rush744
Posts: 9
Joined: Sat Dec 09, 2006 10:11 am

### Aircraft Rotation (The Design)

Hey guys i understand the basic concepts of aircraft rotation, there being enough tail force etc etc however what is the "Zero Lift Pitching Moment"? Its used in the aircraft rotation formula, In the formula it is known as M0 but does not suggest what a value could be, would it be the CofG? If not what and how could this be calculated? Diagrams have an arrow from the front of the wing

The formula for a/c rotation is:

Tmin = 1/x (yW - zLw-M0) = ½pV22S’C’L

(V22 is V Squared and V2)

T is downforce due to tail
x is the distance between location of rear undercarriage and line of action T
y is the distance between location of rear undercarriage and CG
z is the distance between location of rear undercarriage and wing lift Lw
M0 Zero lift pictching moment

I have values for T, x, y & z but am confused to what M0 is!

All help will be greatful

FredT
Posts: 2166
Joined: Thu Feb 07, 2002 9:51 pm

### RE: Aircraft Rotation (The Design)

It's the pitching moment at the zero lift angle of attack, i e the angle of attack where there is no lift generated.

A moment applied to a rigid body is not applied to any specific point of the body. If you applied it through a fixed shaft (without providing a force at the attachment point of the shaft) the resut would be the same regardless of where the shaft was attached.

And yes, the resulting rotation will be about the center of mass of the rigid body.

Rgds,
/Fred
I thought I was doing good trying to avoid those airport hotels... and look at me now.

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