Microwave engine gets a boost

UK research into a propellant-free microwave engine designed for spacecraft propulsion is stirring interest from US and Chinese aerospace companies, its developer has claimed.

Despite sounding like the stuff of science-fiction, SPR (Satellite Propulsion Research), the company behind the EmDrive – which was first reported by The Engineer in November 2004 – insists its technology is gathering momentum in the international aerospace community.

According to the managing director of Roger Shawyer, the engine takes microwave radiation produced by a magnetron and feeds it into a specially shaped resonant cavity. The waves push against the end wall. Because of the difference in wave velocity, being higher at one end that the other, there is a momentum transfer. The result is a measurable net force from the cavity against its surroundings.

The EmDrive is just entering the third of three development phases. The first was an experimental thruster, which Shawyer claims provided a thrust of 2g in over 240 tests, shown as a drop in the engine mass.