August 2015
By John A. Tirpak
Editorial Director
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While flight sciences on the F-35B with 2B software is done, Allen said there’s still a lot to do with the F-35A and C models and quite a bit more testing to do on mission systems. Much of the flight sciences work being done now concentrates on carrying external loads with a variety of weapons, in different and asymmetric combinations, to explore as many conceivable contingencies as possible.
Allen said the
F-35 is “incredibly stable,” and “I don’t know if I want to admit this, … but it’s incredibly easy to fly. It’s not necessarily easy to employ, but it is easy to fly.”
He said pilots don’t spin-test the F-35 because it won’t spin. “We do departure [from controlled flight] resistance, and then recovery from intentional departures,” he said. “We try to put it out of control and see how it behaves,” but for the most part, pilots don’t have to do anything to recover the airplane; it largely rights itself. Even at very high angles of attack—extreme nose-up attitudes while the jet is moving straight ahead—“the jet’s stable,” Allen said.
The F-35 has a dizzying number of capabilities, he said, and they all have to be tested and refined.
“There’s probably buttons on your [TV] remote, and you … probably have no idea what they do, right? It’s the same concept. There’s just so many things that this aircraft will eventually be able to do.”
A typical day adds up to about three test flights, but they require a phenomenal amount of planning, coordination, assets, and conditions—such as tankers, controllers, chase aircraft, ranges, and weather, to name just a few—that must all line up to make a successful mission.
In addition to envelope expansion, the F-35 is actually put through its paces, dropping ordnance, exercising its electronic warfare, and even flying “against” F-16s, though the Vipers are usually targets and not dogfight adversaries. Even live shots are made, against subscale target drones. Weapons drops are performed both to make sure the ordnance separates safely from the jet and also to ensure the F-35’s accuracy. This constitutes an “end-to-end check” that “the kill chain can be completed, from a weapons perspective,” Allen explained.
Ability to Execute
The F-35 has been flown in concert with E-3 AWACS, F-15Es, Navy F/A-18s and E-2Cs, and in interoperability testing with the British Typhoon and ground-based tactical air controllers. However,
these are all systems and compatibility tests. Tactics are developed at Nellis AFB, Nev....
Two years ago, when Allen came to the job, F-35s were available for test about 50 percent of the time, and
now “it’s improved to where it stays on the schedule and we fly an effective sortie … between 60 and 70 percent” of the time. “So it’s much improved, and that’s nothing to make light of.” Besides the skills of the maintainers, “the supply chain is always going to continue to improve and grow.” Moreover, test maintainers have direct access to the engineers and experts who designed the systems. “We have a little more at our fingertips, … more expertise, here,” to make sure flight tests happen on schedule.
Broadly, Allen said the F-35s are meeting contract specifications, although “expectations may be a different discussion.
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In its stability, ability to fly at high angle of attack, and departure resistance, it does very well and has performed “better than expected,” Allen said. The F-35 does “exceptionally well” at instrument approaches and as a stable communication-navigation platform, without the need to reset the computers.The software pieces are tested individually to make sure they work alone—radar, electronic warfare, sensors, targeting system—and then “we start to add things together,” such as how the radar works with the software fusion engine, with electronic warfare, and the Distributed Aperture System that allows the pilot to see 360 degrees in darkness.
“We go out and in a repeatable manner … try to employ the aircraft in the way that we think it will be employed in the near future. And we make assessments on how well it does in each individual mission,” such as offensive or defensive counterair or interdiction.
Ultimately, they “roll everything up in a ball and do more integrated, big-system-level testing. But that’s all after we’ve done all the building-block tests up ... to that graduation-type exercise.”
One of the challenges of flight testing the F-35 is that it will be used by three different services, whose pilots grew up in different communities and have different ideas of “how something should be displayed,” Allen observed. Display and data management preferences will be different for a pilot coming from an air-to-air system, like the F-15C, versus a mainly air-to-ground system, like the Harrier, and there will be differences in how suitable the pilots think the presentation is. But “we’re not going to develop three different versions of the mission system software,” Allen stated.
Allen, who was also an F-22 test pilot, said
the software stability is far more advanced than it was on the F-22 at a similar stage.
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