Finding CG

The proper CG depends on many things: Area of the tail, weight, airfoil, type of model, and others.

A good rule of thumb is between 25% and 33% of the wing chord (include aileron width). Start at 25% and work your way backwards.

Remember, a nose heavy model may fly poorly. A tail heavy model may fly ONCE! Dr.1 Driver "There's a Hun in the sun!"

yea, and A-Men

Find the midway point of each wing (that's root to tip). At that point measure from the leading edge to the trailing edge. If that distance at that point is say 8ins then 2ins (25%) from the leading Edge would be the CG for that wing. Repeat on the other wing and A line between those points is the aircraft's CG. This works very well on swept back wings also.

On 10/6/2003 7:22 AM Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

While 25% - 33% from the leading edge is the USUAL rule, a good RULE OF THUMB is to use the MAIN SPAR as a STARTING POINT and adjust your cg from there for your particular style/type of flying.

ASSUMING the main spar is within those limits. Why not measure and BE SURE?

We all know what assuming does... Dr.1 Driver "There's a Hun in the sun!"

Also, Alan's R/C links has a lot of this kind of stuff listed in one easy to use site.

FredD

Finding the CG is probably not the problem. Knowing where it is suppose to be could be the issue.

Open this page and enter your figures ;-)

Good luck...!

Erik Sollie Trondheim, Norway

Once you know where the CG should be here is a handy little device to tell you where it actually is.

Red S.

But... maybe half way out is not the average wing chord. Add the chord of the root and tip and divide by 2.. this is the length of the average chord.. now you have to measure the wing to find out at what point the measurement occurs.. another method that is used is to draw a line from the root LE to the tip TE and another frome the root TE to the tip LE. the intersection will locate the average chord position.

Are you sure.. I still think the X formula will work with any wing, but the calculators online are great because they will figure out where the balance point is from the LE at the root so all you have to do is make one measurement.