Date Posted: 02-Apr-2004
JANE’S NAVY INTERNATIONAL – MAY 01, 2004
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Bloated JSF on crash diet as flight tests pushed back
Nick Brown
The opening months of 2004 have brought a round of bad news for Lockheed Martin’s F-35 Joint Strike Fighter (JSF), seeing delays force the planned first test flights back from 2005 to early/mid-2006 and the initiation of a major drive to shed weight from the aircraft.
February also saw the Pentagon note that around US$5 billion would have to be shuffled from the JSF procurement budget and into development to keep the programme on track. In addition, a critical design review scheduled for April 2004 has been pushed back to the second quarter of 2005. Michael Wynne, the US Department of Defence’s head of procurement is currently evaluating a revised programme schedule proposed by the JSF joint programme office and Lockheed Martin.
Although there have been avionics stumbling blocks too, the main development ‘speed-bump’ causing all of these issues is down to the airframe’s weight problem. According to programme officials, initial estimates of the aircraft’s weight based on earlier programmes proved inaccurate as the design was refined.
Worst affected by the weight issue is the F-35B Short Take-Off Vertical Landing (STOVL) variant, which needs to shed a projected 1,090kg from the production version, but the F-35A conventional and F-35C carrier-based versions also have to shift a hefty 635kg. This is a major concern as it would affect range, endurance, speed, manoeuvrability and safe ordnance bring-back levels.
However, that is the worst-case scenario and relates directly to the power-to-weight ratio, which means that the required performance parameters could be met with some judicious weight-loss, reducing the drag co-efficient and uprating the thrust from the engine. Work is already underway in all these areas and Lockheed Martin has identified several areas that could be lightened, including removing redundant wiring, work on the landing gear and work to adjust the structural loads carried by the aircraft’s skin.
The main drive is to reduce the all-up weight of the more complex STOVL version and then carry those over with common reductions on the other variants, followed by potentially lightening components unique to each.
Despite the slipping schedule, Tom Burbage, Lockheed Martin’s executive vice president believes that it is crucial to get flight data early on and has announced the company’s intention to push ahead with the programme and get an aircraft into the air as soon as possible. This potentially means flying aircraft before the full weight-reduction effort is completed as the initial test aircraft do not have to be constructed exactly as the final production aircraft.
That is, while the early aircraft could be trialing flight control systems and investigating the hover to conventional flight envelope, industry could be proving out the manufacturing process and filtering weight reduction and performance upgrades through to the test aircraft, according to Burbage.
This year has not all been bad news for the JSF. In mid-February, the programme received some good news to shore up the STOVL programme when the US Air Force (USAF) also stated its intention to buy a number of the F-35Bs to boost close air-support capabilities as the venerable A-10 Thunderbolts bow out of service. The USAF initially only planned to buy conventional versions, but operations in Afghanistan and Iraq have highlighted the potential of aircraft able to operate from rugged, ill-prepared strips close to the front.
This is particularly important as the F-35B is absolutely central to the future of US Marine Corps air power – and particularly to the UK Royal Navy (RN) as the RN’s first FA-2 Sea Harrier squadron (800 Naval Air Squadron) was stood down on 31 March.
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April 2, 2004 at 9:24 pm