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