Parallel to the continued work on its AirMule ducted fan vertical take-off and landing (VTOL) aircraft, Israeli company Urban Aeronautics is also evaluating a high-speed version that will be used for tactical resupply missions.
Work on the design began in 2009, when the company performed initial windtunnel tests of a 250kt (465km/h)-capable cargo variant of its Mule unmanned air system.
The new variant will be powered by a 1,600shp (1,190kW)class turbine engine, and is 20% larger and 50% heavier than the standard AirMule, which is designed for tasks including medical evacuation from the front line.
According to Rafi Yoeli, Urban Aeronautics president, the fast variant is designed to be an answer to operational requirements in the USA and other countries for a ducted fan high-speed unmanned cargo delivery capability.
Data gathered during the windtunnel test shows that the high-speed variant is capable of exceeding 250kt, Yoeli says.
The new variant's performance is accomplished mainly through a "stagger" built into the three main components of the vehicle: forward fan, centre fuselage and rear fan. A horizontal stabiliser is also mounted at the rear of the vehicle and canted sharply upward.
On the ground and in hover, the fans are essentially horizontal to the ground. The vehicle's vane control system and other company-patented aerodynamic and flight control provisions enable it to take advantage of the Mule's characteristics in terms of safety, gust capability and noise, the company claims.
When in cruise flight the vehicle tilts forward (above) so that the lift fans are acting partly as thrusters. Lift is shared throughout the fuselage via a specially designed shape that interacts aerodynamically both with the incoming flow and with the two fans mounted fore and aft.
The baseline AirMule has a flatter air vehicle shape than its high-speed derivative
Source: Flight International