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F-35 Lightning II News

F-35 expands envelope and marks 460 test flights

November 4, 2010 (by Bjørnar Bolsøy) - Good progress is being made in F-35 flight testing by the CTOL and CV versions. F-35B STOVL mode flights have resumed, but the variant is still behind schedule.

CF-1 comes in for a landing at NAS JRB Fort Worth after its seventeenth flight. The 1.8-hour mission, flown by Lockheed Martin test pilot David Nelson, included air worthiness flying qualities testing. [Lockheed Martin photo by Carl Richards]

Despite a smoother flight record, it is neither the CTOL nor the CV model that holds the current speed and g-load records for the F-35. That honor befalls the F-35B STOVL. Recently the jet accomplished Mach 1.32 and 7 g's, the STOVL's maximum design limit.

The record Mach number was achieved in the BF-2 test aircraft at NAS Patuxent River on October 18. Flight objectives was to expand the STOVL flutter and flying-qualities, and supersonic flight envelope at 30,000 feet. Pilot was RAF Squadron Leader Steve Long, and the flight included two sorties and hot pit refueling.

The flight test program has picked up steam and is ahead of plan despite some recent challenges. Some 200 flights have been completed since June and overall the program has logged 460 flights to date. Flights have resumed well after they were suspended in early October to fix a software issue with the jets fuel boost pumps. BF-1 STOVL mode operations were also suspended due to an issue with the auxiliary air inlet (AAI) door hinge. A fix has been implemented and Lockheed confirms that the STOVL restrictions have been lifted and that flights have resumed.

Despite the AAI issue, the STOVL jets have been flying conventional flights. But progress has been slowed due to component reliability issues and the jets are still behind the flight plan. Lockheed says steps are being taken to address root causes and improve tempo. This includes obtaining more spare parts to keep the aircraft flight-ready.

Still, the flight testing managed to stay slightly ahead the plan for the October month. The CTOL jets logged 22 flights against a plan of 17. The STOVL jets flew 27 times against 28 planned, and the CV jet flew three times, two short of the five planned. In all 52 flights were completed against a plan of 50 in October. A further 51 flights are planned for November with a total of 394 due by year's end.

Overall this year, 321 flights have been completed, which is 28 ahead of plan. The CTOL is 66 flights ahead of plan, the CV three flights ahead, however the STOVL lags 41 flights behind the plan.

This years 300th sortie was flown on October 20 at Edwards AFB. Lockheed Martin test pilot Jeff Knowles completed a 2.1 hour sortie in the AF-2 jet with objectives including a negative-g loads test point, gear swings and acceleration to Mach 1.05 at 30,000 feet to validate turn performance.

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