Rebuilt Pattern Plane front end Looking for CG formula Plz help

[rdean72]

Hi,
i have rebuilt a 40 size pattern plane front end. i have mounted a 60 size engine on and would like to find a formula for calculating the cg so i will not be nose or tail heavy. any help would be appreciated. thank you.:confused:

[steve lewin]

The CG should be in the same place it was when it had the correct engine fitted. Overpowering it won't change the correct position for the CG.

Steve

[Ollie]

Take the weight of the 40 size engine and multiply the weight times the distance between the 40's CG and the plane's CG. that is the desired weight moment. Divide the desired weight moment by the weight of the 60. That is the distance the 60's CG should be ahead of the plane's CG.

Example: if the 40 size engine weighs 12 ounces and the 60 size engine weighs 14 ounces (1/6 heavier) and the CG of the 40 size engine is nine inches ahead of the plane's CG, then the 60 size engine's CG should be 7.5 inches (1/6 shorter) ahead of the plane's CG.

[rdean72]

I appreciate the help guys. I did not know the original CG. I put some feelers out in the newsgroups and was directed to this website for info. it has everything you need. I was able to calculate the CG with some of the links on Alans Website. Check it out, i think you might like it.

Again, thanks for taking the time to reply

Richard:D