UNPOWERED AEROMODELS are without a power plant and fly only using the initial force supplied during launching.
The chuck gliders are launched in the air by the chucking action of the hand and are often flown indoors. Hence they are also known as ‘Indoor models’ Some chuck gliders are made using sheets / blocks of ‘thermocol’. These tend to float in air for longer time and have longer wings and higher lift compared to other models of this class. The critical aspect of such aeromodels is the design of the wing, as this decides the time of flight of the model.
Catapult models are also similar to chuck models, except they are launched from a hand-operated catapult, rather than a chuck of the hand. These models are swift, have a longer range and are suitable outdoors. Catapult models need to be stronger than chuck gliders, hence are made of wood / plastic and not thermocol. They are basically model planes which take-off with the aid of a rubber string hooked to it. The tension in the string pushes the model forward when released. These models are usually made out of balsa. The success of the flight depends on the shape of the wings (aerofoil).
Tow-line models are gliders which are launched using a long line with a ring hook, in the open against the wind direction. The launcher runs against the wind after the helper releases the aircraft. Once in air, the aircraft rapidly gains height until it is at the top most point called the ‘zenith’. The model automatically detaches from the tow-line as the ring hook slips and glides back to earth in wide circles. The fin is off-set a couple of degrees while constructing, to aid the glider to descend in circles.