AR731 single-rotor Wankel UAV target engine

The AR731 is a single-rotor Wankel engine from UAV Engines Ltd (UEL), a gasoline rotary combustion engine for target drones and short-service UAV missions. It belongs to the maker's series of Wankel type engines for unmanned aircraft and is rated at 38 bhp (28.3 kW).

The engine has one rotor in a 208 cc chamber and burns gasoline. It weighs 9.9 kg, which gives a high power-to-weight ratio for its class. For an integrator, the output of 38 bhp and the mass of 9.9 kg set the size of airframe it can lift and the payload that remains once fuel is loaded.

The rotary format has properties the maker's engine series is chosen for: high power-to-weight ratio, small cross-section dimensions and low vibration, with fuel consumption only slightly above comparable piston engines. Low vibration reduces the load on avionics, sensors and airframe fatigue, and the narrow cross-section helps fuselage design.

The engine supports both tractor and pusher propeller installations in unmanned airframes, so it can be mounted at the front or the rear of the aircraft. Related engines in the maker's series use an electronic contactless magneto ignition and provide for fitting a 28 volt alternator, which are the points an integrator checks when planning the electrical supply and the starting method for the airframe.

The listed classification is professional grade for the defense market, and the engine is in production. It is intended for target drones, short-life reconnaissance UAVs and one-trip aircraft, where a compact engine with a modest service life is acceptable.

Typical applications are tactical surveillance UAVs, aerial targets and expendable platforms powered by a single engine driving one propeller. The compact rotary layout also suits airframes where engine bay volume is limited, since the engine carries one rotor instead of several reciprocating cylinders with their valve train.