Tow Plane Upsets......

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.

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

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.

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.

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.

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.

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

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.

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.

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