Moving the engine for CG adjustment?
03-23-2005, 06:44 PM
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Moving the engine for CG adjustment?
I am setting up my Wildhare Extra for IMAC and I want to move the CG forward just a tad. Right now I don't have to push when inverted to maintain level flight but I feel it's too pitch sensitive for scale aerobatics. The batteries are forward rudder is already pull-pull and I'd rather not add weight so a friend suggested washers behind the engine standoffs. The spinner plate is really close to the cowl right now so a 1/16" or an 1/8" wouldn't matter but I was just wondering if anyone has bothered with this method and had a noticable effect. It seems like it should make a small differance but before I start messing with it I thought I'd ask around.
03-23-2005, 11:37 PM
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RE: Moving the engine for CG adjustment?
Don't add lead if you don't have to.. Keep your plane as light as possable. The best thing you can do if you have already moved everything foward and still need nose weight is to do what you are doing. Avoid at all costs adding dead weight like lead..
03-24-2005, 12:04 PM
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RE: Moving the engine for CG adjustment?
I would start by finding out how much it would take in the nose to get the CG right. If you are that close you might find it only takes 4-6 ounces. Once you know how much you can do things to take out the weight. Moving the engine. Take a hole saw to the rudder. Get a carbon tail wheel and so on. One ounce out of the tail is usually about 3 to 4 ounces in the nose. You would be surprised where you can find a couple ounces.
Dan
Dan
04-05-2005, 07:19 PM
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RE: Moving the engine for CG adjustment?
If you know the distance that you would like the CG to move, you can apply the weight shift formula, which should tell you how far you would have to move your engine to get the desired result. W*d/w = x where W is total weight of your plane, d is distance you want to move CG, w is weight of your engine, and x is how far you'll have to move the engine.
For example, if you want to move the CG 0.25" forward, plane weighs 15 lbs, engine 4 lbs, 15*.25/4 = .9375" is the distance you'd have to move engine forward.
For example, if you want to move the CG 0.25" forward, plane weighs 15 lbs, engine 4 lbs, 15*.25/4 = .9375" is the distance you'd have to move engine forward.
