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MODEL TRIMMING CHART 
12/31/96

By Mike Chipchase
Pre Trimming Configuration 

TO TEST FOR 

TEST PROCEDURE 

OBSERVATIONS 

ADJUSTMENTS 

1. Control Neutrals

Fly the model straight and level

Use Transmitter trims for  hands-off straight and level  flight 

Adjust clevises to center Transmitter trims

2. Control Throws

Fly model and apply full
deflection of each control in turn 

Check response of each control 

Aileron :- Hi-rate, 3 rolls in 3  to 4 seconds. Lo-rate, 3 rolls  in 6 seconds

Elevator :- Hi-rate to give a smooth square corner, Lo-rate  to give a loop of  approximately
130 feet diameter 

Rudder :- Hi-rate  approximately 30-35 degrees,  for stall turns, Lo-rate to  maintain knife edge flight. 

 

3. Centre of Gravity       (Method 1)

      (Method 2)



Roll model into a near  vertically banked turn

A. Nose drops

B. Tail drops

A. Add weight to tail 

B. Add weight to nose

Roll model inverted

A. Lots of down elevator
required to maintain level flight

 

B. No down elevator required to maintain level flight, or model climbs

A. Add weight to tail

 

B. Add weight to nose

4. Decalage 

Power off vertical dive, cross wind (if any). Release controls when model is vertical(elevator must be neutral). 

A. Model continues straight  down 

 

B. Model starts to pull out,
(nose up).

 

C. Model starts to tuck in,
(nose down).

A. No adjustment required

 

B. Reduce incidence

 

 

C. Increase incidence

5. Tip Weight (coarse
adjustment) 

Fly the model straight and level, upright. Check aileron trim maintains wings level. Roll the model inverted, wings level.  Release aileron stick

A. Model does not drop a wing

 

B. The left wing drops

 

C. The right wing drops

A. No adjustment required

 

B. Add weight to right tip

 

C. Add weight to left tip

6. Elevator  Alignment. (for  models with independent elevator Halves)

 

 

Fly model away from you and into any wind. Pull it into an inside loop or vertical climb, roll it inverted and repeat by pushing it into an outside loop or vertical climb

A. No rolling tendency when elevator applied 

 

B. Model rolls in same
direction in both tests 

 

 

C. Model rolls in opposite
directions in both tests

A. Elevators in correct
alignment

 

B. Elevator halves misaligned.
Either raise one half or lower
the other

C. One elevator half has more throw that the other, (the  model rolls to the side with  the most throw). Reduce  throw on side with the most  throw or increase
throw on the other 

Trimming starts here in earnest

1. Tip Weight (Final adjustment)

Fly the model high into the wind either coming towards you or going away from you, smoothly push the model into a vertical dive, pull out sharply and watch
for a wing dropping. 

A. Neither wing drops on  pulling out.

 

B. The right wing drops on  pulling out.

 

C. The left wing drops on  pulling out

A. No adjustment required

 

 

B. Add weight to the left  wing tip. 

C. Add weight to the right  wing tip

2. Dihedral

Fly the model straight and level into any wind, apply rudder and watch for any tendency for the model to roll. 

a. Test in both directions.
b. Make changes in increments of no more than 1/8" at a time. 
c. Don't worry about the noes pitching down or up.

A. The model does not roll.

B. The model rolls in the  direction of the applied rudder.  (Proverse roll)

C. The model rolls in the  opposite to the direction of the  applied rudder.(Adverse roll)

A. No adjustment required

B. Reduce dihedral

 

C. Increase Dihedral

3. Side Thrust
(During tests  re-trim with rudder  until a straight  vertical is achieved,  then add  side thrust  to the  value of half  the  rudder trim that  was  needed. Zero the  rudder trim)  (Go back and  re-test after adjusting) 

Fly the model away from you, into any wind. Pull it smoothly into a vertical climb going at least to normal maneuver height
(watch for deviations to the left or right as it slows down)

A. Model continues straight up 

 

  

B. Model veers left

 

 

C. Model veers right

A. No adjustment required

 

 

B. Add right thrust

  

 

C. Reduce right thrust

4. Up/Down Thrust

Fly the model cross wind, at a distance of around 100m from you, (elevator trim should be neutral as per test No 3), pull it into a vertical climb and neutralize the elevator, (watch for any deviations up or down as it slows down)

A. Model continues straight up

 

B. Model pitches up, (goes
towards the top of the model)

 

C. Model pitches down, (goes toward the bottom of the model)

A. No adjustment required

 

B. Add down thrust

 

 

C. Reduce down thrust

5. Aileron  Differential
(Set the model up  with 12 Degrees up  and 11 to 12  Degrees  down as a starting  point.)

Fly the model level and into
any wind, going away from
yourself. Pull it up into a
45 Degree climb and roll to
the right.
(After adjusting, try again
in both directions)

A. The model does not veer
sideways.

B. The model's path veers to the
right.

C. The model's path veers to the
left.

A. No adjustment required

B. Increase differential,  increase
the up throw on both ailerons
C. Decrease differential,  increase the down throw on  both ailerons.

6. Pitching in  knife-edge flight
(Method 1)


Fly the model on a normal pass and roll into knife-edge flight, maintain height with top rudder,
(do this test in both left and
right knife-edge flight)

A. There is no pitch up or down
B. The nose pitches up, (the
model climbs laterally)

 

 

C. The nose pitches down, (the
model dives laterally)

A. No adjustment required
B. Alternative cures :-
1. Move the C of G aft
2. Increase wing incidence
3. Add down trim to ailerons

 

C. Reverse the above

6a. Knife-edge  tracking
(Method 2)



Fly the model on a normal pass and roll into knike-edge flight, maintain height with top rudder,
(do this test in both left and
right knife-edge flight)

A. The model does not pitch
up or down
B. The model pitches to the  canopy
in both knife-edges.

 

C. The model pitches to it's  bottom
in both knife-edges

 

D. The model pitches in  opposite
directions in each knife-edge

A. No adjustment required

B. Lower both Ailerons  slightly
Approximately 2 turns

C. Raise both Ailerons slightly
approximately 2 turns

D. Use mixing from rudder to
elevator to fix the problem.

7. Power off  Tracking (Test #1)

Fly the model level into any
wind, pull the power off and
watch for any roll off to either side

A. No roll to either side
B. The model rolls left


 

C. The model rolls right

A. No adjustment required
B. Mix 2% to 3% right aileron
to low throttle, the amount
enough to neutralize the roll.
C. Mix 2% to 3% left aileron
to low throttle, the amount
enough to neutralize the roll.

Test #2

Fly the model high at a distance of approximately 100m into or across wind but sideways to yourself, push it into a vertical dive, watch for any tendency to roll whilst in the dive.

A. The model shown no tendency to roll 

B. The model rolls to it's left

C. The model rolls to it's right

A. No adjustment required

B. Mix some right aileron
to low throttle, the amount
enough to neutralize the roll
C. Mix some left aileron
to low throttle, the amount
enough to neutralize the roll

Test #3

Fly the model high at a distance of approximately 100m across any wind but sideways to yourself,  push  it into  a vertical dive, watch  for any tendency to pitch up or  down whilst in the dive. 

A. There is no pitching, the model continues straight down
B. The model pitches up,  towards the canopy.

C. The model pitches down
towards the bottom of the model

A. No adjustment required

B. Mix 2% to 3% down elevator to low throttle

C. Mix 2% to 3% up elevator
to low throttle.

NOTES:

1. Trimming must be done in calm conditions.

2. Abbreviations are used.

3. Make multiple tests before making adjustments.

4. If any changes are made, go back over previous steps and verify or readjust as necessary

5. A good Decalage starting point is 0 Deg. Wing, 0 Deg. Stab, 1.5 Deg. Downthrust & 1.5 Deg. Right thrust

6. The model should be perfectly aligned whilst it was being constructed.

7. Static balance the model prior to flying it.

8. Setting the C of G to between 34% and 38% of the MAC is a good starting point.

9. All vertical dives are power off.

10. Setting up the model with 12 Degrees up Aileron and between 11 and 12 Degrees down is a good starting point.