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 at 1/2 throttle

Readjust linkages so that Tx trims are centered

Elevator ( Pitch )

Start with elevator level and trim neutral

Fly 1/2 throttle level "hands off"

1. Aircraft pitches up

2. Aircraft pitches down

1. Elevator needs negative/down trim added.

2. Elevator needs positive/up trim added.

Ailerons ( Roll )

Start with both ailerons centered as good as possible and aileron trim centered.

Before flying measure both ailerons' range of travel in both directions (should be equal).

Assuming COG trim is set:

Fly 1/2 throttle level "hands off" / neutral in regards to ailerons

1. Aircraft rolls right (right wing drops ...again, may happen slowly or quickly so be ready to correct if needed)

2. Aircraft rolls left (left wing drops ...again, it may happen slowly or quickly so be ready to correct if needed)

1. Ailerons need left trim added.

2. Ailerons need right trim added.

Rudder ( Yaw )

Start with rudder centered (in line with fuselage) and trim centered.

Assuming COG trim is set:

Fly 1/2 throttle level "hands off"

1. Aircraft yaws right and right wing drops (may be slow or quick so be ready to correct if needed)

2. Aircraft yaws left and left wing drops (may be slow or quick so be ready to correct if needed)

1. Rudder needs left trim added.

2. Rudder needs right trim added.

Center of Gravity (COG)

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

1. COG is good

2. Add nose weight

3. Remove nose weight

Center of Gravity for 3D

(preferred by most 3D pilots, but adjust to your liking)

From level flight set throttle to 1/2 and neutralize controls (trim so that airplane flies level "hands off")

...then roll to inverted (again fly level, 1/2 throttle, go "hands off")

Note: If your airplane is close, the controls should be close to neutral even without going hands off, if not, do NOT go to hands off. Adjust COG (and elevator's trim for level upright flight) until it's close.

1. Aircraft continues fairly level flight

2. Nose pitches up (towards sky)

3. Nose pitches down (towards earth)

1. COG is good

2. Add nose weight

3. Remove nose weight/add weight in tail

Control Throws

Random maneuvers

1. Too Sensitive, jerky controls

2. Not sufficient control

1. Change linkages to reduce throws or increase expo if possible

2. Increase Throws

Engine Thrust Angle

From straight flight, chop throttle quickly

1. Aircraft continues level path for short distance

2. Not sufficient control, nose rises

3. Not sufficient control, nose drops

1. Trim is OK

2. Decrease downthrust

3. Increase downthrust

Aileron Rigging

With wings level, pull to vertical climb and neutralize controls

1. Continues vertical climb 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.