Fatal Towplane Accident 5-9-20

Since we have now decided to re-invent the tow plane to put the tow hook on the CG, has anybody considered a canard design with a front or mid fuselage mounted engine?

On Fri, 15 May 2020 11:57:35 -0700, Rakel wrote:

Since we have now decided to re-invent the tow plane to put the tow hook
on the CG, has anybody considered a canard design with a front or mid
fuselage mounted engine?

Difficult: I've flown a Canard free flight model. Its CG was in front of
the wing and about 1/3 of the way along the wing:stabiliser gap in front
of the wing. The motor was on a short pylon above the CG.

Part of the design would be clear: put the pilot on the CG, fins and
rudders near the tips and anchor the towline no further back than the
wing LE, but where do you put the engine while keeping the propeller away
from the towline without making the poor thing far too nose-heavy?

Move the pilot back to the wing LE, put the engine immediately in front
of him and use a long, light carbon drive shaft to a prop at the front?

Maybe a bigger, more powerful Quickie with twin fins would be better?
https://en.wikipedia.org/wiki/Quickie_Aircraft

Or a Transavia Air Truck?
https://en.wikipedia.org/wiki/Transavia_PL-12_Airtruk

OTOH, just get Bert Rutan out of retirement and point him at the problem.


--
Martin | martin at
Gregorie | gregorie dot org

Great ideas all around. Install a rear view camera...reinvent the tow plane. Has anyone ever tried to get an A&P to invert the Schweizer hook or extend the release handle so it would be easily reachable? It seemed to me that it required an act of God and an amendment to the Constitution to accomplish something like this. Maybe I was just being put off...

I had to argue for the purchase of a mixture cable for a Pawnee. I guess if you have enough money and are willing to spend it you can accomplish anything. It remains to be seen how quickly the commercial operations will come back after this Chinese Communist Virus has decimated our economy. People might not be willing to take the chance of exposing themselves to others and exponentially increase their chances of becoming ill. Don't expect the commercial operation owners or the club members to make big expenditures under these circumstances.

Walt Connelly
Former Tow Pilot
Now Happy Helicopter Pilot

On Friday, May 15, 2020 at 4:36:21 PM UTC-4, wrote:
Great ideas all around. Install a rear view camera...reinvent the tow plane. Has anyone ever tried to get an A&P to invert the Schweizer hook or extend the release handle so it would be easily reachable? It seemed to me that it required an act of God and an amendment to the Constitution to accomplish something like this. Maybe I was just being put off...

I had to argue for the purchase of a mixture cable for a Pawnee. I guess if you have enough money and are willing to spend it you can accomplish anything. It remains to be seen how quickly the commercial operations will come back after this Chinese Communist Virus has decimated our economy. People might not be willing to take the chance of exposing themselves to others and exponentially increase their chances of becoming ill. Don't expect the commercial operation owners or the club members to make big expenditures under these circumstances.

Walt Connelly
Former Tow Pilot
Now Happy Helicopter Pilot

Walt, this is getting abit crazy, next to come will be a ballistic charge that will explode and remove the tow assembly from the tow plane while ensuring the safety of all involved.

On Friday, May 15, 2020 at 5:46:22 PM UTC-4, Bob Youngblood wrote:
On Friday, May 15, 2020 at 4:36:21 PM UTC-4, wrote:
Great ideas all around. Install a rear view camera...reinvent the tow plane. Has anyone ever tried to get an A&P to invert the Schweizer hook or extend the release handle so it would be easily reachable? It seemed to me that it required an act of God and an amendment to the Constitution to accomplish something like this. Maybe I was just being put off...

I had to argue for the purchase of a mixture cable for a Pawnee. I guess if you have enough money and are willing to spend it you can accomplish anything. It remains to be seen how quickly the commercial operations will come back after this Chinese Communist Virus has decimated our economy. People might not be willing to take the chance of exposing themselves to others and exponentially increase their chances of becoming ill. Don't expect the commercial operation owners or the club members to make big expenditures under these circumstances.

Walt Connelly
Former Tow Pilot
Now Happy Helicopter Pilot

Walt, this is getting abit crazy, next to come will be a ballistic charge that will explode and remove the tow assembly from the tow plane while ensuring the safety of all involved.

Bob, A ballistic parachute would be good too along with airbags inside the cockpit to protect the tow pilot and a fire suppression system activated on impact. And I remember having to get ****ed to have someone order a friggin' mixture cable.

I would never in a thousand years think that one would need to be concerned with an instructor pilot screwing up, I thought the squirrels were just old duffers and 15 year old kids with the light on but nobody home. Fact is that the poor guy in this instance didn't stand a chance at the altitude the glider kited. It wouldn't have made a bit of difference if he was flying the Yellow Gorilla, he still would have been doomed.

Still lots of tow pilots out there with Schweizer hooks with standard installation, releases down on the floor and oblivious to the danger in which they have put themselves. I know a lot of operations have made significant changes but still I'm afraid most have not, this is the way we have always done it, the old mantra.

Flying tow is fun, I enjoyed almost 3 years and 7000 tows but the guy or girl in back of you can be too unpredictable. I know I'll get a lot of crap for this but I really think a minimum flight physical needs to be required for glider pilots. Many have bad eyesight, hypertension, diabetes, things that could go wrong with them and might also kill the tow pilot. If it was just the glider pilot I would be okay but it's not just the glider pilot, the tow pilot's life is in the mix. When I can no longer get by my AME it will be time to stop flying.

Walt Connelly
Former Tow PIlot
Now Happy Helicopter Pilot

Originally Posted by Rakel

Since we have now decided to re-invent the tow plane to put the tow hook on the CG, has anybody considered a canard design with a front or mid fuselage mounted engine?

Not quite what you have in mind but I've towed behind one of these back in the 80s and it was a pretty darn good towplane and apparently good to fly

https://en.wikipedia.org/wiki/Transavia_PL-12_Airtruk

I believe that full up elevator is what the towpilot will instinctively do in a kite siuation. This device will detect that and hopefully not give any false positives

release logic something like:-
1) GPS groundspeed ~60kmh for for ~5 seconds (so its not an engine test)
2) engine throttle ~80% for ~5 seconds (so its a take-off)
3) full up elevator (for more then ~0.2 second to filter out a knock)

when 1) and 2) are satisfied the system is "armed". A low groundspeed or Landing flaps could disarm it

I have chosen a low groundspeed in 1) to accomodate a strong head wind

GPS groundspeed and full elevator are easy to measure. Throttle a little trickier - maybe one could use flaps instead. tweak as necessary

Manual override, arm and disarm switches in the cockpit of course. some LEDs.

a simple embedded CPU costing 1$ can easily handle this and is very reliable. The BOM could be under 50$. This can be built by a hobbyist.

The tricky bit is
* Mounting the sensors
* triggering the release if its not electical

Peter

On Saturday, May 16, 2020 at 12:10:01 PM UTC-4, Rhubarb wrote:
I believe that full up elevator is what the towpilot will instinctively do in a kite siuation. This device will detect that and hopefully not give any false positives

release logic something like:-
1) GPS groundspeed ~60kmh for for ~5 seconds (so its not an engine test)
2) engine throttle ~80% for ~5 seconds (so its a take-off)
3) full up elevator (for more then ~0.2 second to filter out a knock)

when 1) and 2) are satisfied the system is "armed". A low groundspeed or Landing flaps could disarm it

I have chosen a low groundspeed in 1) to accomodate a strong head wind

GPS groundspeed and full elevator are easy to measure. Throttle a little trickier - maybe one could use flaps instead. tweak as necessary

Manual override, arm and disarm switches in the cockpit of course. some LEDs.

a simple embedded CPU costing 1$ can easily handle this and is very reliable. The BOM could be under 50$. This can be built by a hobbyist.

The tricky bit is
* Mounting the sensors
* triggering the release if its not electical

Peter

Airspeed is probably better than ground speed.
To sense departure from "normal" measuring line tension and angle are probably the most useful. With those available rate of change of the two would be a very useful indicator of things getting out of hand.
FWIW
UH

Seems to me that the most fool-proof solution is the line tension sensor and a little bit of accumulative logic.

We had a discussion on the club group about this and the example used was a 1800lb tow-plane, 700lb glider being towed. Kiting event takes 2 seconds, ends up with the glider gaining 100ft. Starting speed 60mph (glider being a 1-26). After 2 seconds of glider kiting the glider speed is 75 mph, tow-plane speed is 40mph. Average tension on the rope is 900lb and the tow-plane experiences 1/2G deceleration along the longitudal axis. One could just set a longitudal axis g-meter and alert/cut the line at .5G, but that might trip with slack rope etc. Having a rope tension sensor calculate energy loss due to the pull on rope over the last .1, .2 ,.3 seconds would be easy. The hard part would be to decide what the limit should be. One might test this with boxing the wake, tows trough rotor etc. If the event starts fast, the rope angle doesn't really get much above normal (in reference to the tow-plane) since the strong pull on the rope easily lifts the tail. The energy loss for the tow-plane is the bigger problem.

On Saturday, May 16, 2020 at 9:10:01 AM UTC-7, Rhubarb wrote:
I believe that full up elevator is what the towpilot will instinctively do in a kite siuation. This device will detect that and hopefully not give any false positives

release logic something like:-
1) GPS groundspeed ~60kmh for for ~5 seconds (so its not an engine test)
2) engine throttle ~80% for ~5 seconds (so its a take-off)
3) full up elevator (for more then ~0.2 second to filter out a knock)

when 1) and 2) are satisfied the system is "armed". A low groundspeed or Landing flaps could disarm it

I have chosen a low groundspeed in 1) to accomodate a strong head wind

GPS groundspeed and full elevator are easy to measure. Throttle a little trickier - maybe one could use flaps instead. tweak as necessary

Manual override, arm and disarm switches in the cockpit of course. some LEDs.

a simple embedded CPU costing 1$ can easily handle this and is very reliable. The BOM could be under 50$. This can be built by a hobbyist.

The tricky bit is
* Mounting the sensors
* triggering the release if its not electical

Peter

Wouldn't it be easier to design an electrical detach of tow rope by a button on the stick or throttle. This way the tow pilot decides and it would take a fraction of a second to activate. As stated before, helicopters use both a stick mounted electronic release and a stick mounted Manuel release. Full disclaimer, I am not a tow pilot, not a mechanic, can afford new tape each time I assemble, and I don't unbuckle to stand up in flight to untangle yaw strings. A few days ago I would have thought that was normal, now I am confused.