[NSRCA-discussion] CG

[Ron Van Putte]

On May 29, 2006, at 4:40 PM, Nat Penton wrote:

> The following formula was presented by noted British modeller  
> Gordon Whitehead in How To Make Scale Models Fly ( 1980 ??). I have  
> been using it over 20 years and find it  dead on for pattern:
>
>        CG (from LE MAC) = MAC/6 + 0.25x As/Aw M
>                     As -  area stab       Aw - area wing
>                     M  -  moment arm,     ac to ac
>
> It is easy to use the graphic method to find the wing MAC. You can  
> guess at the stab MAC and be close enough.
>
> The formula works on anything from a tailess to a Quickie.

Nat - I haven't compared the formula with the one I developed more  
than 40 years ago, but I think yours would be better understood if  
you use some parentheses:

	CG (from LE MAC) = MAC/6 + 0.25x (As/Aw) M

Also, the wing and stab area should include the ailerons and  
elevators, respectively.


Ron Van Putte

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