Trimming Your Bird!
A good guide for setting your aircraft's trim adjustments...
Theres a lot more to getting your airplane
trimmed, than just sliding the tabs on your transmitter. A correctly trimmed airplane is much more
stable and fun to fly! When building a model airplane, it
is important that the plane be balanced and wing incidences be set correctly.
Take your time with these procedures! If you don't have an incidence meter,
borrow or buy one. This is the only correct way to check
and set your incidence. Check the balance on the CG front to rear, and from left
to right. One of the easiest ways to do this is by finding the CG on
the fuselage, then finding the center, (left to right) of the plane. Screw in
a small eye hook, and hang your plane. It should balance front to rear,
and side to side. The engine thrust angle and the CG interact with each other.
Double check both to make sure that they are set according to plans. Yaw and
lateral balance create similar symptoms. If you are having problems in this
area, check to see if the fin is straight. It's far easier to make changes
in the building stage than after the model is covered. If you follow the trim
adjustment below, and still have problems, check for non centering servos, play
in control linkages, and aileron and elevator gap.
TRIM
FEATURE |
FLYING
MANEUVERS |
OBSERVATIONS |
CORRECTIONS |
Control Centering |
Fly general circles and random
maneuvers. |
Try for hands off, straight and level
flight. |
Readjust linkages so Tx trims are
centered. |
Control Throws |
Random maneuvers. |
A. Too sensitive. B. Insufficient
control. |
A. Change linkage to reduce
throws. B. Change linkage to
increase throws. |
Engine Thrust Angle |
1. From fast straight flight, cut throttle. 2. With throttle on,
pull to vertical flight. |
1A. Aircraft continues straight flight for a short
distance. 1B. Plane pitches nose up.
1C. Plane pitches nose down. 2A. Plane tends to yaw
right 2B. Plane tends to yaw
left |
1A. Thrust angle is OK. 1B. Decrease
downthrust. 1C. Increase downthrust. 2A.
Add leftthrust. 2B. Add
rightthrust. |
Center of Gravity Longitudinal
Balance |
From level flight at low throttle and in trim, push the nose to 45
dive and neutralize controls. |
A. Plane continues in dive for a short
distance, and gradually pulls out. B. Nose pitches up abruptly. C.
Nose pitches down more (tucks under). |
A. CG is good. B. Add nose
weight. C. Remove nose
weight. |
Split Elevators Yaw and
CG |
Into wind, Pull open loops using only elevator. Repeat test
with outside loops to inverted entry. |
A. Wings are level throughout. B. Plane tends to
left when right side up, and to right when inverted.
C. Planes tends toward right when right side up and left when
inverted. D. Plane goes left, right side up and
inverted. E. Plane goes right, right side up and
inverted. |
A. Trim is fine. B. Add right
rudder, or weight to right wing. C. Add left
rudder, or weight to left wing. D. Raise right half
of elevator, or lower left half of elevator. E.
Raise left half of elevator, or lower right half of elevator. |
Yaw2 |
Into wind, do open loops, using only elevator. Repeat tests
using outside loops from inverted
entry. |
A. Wings are level throughout. B. Yaws to right
in both inside and outside loops. C. Yaws to left
in both inside and outside loops. D. Yaws to
right on inside loops, and left on outside loops.
E. Yaws to left on inside loops, and right on outside
loops. |
A. Trim is correct. B. Add left
rudder trim. C. Add right rudder
trim. D. Add left aileron trim.
E. Add right aileron trim. |
Lateral Balance |
Into wind, do tight inside loops, or pull to straight up
flight into hammerheads. Repeat test from inverted entry. |
A. Wings stay level and plane falls randomly in each
direction from hammerheads. B. Falls off to
left from both inside and outside loops. C. Falls
off to right in both inside and outside loops. D.
Falls off in opposite directions on inside and outside loops. |
A. Trim is correct. B. Add weight to
right wing. C. Add weight to left
wing. D. Change Aileron trim. |
Aileron Rigging. |
With wings level, pull to vertical climb , and
neutralize controls. |
A. Climb continues same path. B. Nose tends to
go to inside loop. C. Nose tends to go to outside
loop. |
A. Trim is correct. B. Raise both
ailerons slightly. C. Lower both ailerons
slightly. |
Wing Incidence |
Knife edge flight. |
A. Plane tends to nose up position (as if up elevator is applied). B. Plane tends to
nose down position (as if down elevator is applied). |
A. Reduce wing incidence. B. Increase wing
incidence. |
Aileron Differential. |
With wings level, roll repeatedly left or right. |
A. Model stays on heading. B. Model yaws in direction of roll
(barrel roll). C. Model yaws opposite the direction of roll. |
A. Aileron Differential is correct. B. Too little differential (reduce
down throw). C. Too much differential (increase down throw). |
Custom CNC Machined Components for the R/C Industry
1405 Patterson Road, Durham NC - (919) 596-0143
1101 Mendenhall Street, Thomasville, NC - (866) 929-0249
2810 Forest Hills Road SW, Wilson, NC - (252) 237-6778
1207 D Kildaire Farm Rd, Cary, NC - 919-465-3353
1475 Beaver Creek Commons Drive, Apex, NC - (919) 387-6615
4505 Fayetteville Rd, Raleigh, NC - (919) 772-1211
Do you own a Hobby Shop and want to place a banner here?
Email the webmaster at wb4iuy@eastrc.org
!!STOP!! If you don't see a menu on the left, click
HERE to jump to the front and begin your RDRC
Experience! RC Video Feeds added, check the 'Miscellaneous' section of the LH menu for these
new webcasts.
RETURN to the RDRC Main Website!
|