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By
Stan Yeo
On
my recent visit to Jersey I was a little embarrassed, as due to
'other' commitments I had not followed my own instructions when
setting up the ailerons on my Rico-SHE. One of the party had and
was putting me to shame at the way his model was flying! Needless
to say this did not go unnoticed by other members of the party!
Actually part of the problem was I had attempted to reset the Rico-SHE
program to fly a fellow party member's model as he was unsure as
to whether it had been set up correctly. Unfortunately he was a
Mode 1 flyer and I fly Mode 2 hence my fiddling with my Tx.
This
led me to thinking back to my days as an aircraft engineer. Here
the basic principle is (before fly by wire) to disconnect the controls
where necessary, lock the control column control system in neutral
with jigs or locking pins, adjust cable tensions where applicable,
lock control surface in neutral and adjust linkages as required
and carry out range of movement checks etc. Obviously it is a little
more involved than this and there are set procedures etc. to be
followed. Setting up a model is not that different, the same principles
apply. The purpose of this article is to take full size principles
and apply them to setting up a model. Although written with sports
aerobatic slope soarers in mind it applies to most models. It is
assumed the model is built and ready to fly except for final setting
up.
The
Transmitter.
With
the advent of computerised transmitters there are many more functions
to set-up when commissioning a new model. For non-computerised Txs
all that is needed is to centre the control trims, set the flap
knob to neutral and set servos to operate in the correct sense.
For
computerised transmitters it is advisable to construct a set-up
check list before starting to program your Tx. Most computerised
Tx manuals have a set-up sheet at the back of the manual which can
be photocopied and used for reference.
For
those not too familiar with the principles of setting up an entry-level
computer Tx below is a brief resume.
Most
computer Txs have two levels of set-up.
Level
One sets:
Tx
transmitting mode (PPM / PCM)
Stick
Mode (1 - 4 most being common Mode 1 & 2)
Model
memory number
Model
name
Pre-set
mixes such as Flapperons
Model
type i.e. Aircraft, Helicopter
Level
Two sets:
Servo
reverse
Dual
rates
Exponential
throws (how the servo moves relative to stick movement)
Free
mixes
Control
surface coupling Landing set-ups.
There
are other options but they will vary between manufacturers and models.
The
system works on 'rotating' logic. In the set-up mode when a function
is selected access is given to individual options within that function.
Scrolling through the menu eventually brings you back to where you
started (see manual flow diagram).
Servo
Rev.
Dual
rates
Exponential
etc.
Main
Menu (Loop)
Ch
1
Ch
2 NORMAL / REVERSE
Ch
3
Secondary
Menu (Loop)
Sorry
about the diagram but it basically demonstrates the loop i.e. 123
123 etc.
All
the entry level computer sets I am familiar with operate in a similar
way although there are some differences in how to gain access to
the various menus. The manuals are generally well written and easy
to follow. All contain system flow diagrams. Once you have mastered
these and the method of accessing the various functions you have
it cracked!
Back
to the article.
Select
a vacant / unused model memory and using the Data / Memory Reset
restore default settings so there are no unwanted mixes etc. that
could confuse the unwary during setting up. The Set-up
1.
In the main menu select Aircraft as opposed to Helicopter. If there
is a choice of aircraft type as in the case of the JR347 / JR388/
JR3810 transmitters then select Acro and NOT Glider. The Glider
mode has a different set of pre-set mixes such as Crow Braking whilst
blocking other pre-set mixes that are required.
2.
Select Flapperons and if required V tail mixing.
3.
Set Flap switch / slider / knob to the mid position.
4.
Select Elevator Flap coupling.
5.
Set all control trims to neutral.
6.
On the model, with Tx and Rx ON, centre all servo arms. It is bad
practice to do this using the sub-trims as it could cause the servo
to run against the stops at full travel.
7.
Using servo reversing, set all controls to operate in the correct
sense. If no matter what you do one control function on the Flaps
/ Ailerons and or Rudder / Elevator (on a V tail) is always operating
in the wrong sense then swop the two channels the servos are plugged
into.
8.
Using the Sub-Trim facility on the Tx align both aileron servos
arms. Look along the wing. It is important that they have the same
neutral position otherwise you will get asymmetric flap / aileron
movement.
9.
Again using the sub-trims, fine adjust the rudder and elevator servo
arms to their centre position. Unfortunately more often than not
servo neutral / centre do not align with Tx neutral.
10.
Produce a female template out of stiff card to slide over the wing
to hold the ailerons in section neutral (I have started putting
section profiles on my plans for this purpose).
11.
Adjust aileron pushrods so that when connected to the control horn
with the aileron locked in neutral they are not under load i.e.
control surface do not move when section template is removed.
12.
Repeat procedure for the rudder and elevator i.e. lock the control
surface in neutral and adjust control rod.
13.
Adjust control surface throws to those recommended in the instructions.
Initially by repositioning the pushrods on the servo arms / control
horns with final adjustment in the transmitter using the Throw Adjust
/ ATV function.
14.
Set Elevator Flap coupling on the Tx to give the required snap-flap
on full elevator throw.
15.
Set the required landing flap in the Tx along with any elevator
compensation. This is best done after test flying when you have
a clearer idea how much up / down elevator is required.
16.
If required 'dial in' exponential throw on one of the Dual rate
positions for aileron and elevator. Exponential will 'soften' the
control response around stick neutral whilst still retaining full
control surface travel with the control sticks at full deflection.
Having
set up the control surfaces check the model for balance laterally
(wings) and longitudinally (C of G).
Before
closing. If using Flapperons try to operate the flaps from pre-set
positions using switches or end travels. If the ailerons / flaps
are not in section neutral or a pre-set specific flight condition
then the performance of the model could be significantly impaired.
Trying to return a rotary flap knob to a mid position whilst flying
is difficult unless it has a built in détente. I have disabled my
flap knob (JR388) and use a 3 position switch to control flap elevator
coupling and landing flap.
Hope
the above has been useful. Quality time spent on setting a model
up will be rewarded with fewer maiden flight disasters and a more
satisfying flight performance. op counting and go back to zero again.
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