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. |