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Old 14th October 2006 | 06:19
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: ATP+Mil
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From: EGDC
We have postulated at length to I agree (I think) that any force, whether it be weight, thrust, torque or drag acts about the C of G of the object (in this case the airframe). If a force has a moment arm about the c of g then the fuselage will rotate until either a. the force is acting straight through the c of g and the moment is zero or b. ( and the case we are are talking generally about here), another force with an opposing moment arm is generated which equals the original to the point where both forces are in equilibrium.

This is the case with TR drift (or translating tendency) - cyclic rolls the fuselage to the left but it doesn't keep going because the TR thrust creates one opposing couple ( the magnitude of which depends on the height of the TR to a great extent). The other opposing force is the vertical component of MR thrust acting about the c of g, the weight acts through the c of g

If you increase TR thrust (the pulling the skids with a rope analogy) that gives more translating tendency and requires more cyclic to oppose it - this results in more left skid low to hold the hover because the balance of forces is achieved in a new position. If you hover the same helo at a. the lightest weight possible and b. max all up mass you will have significantly different hover attitudes (ignoring the change in the c of g position.

Last edited by [email protected]; 14th October 2006 at 06:30.
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