The balancing of radio controlled planes is essential for a successful first flight. Here we explain several methods to accurately balance any model.
Photo shows the Hangar 9 F6F Hellcat ARF. Maybe just after it's first take off! It must have been correctly balanced or it would not be in this position!
I cannot stress the importance of correctly balancing RC airplanes! Failure to accomplish this task can result in total destruction to your brand new plane and cause serious damage to property and injury to spectators.
Every kit or instructions should include the position of the center of gravity (CG) or balance point. The completed airframe, ready to fly but without fuel, MUST balance at the specified point.
You can use your finger tips to balance the plane and may need the assistance of a helper, especially for the larger and heavier low wing models. In such a case, mark the CG point at the wing tips and you and your helper can lift the model by placing your finger tips at the specified points. The model should be level when lifted.
If it is possible to move equipment, such as the battery pack, forward or backward to achieve balance, then you are home free! Ensure that the components cannot move and are secure in their position. If weight must be added, to achieve balance, do not hesitate to do so! It is far better to have a model over weight than out of balance!
WW1 radio controlled planes usually have a short nose and can require pounds of lead to balance. As usual, ensure the weight is securely bolted in position. It is better to err on the side of a forward balance point than a rearward one. If the aircraft is nose heavy then the elevator may not be as effective and a flare upon landing may be difficult to achieve.
A tail heavy plane however, will be very sensitive to pitch (elevator) and if the balance point is too far back it maybe impossible to fly!
The only way to find the ideal balance point for your model is to fly it and observe it's flight characteristics. If you are looking for the ultimate aerobatic machine then you will need a more rearward balance point. If forgiving behavior is your goal then a more forward point will give you this.
A tip I picked up a few years ago may help you in your quest to balance radio controlled planes. It involves embedding an anchor nut into the airframe, at the balance point. It is then possible to screw in a threaded hook and hang the model from a cord.
One advantage of this system is that lateral balance can be checked as well as the usual longitudinal. If one wing tip appears to be heavy, then securely attach weight to the opposite tip, to achieve balance.
The hardware for this can be found at your local hardware store. Please ensure that the anchor nut is well attached and that the system can take the full weight of the model! I like to use a # 10 nut and hook and can lift 25 pound radio controlled planes, with this set-up.
For high wing planes the nut is securely embedded into the wing center section or fuselage cabin top. (For plug-in wings) Low wing planes are best balance inverted, with the anchor nut placed in the lower fuselage bottom, or the underside of the wing center section.
Photos show my 1/5 scale Fairey Swordfish (ARF). The center section of this model is a fiberglass molding. A hole was drilled all the way through for the eye bolt. After balancing, the hole was covered with a patch of Monokote.
The photo at left shows the Great Planes C.G. Machine. This system can accommodate planes up to 40 pounds, according to Great Planes. For planes over say 10lbs I would strongly recommend using a helper to make things easier!
The machine can be adjusted to handle many types of RC airplanes and features ball jointed pads that contact the wing of the model.
Please ensure that the area in contact with the pads can support the weight of the model. If necessary thin ply can be used to distribute the load over a larger area.
Great Planes C.G. Machine (Center of Gravity) is available from Amazon.