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Old 11th Sep 2004, 20:49
  #172 (permalink)  
NickLappos
 
Join Date: Apr 2003
Location: USA
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as355f1

It is an old belief that the height of the main rotor vs the height of the tail rotor is a reason for hovering one skid/wheel down, this is really not correct. All the forces developed by the machine are summed at the center of gravity, which is considerably below the main rotor head.

The aerodynamics of the machine make it such that the higher the tail rotor, the LESS it leans in a hover! Helos with the lowest tail rotors have the most lean, believe it or not.

High tail rotors produce a rolling moment that subtracts the left lean (for a US type system). For a given helo, if the tail rotor is centered on the tail cone, the left lean is about 5 to 6 degrees. If that tail rotor is moved up a few feet to the top of the tail, the lean is reduced to 3 degrees or so.

A question for the group:

In what axis does it wiggle - yaw or roll?

How fast are the wiggles _ in wiggles per second?
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