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- Apr 15, 2008
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- Vessel Name
- FlyWright
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- 1977 Marshall Californian 34 LRC
...ride in helicopters!
This is why you should never....
- Thread starter FlyWright
- Start date
The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
If you have answers, please help by responding to the unanswered posts.
MurrayM
Guru
Whatever they used to strap it to the tarmac for that awesome "bouncification until complete failure" effect would make for great snubber material 
Interesting to note the rotors didn't break apart...was that what they were testing?
Interesting to note the rotors didn't break apart...was that what they were testing?
Last edited:
LarryM
Guru
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- Aug 5, 2011
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- USA
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- Pelago
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- Wellcraft 3300 Coastal
This is an example of Ground Resonance.
It happens in helicopters with lead-lag hinges. It occurs only on the ground and starts when the blades "bunch up" on one side of the rotor disc where they generate an unbalanced centrifical force that gets in phase with the natural frequency of the aircraft rocking on it's landing gear. Modern helicopters avoid this by using dampers on the blades and on the gear (shock absorbed struts). It is found less on wheeled helicopters, but can still. The recovery is to lift the aircraft to a hover.
Ground resonance has not been "solved", and is still a big concern for anyone who flies a helicopter with a fully-articulated rotor system. It basically is an out-of-balance condition in the rotor system of a helicopter on the ground that rapidly increases in frequency until the helicopter shakes itself apart. It is usually caused by a hard ground contact, and is much more likely in aircraft with improperly maintained landing gear (deflated oleo struts, for example).
It cannot occur in a two bladed semi-rigid see-saw type rotor system, because the blades do not lead and lag.
It happens in helicopters with lead-lag hinges. It occurs only on the ground and starts when the blades "bunch up" on one side of the rotor disc where they generate an unbalanced centrifical force that gets in phase with the natural frequency of the aircraft rocking on it's landing gear. Modern helicopters avoid this by using dampers on the blades and on the gear (shock absorbed struts). It is found less on wheeled helicopters, but can still. The recovery is to lift the aircraft to a hover.
Ground resonance has not been "solved", and is still a big concern for anyone who flies a helicopter with a fully-articulated rotor system. It basically is an out-of-balance condition in the rotor system of a helicopter on the ground that rapidly increases in frequency until the helicopter shakes itself apart. It is usually caused by a hard ground contact, and is much more likely in aircraft with improperly maintained landing gear (deflated oleo struts, for example).
It cannot occur in a two bladed semi-rigid see-saw type rotor system, because the blades do not lead and lag.
Hurrying Nowhere
Veteran Member
Been flying helicopters since i was 17....shhh don't tell anyone...no i didn't get an actual license until i was 19....45 now and not ever seen that happen.
