So you’ve bought yourself a new radio controlled plane? You might think that all you have to do now is to launch it into the air and enjoy hours of flying fun.
But not so fast. Before you can use your RC airplane, you must balance it. Balancing means finding the plane’s center of gravity (CG). Getting this right means you can fly safely and securely.
If you mess up the positioning of the airplane’s CG, you risk your plane crashing into the ground mere seconds after taking off. Moreover, even if you manage to keep your unbalanced plane in the air, trying to land a tail-heavy airplane is difficult.
The most important and critical balancing to get right is longitudinal balance. This is the point at which the nose and the tail exert equal gravitational forces. You can consider it being like a child’s seesaw that is perfectly level.
If you’ve built your RC airplane from a kit, it is likely that the CG will be clearly marked on your plan.
Check Your Manual
If, however, your plane was bought in a ready-to-fly condition, or almost ready-to-fly, then you will have to check your manual for the location of the CG.
Often, it is indicated as being a certain distance from the wing’s leading-edge or the nose. Sometimes manufacturers will highlight a range where the CG is rather than an exact point for it. If you’ve bought a cheap plane, the manual may not even mention where the CG is. In that case, you will have to determine it for yourself by using the method below.
Be aware that you should only try to find the CG point when your plane is completely ready to fly. This means, for an RC airplane, that your battery pack should be in the exact place it would be when the plane is airborne.
Finding The Balancing Point
The quick way of finding the CG for an RC airplane is to put a fingertip under each wing. Make sure your fingers are a short distance out from the sides of the fuselage.
Now, while the plane is resting on your fingertips, lift it up and see whether the nose tilts downwards or upwards. The plane is balanced when it is completely level, or when the nose is pointing slightly downwards. Don’t allow it to become tail-heavy because this is going to give you some major headaches when you are trying to land it.
If your RC plane is not in balance, the first thing to do is to try to move your battery pack forwards or backwards. This is the most efficient method of setting the CG point because the battery pack is the heaviest item on the airplane. Just nudging it forwards and backwards a little bit will often make a big difference to the balancing.
Once you found the perfect CG balancing point, secure your battery pack well. You do not want it coming loose while you are flying.
Add Ballast Only If Necessary
If you find that your battery pack cannot be moved, then you will have to resort to adding ballast to find the right balancing point. Just be sure to use the smallest amount possible. Ballast adds unnecessary weight to the plane and can interfere with its performance in the air.
If you take the time to balance your airplane properly, you will be repaid with smooth and easy handling during the flight. So it is well worth the small time investment to do it correctly.