Rolls-Royce is looking at whether technology developed for a marine electromagnetic rim-driven thruster could be applied in unmanned air vehicle powerplants to generate large amounts of electrical power.
The rim-driven thruster is designed to be mounted on ships to assist with docking. However, the UK manufacturer believes similar electromagnets could be mounted around the shaft of a UAV's turbofan engine to supply power-hungry on-board systems such as directed energy weapons or a pulse Doppler radar.
"It's all-electric drive and we've embedded very modern technology magnets into [the rim-driven thruster]," says Colin Smith, R-R's director of engineering and technology. "There's no mechanical drive, no oil lubrication, no chance of leakage, no cavitation, and it's very quiet and very efficient," he adds.
"This is the sort of technology we will use on unmanned air vehicles where you have high embedded electricity generation."
R-R has already run a small "cruise missile-style" demonstrator engine "using almost the same technology", says Smith, who adds that "in theory" it should be possible to install the magnets in the tips of the compressor blades to create the engine torque for electrical power generation.
The company is also a participant in the Power Optimised Aircraft project, which is part of the European Commission's fifth framework research and technology programme.
Smith says this included the demonstration of a Trent 700-based engine, which had an "electromagnetic, auto-levitated bearing in the back", as well as "embedded generators in the low-pressure turbine", and "right on the core of the engine, where the gear box normally is".
A shaft-mounted, brushless DC electrical generator equipped with neo-dymium iron boron magnets could efficiently deliver substantially more power for more-electric or all-electric aircraft, but must be able to cope with operating temperatures in excess of 220° (428°), requiring the use of advanced materials and innovative cooling systems.
Source: Flight International
