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Aviation History
2003
2003 - 1701.PDF
DEFENCE The first F-35 should follow the demonstrator aircraft (above) into the air in late 2005 JOINT STRIKE FIGHTER GRAHAM WARWICK / PARIS JSF back on track after airframe design rework Weight estimates 35% over target led to efforts to improve structural efficiency After an intensive eight-week nose-to-tail rework to improve the structural efficiency of the F-35 Joint Strike Fighter, Lockheed Martin expects the preliminary design review (PDR) to be closed out on 26 June. Completion of the PDR, which was delayed from March by con cerns over the maturity of airframe design, keeps the programme on track for a first flight in late 2005, according to programme general manager Tom Burbage. The airframe PDR was kept open after weight estimates raised con cerns about the maturity of the design. "The first bottom-up roll up of weight came out higher than expected," says Burbage. Typically initial weight estimates are 20-25% over target, but the F-35 came out 35% over. Following the rework, weight is now within 10% of tar get. "That's about where we should be. Now we can go get the last 10%," he says. Burbage says certain design fea tures - in the aircraft for affordabil- ity reasons - were driving the weight up, including quick-mate joints incorporated to speed final assembly. A panel-by-panel review of the structure revealed that an autosizing routine used to design the wing carrythrough structure was focusing the loads on one frame, which came out too heavy. "Now PROPULSION SYSTEM GUY NORRIS / LOS ANGELES Partners say F135 is 'meeting or exceeding requirements' Pratt & Whitney, Rolls-Royce and Hamilton Sundstrand have completed the critical design review (CDR) for the F135 engine and, according to P&W, have shown it is "meeting or exceeding requirements as specified in its sys tems development and demonstration programme". The F135 CDR completed a seven-month process and clears the way for the first production configuration engine for the conventional take-off and landing/carrier) variant to go to test around October. The short take-off and vertical landing (STOVL) propulsion system starts tests in Florida in the second quarter of next year, while flight tests in the Lockheed Martin F-35 are scheduled to begin in 2005. First production F135s are due to begin delivery in 2007. For the F135, P&W provides the main engine and is responsible for the system integration; Rolls-Royce supplies the lift fan, three-bearing swivel nozzle and roll posts for the STOVL F-35B. Hamilton Sundstrand provides the control system, external accessories and gearbox. the loads are stretched over all four frames," which are thinner, he says. Most of the design issues related to packaging. "We are trying to shrink-wrap the aircraft around a lot of stuff," says Burbage. The F-35 is the first fighter to have power-by- wire flight controls, and routing of wiring for the electro-hydraulic actuators has been a challenge. The design rework "has been a huge benefit to the programme", says Burbage. The challenge now is to re integrate the airframe design, which has been offline for eight weeks, with that for the rest of weapon system, says Burbage. Lockheed Martin and partners Northrop Grumman and BAE Systems must now complete detail design and release build-to pack ages for the first aircraft. "The pro gramme is massively parallel," he says. "We had four months of schedule reserve to first flight, but we've eaten most of that up." In the run up to next year's critical design review, the F-35 team must progressively close the design. To that end, Burbage has reorganised the programme struc ture to create an office of the chief engineer responsible for design closure. Lockheed Martin is aiming for 80-85% drawing release by CDR. After the critical design review, all changes to the design must be incorporated into produc tion blocks. UPGRADES UK Tornados to be updated through 2018 UK Royal Air Force Panavia Tornado GR4s are to receive a continuous series of modifica tions to maintain capability until the strike fighter's planned out- of-service date of around 2018. BAE Systems, a Panavia partner company, handed over earlier this month the last Tornado to be upgraded to GR4 standard and is preparing for the combined maintenance and upgrade (CMU) programme. Mark Greenhaigh, BAE cus tomer solutions and support director strike operations, says a "rolling set of upgrades continue at the main operating bases on a planned and opportunity basis". He adds that a continual modifi cation programme is "key" as the RAF cannot have a large num ber of aircraft out of service being modified. The GR4 programme upgrades the avionics - includ ing a new main computer - and improves capability. BAE is also under contract to introduce new software, written in Ada rather than a legacy language; incorpo rate the MBDA Brimstone missile; double Storm Shadow carriage to four missiles; add Successor IFF transponders; and improve the cockpit displays. Potential upgrades include tactical datalink; a collision warn ing system required for operations in civil controlled air space; a revamped defensive warning suite; and further improvements to the main com puter. Greenhaigh says the tactical datalink could be an improved data modem or a Link 16 system as the RAF require ment would need both systems. BAE has a contract that expires in the second half of this year to prove CMU on three GR4s. Greenhaigh says CMU takes "best practice from our hangars and takes it to the main operating bases". It will allow incremental upgrades of the air craft to be implemented as part of the fighter's scheduled main tenance programme. www.flightinternational.com FLIGHT INTERNATIONAL 24-30 JUNE 2003 35
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