F-35 Lightning II (2) testing and production thread

I couldn't find in searching the threads a thread deicated testing phase of the F-35 and figured there should be someway of keeping people on the forums up todate regardless any personal openion on the plane or program it would be good to get the information here on ATS.

Currently the F-35 programe is on its 10th flight and they are now starting to open up the flight envelope and start to push the aircraft.

Lockheed Martin’s F-35 Joint Strike Fighter has completed its first manoeuvring flight tests, complete with full-stick rolls.
"It worked exceedingly well," says F-35 chief test pilot Jon Beesley, who praises the aircraft and its "robust" handling characteristics.

Of peticular interest is the comments about the handling in comparison to the F-22 and also the effect of the intakes on the take off role.

"The aircraft is very stiff compared to the F-22 in which you feel as if you're at the end of a diving board. With the F-35 you're standing at the other end," Beesley told a symposium of test pilots late last week.
One peculiarity of the JSF design, he says, is the splitterless inlet which "picks up an extra 2,000lb thrust" as the aircraft accelerates between 80kt and 100kt for take-off. The jump in thrust is "definitely noticeable in the cockpit," Beesley says.

link: www.flightglobal.com...

WRT opening up the flight envelope, how relevant is this testing given that it is only a prototype and not a representative F-35?

i've heard people mention this waynos and I fail to see this as I was under the info that the prototype was flowen to win the competion with boeing much like the F-22 vs the F-23. Has Lockheed said much about what you just said waynos? I'm aware that it has test exquipment on the plane but does that mean its no production? Just a bunch of questions feel free to address them as you see fit. Thanks again.

Yes mate

As far as I know the currently flying F-35A was intended to be the first production standard JSF following on from the X-35, which was not a prototype but a demonstrator.

However, a very significant number of changes became necessary to the basic F-35 design, much of it surrounding weight issues, which were not possible to incorporate into the one already under construction, so this 'became' the F-35A prototype (there originally wasn't going to be one at all) and it now represents more of a halfway house between the X-35 and the F-35 that will enter service.

That was the reason that I was asking about opening up the flight envelope, I wondered if the limits established by this aircraft would still be fully relevant to the new production standard? The redesigned and lighter structure will not necessarily be any weaker, but it will require testing of its own I would have thought.

[edit on 29-3-2007 by waynos]

Originally posted by waynos

That was the reason that I was asking about opening up the flight envelope, I wondered if the limits established by this aircraft would still be fully relevant to the new production standard? The redesigned and lighter structure will not necessarily be any weaker, but it will require testing of its own I would have thought.

What will happen is various 'blocks' will be delivered, each one increasing the performance envelope by degrees until the final production standard is reached.

As an example, take the Eurofighters development and delivery standards over the past 4 years of the Tranche 1 delivery stage.

THe first aircraft delivered to member nations were IPA development models, twin seat for trainer purposes.

The first production standard models were Block 1.

Then the standard was increased to Block 2, and further to Block 2A, both increases having a positive effect on the envelope.

Block 5 was finalised and received type acceptance in February 2007, and will begin to be delivered later this year with a further increase in performance.

There is an upgrade program ongoing at the moment to bring all delivered aircraft up to Block 5 standard by 2010.

The same process will happen with the JSF - the first set of aircraft delivered will be certified to the same standard as the flight test aircraft, and the performance envelope will gradually be opened up through validation of improvements which will receive type acceptance.

Thanks for the reply Richard, but I cannot reconcile it with the information I have looked at.
From what I've seen its not just a case of the earliest F-35's being to the same standard as the one now flying (though the general point you made is spot on, I recognize that). It is more to do with the fact that the single, currently flying F-35 is itself a bit of an oddjob that is almost as different from the next F-35 down the line (and every one after it) as it is from the X-35, due to the design changes made since its construction began and which could not be incorporated into it without starting again. (according to the roll-out report I read in Flight, anyway). According to them, this F-35A is a very different aeroplane from the first F-35A that the USAF will eventually receive because of these changes and as soon as representative airframes are flying it will play no further part in development.



[edit on 29-3-2007 by waynos]

Originally posted by waynos
Thanks for the reply Richard, but I cannot reconcile it with the information I have looked at.
From what I've seen its not just a case of the earliest F-35's being to the same standard as the one now flying (though the general point you made is spot on, I recognize that). It is more to do with the fact that the single, currently flying F-35 is itself a bit of an oddjob that is almost as different from the next F-35 down the line (and every one after it) as it is from the X-35, due to the design changes made since its construction began and which could not be incorporated into it without starting again. (according to the roll-out report I read in Flight, anyway).

[edit on 29-3-2007 by waynos]

It doesnt matter that the production series aircraft are different, so long as their envelope is set at whatever the test aircraft was tested to.

Take as another example the A380 - MSN001, the first aircraft, is fundamentally different to the production series in many different ways. The wings are different, the engines are different, the structure is slightly different.

And yet MSN001 did the lions share of the test programme and both EASA and the FAA issued a type certification based on the results of that aircrafts tests.

As better airframes are produced and individually tested, the envelope will be increased, so the testing you are on about will happen in due course. Do not be surprised to see a Block 1 series with the same characteristics of the test aircraft, and then an upgrade program later on.

Yes, I see that now (and it still works even after my edit ) Thanks for that. I was just wondering what would happen if (though unlikely) the actual production standard was found, on entering service, to be actually weaker than the heavier version now flying and accidents resulted from failures in the structure that the current prototype was immune from. If you get my drift.

Waynos-

In addition to the above points, there will be 15 prepropduction aircraft built and tested over the next 5 years, so the incremental improvements will get tested anyway.

Wow, you answered my query even as I was posting it. Thats some ability you have there Richard! Or am I just predictable?

Thanks

Originally posted by waynos
Yes, I see that now (and it still works even after my edit

) Thanks for that. I was just wondering what would happen if (though unlikely) the actual production standard was found, on entering service, to be actually weaker than the heavier version now flying and accidents resulted from failures in the structure that the current prototype was immune from. If you get my drift.

The design changes will not just be accepted adhoc, they have to go through a process of validation by data analysis - that will give a clear indication of whether the new design achieves the same standard as the type accepted design.

Think of them as data points - one is tested physically, the results of which will validate the analysis testing procedure, which can be used to confirm the second.

The A380 wing failed below certified requirements, but that data was used to calibrate the analysis procedure and certify the changes without a full new test.

Wow thanks Richard! You and waynos where able to have the converstaion I would of ended up having and now I feel much more informed thanks too you both. It does make sence the progression that you described Richard and it should result in a properally tested plane much like the 22/Typhoon.

On a slightly older note a couple days back I saw news as well on the CatBird avionics testbed. It sounds like a great way to do the testing and I'm also under the impression that most plane now have a flying test bed for this since I remeber a F-22 testbed etc. Can anyone validate that this seems to be the way the companies are testing their avionics from now on?

“The arrival in Fort Worth of the Cooperative Avionics Test Bed, or ‘CATBird,’ aircraft is a defining moment for the F-35TM program,” said Doug Pearson, Lockheed Martin vice president of the F-35 Integrated Test Force. “It is a visible symbol of the progress we have made as a team and moves us one step closer to delivering war-fighting capability to our customers.”

The CATBird will integrate and validate the performance of all F-35 sensor systems before they are flown on the first Lightning II aircraft.

Yes thats right Canada, though that nose job doesn't do a lot for the 737's looks does it

Its not actually a new trend, except maybe in America (?) as apart form the CAT bird and a similar F-22 tesbed (I think I remember US test beds based on a 757 and BAC One Eleven, but cannot remember what they were for) I know of several UK test beds since 1945, starting with Lancaster/Lancastrian conversions and following right through to converted testbeds such as the Buccaneer (TSR 2, Tornado, Sea Harrier radars) Vulcan (TSR 2 &Concorde engines) DH Comet (Various) and several others, including, I think, a UK based BAC One Eleven in the EAP/Eurofighter and F-35 programmes.

I'm a bit sketchy on the details so someone with a bit more time may fill in the blanks.

[edit on 29-3-2007 by waynos]

Hello peeps, I bring you some interesting and entertaining quotes from the F-35 test programme courtesy of test pilot Jon Beesley

"Traditionally we had the auxilliary power unit, environmental control system and emergency power units and we had problems with all three. So we integrated them into one system called the Integrated Power Jack so we'd just end up having all those problems with that one"

"...one of the areas was evaluating the effects of fist-on-glass, sorry finger-on-glass control. "

And when pointing out his concerns over the potential crosswind issues of having the large single nose gear door;

"I tried to fight it and got thanked for my interest in aviation"



Sounds like a witty guy.

The 757 mentioned was the Flying Testbed. It was the first 757 built (N757A), and had an F-22 nose and sensors mounted on it. They tested how the sensors integrated with everything and each other and a lot of other flight tests before they ever flew on the F-22. It saved a lot of flight test hours for the program.

Boeing has delivered an updated F-22 avionics software package to its 757 Flying Test Bed ahead of schedule. The update includes the F-22 Raptor's final two integrated avionics sensors -- electronic warfare and communication, navigation and identification.

The delivery completes the Defense Acquisition Board's 1999 requirements for the program - milestones that had to be met before the Pentagon will consider putting the F-22 into low-rate production.

In conjunction with the delivery, Boeing completed a number of modifications to the Flying Test Bed. CNI and EW systems, including missile-launch detectors, were installed in the aircraft's cabin, on its "sensor wing" and on a special pod attached to the underside of the fuselage.

The modifications, together with the updated Block 2 software, will provide the F-22 team its first opportunity to accomplish multiple sensor fusion in an airborne environment.

www.boeing.com...

Originally posted by waynos
And when pointing out his concerns over the potential crosswind issues of having the large single nose gear door;

"I tried to fight it and got thanked for my interest in aviation"

Sounds like a witty guy.

Actually its funny that you quoted that because I remeber seeing the protoype and thinking that the single huge door was pretty funny looking. Also pretty humorous how easy it is now a days to brush off a test pilot. Gone are the days where pilots would fly out into the middle of the desert and come back make a suggestion and it would get done the next day.

Well another news update this time on the F-35B STOL version with the dilvery by BAE of the first Aft Fuselage. With this stage of the development being estimated to be worth more than £1.3 billion to the company its a good thing its on time. Hopefully we wont have to see too many airframes from this version in testing like the 35A as this airframe is almost double the cost.

Samlesbury, United Kingdom.– BAE Systems today celebrated the official handover of the first aft fuselage of the F-35 Lightning II short take-off and vertical landing (STOVL) variant to its industry partner, Lockheed Martin. This represents a major milestone in the System Development and Demonstration (SDD) phase of the F-35 programme, as progress on manufacturing and assembly is made ahead of the STOVL aircraft's first flight in 2008.

"Focus now turns to the manufacturing and delivery of the next major milestone components, the vertical and horizontal tails for the first STOVL aircraft later this year. The BAE Systems team has already created an industry first with the tails. The structure and carbon skin components – produced for the first time on independent machines, and involving 800 separate holes – proved a "perfect match" when they were trial fitted recently."

Well they are testing these engines to the max it seems and it only will pay off in the end. Flight Global has an artical today on how they resently broke one of the F135 engine in a test of a hard stall on the shaft driven lft fan. They were testing 300% past normal operating procedures and it shattered it sounds like. From the wording of the things they said and the fact that these people normally are pretty carefull in what they say.

“We stalled the lift fan 28 times by closing the vanebox area 250% beyond normal operating conditions,” says Gostic. “On the 29th time we went to 300% for a particularly aggressive stall and fractured the shaft connecting the lift fan to the engine. It separated from the main engine and lift fan.”

“It stalled really hard,” says Rob Burns, director of propulsion for the Joint Strike Fighter programme office. Pieces of the hollow shaft and test instrumentation were ingested by the F135, breaking aerofoils through the engine, he says

I guess the good thing is that everything was ingested though. If it would of left the housing this would of been a very different post.

www.flightglobal.com...

Originally posted by Canada_EH

I guess the good thing is that everything was ingested though. If it would of left the housing this would of been a very different post.

www.flightglobal.com...

See the rig in that article? Thats a standard engine test rig, when they do tests like these they don't have anyone standing around the rig for precisely this reason - stuff breaks, and stuff becomes deadly projectiles.

Infact on rigs like these, they deliberately cause destructive testing - blade off events for one (very very impressive if you have ever seen one, remind me and I will post some photos of the Trent900 bladeoff test, spectacular).

The fact that debris was ingested into the engine here is actually a bad thing, since it means a full engine rebuild rather than a replacement of the broken parts, a check over and back into the program.

I was under the impression from my research that any time blades shafts etc leave the cowlings etc it means even more testing to fix the problem.

But either way the engine is toast or the plane is toast. If a blad breaks in the fan you could have a pilot minus a head also.

[edit on 22/08/06 by Canada_EH]