Multiplex 21 4190, Building Instructions, Page: 11 / 36

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them to the model, either following our scheme (kit box
illustration) or using your own arrangement. Colour the
cabin down to the edge using a black waterproof felt-tip
pen.
18. Preparing for the first flight
Wait for a day with as little breeze as possible for the
first flight. The evening hours often provide the best
conditions.
Be sure to carry out a range check before the first
flight!
The transmitter battery and flight pack must be fully
charged according to the instructions. Ensure that the
channel you are using is not already in use before you
switch on the transmitter.
Collapse the transmitter aerial, and ask a friend to walk
away from you holding the transmitter.
As he walks away your friend should constantly operate
one control function while you watch the model’s servos.
The servo not being operated should stay motionless
up to a range of around 60 m, and the other servo should
follow the transmitter stick movements smoothly and
immediately. This test only provides meaningful results
if the radio band is “clean” (not suffering interference),
and if no other radio control transmitters are switched
on, even if they are on different channels. If successful,
repeat the check
with the motors running . The
effective range should not be significantly reduced when
the motors are running.
If you are not sure about anything, do not fly the model!
If you cannot eliminate the problem send the whole radio
control system (including battery, switch harness,
servos) to the manufacturer’s service department for
checking.
The first flight ....
Do not test-glide this model!
The model is designed for hand-launching - always
exactly into wind.
We recommend that you ask an experienced
modeller to help you during the first flight.
Allow the model to climb to a safe altitude, then adjust
the trims on the transmitter so that the model flies straight
ahead without any help from you.
At a safe height switch off the motors and make yourself
familiar with the model’s control response on the glide.
Carry out a dummy landing approach at a good height,
so that you will feel confident about the real landing
when the flight pack is flat.
Don’t attempt tightly banked turns close to the ground
at first, and especially not on the landing approach.
It is always better to land safely some distance away,
and have to walk to collect the model, than to risk
damaging it by dragging it close to your feet.
19. Safety
Safety is the First Commandment when flying any
model aircraft. Third party insurance should be
considered a basic essential. If you join a model club
suitable cover will usually be available through the
organisation. It is your personal responsibility to
ensure that your insurance is adequate (i.e. that its
cover includes powered model aircraft).
Make it your job to keep your models and your radio
control system in perfect order at all times. Check the
correct charging procedure for the rechargeable
batteries used in your RC set. Make use of all
sensible safety systems and precautions which are
advised for your system. An excellent source of
practical accessories is the MULTIPLEX main
catalogue, as our products are designed and
manufactured exclusively by practising modellers for
other practising modellers.
Always fly with a responsible attitude. You may think
that flying low over other people’s heads is proof of
your piloting skill; others know better. The real expert
does not need to prove himself in such childish ways.
It is in all our interests that you let other pilots know
that this is also what you think. Always fly in such a
way that you do not endanger yourself or others. Bear
in mind that even the best RC system in the world is
subject to outside interference. No matter how many
years of accident-free flying you have under your belt,
you have no idea what will happen in the next minute.
We - the MULTIPLEX team - hope you have many
hours of pleasure building and flying your new model.
Klaus Michler
Product development
MULTIPLEX Modelltechnik