Graham Warwick/ATLANTA
GENERAL ELECTRIC'S YF120 has been selected by the US/UK Joint Strike Fighter (JSF) programme office as the alternative engine to the Pratt & Whitney F119 already chosen.
The JSF programme office has been studying derivatives of the GE F110 and YF120 as an alternative to the F119, around which all three JSF teams have based their designs. The decision follows airframe manufacturers' recommendations in favour of the YF120.
US Congress directed selection of an alternative powerplant to introduce competition and minimise the impact on the 3,000-aircraft programme of any develop- ment or operational problems with the JSF powerplant. GE has supplied airframers and the programme office with data on "more than 20" derivatives of its existing F110 and next-generation YF120.
Phil Combs, GE's general manager for new and derivative military engines, says that the programme office is discussing the options with JSF customers: the US Air Force, Navy and Marine Corps and the Royal Navy in the UK. A selection is expected to be tied to a decision on whether all the JSF engines will be competed, or only those for specific variants or customers.
Phase 2 of the competitive-engine programme will run from 1997 to 2000 and involve ground testing of the chosen core, plus demonstration of a complete turbofan, if funds allow, Combs says. Phase 3, from 2001 to 2004, will involve pre-development testing of the turbofan and possible flight-testing in the winning JSF design. Engineering and manufacturing development will begin in 2004 and the engine is planned to be available 18 months after the F119. "Two engines will be available from the 72nd [JSF] aircraft onwards," Combs says.
The advantage of the YF120 over the F110, he says, is that its larger core can be matched with minimum modification to whichever airframe wins the JSF contest. All three designs use different vertical-lift propulsion concepts: McDonnell Douglas using a lift engine separate from the main engine; Lockheed Martin, a lift fan shaft-driven from the cruise engine; and Boeing, a single lift/cruise engine.
"The YF120 core size can meet any [JSF] need," says Combs. "We do not need to change the core, just use a different low-pressure system. The YF120 is the largest military core known to man and adapts well to JSF requirements," he says, noting that the dry-thrust requirement is "very much higher" than that of the Advanced Tactical Fighter for which the YF120 was developed.
The GE/Allison team has been joined by Rolls-Royce on the YF120 bid. The UK company will supply the complete fan module. Combs says that Allison parent R-R favoured selection of the YF120, as it will increase UK content in the JSF programme. The UK engine-manufacturer also wants to be able to offer the YF120 to power the UK's planned Future Offensive Aircraft, he says.
Source: Flight International
