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F-35 flight testing on pause while AA-1 test aircraft gets scheduled software update

02/16/2007 (Air Force Aim Points) -- Michael Sirak

Having notched seven successful flights to date, the first F-35 Lightning II stealth fighter test aircraft will remain on the ground until early next month while engineers load new software necessary for the upcoming series of flight evaluations, the director of the F-35 program said yesterday.

"It is now in a planned lay-up period to put some new flight-test updates into the software," Brig. Gen. Charles Davis, the F-35 program executive officer, said yesterday at the Aviation Week Defense Technology & Requirements conference in Washington, D.C.

Davis said he anticipates the aircraft, which is designated AA-1, returning to the air in the
first week of March upon installation of the software, which is designated FTU-1.

AA-1 is the first test aircraft built during F-35 program's system development and demonstration phase (SDD). It is a conventional- takeoff-and-landing (CTOL) model, one of three variants that the Lockheed Martin [LMT]-led global industry team is building for the U.S. military and eight international partners.

The test aircraft had its maiden flight last December (Defense Daily, Dec. 18, 2006). It has
already flown at 23,000 feet and has reached speeds of Mach 0.8 and a 16-degree angle of attack,
Lockheed Martin said earlier this week (Defense Daily, Feb. 14).

"It is progressing well," Davis said of the F-35 flight test program to date. The aircraft has cleared about 40 percent of its flight envelope, he said. Features unique to the F-35, such as its self-contained non-hydraulic flight actuators "have worked really well" thus far, he said.

The next planned software upgrade of the aircraft is planned around May, according to Lockheed Martin.

AA-1 likely will fly well into 2008, if not longer, Davis said.

"It just depends on the projects that we find for it," he told reporters after his presentation.

The next F-35 test aircraft, a short-takeoff-and-vertical-landing

(STOVL) version of the stealth jet, is scheduled to begin flying in May 2008, followed about one year later by a CTOL aircraft that, unlike, AA-1, is optimized for weight, Davis said.

There are now 11 F-35 aircraft (five CTOL; five STOVL; and components for the first carrier variant) in various stages of assembly, Davis said. By the end of this year, that number will increase to 21, he said.

In related news, Davis said Denmark is expected to sign the F-35 Production, Sustainment and Follow-on Development memorandum of understanding on Feb. 27.

The other partner nations (i.e. Australia, Canada, Italy, The Netherlands, Norway, Turkey and the United Kingdom) have already signed the document, which provides the framework for the nations' cooperation beyond the current SDD phase.

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Quote:

The test aircraft had its maiden flight last December (Defense Daily, Dec. 18, 2006). It has
already flown at 23,000 feet and has reached speeds of Mach 0.8 and a 16-degree angle of attack,
Lockheed Martin said earlier this week (Defense Daily, Feb. 14).

"It is progressing well," Davis said of the F-35 flight test program to date. The aircraft has cleared about 40 percent of its flight envelope, he said. Features unique to the F-35, such as its self-contained non-hydraulic flight actuators "have worked really well" thus far, he said.

An interesting comment by General Davis.

If Mach 0.8, 23,000 ft and 16-degree AoA is roughly 40% of the flight envelope, what is 100%?

F-16.net Editor Joined: Sep 23, 2003 Posts: 2848

dwightlooi wrote:

Quote:

The test aircraft had its maiden flight last December (Defense Daily, Dec. 18, 2006). It has
already flown at 23,000 feet and has reached speeds of Mach 0.8 and a 16-degree angle of attack,
Lockheed Martin said earlier this week (Defense Daily, Feb. 14).

"It is progressing well," Davis said of the F-35 flight test program to date. The aircraft has cleared about 40 percent of its flight envelope, he said. Features unique to the F-35, such as its self-contained non-hydraulic flight actuators "have worked really well" thus far, he said.

An interesting comment by General Davis.

If Mach 0.8, 23,000 ft and 16-degree AoA is roughly 40% of the flight envelope, what is 100%?

100% = mach 2

100% = 57500 ft

100% = 40 degrees AOA

Laughing

Nice thing about not being an engineer is that I'm not inhibited by all that baggage. Laughing

That old film of that big bridge twisting in the wind? Probably someone in my family engineered that. Laughing

Not necessarily. It means roughly 40% overall and not 40% in every measure. Some may be higher, others may be lower. For instance, it shouldn't be hard for the aircraft to get past 40 degree AoA. It may be harder to get to Mach 2. And roughly 40% comment can have a significant margin or error in it. Besides, it is just a comment!

But nonetheless, if its a more positive indicator that ultimately performance maybe better than what most people believe.

Quote:

"It is progressing well," Davis said of the F-35 flight test program to date. The aircraft has cleared about 40 percent of its flight envelope, he said.

He said 40% of 'its' envelope, not 'the' envelope. He is referring to 40% of the cleared envelope for AA-1, which itself is actually a small portion of what will be the final F-35 envelope. Where he got the 40% number I have no idea, but it's worthless as a clue to the final, full envelope.

Raptor_claw wrote:

He said 40% of 'its' envelope, not 'the' envelope. He is referring to 40% of the cleared envelope for AA-1, which itself is actually a small portion of what will be the final F-35 envelope. Where he got the 40% number I have no idea, but it's worthless as a clue to the final, full envelope.

No, it is not a clue with which we can extrapolate with any kind of reasonable acccuracy how fast the F-35 should eventually be, or how high if can fly or how sharply in can turn. But the AA-1's envelope should be similar if now lower than the AF-1's. And it is certainly a more encouraging statement than if he had said 60% of the envelope or something along those lines.

dwight is correct. By that logic you could also "a$$"ume AA-1 is only 40% of its final weight, 40% of its final thrust rating, 40% of its final internal stores count... Razz

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