Strange behaviour on the wind
Strange behaviour on the wind
(OP)
I have encountered a strange problem when our small rotorcraft (2 meters rotor diameter, rotates clockwise when looking from the top) is hovering while an oncoming wind (about 10 knots) is blowing onto the platform. The craft begins to roll counterclockwise (if looking at the craft from the tail end forward and the nose of the rotorcraft to the wind.), loses altitude and if we don't take the controls and intervene rapidly, the craft could be lost. It rolls always in the same direction relatively to the wind. It means if we rotate the helicopter 90 deg, lets say right side to the wind, now it will pitch to the nose (again counterclockwise to the wind). At first we had twisted blades, which we thought might be causing the problem. However, after replacement with an untwisted blades, we still have the same problem. By the way, if there is no wind, then there is no problem. The helicopter has Bell-Hiller stabilization flybar with the pedals.
Thank you.
Thank you.





RE: Strange behaviour on the wind
The incoming wind is creating more lift on the advancing blade and less on the retreating blade... Thats why helicopters are so much "fun" to fly - everything is changing very rapidly.
BTW - what kind of rotocraft has only a 2m blade - a model or unmanned ??
RE: Strange behaviour on the wind
The helicopter is a model.
RE: Strange behaviour on the wind
RE: Strange behaviour on the wind
Gyroscopic action may be the answer as suggested or if the blades are rather flexible - may be they are twisting into the wind and actaully creating less lift?? Seems like I have read something where the swash plate handles this. Maybe I am wrong - kind of out of my element here.
Sounds like an interesting problem.
Most small model helicopters have blades so rigid that they can fly upside down. Maybe yours is starting to behave like a big boy helicopter
RE: Strange behaviour on the wind
http://www.swashplate.co.uk/ehbg-v17/ch30.html
and less so, this:
http://www
Mike Halloran
Pembroke Pines, FL, USA
RE: Strange behaviour on the wind
Thanks to everybody.
RE: Strange behaviour on the wind
RE: Strange behaviour on the wind
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Regards,
Lyle