# Canard Configuration and Sum of Moments

1. May 3, 2006

### mpm

I'm in an aerodynamics class, and I have this canard configuration I'm trying to figure out for a final exam.

I need to find the sum of the moment about the center of gravity.

I may cannot be helped without the drawing being posted.

So far this is what i have:

Mcg = Mac - (lcg + lw)Lw + (lc-lcg)Lc

CMcg=-aw*alpha(hn-hcg) + Cmo

Each letter after the first letter (ie Mcg) is a subscript. So cg would be the subscript. I just dont know how to do that on here.

Anyway, my remaining equations which I can't seem to figure out is to derive expressions for hn and Cmo

Can anyone possibly help me with this or is more info needed?

2. May 3, 2006

### Staff: Mentor

use and [/ sub] for subscript, but remove space between / and sub.

I am guessing that M is moment, L is lift, and l is moment arm for the L components. And subsript 'c' refers to canard, and 'cg' center of gravity.

There should be N equations for N unknowns, which included equations for forces (e.g. lift and weight, drag and thrust) and moments.

3. May 3, 2006

### mpm

LC is lift due to canard

LW is lift due to wing

Alpha is the angle of attack for the wing.

aw is lift curve slope of the wing

hn is the distance to the neutral point

hcg is the distance to center of gravity

I believe you are right on the moment arms being the l's.

CMcg is the slope of the moment curve I believe.

VH is the volume ratio

I think this is all that is needed. I may try and scan a picture of the diagram that I have if more is still needed.

Just let me know if more is needed.

Thanks in advance for all the help.