Comments on: Ground Resonance Shakes Apart Chopper? https://gregladen.com/blog/2012/02/27/ground-resonance-shakes-apart/ Tue, 28 Feb 2012 05:30:03 +0000 hourly 1 https://wordpress.org/?v=6.4.6 By: Brad https://gregladen.com/blog/2012/02/27/ground-resonance-shakes-apart/#comment-491526 Tue, 28 Feb 2012 05:30:03 +0000 http://scienceblogs.com/gregladen/2012/02/27/ground-resonance-shakes-apart/#comment-491526 No, it’s real. Lots of videos of the phenomenon on youtube.
http://www.heli-chair.com/aerodynamics_102.html
The asymmetric force from the landing gear moves the rotor mast sideways, and the rotor blades move so the rotor center of mass is no longer at the mast. Then the other skid imparts the same effect in a positive feedback loop until everything breaks. Solution: get off the ground before everything breaks.
http://www.youtube.com/watch?v=D2tHA7KmRME is an impressive example.

]]> By: Brad https://gregladen.com/blog/2012/02/27/ground-resonance-shakes-apart/#comment-491525 Tue, 28 Feb 2012 04:01:23 +0000 http://scienceblogs.com/gregladen/2012/02/27/ground-resonance-shakes-apart/#comment-491525 No, it’s real. Lots of videos of the phenomenon on youtube.
http://www.heli-chair.com/aerodynamics_102.html
The asymmetric force from the landing gear moves the rotor mast sideways, and the rotor blades move so the rotor center of mass is no longer at the mast. Then the other skid imparts the same effect in a positive feedback loop until everything breaks. Solution: get off the ground before everything breaks.
http://www.youtube.com/watch?v=D2tHA7KmRME is an impressive example.

]]> By: Chris Winter https://gregladen.com/blog/2012/02/27/ground-resonance-shakes-apart/#comment-491524 Tue, 28 Feb 2012 01:25:48 +0000 http://scienceblogs.com/gregladen/2012/02/27/ground-resonance-shakes-apart/#comment-491524 Ground resonance as in “a resonance that took place while the chopper was grounded”? I’d agree with that. But the resonance was not caused by the ground (i.e. an earthquake). My guess would be mechanical failure: a bearing that cracked or fell off in the rotor assembly, or maybe something seized up due to lack of lubrication.

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