Graham Warwick/WASHINGTON DC
Pratt & Whitney has mounted the modified F119 engine for Lockheed Martin's X-35 Joint Strike Fighter (JSF) concept demonstrator in a test stand at its West Palm Beach, Florida, site ready to begin ground testing.
Ground testing of the modified F119 powerplant for Boeing's X-32 JSF concept demonstrator is also imminent. The first to be ready will be the first to be run, says JSFF119 programme manager Bob Cea, adding: "They are both very close."
The two engines represent the powerplant configurations for the conventional take-off and landing (CTOL) variants of the competing JSF designs. Two more ground-test engines, in the short take-off and vertical landing (STOVL) configurations, will be run in the fourth quarter, Cea says.
Additional ground-test engines are planned and the first flight-test powerplants are scheduled to be delivered "this time next year", he says. P&W plans to have accumulated 2,800h ground testing on the four engine configurations before the first flights in 2000.
The JSF engines share a common core with the F119s powering the Lockheed Martin/Boeing F-22. The low-pressure systems are tailored to the requirements of the competing JSF designs, including the radically different STOVL propulsion concepts - direct lift for Boeing and shaft-driven lift fan for Lockheed Martin.
The US Air Force, meanwhile, is conducting a more detailed analysis of the potential requirement for STOVL JSFs, despite an earlier "quick look" study which decided there was no compelling need for such an aircraft.
Last year, then chief of staff Gen Ronald Fogelman suggested that the USAF could buy some of its planned 1,763 JSFs as STOVL variants. A subsequent Air Combat Command (ACC) study decided there was no operational requirement for STOVL capability.
Now USAF chief of staff Gen Michael Ryan has asked ACC to conduct a more detailed analysis and present the results by year end. "STOVL is being looked at for basing flexibility," says Harry Disbrow, USAF deputy director, operational requirements. "It is being looked at by ACC and the results will be available by early 1999," he adds.
Disbrow says the USAF would procure STOVL JSFs, if required, as "block upgrades" to the basic CTOL aircraft. The ability to operate away from large airbases fits in with the USAF's drive to become an expeditionary force, but the issue, he says, is the service's ability to support forward-deployed STOVL operations.
"When a Marine Corps [STOVL] aircraft lands, it lands amongst Marines, but an Air Force aircraft would have to land among the Army, and they wouldn't know how to support our aircraft," Disbrow explains.
US Navy interest in the STOVL JSF has waned, meanwhile, leaving the US Marine Corps and the UK Royal Navy as the only services with firm requirements for this variant of the joint-service strike fighter, accounting for under 700 of the planned total of some 2,900 aircraft.
Source: Flight International
