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F-22 Lessons Drive Faster F-35 Testing


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AW_08_23_2010_p31-249425.xml&headline=F-22 Lessons Drive Faster F-35 TestingAviation Week and Space Technology/Guy Norris:


Flight-testing of the F-35 Joint Strike Fighter here is running almost three times faster than expected, forcing program officials to accelerate follow-on support testing to keep pace.


At the same time, program officials also confirm plans to add extra resources to the flight tests here, just as they are at the U.S. Navy’s test center at NAS Patuxent River, Md., to ensure the program stays on a revised schedule that extends development by 13 months.


Since ferrying from Lockheed Martin’s Fort Worth facility on May 17, the two initial conventional-takeoff-and-landing (CTOL) F-35As have completed 53 sorties, 36 beyond the 17 they were slated to have finished by now. “We’ve also executed 536 unique test points out of a planned 150,” says Lt. Col. Hank Griffith, commander of the 461st Flight Test Sqdn. and director of the F-35 Integrated Test Force (ITF).


Maj. Gen. David Eichhorn, commander of the Air Force Flight Test Center here, says the F-35A is “exceeding expectations at this point in the program” and that the accelerated test rate is linked directly to aircraft performance and availability. “We want to run as fast as the aircraft will let us,” he says. As a result, tests of inlet rigs and weapons bay door opening at Lockheed Martin will be conducted sooner than originally planned. “Now they are having to move that analysis forward. So maybe it is possible we could continue and finish early,” Griffith says.


“It’s a testament to the health and reliability of the CTOL aircraft as well as the experienced people here in the test team,” says Griffith, who notes that lessons from the F-22 test program are paying dividends. As well as recruiting people to work on the F-35 directly from the F-22, Griffith says early planning between the ITF and Lockheed Martin helped avoid the extended preflight-test delays experienced early on in the F-22 program.


“With the F-22, we didn’t start the flight test for a long time because they basically had to finish building it. So with the F-35, we worked very closely with Lockheed Martin to understand the traveled work,” Griffith says, referring to items that may have had to be completed here. As it turned out, the initial pair of aircraft arrived “squawk-free” and test-ready. “We flew the first test mission two days after we arrived and in the first two weeks we did nine sorties,” he adds. In addition, maintenance and support personnel from here traveled to Patuxent River to gain experience on the F-35 before delivery.


However, tempering the exuberance of this initial “honeymoon” phase, Eichhorn is also pragmatic. “I’m cautiously optimistic, but you never know what’s around the next corner in flight test. Once you get into the missions systems, it’s a different side of flying.” There are “things that need to be tweaked, and things that need to be changed, and we’re working that as a team with Lockheed Martin and the government,” he says.


“The F-35 is a typical test program and we’re running into the typical things you’d run into. What we don’t know yet is the cumulative effect of those things,” Eichhorn says. Griffith describes the issues as “normal program hiccups,” but says the overall performance of the aircraft has been solid, with sustained test sorties. Although the integrated power pack (IPP) is mentioned as the cause of a “few issues,” Griffith says that even these “have not really impacted us at all.” The IPP combines the auxiliary and emergency power units and environmental control system to save weight, and it is required to start the engine and power the aircraft.


Thermal management, another potential concern for the F-35 test team, has not been an issue. “We’ve been operating the jet out in the sun for three hours and never overheated,” says Griffith, noting that chilled fuel has been available but not used. However, the litmus test of the power and thermal management system, of which the IPP is a subsystem, will come during upcoming tests of the first fully equipped systems aircraft, AF-3. Cooling requirements will be more acute on it because it will be configured with Block 0.5 mission system software, airborne radar and electronic warfare systems.


AF-3 is undergoing anechoic tests at Lockheed Martin and is expected to ferry here in October. Although the initial systems tests will begin in the relatively cooler winter weather here, the higher temperatures in the spring and summer of 2011 will be the true test, Griffith says. “Come and ask me the same question this time next year,” he says. AF-4, the second systems aircraft, will arrive by year-end, but will have its radar removed for weight and balance reasons before being used for high angle-of-attack testing.


The F-35s were delivered here to undertake developmental test and evaluation (DT&E) for propulsion, aerial refueling, logistical support, weapons integration and flight-envelope expansion. They form part of an extended ITF that also includes the Navy’s test center, where four short-takeoff-and-vertical-landing (Stovl) F-35Bs are based, as well as Lockheed Martin’s Fort Worth site.


The first two aircraft, AF-1 and -2, are focused on flight sciences objectives, including envelope expansion, loads testing, flutter clearance and flying qualities. “Our objective by the end of 2010 is to clear the envelope to 40,000 ft. subsonic with 80% of the potential design limit load,” Griffith says. In June, initial supersonic testing for loads and flutter was completed to Mach 1.2/580 KCAS and 39,000 ft. Air refueling clearance tests at 15,000 ft. are also getting underway. The refueling envelope has already been cleared at 20,000 and 30,000 ft.


The ITF here will eventually include eight F-35As, two more than initially planned under the revised resource allocation. The two extra low-rate initial production aircraft will join the program in 2011. Recruiting is also underway to staff additional operational test positions. “We’re trying to get about a year ahead to keep up with the pace of the test program,” says Eichhorn.More people will be added to support the growing numbers of chase aircraft and tanker aircraft. Lockheed Martin will lead an industry team effort to add 112 maintenance and test operations employees. The total is expected to grow to 740, including industry and government personnel, says Griffith.


Planning for the establishment of the JSF Operational Test Team (JOTT) here from 2012 also continues, with signs of a strengthened bond between the developmental and operational test teams. “We’ve grown closer together. The JOTT team is already integrated with test planning and the weapons scenarios we will use in DT&E,” says Griffith. The unit will include 20 CTOL, carrier and Stovl variants, two of which will be U.K. aircraft. Eichhorn says that despite the increasing indications of harmony, the “integrated developmental and operational testing is still a work in progress.”



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