot so this could be rubbish,but
> Could an alarm be fitted at 90%back stick just to remind tug pilots just
> how
> much up elevator they are using to prevent gradually drifting into a
> potential
> dangerous situation from which there will be no escape.

I doubt most of us need an alarm to know we're pulling that much.
UH

[Dan Marotta]

....And the pitch rate is very high in a kiting incident. The tuggie can
be at full back stick and no longer in control quicker than he can
recognize and act.

On 4/26/2017 3:31 PM, wrote:
> On Wednesday, April 26, 2017 at 2:45:05 PM UTC-4, Jonathon May wrote:
>> At 17:49 26 April 2017, Bob Kuykendall wrote:
>>> On Wednesday, April 26, 2017 at 10:30:05 AM UTC-7, George Haeh wrote:
>>>> Well yes, we really don't want to go to extreme attitudes...
>>> I definitely agree that we should teach recognition and remediation.
>>>
>>> But I also think that the main point here is that a true kiting incident
>> is
>>> a divergent condition such that, once established, can easily escalate at
>> a
>>> rate beyond human control. So we have to be careful about how we teach
>> it.
>>> --Bob K.
>>>
>> I'm not a power/ tow pilot so this could be rubbish,but
>> Could an alarm be fitted at 90%back stick just to remind tug pilots just
>> how
>> much up elevator they are using to prevent gradually drifting into a
>> potential
>> dangerous situation from which there will be no escape.
> I doubt most of us need an alarm to know we're pulling that much.
> UH

--
Dan, 5J

[Jonathon May]

At 21:31 26 April 2017, wrote:
>On Wednesday, April 26, 2017 at 2:45:05 PM UTC-4, Jonathon May wrote:
>> At 17:49 26 April 2017, Bob Kuykendall wrote:
>> >On Wednesday, April 26, 2017 at 10:30:05 AM UTC-7, George Haeh
wrote:
>> >> Well yes, we really don't want to go to extreme attitudes...
>> >
>> >I definitely agree that we should teach recognition and remediation.
>> >
>> >But I also think that the main point here is that a true kiting
incident
>> is
>> >a divergent condition such that, once established, can easily escalate
>at
>> a
>> >rate beyond human control. So we have to be careful about how we
teach
>> it.
>> >
>> >--Bob K.
>> >
>>
>> I'm not a power/ tow pilot so this could be rubbish,but
>> Could an alarm be fitted at 90%back stick just to remind tug pilots
just
>> how
>> much up elevator they are using to prevent gradually drifting into a
>> potential
>> dangerous situation from which there will be no escape.
>
>I doubt most of us need an alarm to know we're pulling that much.
>UH
>I am sure you are right,it's just as a glider pilot I rely on feel,and
this
changes with trim,which is why we should always trim for the approach or
take off.

[Peter Whitehead]

Please do not consider training unless using simulation (only). There have been enough deaths and broken kit already. Chris Rollings in an earlier thread gave a detailed account of well constructed trials performed at height. It is not necessary to repeat these, surely. Please note his conclusions.If your glider has an approved mod. for a nose hook ( if it has only a winch hook) then consider having one fitted. Otherwise know that you could kill the tug pilot if for one brief moment you take your eyes off the tug (and respond immediately to the tug slipping below your field of view or to the strange accelerations which go with this in a "kiting" situation. ).

[Walt Connelly]

On 4/25/2017 5:18 AM, Walt Connelly wrote:

snip
....

AND that the release handle
MUST be immediately available to the tow pilot, not down on the floor or
where one must bend and reach and feel for it and it must provide enough
mechanical advantage to accomplish the job.

/snip

It's been over a year but, IIRC, the release levers on the three tugs at
Sundance Aviation (Moriarty) are hinged at the floor with an
approximately 3-foot lever at about the same height as the throttle.
Easy to grab without looking and LOTS of mechanical advantage. Not
commenting at this time about the relative merits or each type of release.

Dan,

Were these 3 foot handles the original design approved by the FAA or were they conversions later? I understand that it is not permissible to simply fabricate a longer handle and have it installed.

Walt

[Dan Marotta]

Walt, I can't answer that.

When I started towing at Sundance, both the CallAir and the Pawnee had
long handles. When the Ag Wagon came, it did, too. As I said, it's
been over a year since I looked into any of those cockpits, so I may not
be remembering correctly. I'll try to remember to take a look next time
I go to the airport.

Dan

On 4/27/2017 5:34 AM, Walt Connelly wrote:
> Dan Marotta;944164 Wrote:
>> On 4/25/2017 5:18 AM, Walt Connelly wrote:
>>
>> snip
>> ....
>>
>> AND that the release handle
>> MUST be immediately available to the tow pilot, not down on the floor or
>> where one must bend and reach and feel for it and it must provide enough
>> mechanical advantage to accomplish the job.
>>
>> /snip
>>
>> It's been over a year but, IIRC, the release levers on the three tugs at
>>
>> Sundance Aviation (Moriarty) are hinged at the floor with an
>> approximately 3-foot lever at about the same height as the throttle.
>> Easy to grab without looking and LOTS of mechanical advantage. Not
>> commenting at this time about the relative merits or each type of
>> release.
> Dan,
>
> Were these 3 foot handles the original design approved by the FAA or
> were they conversions later? I understand that it is not permissible to
> simply fabricate a longer handle and have it installed.
>
> Walt
>
>
>
>

--
Dan, 5J

[Charles Longley]

Dan,

Were these 3 foot handles the original design approved by the FAA or
were they conversions later? I understand that it is not permissible to
simply fabricate a longer handle and have it installed.

Walt

It actually is relatively easy to approve a longer handle Walt. AC 43.13-2B You would need to do 337 and have an IA sign off on it.

[firsys]

On Sunday, April 23, 2017 at 8:43:12 PM UTC-4, Walt Connelly wrote:
> I have been towing for about two and a half years and have logged over
> 6,500 tows. Having recently experienced a couple of rather violent
> glider kiting incidents, one at about 300 feet AGL I decided to
> investigate the experiences of other tow pilots in these circumstances.
> I have spent several hours reading posts about gliders kiting and
> upsetting the tow plane, many of the posts deal with creating an
> automatic release that will recognize the actions of the glider and
> release without input from the tow pilot. Nice idea, some really
> creative approaches and the bottom line is anything can be done if you
> have enough money and can get the FAA to buy into it and give
> approval.
>
> Lots of opinions and ideas as to why these things happen. Bottom line
> is that they do happen, they have resulted in loss of tow pilot lives
> and the causes are well known.
>
> Of my two most recent experiences one was with a 67 year old licensed
> private pilot, glider only, no other pilot ratings who at 2000 feet
> tried to release, “slipped back in the seat pulling back on the stick
> and going vertical.� I took a stab at the release to no avail, the
> pressure was too great and I soon found myself at about 75 degrees nose
> down at full power. The natural instinct at this point is to pull back
> the power and try again to release. He managed to release before I
> could try for a second time and I recovered. If this has to happen to
> you, 2000 feet is a good place to be. My understanding is that this was
> his first tow in more than a year. Something to think about.
>
> My second experience in the same week was with a 15 year old student on
> her 3rd solo pattern tow. At about 250 to 300 feet I started a turn
> from the downwind drift to the right. I felt a tug on my tail pulling
> my nose to the left. After a few seconds I tried again to turn to the
> right knowing that she was behind me to the right. Could not see her,
> no mirror on the right. (much easier if she was a little to the left)
> The second time the pull of my tail to the right and nose to the left
> was a bit more violent…..followed by a very hard tug of my tail UP and
> to the right. We could not have been much more than 300 feet when I
> found myself nose down and trying to release….again the pressure was too
> much to overcome and I needed to retard the throttle. Before I could
> make a second attempt at release I heard a loud BANG as the rope broke,
> I regained control and recovered just above the trees. (glad that I had
> made a pit stop before I started towing). She made it back to the field
> and didn’t seem at all concerned……I shall withhold my comments at this
> point.
>
> I had to straighten out the Schweizer hook which was off to the right
> about 30 degrees before I could make the last 8 tows of the day.
>
> While I have concerns with both of these pilots my major concern is that
> the difficulty of actuating the release when the glider kites is well
> documented. To make matters worse, the release in the tug I was flying,
> although a bit more manually accessible than the other two I fly
> requires that the pilot pull it back and push down to fully actuate the
> release. Not an easy thing to do under the circumstances. The other
> two release handles are down on the floor to the left and for someone of
> my height, sitting on a cushion and trying to grab the release is very
> difficult. It would seem to me that an easy fix would be to simply make
> a longer handle curved up so one could both see and feel for it in an
> emergency. A longer handle would also provide a bit more mechanical
> advantage although having read many of the posts I am not sure this
> would overcome the pressure on the Schweizer hook. Of course I hear all
> the noise about needing to apply for a 337 and get FAA approval….next I
> will need approval to put a cushion on the seat or to have an inspection
> after washing the airplane.
>
> So, the fixes appear to be going to a Tost hook or inverting the
> Schweizer hook which I understand can be done with an available STC.
> In my case I would also like to see a more accessible release
> handle…would (or should) an STC be required for this? This would be
> the short term fix I would like to see. If the handle was made from the
> same stock as the current device, just a foot or so longer it would seem
> that this should be able to be done without a long drawn out approval
> process.
>
> I love flying, enjoy the gliderport environment and people but I am NOT
> willing to give up my life. When the glider kites things happen very
> fast. Unless your hand is on the handle (not feasible in my
> circumstances) you will not be able to release before the pressure gets
> too great. If it happens much lower than I experience it will be lights
> out. So remember my glider pilot friends….fly well….the life you save
> might be your tow pilot.
>
> Walt Connelly
>
>
>
>
> --
> Walt Connelly

In his excellent and erudite post on aerotow upset testing, Chris Rollings
said " the speed at which things happen is proportional to the length of the rope"
I think he intended to say INVERSELY proportional to the length.

John F

[Chris Rollings[_2_]]

At 01:13 28 April 2017, firsys wrote:
>On Sunday, April 23, 2017 at 8:43:12 PM UTC-4, Walt Connelly wrote:
>> I have been towing for about two and a half years and have logged over
>> 6,500 tows. Having recently experienced a couple of rather violent
>> glider kiting incidents, one at about 300 feet AGL I decided to
>> investigate the experiences of other tow pilots in these
circumstances.=
>=20
>> I have spent several hours reading posts about gliders kiting and
>> upsetting the tow plane, many of the posts deal with creating an
>> automatic release that will recognize the actions of the glider and
>> release without input from the tow pilot. Nice idea, some really
>> creative approaches and the bottom line is anything can be done if you
>> have enough money and can get the FAA to buy into it and give
>> approval.
>>=20
>> Lots of opinions and ideas as to why these things happen. Bottom line
>> is that they do happen, they have resulted in loss of tow pilot lives
>> and the causes are well known.=20
>>=20
>> Of my two most recent experiences one was with a 67 year old licensed
>> private pilot, glider only, no other pilot ratings who at 2000 feet
>> tried to release, =E2=80=9Cslipped back in the seat pulling back on the
>s=
>tick
>> and going vertical.=E2=80=9D I took a stab at the release to no avail,
>t=
>he
>> pressure was too great and I soon found myself at about 75 degrees nose
>> down at full power. The natural instinct at this point is to pull back
>> the power and try again to release. He managed to release before I
>> could try for a second time and I recovered. If this has to happen to
>> you, 2000 feet is a good place to be. My understanding is that this
was
>> his first tow in more than a year. Something to think about. =20
>>=20
>> My second experience in the same week was with a 15 year old student on
>> her 3rd solo pattern tow. At about 250 to 300 feet I started a turn
>> from the downwind drift to the right. I felt a tug on my tail pulling
>> my nose to the left. After a few seconds I tried again to turn to the
>> right knowing that she was behind me to the right. Could not see her,
>> no mirror on the right. (much easier if she was a little to the left)
=20
>> The second time the pull of my tail to the right and nose to the left
>> was a bit more violent=E2=80=A6..followed by a very hard tug of my
tail
>=
> UP and
>> to the right. We could not have been much more than 300 feet when I
>> found myself nose down and trying to release=E2=80=A6.again the
pressure
>=
>was too
>> much to overcome and I needed to retard the throttle. Before I could
>> make a second attempt at release I heard a loud BANG as the rope broke,
>> I regained control and recovered just above the trees. (glad that I
had
>> made a pit stop before I started towing). She made it back to the
field
>> and didn=E2=80=99t seem at all concerned=E2=80=A6=E2=80=A6I shall
>withhol=
>d my comments at this
>> point. =20
>>=20
>> I had to straighten out the Schweizer hook which was off to the right
>> about 30 degrees before I could make the last 8 tows of the day.
>>=20
>> While I have concerns with both of these pilots my major concern is
that
>> the difficulty of actuating the release when the glider kites is well
>> documented. To make matters worse, the release in the tug I was
flying,
>> although a bit more manually accessible than the other two I fly
>> requires that the pilot pull it back and push down to fully actuate the
>> release. Not an easy thing to do under the circumstances. The other
>> two release handles are down on the floor to the left and for someone
of
>> my height, sitting on a cushion and trying to grab the release is very
>> difficult. It would seem to me that an easy fix would be to simply
make
>> a longer handle curved up so one could both see and feel for it in an
>> emergency. A longer handle would also provide a bit more mechanical
>> advantage although having read many of the posts I am not sure this
>> would overcome the pressure on the Schweizer hook. Of course I hear
all
>> the noise about needing to apply for a 337 and get FAA
>approval=E2=80=A6.=
>next I
>> will need approval to put a cushion on the seat or to have an
inspection
>> after washing the airplane. =20
>>=20
>> So, the fixes appear to be going to a Tost hook or inverting the
>> Schweizer hook which I understand can be done with an available STC.
=20
>> In my case I would also like to see a more accessible release
>> handle=E2=80=A6would (or should) an STC be required for this? This
>wou=
>ld be
>> the short term fix I would like to see. If the handle was made from
the
>> same stock as the current device, just a foot or so longer it would
seem
>> that this should be able to be done without a long drawn out approval
>> process. =20
>>=20
>> I love flying, enjoy the gliderport environment and people but I am NOT
>> willing to give up my life. When the glider kites things happen very
>> fast. Unless your hand is on the handle (not feasible in my
>> circumstances) you will not be able to release before the pressure gets
>> too great. If it happens much lower than I experience it will be
lights
>> out. So remember my glider pilot friends=E2=80=A6.fly
well=E2=80=A6.the
>=
>life you save
>> might be your tow pilot.
>>=20
>> Walt Connelly
>>=20
>>=20
>>=20
>>=20
>> --=20
>> Walt Connelly
>
>In his excellent and erudite post on aerotow upset testing, Chris
Rollings
>said " the speed at which things happen is proportional to the length of
>th=
>e rope"
>I think he intended to say INVERSELY proportional to the length.
>
>John F
>

Directly proportional, if the rope is twice as long, the time the
divergence takes is also twice as long.

[Bruce Hoult]

On Friday, April 28, 2017 at 12:00:58 PM UTC+3, Chris Rollings wrote:
> At 01:13 28 April 2017, firsys wrote:
> >In his excellent and erudite post on aerotow upset testing, Chris
> Rollings
> >said " the speed at which things happen is proportional to the length of
> >th=
> >e rope"
> >I think he intended to say INVERSELY proportional to the length.
>
> Directly proportional, if the rope is twice as long, the time the
> divergence takes is also twice as long.

The time is directly proportional to the rope length. The *speed* at which it happens is inversely proportional.

But I'm not convinced and angle achieved in divergence is even the primary factor. If the glider goes into "winch launch" mode then it's pulling backwards with a tension of its own weight or more. Winch launch weak links range from 500 - 1000 kg. How many tugs have the thrust to prevent being drastically slowed -- and stalled -- by that vs the normal 50 - 100 kg tension in the rope? None, I should think. Even if the rope is thousands of feet long very bad things are going to happen.

[[email protected]]

I've seen this twice from the glider. The second time caught on a GoPro.

The failure mode appears to be recovering from slack in a nose up condition..
The cause is a combination of physics, glider pilot training, and towing in sporty conditions.

My first experience was at altitude behind a Pawnee. From the glider, the stick was full forward, little elevator authority, rope tight, and pilot leaning forward. Glider nose was slowly lowering so the situation was converging. Talking on the ground, the tow pilot never lost elevator authority or felt the need to release his end. The lesson learned was the wrong one with little understanding. That this was strange, but safe and recoverable event.

The second experience was just after launch behind a CallAir. Similar story from the glider, but a much different story from the tow end. Loss of elevator authority, ground getting close, but situation improving. If I had had any clue that there was a problem at the other end of the rope, I would have released, but from the first experience, I saw things as ok and improving. Thankfully, it turned out ok, but with a much different lesson and understanding on the second try.

Having had some time to think about it. I think an understanding of kiting should be required for anybody towing with a CG hook. Actually trying to train it at altitude is not a good idea because of loss of sight of the tow plane. Remembering not to be nose up on slack recovery is. If you get to this mode, just quickly release and go again.

I've since put a nose hook on my glider. This was a non-trivial exercise, but the opportunity presented itself and since I tow in sporty conditions, it seemed worth it. Given an understanding of the problem, this is kind of belt and suspenders, so it probably should not be a requirement, but the training is a must.

[George Haeh]

Could you tell us about glider type, CG, weight and tow speed, especially
in
relation to manufacturer recommended tow speed?


At 14:01 30 April 2017, wrote:
>I've seen this twice from the glider. The second time caught on a GoPro.
>
>The failure mode appears to be recovering from slack in a nose up
>condition=
>..
>The cause is a combination of physics, glider pilot training, and towing
>in=
> sporty conditions.
>
>My first experience was at altitude behind a Pawnee. From the glider,
the
>=
>stick was full forward, little elevator authority, rope tight, and pilot
>le=
>aning forward. Glider nose was slowly lowering so the situation was
>conver=
>ging. Talking on the ground, the tow pilot never lost elevator authority
>o=
>r felt the need to release his end. The lesson learned was the wrong one
>w=
>ith little understanding. That this was strange, but safe and
recoverable
>=
>event.
>
>The second experience was just after launch behind a CallAir. Similar
>stor=
>y from the glider, but a much different story from the tow end. Loss of
>el=
>evator authority, ground getting close, but situation improving. If I
had
>=
>had any clue that there was a problem at the other end of the rope, I
>would=
> have released, but from the first experience, I saw things as ok and
>impro=
>ving. Thankfully, it turned out ok, but with a much different lesson and
>u=
>nderstanding on the second try.
>
>Having had some time to think about it. I think an understanding of
>kiting=
> should be required for anybody towing with a CG hook. Actually trying
to
>=
>train it at altitude is not a good idea because of loss of sight of the
>tow=
> plane. Remembering not to be nose up on slack recovery is. If you get
>to=
> this mode, just quickly release and go again.
>
>I've since put a nose hook on my glider. This was a non-trivial
exercise,
>=
>but the opportunity presented itself and since I tow in sporty
conditions,
>=
>it seemed worth it. Given an understanding of the problem, this is kind
>of=
> belt and suspenders, so it probably should not be a requirement, but the
>t=
>raining is a must.
>
>
>
>

[Dan Marotta]

Following up on the tow release levers in the three tugs at Moriarty:

Pawnee - lever is 2 1/2 feet long, hinged below the floor. Has a throw
of about 2 feet.
CallAir - Very similar to the Pawnee.
Ag Wagon - Lever is only about 8 inches long, mounted near the throttle,
and is pushed (rather than pulled) to actuate. I'm not too sure that
one would be of much use when the Schweizer hook is under high load.

Dan

On 4/30/2017 1:24 PM, George Haeh wrote:
> Could you tell us about glider type, CG, weight and tow speed, especially
> in
> relation to manufacturer recommended tow speed?
>
>
> At 14:01 30 April 2017, wrote:
>> I've seen this twice from the glider. The second time caught on a GoPro.
>>
>> The failure mode appears to be recovering from slack in a nose up
>> condition=
>> ..
>> The cause is a combination of physics, glider pilot training, and towing
>> in=
>> sporty conditions.
>>
>> My first experience was at altitude behind a Pawnee. From the glider,
> the
>> =
>> stick was full forward, little elevator authority, rope tight, and pilot
>> le=
>> aning forward. Glider nose was slowly lowering so the situation was
>> conver=
>> ging. Talking on the ground, the tow pilot never lost elevator authority
>> o=
>> r felt the need to release his end. The lesson learned was the wrong one
>> w=
>> ith little understanding. That this was strange, but safe and
> recoverable
>> =
>> event.
>>
>> The second experience was just after launch behind a CallAir. Similar
>> stor=
>> y from the glider, but a much different story from the tow end. Loss of
>> el=
>> evator authority, ground getting close, but situation improving. If I
> had
>> =
>> had any clue that there was a problem at the other end of the rope, I
>> would=
>> have released, but from the first experience, I saw things as ok and
>> impro=
>> ving. Thankfully, it turned out ok, but with a much different lesson and
>> u=
>> nderstanding on the second try.
>>
>> Having had some time to think about it. I think an understanding of
>> kiting=
>> should be required for anybody towing with a CG hook. Actually trying
> to
>> =
>> train it at altitude is not a good idea because of loss of sight of the
>> tow=
>> plane. Remembering not to be nose up on slack recovery is. If you get
>> to=
>> this mode, just quickly release and go again.
>>
>> I've since put a nose hook on my glider. This was a non-trivial
> exercise,
>> =
>> but the opportunity presented itself and since I tow in sporty
> conditions,
>> =
>> it seemed worth it. Given an understanding of the problem, this is kind
>> of=
>> belt and suspenders, so it probably should not be a requirement, but the
>> t=
>> raining is a must.
>>
>>
>>
>>

--
Dan, 5J

[[email protected]]

When I towed at the Air Force Academy a long time ago in a galaxy far away.....we had a T-handle mounted on the panel right in front of the throttle. As soon as I had full throttle in, I could hold the throttle with the butt of my hand and have my fingers resting on the handle ready for any surprises. I did run into several instances when I couldn't release due to the glider (2-33) swinging high and outside in the turn in a slack rope recovery gone bad. The rope would usually snap tight, the towplane (180 hp Super Cub) would lurch violently sideways and nose down. Due to the side load I could not release from my end, the glider couldn't release, and usually a rope break would solve the problem.

I witnessed a kiting incident of a Ventus with a cg hook right after liftoff at the old Black Forest Glider Port. The Ventus went up, did a wingover from maybe 50 feet a nosed into the ground. The towplane almost had a prop strike but the rope broke, or maybe got released in time. Fortunately the Ventus pilot was not severely injured, but lots of damage on the nose and cockpit area.

As far as the release handle on the Pawnee and Call Air, it seems to me that the handle for the dump gate would give lots of leverage. Same with the AgWagon, if you used the lever for the dump gate instead of spray valve handle.

I'm all for Tost releases on the towplane end. As simple as the Schwiezer hitch is, it is an accident waiting to happen....again.

Just my 2 cents worth.

[[email protected]]

On Sunday, April 30, 2017 at 6:00:26 PM UTC-4, Dan Marotta wrote:
> Following up on the tow release levers in the three tugs at Moriarty:
>
> Pawnee - lever is 2 1/2 feet long, hinged below the floor. Has a throw
> of about 2 feet.
> CallAir - Very similar to the Pawnee.
> Ag Wagon - Lever is only about 8 inches long, mounted near the throttle,
> and is pushed (rather than pulled) to actuate. I'm not too sure that
> one would be of much use when the Schweizer hook is under high load.
>
> Dan
>
> On 4/30/2017 1:24 PM, George Haeh wrote:
> > Could you tell us about glider type, CG, weight and tow speed, especially
> > in
> > relation to manufacturer recommended tow speed?
> >
> >
> > At 14:01 30 April 2017, wrote:
> >> I've seen this twice from the glider. The second time caught on a GoPro.
> >>
> >> The failure mode appears to be recovering from slack in a nose up
> >> condition=
> >> ..
> >> The cause is a combination of physics, glider pilot training, and towing
> >> in=
> >> sporty conditions.
> >>
> >> My first experience was at altitude behind a Pawnee. From the glider,
> > the
> >> =
> >> stick was full forward, little elevator authority, rope tight, and pilot
> >> le=
> >> aning forward. Glider nose was slowly lowering so the situation was
> >> conver=
> >> ging. Talking on the ground, the tow pilot never lost elevator authority
> >> o=
> >> r felt the need to release his end. The lesson learned was the wrong one
> >> w=
> >> ith little understanding. That this was strange, but safe and
> > recoverable
> >> =
> >> event.
> >>
> >> The second experience was just after launch behind a CallAir. Similar
> >> stor=
> >> y from the glider, but a much different story from the tow end. Loss of
> >> el=
> >> evator authority, ground getting close, but situation improving. If I
> > had
> >> =
> >> had any clue that there was a problem at the other end of the rope, I
> >> would=
> >> have released, but from the first experience, I saw things as ok and
> >> impro=
> >> ving. Thankfully, it turned out ok, but with a much different lesson and
> >> u=
> >> nderstanding on the second try.
> >>
> >> Having had some time to think about it. I think an understanding of
> >> kiting=
> >> should be required for anybody towing with a CG hook. Actually trying
> > to
> >> =
> >> train it at altitude is not a good idea because of loss of sight of the
> >> tow=
> >> plane. Remembering not to be nose up on slack recovery is. If you get
> >> to=
> >> this mode, just quickly release and go again.
> >>
> >> I've since put a nose hook on my glider. This was a non-trivial
> > exercise,
> >> =
> >> but the opportunity presented itself and since I tow in sporty
> > conditions,
> >> =
> >> it seemed worth it. Given an understanding of the problem, this is kind
> >> of=
> >> belt and suspenders, so it probably should not be a requirement, but the
> >> t=
> >> raining is a must.
> >>
> >>
> >>
> >>
>
> --
> Dan, 5J

The handle on the Pawnee that you make reference to was the original dump handle for the gate on the hopper. It is located on the left side extending up from below the surface of the floor. The assembly has two attach points that hold it in place. This assembly makes a great release mechanism for the release handle. Just yesterday I finished the assembly of my Tost Tow Hook on my Pawnee, I used this handle as the release handle, the location of this handle along with the length of the arm provides the best option for a release assembly. I also plan on adding a spring on the arm that will act as a positive pressure upon being in the closed position.

[Dan Marotta]

The Moriarty Ag Wagon was never used as a sprayer. According to the
plaque on the instrument panel it was "Designed and built especially for
Billy R. Shurley". I towed behind him and that plane out of Marfa in
the 80s. He also had the trigger on the stick grip wired to connectors
mounted on the wings at the strut attach points. There was also a
"Master Arm" stitch on the panel. I'm told he mounted shotguns under
the wings to "chase" coyotes on his very large ranch.

On 4/30/2017 7:07 PM, wrote:
> When I towed at the Air Force Academy a long time ago in a galaxy far away....we had a T-handle mounted on the panel right in front of the throttle. As soon as I had full throttle in, I could hold the throttle with the butt of my hand and have my fingers resting on the handle ready for any surprises. I did run into several instances when I couldn't release due to the glider (2-33) swinging high and outside in the turn in a slack rope recovery gone bad. The rope would usually snap tight, the towplane (180 hp Super Cub) would lurch violently sideways and nose down. Due to the side load I could not release from my end, the glider couldn't release, and usually a rope break would solve the problem.
>
> I witnessed a kiting incident of a Ventus with a cg hook right after liftoff at the old Black Forest Glider Port. The Ventus went up, did a wingover from maybe 50 feet a nosed into the ground. The towplane almost had a prop strike but the rope broke, or maybe got released in time. Fortunately the Ventus pilot was not severely injured, but lots of damage on the nose and cockpit area.
>
> As far as the release handle on the Pawnee and Call Air, it seems to me that the handle for the dump gate would give lots of leverage. Same with the AgWagon, if you used the lever for the dump gate instead of spray valve handle.
>
> I'm all for Tost releases on the towplane end. As simple as the Schwiezer hitch is, it is an accident waiting to happen....again.
>
> Just my 2 cents worth.

--
Dan, 5J

[[email protected]]

I don't want to get a thread drift going, but that reminds me of one of our captains who strapped a pair of MAC-10's on his Quicksilver ultralight and strafed the desert!! We used to hunt coyotes out of J-3's and Super Cubs. Several great prop strike stories....
But back to tow planes-- the AgWagon and Pawnees I used to spray and dust (yes, real sulpher dust) with had the dump gate lever on the left side of the cockpit mounted on the floor with a mechanism under the floor leading to the gate itself. As I recall, there was an adjustable stop to regulate the flow of dust from the hopper through the spreader (and into the cockpit--at least I never had fleas). When they convert a Pawnee to a towplane the hopper is usually removed along with all the hardware. Maybe everyone should think twice about taking that lever out. It can provide a lot of leverage on the tow hook.

[[email protected]]

Usually the hopper is cut down and the upper part is still used as part of the front turtle deck. The dump handle as you discussed has a mechanical screw jack that regulates the opening of the hopper gate. With all that said I would encourage anyone doing a conversion to a towplane to use that hopper dump handle as their tow release handle. It is a great release mechanism.

[Heinz Gehlhaar]

Glider pilot only. I am just reading all these experiences and I am thinking: What would happen if the Towpilot put full DOWN-elevator when he is in that position (and has some altitude)? Would that not break the towline?
Heinz

[[email protected]]

"Could you tell us about glider type, CG, weight and tow speed, especially
in relation to manufacturer recommended tow speed? "

Ventus B, 15M with winglets, dry. CG at 56% of range, 740 pounds, 60 Knots, Flaps +1, Spoilers closed.

Maintaining position with stick and rudder. (slips instead of airbreaks)
I think pretty nominal, but if you see something I'd like to hear.


Again, the lesson I took was to be aware of the failure mode, stay low near the prop wash, takeup slack nose down, and be willing to release if things get out of hand.

With the second lesson, I've towed through fairly violent rotors with a CG hook. I've released when I'd had enough, but there wasn't a kiting issue.

Training is key.

[Tango Eight]

On Tuesday, May 2, 2017 at 9:00:41 AM UTC-4, wrote:
> "Could you tell us about glider type, CG, weight and tow speed, especially
> in relation to manufacturer recommended tow speed? "
>
> Ventus B, 15M with winglets, dry. CG at 56% of range, 740 pounds, 60 Knots, Flaps +1, Spoilers closed.

Better double check that W&B, because the behavior you describe suggests a CG close to or behind aft limit. There are probably a few Ventus Bs around with undocumented tail weight added. That was sort of the fashion in the 1980s.

If you are indeed at 56%, then there is some other significant issue.

best,
Evan Ludeman / T8

[Dan Marotta]

Slack in the rope? What's that other than a training exercise? I'd be
willing to bet that kiting incidents are caused by glider pilots losing
sight of the tug and not releasing immediately. Either that or they're
not qualified to be towing as pilot in command. I don't think students
see many difficult situations until after they're soloed and then
they're not prepared to handle them.

What Stu said: Training is key.

On 5/2/2017 7:00 AM, wrote:
> "Could you tell us about glider type, CG, weight and tow speed, especially
> in relation to manufacturer recommended tow speed? "
>
> Ventus B, 15M with winglets, dry. CG at 56% of range, 740 pounds, 60 Knots, Flaps +1, Spoilers closed.
>
> Maintaining position with stick and rudder. (slips instead of airbreaks)
> I think pretty nominal, but if you see something I'd like to hear.
>
>
> Again, the lesson I took was to be aware of the failure mode, stay low near the prop wash, takeup slack nose down, and be willing to release if things get out of hand.
>
> With the second lesson, I've towed through fairly violent rotors with a CG hook. I've released when I'd had enough, but there wasn't a kiting issue.
>
> Training is key.
>

--
Dan, 5J

[SoaringXCellence]

If you think slack line only happens in training, why are you doing it? What real world event are we training to prevent?

Of the course the answer is that slack line is NOT just something to practice.

Tow into some rotor or other severe turbulence and you have slack line that you can't prevent, no matter how good you think you can control a glider.

I know you know that Dan.

[Dan Marotta]

I've been in severe rotor turbulence on both ends of the tow line and
it's no fun, but the slack lines that I've seen, again from both ends of
the rope, never got out of hand. At those times both pilots are quite
alert. The only other slack lines I've seen have been due to
inattention or lack of skill.

Why is everyone so reluctant to call a spade a space?

On 5/2/2017 11:49 AM, SoaringXCellence wrote:
> If you think slack line only happens in training, why are you doing it? What real world event are we training to prevent?
>
> Of the course the answer is that slack line is NOT just something to practice.
>
> Tow into some rotor or other severe turbulence and you have slack line that you can't prevent, no matter how good you think you can control a glider.
>
> I know you know that Dan.

--
Dan, 5J

[[email protected]]

Why is everyone so reluctant to call a spade a space?

Because they are spelled differently.

[Bret Wills]

In our PA-25 we mounted the schweizer hook inverted, which in theory prevents that difficult/impossible release scenario. Having said that though, having experienced an upset at about 1,000 feet, the shocking speed of the upset makes me think that if it happened at 200 feet instead, no matter what kind of release system was installed, there would be no way to react in time.. I sometimes have to complain to instructors who let their students get way too out of shape when down low.

[[email protected]]

On Sunday, April 23, 2017 at 8:43:12 PM UTC-4, Walt Connelly wrote:
> I have been towing for about two and a half years and have logged over
> 6,500 tows. Having recently experienced a couple of rather violent
> glider kiting incidents, one at about 300 feet AGL I decided to
> investigate the experiences of other tow pilots in these circumstances.
> I have spent several hours reading posts about gliders kiting and
> upsetting the tow plane, many of the posts deal with creating an
> automatic release that will recognize the actions of the glider and
> release without input from the tow pilot. Nice idea, some really
> creative approaches and the bottom line is anything can be done if you
> have enough money and can get the FAA to buy into it and give
> approval.
>
> Lots of opinions and ideas as to why these things happen. Bottom line
> is that they do happen, they have resulted in loss of tow pilot lives
> and the causes are well known.
>
> Of my two most recent experiences one was with a 67 year old licensed
> private pilot, glider only, no other pilot ratings who at 2000 feet
> tried to release, “slipped back in the seat pulling back on the stick
> and going vertical.� I took a stab at the release to no avail, the
> pressure was too great and I soon found myself at about 75 degrees nose
> down at full power. The natural instinct at this point is to pull back
> the power and try again to release. He managed to release before I
> could try for a second time and I recovered. If this has to happen to
> you, 2000 feet is a good place to be. My understanding is that this was
> his first tow in more than a year. Something to think about.
>
> My second experience in the same week was with a 15 year old student on
> her 3rd solo pattern tow. At about 250 to 300 feet I started a turn
> from the downwind drift to the right. I felt a tug on my tail pulling
> my nose to the left. After a few seconds I tried again to turn to the
> right knowing that she was behind me to the right. Could not see her,
> no mirror on the right. (much easier if she was a little to the left)
> The second time the pull of my tail to the right and nose to the left
> was a bit more violent…..followed by a very hard tug of my tail UP and
> to the right. We could not have been much more than 300 feet when I
> found myself nose down and trying to release….again the pressure was too
> much to overcome and I needed to retard the throttle. Before I could
> make a second attempt at release I heard a loud BANG as the rope broke,
> I regained control and recovered just above the trees. (glad that I had
> made a pit stop before I started towing). She made it back to the field
> and didn’t seem at all concerned……I shall withhold my comments at this
> point.
>
> I had to straighten out the Schweizer hook which was off to the right
> about 30 degrees before I could make the last 8 tows of the day.
>
> While I have concerns with both of these pilots my major concern is that
> the difficulty of actuating the release when the glider kites is well
> documented. To make matters worse, the release in the tug I was flying,
> although a bit more manually accessible than the other two I fly
> requires that the pilot pull it back and push down to fully actuate the
> release. Not an easy thing to do under the circumstances. The other
> two release handles are down on the floor to the left and for someone of
> my height, sitting on a cushion and trying to grab the release is very
> difficult. It would seem to me that an easy fix would be to simply make
> a longer handle curved up so one could both see and feel for it in an
> emergency. A longer handle would also provide a bit more mechanical
> advantage although having read many of the posts I am not sure this
> would overcome the pressure on the Schweizer hook. Of course I hear all
> the noise about needing to apply for a 337 and get FAA approval….next I
> will need approval to put a cushion on the seat or to have an inspection
> after washing the airplane.
>
> So, the fixes appear to be going to a Tost hook or inverting the
> Schweizer hook which I understand can be done with an available STC.
> In my case I would also like to see a more accessible release
> handle…would (or should) an STC be required for this? This would be
> the short term fix I would like to see. If the handle was made from the
> same stock as the current device, just a foot or so longer it would seem
> that this should be able to be done without a long drawn out approval
> process.
>
> I love flying, enjoy the gliderport environment and people but I am NOT
> willing to give up my life. When the glider kites things happen very
> fast. Unless your hand is on the handle (not feasible in my
> circumstances) you will not be able to release before the pressure gets
> too great. If it happens much lower than I experience it will be lights
> out. So remember my glider pilot friends….fly well….the life you save
> might be your tow pilot.
>
> Walt Connelly
>
>
>
>
> --
> Walt Connelly

Those Schweitzer hooks should have been replaced long ago. I just last week installed a Tost hook on my Pawnee and I am certainly glad that I did. Tow pilot safety is a must, no substitute for doing all possible to protect the tow pilot and glider pilot as well.

[Frank Whiteley]

On Monday, May 22, 2017 at 12:59:04 AM UTC-6, wrote:
> On Sunday, April 23, 2017 at 8:43:12 PM UTC-4, Walt Connelly wrote:
> > I have been towing for about two and a half years and have logged over
> > 6,500 tows. Having recently experienced a couple of rather violent
> > glider kiting incidents, one at about 300 feet AGL I decided to
> > investigate the experiences of other tow pilots in these circumstances.
> > I have spent several hours reading posts about gliders kiting and
> > upsetting the tow plane, many of the posts deal with creating an
> > automatic release that will recognize the actions of the glider and
> > release without input from the tow pilot. Nice idea, some really
> > creative approaches and the bottom line is anything can be done if you
> > have enough money and can get the FAA to buy into it and give
> > approval.
> >
> > Lots of opinions and ideas as to why these things happen. Bottom line
> > is that they do happen, they have resulted in loss of tow pilot lives
> > and the causes are well known.
> >
> > Of my two most recent experiences one was with a 67 year old licensed
> > private pilot, glider only, no other pilot ratings who at 2000 feet
> > tried to release, “slipped back in the seat pulling back on the stick
> > and going vertical.� I took a stab at the release to no avail, the
> > pressure was too great and I soon found myself at about 75 degrees nose
> > down at full power. The natural instinct at this point is to pull back
> > the power and try again to release. He managed to release before I
> > could try for a second time and I recovered. If this has to happen to
> > you, 2000 feet is a good place to be. My understanding is that this was
> > his first tow in more than a year. Something to think about.
> >
> > My second experience in the same week was with a 15 year old student on
> > her 3rd solo pattern tow. At about 250 to 300 feet I started a turn
> > from the downwind drift to the right. I felt a tug on my tail pulling
> > my nose to the left. After a few seconds I tried again to turn to the
> > right knowing that she was behind me to the right. Could not see her,
> > no mirror on the right. (much easier if she was a little to the left)
> > The second time the pull of my tail to the right and nose to the left
> > was a bit more violent…..followed by a very hard tug of my tail UP and
> > to the right. We could not have been much more than 300 feet when I
> > found myself nose down and trying to release….again the pressure was too
> > much to overcome and I needed to retard the throttle. Before I could
> > make a second attempt at release I heard a loud BANG as the rope broke,
> > I regained control and recovered just above the trees. (glad that I had
> > made a pit stop before I started towing). She made it back to the field
> > and didn’t seem at all concerned……I shall withhold my comments at this
> > point.
> >
> > I had to straighten out the Schweizer hook which was off to the right
> > about 30 degrees before I could make the last 8 tows of the day.
> >
> > While I have concerns with both of these pilots my major concern is that
> > the difficulty of actuating the release when the glider kites is well
> > documented. To make matters worse, the release in the tug I was flying,
> > although a bit more manually accessible than the other two I fly
> > requires that the pilot pull it back and push down to fully actuate the
> > release. Not an easy thing to do under the circumstances. The other
> > two release handles are down on the floor to the left and for someone of
> > my height, sitting on a cushion and trying to grab the release is very
> > difficult. It would seem to me that an easy fix would be to simply make
> > a longer handle curved up so one could both see and feel for it in an
> > emergency. A longer handle would also provide a bit more mechanical
> > advantage although having read many of the posts I am not sure this
> > would overcome the pressure on the Schweizer hook. Of course I hear all
> > the noise about needing to apply for a 337 and get FAA approval….next I
> > will need approval to put a cushion on the seat or to have an inspection
> > after washing the airplane.
> >
> > So, the fixes appear to be going to a Tost hook or inverting the
> > Schweizer hook which I understand can be done with an available STC.
> > In my case I would also like to see a more accessible release
> > handle…would (or should) an STC be required for this? This would be
> > the short term fix I would like to see. If the handle was made from the
> > same stock as the current device, just a foot or so longer it would seem
> > that this should be able to be done without a long drawn out approval
> > process.
> >
> > I love flying, enjoy the gliderport environment and people but I am NOT
> > willing to give up my life. When the glider kites things happen very
> > fast. Unless your hand is on the handle (not feasible in my
> > circumstances) you will not be able to release before the pressure gets
> > too great. If it happens much lower than I experience it will be lights
> > out. So remember my glider pilot friends….fly well….the life you save
> > might be your tow pilot.
> >
> > Walt Connelly
> >
> >
> >
> >
> > --
> > Walt Connelly
>
> Those Schweitzer hooks should have been replaced long ago. I just last week installed a Tost hook on my Pawnee and I am certainly glad that I did. Tow pilot safety is a must, no substitute for doing all possible to protect the tow pilot and glider pilot as well.

True, but not all FSDO's have cooperated. A few years ago, a 260 Pawnee with a restricted A/W here in Colorado had to go to Wichita for 337 approval to install a TOST hook.

[Walt Connelly]

On Sunday, April 23, 2017 at 8:43:12 PM UTC-4, Walt Connelly wrote:
I have been towing for about two and a half years and have logged over
6,500 tows. Having recently experienced a couple of rather violent
glider kiting incidents, one at about 300 feet AGL I decided to
investigate the experiences of other tow pilots in these circumstances.
I have spent several hours reading posts about gliders kiting and
upsetting the tow plane, many of the posts deal with creating an
automatic release that will recognize the actions of the glider and
release without input from the tow pilot. Nice idea, some really
creative approaches and the bottom line is anything can be done if you
have enough money and can get the FAA to buy into it and give
approval.

Lots of opinions and ideas as to why these things happen. Bottom line
is that they do happen, they have resulted in loss of tow pilot lives
and the causes are well known.

Of my two most recent experiences one was with a 67 year old licensed
private pilot, glider only, no other pilot ratings who at 2000 feet
tried to release, “slipped back in the seat pulling back on the stick
and going vertical.� I took a stab at the release to no avail, the
pressure was too great and I soon found myself at about 75 degrees nose
down at full power. The natural instinct at this point is to pull back
the power and try again to release. He managed to release before I
could try for a second time and I recovered. If this has to happen to
you, 2000 feet is a good place to be. My understanding is that this was
his first tow in more than a year. Something to think about.

My second experience in the same week was with a 15 year old student on
her 3rd solo pattern tow. At about 250 to 300 feet I started a turn
from the downwind drift to the right. I felt a tug on my tail pulling
my nose to the left. After a few seconds I tried again to turn to the
right knowing that she was behind me to the right. Could not see her,
no mirror on the right. (much easier if she was a little to the left)
The second time the pull of my tail to the right and nose to the left
was a bit more violent…..followed by a very hard tug of my tail UP and
to the right. We could not have been much more than 300 feet when I
found myself nose down and trying to release….again the pressure was too
much to overcome and I needed to retard the throttle. Before I could
make a second attempt at release I heard a loud BANG as the rope broke,
I regained control and recovered just above the trees. (glad that I had
made a pit stop before I started towing). She made it back to the field
and didn’t seem at all concerned……I shall withhold my comments at this
point.

I had to straighten out the Schweizer hook which was off to the right
about 30 degrees before I could make the last 8 tows of the day.

While I have concerns with both of these pilots my major concern is that
the difficulty of actuating the release when the glider kites is well
documented. To make matters worse, the release in the tug I was flying,
although a bit more manually accessible than the other two I fly
requires that the pilot pull it back and push down to fully actuate the
release. Not an easy thing to do under the circumstances. The other
two release handles are down on the floor to the left and for someone of
my height, sitting on a cushion and trying to grab the release is very
difficult. It would seem to me that an easy fix would be to simply make
a longer handle curved up so one could both see and feel for it in an
emergency. A longer handle would also provide a bit more mechanical
advantage although having read many of the posts I am not sure this
would overcome the pressure on the Schweizer hook. Of course I hear all
the noise about needing to apply for a 337 and get FAA approval….next I
will need approval to put a cushion on the seat or to have an inspection
after washing the airplane.

So, the fixes appear to be going to a Tost hook or inverting the
Schweizer hook which I understand can be done with an available STC.
In my case I would also like to see a more accessible release
handle…would (or should) an STC be required for this? This would be
the short term fix I would like to see. If the handle was made from the
same stock as the current device, just a foot or so longer it would seem
that this should be able to be done without a long drawn out approval
process.

I love flying, enjoy the gliderport environment and people but I am NOT
willing to give up my life. When the glider kites things happen very
fast. Unless your hand is on the handle (not feasible in my
circumstances) you will not be able to release before the pressure gets
too great. If it happens much lower than I experience it will be lights
out. So remember my glider pilot friends….fly well….the life you save
might be your tow pilot.

Walt Connelly




--
Walt Connelly

Those Schweitzer hooks should have been replaced long ago. I just last week installed a Tost hook on my Pawnee and I am certainly glad that I did. Tow pilot safety is a must, no substitute for doing all possible to protect the tow pilot and glider pilot as well.

I totally agree. Unfortunately too many tow planes out there continue to operate with a system that might cause the death of a tow pilot. Until a low kiting incident happens to a tow pilot, he or she will not understand the speed at which it occurs or what it feels like to try to operate the release with no response.

Walt Connelly

[Walt Connelly]

On Monday, May 22, 2017 at 12:59:04 AM UTC-6, wrote:
On Sunday, April 23, 2017 at 8:43:12 PM UTC-4, Walt Connelly wrote:
I have been towing for about two and a half years and have logged over
6,500 tows. Having recently experienced a couple of rather violent
glider kiting incidents, one at about 300 feet AGL I decided to
investigate the experiences of other tow pilots in these circumstances.
I have spent several hours reading posts about gliders kiting and
upsetting the tow plane, many of the posts deal with creating an
automatic release that will recognize the actions of the glider and
release without input from the tow pilot. Nice idea, some really
creative approaches and the bottom line is anything can be done if you
have enough money and can get the FAA to buy into it and give
approval.

Lots of opinions and ideas as to why these things happen. Bottom line
is that they do happen, they have resulted in loss of tow pilot lives
and the causes are well known.

Of my two most recent experiences one was with a 67 year old licensed
private pilot, glider only, no other pilot ratings who at 2000 feet
tried to release, “slipped back in the seat pulling back on the stick
and going vertical.� I took a stab at the release to no avail, the
pressure was too great and I soon found myself at about 75 degrees nose
down at full power. The natural instinct at this point is to pull back
the power and try again to release. He managed to release before I
could try for a second time and I recovered. If this has to happen to
you, 2000 feet is a good place to be. My understanding is that this was
his first tow in more than a year. Something to think about.

My second experience in the same week was with a 15 year old student on
her 3rd solo pattern tow. At about 250 to 300 feet I started a turn
from the downwind drift to the right. I felt a tug on my tail pulling
my nose to the left. After a few seconds I tried again to turn to the
right knowing that she was behind me to the right. Could not see her,
no mirror on the right. (much easier if she was a little to the left)
The second time the pull of my tail to the right and nose to the left
was a bit more violent…..followed by a very hard tug of my tail UP and
to the right. We could not have been much more than 300 feet when I
found myself nose down and trying to release….again the pressure was too
much to overcome and I needed to retard the throttle. Before I could
make a second attempt at release I heard a loud BANG as the rope broke,
I regained control and recovered just above the trees. (glad that I had
made a pit stop before I started towing). She made it back to the field
and didn’t seem at all concerned……I shall withhold my comments at this
point.

I had to straighten out the Schweizer hook which was off to the right
about 30 degrees before I could make the last 8 tows of the day.

While I have concerns with both of these pilots my major concern is that
the difficulty of actuating the release when the glider kites is well
documented. To make matters worse, the release in the tug I was flying,
although a bit more manually accessible than the other two I fly
requires that the pilot pull it back and push down to fully actuate the
release. Not an easy thing to do under the circumstances. The other
two release handles are down on the floor to the left and for someone of
my height, sitting on a cushion and trying to grab the release is very
difficult. It would seem to me that an easy fix would be to simply make
a longer handle curved up so one could both see and feel for it in an
emergency. A longer handle would also provide a bit more mechanical
advantage although having read many of the posts I am not sure this
would overcome the pressure on the Schweizer hook. Of course I hear all
the noise about needing to apply for a 337 and get FAA approval….next I
will need approval to put a cushion on the seat or to have an inspection
after washing the airplane.

So, the fixes appear to be going to a Tost hook or inverting the
Schweizer hook which I understand can be done with an available STC.
In my case I would also like to see a more accessible release
handle…would (or should) an STC be required for this? This would be
the short term fix I would like to see. If the handle was made from the
same stock as the current device, just a foot or so longer it would seem
that this should be able to be done without a long drawn out approval
process.

I love flying, enjoy the gliderport environment and people but I am NOT
willing to give up my life. When the glider kites things happen very
fast. Unless your hand is on the handle (not feasible in my
circumstances) you will not be able to release before the pressure gets
too great. If it happens much lower than I experience it will be lights
out. So remember my glider pilot friends….fly well….the life you save
might be your tow pilot.

Walt Connelly




--
Walt Connelly

Those Schweitzer hooks should have been replaced long ago. I just last week installed a Tost hook on my Pawnee and I am certainly glad that I did. Tow pilot safety is a must, no substitute for doing all possible to protect the tow pilot and glider pilot as well.

True, but not all FSDO's have cooperated. A few years ago, a 260 Pawnee with a restricted A/W here in Colorado had to go to Wichita for 337 approval to install a TOST hook.

Please educate me on this. Do I understand that a FSDO can deny an operator a change from a Schweizer to Tost release?

Walt Connelly