Center of lift...

ccsmith51 · #1 04-30-2011, 06:57 PM

Can someone tell me where the center of lift is on the RV-4? I'm wondering where it is relative to the CG range of 68.7" - 77.4".

Thanks,

RPaul · #2 04-30-2011, 07:28 PM

The center of lift moves around with angle of attack.
The neutral point is fixed and located behind the CG range.

ccsmith51 · #3 04-30-2011, 07:44 PM

Thanks for the info!

kcameron · #4 05-01-2011, 06:42 PM

I've always assumed the center of lift on any wing I'm looking at will be very close to the main spar. Wrong?

Bill Wightman · #5 05-01-2011, 08:41 PM

With respect to the wing alone, the airfoil's AC is at about 24% back from the leading edge. I believe that puts it pretty close to the wing spar. Angle of attack has very little influence on it.

edit: since you asked about where the AC of the airplane is - that's the combined effect of the wing/tail/fuselage/propeller system which is also called the "neutral point". Assuming a 20% static margin (distance from NP to CG expressed as a % of mean aero chord) that would put the CG 12" (20% of 5 feet - the wing MAC) ahead of the neutral point which also is considered the aero center for the airplane. So if your CG is at 70" then the aero center (neutral point) for the airplane would be at 82", as a real rough example.