Providing a safe flying environment for model aeroplane and helicopter enthusiasts
Trimming your model
How to trim your model aircraft
Wing incidence set too positive.
- When pulling out of a dive, the model tends to zoom upward instead of returning to level flight.
- When full throttle is applied the model tends to zoom upward.
- The model tends to climb through right and left turns.
Wing incidence set too negative.
- The model tends to dive throughout the complete flight.
- When full throttle is applied the model tends to zoom downwards.
- The model tends to decend through right and left turns.
Center of gravity too far forward.
- The nose tends to drop in steep left and right turns.
- Rolls will be of the barrel type rather than axial.
Center of gravity too far rearward.
- The tail tends to drop during turns.
- The controls will be too sensitive.
- Poor wind penetration.
- The model will tend to balloon when turned into the wind.
- The model lacks stability during flight.
Too much engine down thrust.
- The model jumps up from straight and level flight when the engine is suddenly cut.
- The elevator requires excessive up-trim to maintain level flight.
Not enough engine down thrust or slight engine up thrust.
- The model goes into a dive from level flight when the engine is slightly cut.
- The engine requires down trim for level flight.
Not enough engine right thrust.
- During a steep climb, the model tends to pull up to the left as it loses speed.
- Model tends to pull to the left near the top of a loop.
Too much engine right thrust.
- During a steep climb, the model tends to pull up to the right as it loses speed.
- Model tends to pull to the right near the top of a loop.
One wing panel is too heavy.
- The same wing panel will tend to pull outward during inside and outside loops.
- A heavy wing panel will cause the ailerons to trim with one aileron up, and the other down.
Too much dihedral. (Pattern aircraft).
- The model will roll in the direction of the applied rudder.
- Rolls will be barrel rather than axial.
- The model will want to roll out of knife edge flight.
- Inverted manoeuvres will be difficult.
Too little dihedral. (Pattern aircraft).
- The model will roll in the opposite direction of the applied rudder.
- The wing wants to tuck under during knife edge flight.
- Poor tracking through inside loops.
- The model tends to lack stability during upright flight.
If the model cannot be trimmed properly when the probable cause has been established,
- Check all surfaces for warps.
- Check model alignment.
- Check for aileron and elevator gap seals.
- Check for play in control linkage and servos.
- Check for poor servos that don’t center properly.
- Ensure that there is no problem with the radio.