7C
March 4th 14, 11:41 PM
There have been a couple of interesting discussions about towing on RAS. I think Chris Rollings opened a few eyes as to what actually starts a tug upset in his post:
>Third test: Terrier Tow-Plane, K 8b on C of G hook. I pitched the glider
> about 25 degrees nose up.
( https://groups.google.com/d/msg/rec.aviation.soaring/1eZiSHzqC7g/Uz0Ga95XVCsJ )
This combined in my mind with a rather disturbing incident I had flying my LS4 behind a microlight tug in NZ. The tow got so slow that I lost elevator control resulting in me sinking into the propwash. I'm not 100% sure but I'd guess my stick was very close to the backstop and the glider felt very stalled.
(See https://groups.google.com/d/msg/rec.aviation.soaring/X6Owt5P0L2A/fq0_agD32psJ for discussion on why 55 knots might have been too slow!)
Had we rapidly accelerated (for example due to the tug hitting lift or realising he was too slow) it could very easily have resulted in a kiting movement.
I've never seen any discussion on contributing factors in tug upsets. It seems odd that the most dramatic divergence is caused by a high angle of attack (i.e. stick back) climbing motion. In all the other tows I have ever down I've never had a reason to have the stick back enough to 'kite' and I can't imagine why a fully aware and competent pilot would pull back hard enough to induce a high angle of attack.
If the tow speed is relevant it might explain why low tow is superior - you are less likely to hit the aerodynamic wash and therefore lose flying authority.
Am I drawing an incorrect correlation between two tow related situations?
>Third test: Terrier Tow-Plane, K 8b on C of G hook. I pitched the glider
> about 25 degrees nose up.
( https://groups.google.com/d/msg/rec.aviation.soaring/1eZiSHzqC7g/Uz0Ga95XVCsJ )
This combined in my mind with a rather disturbing incident I had flying my LS4 behind a microlight tug in NZ. The tow got so slow that I lost elevator control resulting in me sinking into the propwash. I'm not 100% sure but I'd guess my stick was very close to the backstop and the glider felt very stalled.
(See https://groups.google.com/d/msg/rec.aviation.soaring/X6Owt5P0L2A/fq0_agD32psJ for discussion on why 55 knots might have been too slow!)
Had we rapidly accelerated (for example due to the tug hitting lift or realising he was too slow) it could very easily have resulted in a kiting movement.
I've never seen any discussion on contributing factors in tug upsets. It seems odd that the most dramatic divergence is caused by a high angle of attack (i.e. stick back) climbing motion. In all the other tows I have ever down I've never had a reason to have the stick back enough to 'kite' and I can't imagine why a fully aware and competent pilot would pull back hard enough to induce a high angle of attack.
If the tow speed is relevant it might explain why low tow is superior - you are less likely to hit the aerodynamic wash and therefore lose flying authority.
Am I drawing an incorrect correlation between two tow related situations?