Superman: Escape from Krypton has been terrifying Six Flags Magic Mountain theme park visitors since 1997. Once the tallest roller coaster on the planet and the first to employ a linear motor system, Superman launched riders up a 126-metre vertical track at 160 KPH. Now GE is working to convert the technology behind the amusement park ride into an electric catapult capable of flinging F-35s into action.
US aircraft carriers have used the steam-powered CATOBAR (Catapult Assisted Take Off But Arrested Recovery) system to launch piloted aircraft from their tightly packed decks for years. The problem is, “traditional steam launch catapults rely on steam raising plants that are large, complex and expensive to buy, run and maintain,” Graham Bellamy, senior engineering leader at GE Power Conversion, Naval, explained in a press release. “That was not so much of a problem when ships needed to produce steam for various purposes, not just for launching aircraft. But today, ships don’t need so much steam, so boilers of the size and type required for catapults are rare. But modern navy ships do have large electrical generating capacity. This can be used to satisfy the needs of EMCAT (Electro Magnetic Catapults) in short bursts.”
So rather than rely on vapour pressure, GE’s powerful new medium voltage advanced linear induction machine (MV ALIM) utilises a pulsating electromagnetic field — like those used in naval rail guns — to hurl both piloted and unmanned aircraft off of the flight deck with as much as 230 kN of thrust. It can accelerate anything from a 50kg UAV to a 37-ton fighter jet to 300 KPH. Piloted aircraft endure up to 3.3 G along a standard carrier runway, while UAVs are squeezed under as much as 12 G during their abbreviated launch. “In terms of force, this is probably the most powerful linear motor ever built,” says Mark Dannatt, director of naval business at GE Power Conversion.
To minimise wear on both the launch system and the vehicle itself, the MV ALIM also incorporates magnetic levitation technology, the same you’ll find on Japan’s bullet trains, to drive a steel plate upon which the vehicle’s front end rests. “There is an air gap between the plate and the track,” Dannatt explained. “There are no bits wearing down. It’s much better for maintenance.”
“The tests on the MV ALIM are the culmination of more than a decade of substantial investment and development in EMCAT,” Bellamy said. “Thousands of launches have been proven previously on the smaller EMKIT variant, which allows aircraft weighing up to 11 tons at speeds of up to 50 meters per second to be launched. Smaller aircraft can be accelerated to speeds of up to 120 meters per second.”
There’s no word yet on when the technology will actually make it aboard US carriers but GE executives are already eyeing civilian industry — automotive crash testing and private sector UAV operations for example — as potential markets.