18
L.H. wing
panel
Elevator
GB
Spinner
Wing section
The wing features a cambered airfoil section over which the air
flows when the model is flying. In a given period of time the air
flowing over the top surface of the wing has to cover a greater
distance than the air flowing under it. This causes a reduction in
pressure on the top surface, which in turn creates a lifting force
which keeps the aircraft in the air.
Fig. A
Centre of Gravity (CG)
To achieve stable flying characteristics your model aircraft must
balance at a particular point, just like any other aircraft. It is
absolutely essential to check and set the correct CG position
before flying the model for the first time.
The CG position is stated as a distance which is measured aft
from the wing root leading edge, i.e. close to the fuselage. Sup-
port the model at this point on two fingertips (or - better - use the
MPX CG gauge, # 69 3054); the model should now hang level.
Fig. B
If the model does not balance level, the installed components
(e.g. flight battery) can be re-positioned inside the fuselage. If
this is still not sufficient, attach the appropriate quantity of trim
ballast (lead or plasticene) to the fuselage nose or tail and secure
it carefully. If the model is tail-heavy, fix the ballast at the fuselage
nose; if the model is tail-heavy, attach the ballast at the tail end of
the fuselage.
The
longitudinal dihedral
is the difference in degrees between
the angle of incidence of the wing and of the tail. Provided that
you work carefully and attach the wing and tailplane to the
fuselage without gaps, the longitudinal dihedral will be correct
automatically.
If you are sure that both these settings (CG and longitudinal
dihedral) are correct, you can be confident that there will be no
major problems when you test-fly the model.
Fig. C
Control surfaces, control surface travels
The model will only fly safely, reliably and accurately if the control
surfaces move freely and smoothly, follow the stick movements
in the correct “sense”, and move to the stated maximum travels.
The travels stated in these instructions have been established
during the test-flying programme, and we strongly recommend
that you keep to them initially. You can always adjust them to
meet your personal preferences later on.
Transmitter controls
The transmitter features two main sticks which the pilot moves
to control the servos in the model, which in turn operate the
control surfaces.
The functions are assigned according to Mode A, although other
stick modes are possible.
The transmitter controls the control surfaces as follows:
Rudder (left / right)
Fig. D
Elevator (up / down)
Fig. E
Aileron (left / right)
Fig. F
Throttle (motor off / on)
Fig. G
Unlike the other controls, the throttle stick must not return to the
neutral position automatically. Instead it features a ratchet so
that it stays wherever you put it. Please read the instructions
supplied with your radio control system for the method of setting
up and adjusting the transmitter and receiving system.
Basic information relating to model aircraft
Any aircraft, whether full-size or model, can be controlled around the three primary axes: vertical (yaw), lateral (pitch) and longitudinal
(roll).
When you operate the elevator, the model’s attitude alters around the lateral axis. If you apply a rudder command, the model swings
around the vertical axis. If you move the aileron stick, the model rolls around its longitudinal axis. External influences such as air
turbulence may cause the model to deviate from its intended flight path, and when this happens the pilot must control the model in
such a way that it returns to the required direction. The basic method of controlling the model’s height (altitude) is to vary motor
speed (motor and propeller). The rotational speed of the motor is usually altered by means of a speed controller. Applying up-
elevator also causes the model to gain height, but at the same time it loses speed, and this can only be continued until the model
reaches its minimum airspeed and stalls. The maximum climb angle varies according to the power available from the motor.
Fuselage
Canopy
Rudder
L.H.Aileron
Fin
Tailplane
R.H. wing
panel
Longitudinal axis
vertical axis
lateral axis
R.H. Aileron