Model Trimming Guidelines

This table is an excellent reference point for putting those finishing touches on your model that can transform it from a mediocre model into an outstanding perfomer.

If nothing else, just running through this list of manuevers several times can help you recognise a deviation from normal flight characteristics and make the appropriate adjustments to overcome a misalignment in your airplane.

TRIM FEATURES

MANEUVERS

OBSERVATIONS

CORRECTIONS

Control Centering

Fly general circles and random maneuvers

Try for hands off straight and level flight

Readjust linkages so that Tx trims are centered

Control Throws

Random maneuvers

  1. Too Sensitive, jerky controls

  2. Not sufficient control

  1. Change linkages to reduce throws

  2. Increase Throws

Engine Thrust Angle

From straight flight, chop throttle quickly

  1. Aircraft continues level path for short distance

  2. Not sufficient control

If A, trim is OK

If B, decrease downthrust

If C, increase downthrust

Center of Gravity

From level flight roll to 45 degree bank and neutralize controls

  1. Continues in bank for a moderate distance

  2. Nose pitches up

  3. Nose pitches down

If A, trim is good

If B, Add nose weight

If C, Remove nose weight

Split Elevators

Into the wind, do open loops, using only elevator

Repeat tests doing outside loops from inverted entry

  1. Continues in bank for a moderate distance

  2. Nose pitches up

  3. Nose pitches down

If A, trim is good

If B, Add nose weight

If C, Remove nose weight

Yaw

  1. Continues in bank for a moderate distance

  2. Nose pitches up

  3. Nose pitches down

If A, trim is good

If B, Add nose weight

If C, Remove nose weight

Lateral Balance

  1. Continues in bank for a moderate distance

  2. Nose pitches up

  3. Nose pitches down

If A, trim is good

If B, Add nose weight

If C, Remove nose weight

Aileron Rigging

With wings level, pull to vertical climb and neutralize controls

  1. Continues in bank for a moderate distance

  2. Nose pitches up

  3. Nose pitches down

If A, trim is correct

If B, raise both ailerons very slightly

If C, lower both ailerons very slightly

Wing Incidence

Knife Edge Flight

  1. Model tends to veer in nose up direction

  2. Model tends to veer in nose down direction

If A, reduce wing incidence

If B, Increase wing incidence

  1. Engine thrust angle and C.G interact. Check Both

  2. Yaw and lateral balance produce similar symptoms. Note that fin may be crooked. Right and left references are from the plane's vantage point

  3. Ailerons cannot always be trimmed without sealing the hinge gap.