Forum: Program and politics

"The question for me is not: 'F-35 or not?'" Venlet said. "The question is, how many and how fast? I'm not questioning the ultimate inventory numbers, I'm questioning the pace that we ramp up production for us and the partners, and can we afford it?"

C'mon guys. Have any of you ever flown military jets? As the Admiral says in the article, this is not unusual stuff. What is unusual is the degree of concurrency and the bills they can afford to pay or not pay in this budget climate.

Every U.S. TACAIR asset flying today has had structural issues -- ALL of them. .

What about non-US jets?

I have not (yet) heard reports of structural issues in the Gripen, Rafale and Typhoon fighters.

Gripen passed 160,000 hours this summer, Typhoon passed 100,000 hours in January.

@elp, as far as Canda goes it's not really a concern as the the first aircraft are suppose to roll of the production line in low numbers in 2016. As far as europe and the USA are concerned, well they have no money to purchase fighters any way. So a slower ramp ramp up of the F-35 production line isn't really going to hurt any one except Lockheed Martins share holders.

In this age of engineering "Concurrency" is the norm. .

This is the key takeaway-

Venlet also took aim at a fundamental assumption of the JSF business model: concurrency. The JSF program was originally structured with a high rate of concurrency -- building production model aircraft while finishing ground and flight testing -- that assumed less change than is proving necessary.

"Fundamentally, that was a miscalculation," Venlet said. "You'd like to take the keys to your shiny new jet and give it to the fleet with all the capability and all the service life they want. What we're doing is, we're taking the keys to the shiny new jet, giving it to the fleet and saying, 'Give me that jet back in the first year. I've got to go take it up to this depot for a couple of months and tear into it and put in some structural mods, because if I don't, we're not going to be able to fly it more than a couple, three, four, five years.' That's what concurrency is doing to us."

The truth be told if your airplane is not cracking during fatigue testing then you over built the airplane and you carrying unnecessary weight. You want to be finding hot spots and beefing these areas up as you go. This trial and error process is a very tedious way to do it but the only one that will deliever the lightest structural airframe possible. Since Lockheed Maritn is designing and building jet fighter here and not sherman tanks this is the way it has to be.



Here is a good article on the sturcutral testing of the F-35 from Composites World.

http://www.compositesworld.com/news/f-35-program-completes-static-structural-testing

Fatigue testing has barely begun, Venlet said. The CTOL variant's fatigue testing is about 20 percent complete; the CV variant has not started yet. For the STOVL variant, fatigue testing was halted at 6 percent last year and has not resumed after a crack in a large bulkhead in the wing was found, requiring a major redesign of that part.

C'mon guys. Have any of you ever flown military jets? As the Admiral says in the article, this is not unusual stuff. What is unusual is the degree of concurrency and the bills they can afford to pay or not pay in this budget climate.

Every U.S. TACAIR asset flying today has had structural issues -- ALL of them. Ever notice those plates bolted on the LEX of F-18s? They reduce the adverse effect that LEX-generated vortices have on the verticals. How long ago were those installed? Ever notice the plates of metal bolted on the bases of the verticals on F-18s? Whaddaya think those are for? Ask older F-18 maintainers about center barrel replacements. Ask about life-limited E/Fs. Are these jets dead? No, they just have to go to a depot or drive-in mod for replacement or modification of some structural stuff. Can be expensive and time consuming. Seems that the Admiral wants to avoid as much of that as possible given the budget climate.

Ever notice the square/rectangular pieces of tape in the intakes of AV-8B? Keeps the rivets in that section of the intake from from popping out and being ingested by the engine. How come that's an issue? Because the stiffeners put in the fuselage to stop cracks after the jet was in service caused a load transfer into the intake just in front of the engine -- causes rivets to pop out and feed the engine. Tape prevents that.

Ask experienced F-16 maintainers about the structural load transfers (and resulting unexpected cracks) they've chased around the Viper for a couple decades. What ever happened to those F-16Ns that Top Gun flew?

I highly recommend you read the whole article and the Admiral's quotes -- not just the snippets above.

Two points:

#1 Isn't Venlet just stating the obvious? Congress has been witholding funding for LRIP lots for the past three FYs... and it didn't seem as if they would be changing that policy for LRIP5. If anything its just an admission of whats been going on.

#2 Canada: the Government revealed last month that most of the buys will occur after 2020...over 40 of the 65 total aircraft. The RCAF says that production schedule is fine for them. This is also another great example of shoddy Canadian reporting. Basically nobody realized that Congress's LRIP cuts could have driven up Canada's costs based on the preliminary delivery schedule that had most of the deliveries before 2020.Then they release a new delivery schedule, which is far less influenced by concurrency cuts... aaaaand then someone reports that concurrency cuts could affect the aircraft's costs.

With the American Congress cutting funding below what was promised (and somehow getting anti-F-35 people to blame Lock-Mart for the resulting delays), I don't see why we couldn't let foreign countries start putting money in and getting their first planes a bit sooner. Total production rate would be higher, as originally planned, which would help with the overall costs and timing; the only difference would be who paid and where they went...

Geo, I thing you missed this quote:



Notice that he is not questioning the total F-35, just the ramp-up. This means no interim new fighter buys. What will happen is what has already been planed for, namely upgrades, SLEPs, etc for current 4th gen assets.

I hadn't realized quite how enormous these bulkhead forgings are. Take a look at the sizes of these things: http://www.alcoa.com/forged_products/en ... Sheets.pdf

I also noticed they're making six for the B, five for the A and four for the C. So I assume one of the bulkheads on the A and two on the C are titanium. I wonder what the total weight savings was going to aluminum for each of those models?

Finally, it's interesting that the alloy is "Al7085-T7452, a proprietary aluminum alloy developed by the Alcoa Technical Center." I would think that alloy was tested for for strength and fatigue over life which provided a table of properties on which the structural analysis was based. I wonder if the alloy is simply not performing to prediction.

Perhaps the US jets on average have more hours on the airframes than Gripen, Rafale and Typhoon, and are just old? The F/A-18's that need center barrels entered service in the late 70's - early 80's....