Multiplex BIG LIFT II Notice De Construction page 10

16. Installing the electric motor or engine
We cannot say much that is specifically useful here, as each power
plant has to be handled differently. However, the Big Lift II is not a
beginner's model in any case, and any experienced modeller will know
what has to be done here. We have deliberately left the cowl 18
overlength, to give you the option of making a short-nose or long-
nose version, depending on the weight of your motor.Trim the cowl
and windscreen to fit, and secure them using the screws 71.
17. Fitting the wing strut mountings
Cut a vertical 2 x 16 mm slot in each fuselage side to accept the strut
joiner 55; the slots should be located immediately aft of the plywood
reinforcement, and should start at the bottom of the fuselage. Trim
the slots so that the strut joiner 42 fits straight though them. Set the
joiner exactly central and glue it to the fuselage together with the strut
support 37 (10 x 10 mm spruce), using UHU plus.
Fig. 18
18. Fitting the wing struts
Assemble the wing struts from parts 50, 51, 52, 53, 54 and 56. The
length of the struts will be about 450 mm, but the precise length must
be measured from your actual model. When the struts are in place
there should be about 1° dihedral on each side. This is best measured
at the underside of the wing (measure both wings, as the sub-surface
may not be flat). Each wingtip should be about 20 mm higher than the
root. Glue the tear-drop strut fairings 57 to the struts (2 x strip 57),
noting that the "round" side should face forward.
Figs. 19 / 19.1
19. Covering the model, applying the decals
Before you start on the finishing procedure it is a good idea to assemble
the model completely, check that everything fits correctly, then
dismantle it again.
The model components need to be prepared in different ways
according to your preferred covering method.
a. If you intend to use silk or self-adhesive film all the parts should be
cleaned carefully and given 1 or 2 coats of sanding sealer. Don't forget
to sand down between coats.
b. If you wish to use iron-on film, sand as under a., but do not apply
sanding sealer.
c. If you prefer to apply a painted finish sand the airframe down as
under a.), but apply tissue to the fuselage before applying the sanding
sealer.
20. Test-flying
Test-flying always starts in the workshop!
19.1 Check the longitudinal dihedral
19.2 Check the Centre of Gravity (CG)
root leading edge; see Fig. 20
We recommend the following instruments for carrying out these
measurements:
Incidence gauge
CG gauge
21. Please note these points when finally assembling the model:
20.1 Plug in the wings fully and fit strong rubber bands between the
retaining hooks to secure them.
20.2 Connect and secure the wing struts.
20.3 Re-check the control surface linkages.
20.4 Carry out a range check.
Ensure that the transmitter and receiver batteries are fully charged
as described in the RC system instructions. Ensure that "your" channel
is not already in use before you switch on the transmitter. The channel
pennant on your transmitter aerial is mandatory, and shows other
pilots which channel you are using. If other modellers are present at
the site, make sure that you tell them clearly and unambiguously which
channel you are on.
A range check should be carried out before flying the model for the
first time, and should be repeated at the start of each day's flying
session. Hold the model in such a way that the aerial is not blanked
off.
Ask a friend to walk away from the model, holding the transmitter.
The aerial should be fitted but completely collapsed.
Your colleague should operate one of the functions constantly while
you watch the servos. The non-controlled servo should stay motionless
10
= 2.5°
= 100 mm aft of the wing
# 69 3053
# 69 3054
up to a range of about 80 m, and the controlled one should follow the
stick movements smoothly and without any delay. If the range check
is successful, repeat it with the motor running. Even at the limit of
range it is important that the motor should cut immediately when you
give the appropriate command.
Please note that this check can only give reliable results if the radio
band is clear of interference, and if no other radio control transmitters
are in use - even on different channels. In high mountain terrain a
range check does not give meaningful results due to extreme field
strengths and the excessive effective range of other transmitters.
If you are not sure about anything, please don't risk a flight - even if
you can't wait to see the aircraft in the air and your mates are egging
you on. Check whether your channel really is vacant, and if this is so
send the whole system (including battery, switch harness and servos)
to the service department of your RC system manufacturer and ask
them to check it.
Faults do not cure themselves!
20.5 Check one last time that all the control surfaces are deflecting in
the correct direction (that applies to you experts, too).
20.6 Depending on the power of your engine, the Big Lift II will lift its
tail after a ground-roll of about 5 - 10 m, and will lift off after 20 - 30 m.
Fly a few circuits so that you get an idea of the model's handling and
control response, including its behaviour when throttled back. For the
first landing we recommend that you do not deploy the landing flaps.
Before you lower the flaps for a landing, carry out a "dry run" at a few
metres altitude so that you have a clear idea of how much throttle is
required to keep the airspeed at a safe level.
If you have fitted a powerful engine, never fly at full-throttle with the
landing flaps lowered.
22. Aero-towing
This is one of the finest methods of launching a sailplane, and
represents a fascinating challenge for both tug and glider pilot.
Equipment: you must have powerful servos to operate the tow release
at each end of the line. As a test, place the towline under about 10 kg
of tension and try to release it - it must work reliably every time!
A suitable towline can be made from 3 mm Ø braided nylon line. This
material is available from virtually all building suppliers and DIY shops.
Tie a loop of 0.8 - 1 mm Ø mono-filament nylon at each end. The
optimum overall length of the aero-tow line is about 20 m.
Set up both models on the take-off strip, and engage the towline at
both ends. The tug now taxis forward slowly until the line is taut. The
pilots should make sure that they understand each other, and at a
given signal the tow commences.
The glider should be steered exactly in line behind the tug, and will
normally lift off first. Keep the glider low over the ground until the tug
also takes off. Both machines now climb steadily to altitude. It is
important that the glider follows a course exactly behind the powered
tug, and never flies inside the turn, "cutting the corner". The tug should
be kept in a steady climb, at a constant rate, but not so steep that the
glider loses airspeed. Turns must always be broad, and this does
require practice.
Please note that there is effectively no wind when you are aero-towing.
Again and again we hear nonsense spoken about this: "now we'll turn
back into wind and start climbing again." This is just an optical illusion.
The fact is that the rate of climb is constant; it is just that the air is
moving relative to the ground, and it simply takes longer to fly from
one end of the site to the other. The actual danger is that it looks as if
the climb is not steep enough when you are flying downwind, and the
pilots then try all manner of manoeuvres in an attempt to increase the
rate. Usually this means that the glider catches up with the tug, and
chaos invariably ensues. This must be prevented, and again the
technique requires practice.
We - the MULTIPLEX team - hope you have many hours of pleasure
building and flying your new model.
MULTIPLEX Modellsport GmbH & Co. KG
Product development and maintenance
Klaus Michler