MODEL AIRCRAFT
Model aircraft are flying or non-flying models of existing aircraf – more often scaled-down versions of full size planes. Materials used are polystyrene, balsa wood, foam and fibreglass. And you can design anything from a glider to a very large full scale model.
Flying models come in 3 groups, i.e. Free flight – no external control from the ground, control line whicih uses two cables lelading from the wing to the pilot and radio controlled; the transmitter is operated by a pilot on the ground who sends signals to a receiver in the aircraft.
Flying models mimic construction techniques from full-sized aircraft, for example making a frame using thin strips of balsa wood, covering it with fabric and doping it so that the frame is also airtight.
Power sources
Powered models have an onboard powerplant to propel the aircraft through the air – the most common propulsion being electric motors and internal combustion although a small turbine,a pulsejet, compressed gas and even a twisted rubber band will work as well.
Electric power
In electric-powered models, the powerplant is a battery powered motor. Throttle control regulates the motor’s output. High capacity nickel metal hydride (niMh) (NiMh) batteries will improve flight times and the newly developed lithium polymer batteries (LiPoly or LiPo) will in many cases surpass that of glow-engines.
Control Line
Finally, when you have built (or bought) your model aircraft and equipped it with the necessary power centre, you need to find an open field in which to fly it. To do this a control line is used by the pilot on the ground to control the aircraft and can allow a pilot to fly three models at a time. The aircraft are flown in a circle and controlled by the pilot who stands in the center holding a handle connected to two thin steel wires. These wires connect through the inboard wing tip of the plane to a mechanism that transmits the handle movements to the aircraft elevator, allowing maneuvers to be performed.
