Motor glider
A motor glider is a fixed-wing aircraft that can be flown with or without engine power. The FAI Gliding Commission Sporting Code definition is: a fixed-wing aerodyne equipped with a means of propulsion (MoP), capable of sustained soaring flight without thrust from the means of propulsion. In the US, a powered glider may be certificated for up to two occupants, up to 850 kg maximum weight, and with a maximum ratio of weight to wing span squared of 3 kg/m2. Similar requirements exist in European JAA/EASA regulations, at a maximum weight of 750 kg.
In 1935, an occasional or auxiliary motor that could be retracted was suggested by Sir John Carden. This was incorporated into the Carden-Baynes Auxiliary that first flew on 8 August of the same year.
Most motor gliders are equipped with a propeller, which may be fixed, feathering, or retractable. However jet engine-powered motorgliders are now available from some manufacturers, some of which are intended for use only as "sustainer" engines, i.e. for sustaining gliding flight rather than as self-launching aircraft.
Motor with fixed or full feathering propellers are generally classified as Touring Motor Gliders (TMGs). TMGs can take off and cruise like an airplane or soar with power off, like a glider.
They are fitted with front-mounted engines, similar to a small airplane. The large wingspans of TMGs provide a moderate gliding performance, not as good as that of unpowered gliders. However TMGs are more efficient than conventional light aircraft.
Most TMGs are designed with engines of 80 to 100 hp (75 kW) and typically cruise (under power) at 85–100 knots (190 km/h). Most have fuel tanks capable of holding between 50 and 100 liters (13 to 26 US gallons) of fuel, giving a range under power of up to 450 nautical miles (approximately 830 kilometers). Modern TMGs like the Phoenix Air Phoenix are capable of higher speeds and longer range under power.
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