Tow Plane Upsets......

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.

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

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.

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.

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.