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Tow-plane pilot for gliders is a dangerous profession. A simple mistake by the glider pilot can kill the tow plane pilot, with not enough time to react. I saw t

Tow-plane pilot for gliders is a dangerous profession. A simple mistake by the glider pilot can kill the tow plane pilot, with not enough time to react. I saw this happen in person once (https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101258/pdf https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/G...). Gliders and towing them is neither easy nor safe.

deleted 1y ago
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aseg 1y ago
In gliding, tow upsets are pretty common and, in rare cases, can be fatal. An out-of-position glider out can _easily_ and very quickly overcome the tow planes elevator authority (ability to pitch up or down) which leads to accidents like this. This video does a good job explaining explaining the root causes and potential dangers (https://youtu.be/5cpqFzhM9dY?si=J7GxP1dI9Xopy3xu https://youtu.be/5cpqFzhM9dY?si=J7GxP1dI9Xopy3xu). Also read the comments from testimonials from other glider pilots. This is my biggest concern with this concept as well. Towing things is challenging because the tow plane's center of gravity can change drastically depending on the forces on the glider it is towing -- if the glider deploys its spoilers / crabs in a crosswind / gets in your wake turbulence you're not going to be able to predict how it changes your CG (and your control authority) without training or experience. Also, with gliders, the tow plane is traveling at around 60MPH to 90MPH, with a decision window of 2-3 seconds. Commercial planes travel at ~500 MPH... The concept seems like a hard sell to the pilot unions. I bet they've thought about this though.
- tgsovlerkhgsel 1y ago
  > An out-of-position glider out can _easily_ and very quickly overcome the tow planes elevator authority Would this not be trivially solvable with a system that detects the situation (e.g. by measuring the forces acting on the towing plane's attachment point) and detaches the tow? If in the final concept the towed plane would be unmanned and wouldn't contain fuel, even a crash would not be particularly catastrophic.
  - dmitrygr 1y ago
    You misread. It causes the crash of the leading plane, not of the following one, so the glider having no fuel is completely irrelevant As for a system that measures forces, that’s not likely to work either. Transient forces are OK, but the same force over a little bit of time is enough to force a nose down attitude that is unrecoverable. Attempting to draw the line unequivocally between the two is difficult because it depends on conditions, weights, centers of gravity, and many other things.
    - garrettgrimsley 1y ago
      They didn't misread, what they're saying is that the lead plane would detect conditions/forces that would result in a tow upset and then cut the tow tether. There's a video in this thread that shows that currently, in manned gliders, the glider pilot can and has a responsibility to release if a tow upset is happening.
      - dmitrygr 1y ago
        It. Does. Not. Always. Work! Read linked NTSB report (i understand it well - have been flying planes for over 13 year now)
  - aseg 1y ago
    The force at the attachment point is constantly changing and depends on several factors. - the weight of either airplane. - the performance of the engine on that particular day (varies by altitude / airspeed / temp / mixture / type of fuel / ...) - the instantaneous weather conditions - the performance characteristics of either plane. - slack in the rope (no tension to two times the weight of the glider) - the glider's towing position (below / above wake) - crosswinds - the glider's preferred towing position (depends on visibility from the cockpit, e.g. if someone has a phone or a tablet on the dash, the towing position will be different) So it isn't really a trivial problem, especially when false positive or false negative will lead to a crash. Oh btw, it needs to be able to react in milliseconds (so no AI, unfortunately). Here's an example of what an early release looks like btw: https://youtu.be/Gu0mZC2mLEg?si=dzVMxG-rW5624T_m https://youtu.be/Gu0mZC2mLEg?si=dzVMxG-rW5624T_m notice how he's always on the stick. Also notice how fast it goes from stable to unstable positions. > even a crash Recklessness is never the answer in aviation (or coding matter of fact). Practically, good luck convincing insurance to cover a 100 ton (any appreciable cargo load) plane that might fall out of the sky on any property in the general vicinity.
satiated_grue 1y ago
I was always amazed that the idea of towing a plane with three other planes (the "Troika-Schlepp") was not only conceived, but performed. https://en.wikipedia.org/wiki/Messerschmitt_Me_323_Gigant#Me_323 https://en.wikipedia.org/wiki/Messerschmitt_Me_323_Gigant#Me... https://ww2talk.com/index.php?threads/glider-towing.22518/ https://ww2talk.com/index.php?threads/glider-towing.22518/
leoh 1y ago
What do we think we can do to make it all safer?

deleted 1y ago

[deleted]

aseg 1y ago

In gliding, tow upsets are pretty common and, in rare cases, can be fatal. An out-of-position glider out can _easily_ and very quickly overcome the tow planes elevator authority (ability to pitch up or down) which leads to accidents like this. This video does a good job explaining explaining the root causes and potential dangers (https://youtu.be/5cpqFzhM9dY?si=J7GxP1dI9Xopy3xu https://youtu.be/5cpqFzhM9dY?si=J7GxP1dI9Xopy3xu). Also read the comments from testimonials from other glider pilots. This is my biggest concern with this concept as well. Towing things is challenging because the tow plane's center of gravity can change drastically depending on the forces on the glider it is towing -- if the glider deploys its spoilers / crabs in a crosswind / gets in your wake turbulence you're not going to be able to predict how it changes your CG (and your control authority) without training or experience. Also, with gliders, the tow plane is traveling at around 60MPH to 90MPH, with a decision window of 2-3 seconds. Commercial planes travel at ~500 MPH... The concept seems like a hard sell to the pilot unions. I bet they've thought about this though.

tgsovlerkhgsel 1y ago
> An out-of-position glider out can _easily_ and very quickly overcome the tow planes elevator authority Would this not be trivially solvable with a system that detects the situation (e.g. by measuring the forces acting on the towing plane's attachment point) and detaches the tow? If in the final concept the towed plane would be unmanned and wouldn't contain fuel, even a crash would not be particularly catastrophic.
- dmitrygr 1y ago
  You misread. It causes the crash of the leading plane, not of the following one, so the glider having no fuel is completely irrelevant As for a system that measures forces, that’s not likely to work either. Transient forces are OK, but the same force over a little bit of time is enough to force a nose down attitude that is unrecoverable. Attempting to draw the line unequivocally between the two is difficult because it depends on conditions, weights, centers of gravity, and many other things.
  - garrettgrimsley 1y ago
    They didn't misread, what they're saying is that the lead plane would detect conditions/forces that would result in a tow upset and then cut the tow tether. There's a video in this thread that shows that currently, in manned gliders, the glider pilot can and has a responsibility to release if a tow upset is happening.
    - dmitrygr 1y ago
      It. Does. Not. Always. Work! Read linked NTSB report (i understand it well - have been flying planes for over 13 year now)
- aseg 1y ago
  The force at the attachment point is constantly changing and depends on several factors. - the weight of either airplane. - the performance of the engine on that particular day (varies by altitude / airspeed / temp / mixture / type of fuel / ...) - the instantaneous weather conditions - the performance characteristics of either plane. - slack in the rope (no tension to two times the weight of the glider) - the glider's towing position (below / above wake) - crosswinds - the glider's preferred towing position (depends on visibility from the cockpit, e.g. if someone has a phone or a tablet on the dash, the towing position will be different) So it isn't really a trivial problem, especially when false positive or false negative will lead to a crash. Oh btw, it needs to be able to react in milliseconds (so no AI, unfortunately). Here's an example of what an early release looks like btw: https://youtu.be/Gu0mZC2mLEg?si=dzVMxG-rW5624T_m https://youtu.be/Gu0mZC2mLEg?si=dzVMxG-rW5624T_m notice how he's always on the stick. Also notice how fast it goes from stable to unstable positions. > even a crash Recklessness is never the answer in aviation (or coding matter of fact). Practically, good luck convincing insurance to cover a 100 ton (any appreciable cargo load) plane that might fall out of the sky on any property in the general vicinity.

satiated_grue 1y ago

I was always amazed that the idea of towing a plane with three other planes (the "Troika-Schlepp") was not only conceived, but performed. https://en.wikipedia.org/wiki/Messerschmitt_Me_323_Gigant#Me_323 https://en.wikipedia.org/wiki/Messerschmitt_Me_323_Gigant#Me... https://ww2talk.com/index.php?threads/glider-towing.22518/ https://ww2talk.com/index.php?threads/glider-towing.22518/

leoh 1y ago

What do we think we can do to make it all safer?