hph

Hi

Can some one please tell me how to locate the CG on a plane. Once the CG is found, does the battery packs, control gears etc have to be placed in a way to maintain the balance on the CG.

Thanks.

Tippie

Everything, ready to fly, has to be in the airplane, Battery, receiver, servo's, ESC and motor. On a non electric plane it is balanced with no fuel in the tank but on an electric it is with everything. The battery is the heaviest element and is usually the part of the system that is moved forward/back to balance the airplane. The motor next heaviest but no choice where that is at. From front to back it is usually, motor, ESC, battery and servos/receiver. Airplane style dictates where the servo's and receiver are located. You don't say what kind of airplane it is so I can't give you a location for the CG. The CG varies any given airplane. Some balance at the main spar, some further back. Any instructions with the airplane? Usually shown on the plans or with the instructions.

goofup

You can out where the CG is on the plane's plans or in the instructions that came with the plane.

If it's a one of a kind type plane you created yourself you're on you own, but you can start with about 10% of the width of the wing back from the highest point on the upper part of the wing.

To answer the second part, yes, all the parts must remain in their respective locations in order to maintain (CG) balance (especially in the air!). Usually one component can be adjustable. Most of us pick the battery because it's being changed out all the time anyway, and it's also the easiest one to adjust back and forth to keep the CG correct. We mount the other parts down so they don't move.

What plane are we talking about anyway?

Goofup

thstone

Simple, cheap approach:

Place the index finger of each hand on each side of the fuselage with the plane facing forwards (you are looking at the tail of the plane). Your two fingers will act as a "pivot" point along the fuselage. Start behind the trailing edge of the wing.

Initially, the nose will be heavier than the tail and the nose will point down. Move your fingers/pivot point forward along the fuselage towards the nose until the plane balances evenly/level between nose and tail.

Where your fingers are is the CG. It is usually measured from the nose of the plane or some other reference point specified by the plane manufacturer.

If your CG is not correct, try moving the battery in the appropriate direction in small increments until the plane CG is in the proper location. If this fails to correct it, you may have to move the servos and/or other components also (depending on the plane and gear).

Best of luck.

Tom

hph

Its a Sky Rider foam glider (large version) from toys r us which I intend to convert it to rc. I'd been playing around with 2 channel parkflyers and am thinking of moving to something a bit more advance.

Thanks for the speedy reply.

Tippie

Ok, since it's a foam glider, try this. Without any equipment installed check the present CG by the method the "thstone" said, with an index finger under the wing on each side of the fuse. Find the point where the glider balances, fore and aft. Mark that point under each wind and use it as a reference point, then as you add components you want to maintain balance at that point or slightly to the rear so you have a slight down nose angle with everything installed. The object is to be just slightly nose heavy. Instead of using your fingers you can take a 2" x 6" piece of wood maybe 2' long and drill two holes about 4" each side of center (8" apart) and make the holes just large enough to insert wood pencils with an eraser on the end. Sharpen or round the eraser slightly and use those instead of the fingers. Then your hands are free and you can "play" around and find the CG on a bare glider and work from there. Don't know how successful you will be converting a foam glider. You may want to consider buying a ready to fly electric airplane with at least a 3 channel radio. A lot less headaches.