I need input on the calculation of the CG for a model of the F-18. I've heard that the leading edge extensions (LEX) affect the final calculations. Since this is my own design, I have no other sources to confirm I'm close.
Thanks,Chris

I calculate all my CG''s with formulae out of an engineering stability text. Except for LEX
With LEX the best I can do is get an estimate. If you have an F-18, then you can just use the CG measurements for another F-18 model scaled to your size.

The YA F-18 balances 12.5" forward of the TE at the root. Assuming your F-18 is accurate, just take the ratio of your wingpan to the YA wingspan and multiply by 12.5 and there you have it.

Thanks John, sounds like that will get me close. My f-18 is about 10% larger than the YA single. Using your calculation that puts the CG within 3/8 inch of my estimate. What concerns me is my LEX is more like the Super hornet and has more lifting area.
Chris

Did you already saw this page? I am 99% using these concepts and they worked well for me until now.

http://www.twitt.org/HoeyCalcs.html


Regards, Enrique.