Chord: What is it?

[crashsiegel]

I'm looking at mod'ing a plan and I have a question.
What is the chord?
This fundamental measurement seems to affect everything!
Here's a sketch: below

I think (likely to be wrong) the chord is 14.5 inches, ie the chord is the fixed airfoil part PLUS the aileron part.

If I use that idea to find the MAC, then if I go half way out the wing, the chord (measure LE to TE parallel to root rib) should be that measurement. At that point on the wing, if I take 25% of MAC, measure from the LE at towards the TE, Then go straight in tho the fuse (right angles to the root rib) I should have the location of the CG.

Yes?
Thanks,
Crash

[CloudyIFR]

The chord of a wing is from the leading edge to the trailing edge of the airfoil. Thus your root chord is 14.5 and tip chord 10.

Then you have the Mean Chord and the Mean Aerodynamic Chord.

What's the span and what's the distance from the root leading edge to the tips leading edge, i.e. sweep distance.

Curtis

[kcaldwel]

The root chord is 14.5 and the tip chord is 10. Your method of finding the 1/4C point also will work on this straight taper wing. But, the CG doesn't necessarily go at the 1/4C point.

The CG goes ahead of the aircraft neutral point by a percentage of the MAC. 10% is a good place to start. The location of the neutral point depends on the tail movement (1/4C of the wing, to 1/4 of the stab), the size of the stab, the height of the CG, the moment coefficient of the airfoils, the lift curve slope of the airfoils, etc.

There are some good calculators around to simplify this calculation:

http://www.geistware.com/rcmodeling/cg_super_calc.htm

Kevin

[BMatthews]

That's "tail MOMENT" and not "movement". Or more accurately the tail moment arm.

I know it's a typo or a brain burp on your part but poor crashsiegal might get confused.... :D

[kcaldwel]

If that's all I got wrong, it's been a good day!

Kevin