The center of gravity (CG) is the point where an airplane balances fore and aft. Correct CG is one of the most important requirements for a safe, controllable first flight.
Why CG matters
A nose-heavy airplane usually feels stable but may require more elevator, fly faster, and be difficult to flare. A tail-heavy airplane can become overly sensitive, unstable, and difficult or impossible to recover. When uncertain, start at the forward end of the manufacturer’s recommended range.
Find the specified balance point
Use the location in the manual or on the plans. It may be measured back from the wing’s leading edge at the fuselage or marked directly on the wing. Do not substitute a percentage rule when a tested manufacturer’s value is available.
How to balance the airplane
- Assemble the model in flight-ready condition, including propeller, spinner, landing gear, receiver battery, and accessories.
- Install the flight battery where it will be secured for flight.
- Mark the recommended CG position on both sides of the wing.
- Support the airplane at those marks with fingertips, a balancing stand, or padded points.
- Hold the model level in the attitude specified by the manufacturer and observe whether the nose or tail drops.
Large or heavy models should be balanced with a purpose-built stand or sling and a helper.
Correcting the balance
Move existing equipment before adding ballast. Sliding the flight battery is usually the easiest adjustment on an electric model. Secure every component after moving it. If ballast is necessary, attach it permanently and as far forward or aft as practical so less weight is required.
Lateral balance
Support the model at the spinner and tail, or use the method in the manual, to see whether one wing consistently drops. Check for unequal batteries, retracts, repairs, or accessories before adding wingtip weight.
Recheck after changes
Balance again after repairs, a different battery, a new engine or motor, added paint, landing-gear changes, or equipment relocation. Mark a repeatable battery position inside the model.
CG and the maiden flight
- Use the forward part of the recommended range.
- Keep control throws conservative.
- Choose calm weather and a large flying area.
- Have an experienced pilot inspect and fly the model if possible.
- Make small adjustments between flights rather than large changes.
Never try to cure an incorrect CG with excessive trim or transmitter mixing. Start with mechanical balance, then fine-tune only within the approved range.
Continue with pre-flight checks and our guide to preventing common crashes.