So basically, no one has made a formal statement that the previous plan has actually been changed.

That was the last official number set, and while there have been discussions about what changes might be made to the split, there has been no statement of a change actually being made?

In the absence of a change, the last numbers still hold. They don't "expire" and become irrelevant just because no one has re-confirmed them in a while.

GK,
No, I don't pull this stuff out of my ear. See:

http://www.gao.gov/new.items/d08388.pdf

Page 28... the GAO (which may sometimes be out of date, often skeptical, but seldom actually wrong) says the split is undecided.

The GAO reports that the Navy is undecided on the split, but wants the Marines to buy some Dave-Cs... the USMC has established a formal requirement for 420 aircraft and continue to insist on all of them being Dave-Bs.



Thanks... you finally supplied an authoritative source that says there IS doubt as to the final split... which is what I had asked for, and you hadn't provided until now.

Many of us lack your detailed knowledge :hmm: of where such documents are to be found, or even if they exist. That's why we ask for sources... so we can learn facts, and not rumors.

Point to you... finally.

Skimming through that GAO report, I come across a sentences such as this:

"... We found that the JSF cost model is highly complex and the level of documentation is not sufficient for someone unfamiliar with the program to easily recreate it. Specifically, we found that the program office does not have formal documentation for the development, production, and operation and support cost models and could not provide detailed documentation such as quantitative analysis to support its assumptions...."

"Not enough formal documentation ... could not provide detailed documentation..." One possible translation of same: those bookkeeper gadfly busybody a-holes just want more and more paperwork. More and more paperwork requires a nontrivial increase in time and money spent on the program.

I've seen it myself, goofing off and strolling around the different floors of an eleven story building of a former employer. I counted more heads in Contracts Support Administration than actual engineers on the engineering floors.

The JSF Cost Estimate Is Not Well Documented

Cost estimates are well documented when they can be easily repeated or updated and can be traced to original sources through auditing. Rigorous documentation increases the credibility of an estimate and helps support an organization’s decision-making process. The documentation should explicitly identify the primary methods, calculations, results, rationales, assumptions, and sources of the data used to generate each cost element. All the steps involved in developing the estimate should be documented so that a cost analyst unfamiliar with the program can recreate the estimate with the same result.

We found that the JSF cost model is highly complex and the level of documentation is not sufficient for someone unfamiliar with the program to easily recreate it. Specifically, we found that the program office does not have formal documentation for the development, production, and operation and support cost models and could not provide detailed documentation such as quantitative analysis to support its assumptions. For the development cost estimate, the JSF program officials said they did not have a cost model that was continually updated with actual costs.

10 Earned value management is a method of tracking and measuring the value of work accomplished in a given period and comparing it with the planned value of work scheduled and the actual cost of work accomplished. Its use is required by federal regulations.
Page 22 GAO-08-388 Joint Strike Fighter

http://www.gao.gov/new.items/d08388.pdf

ME - What's interesting about that part of the report is that it concerns the aspect of the enterprise that the GAO's spreadsheet jockeys know most about. How much are we spending, and how much are we accomplishing for what we spend?

GK - Thanks, sometimes it is busy and rooting around the JSF directory for the source takes time. By the way, if the Marines get 420 jets the Navy gets 260... which is not a huge return on the Navy-specific development costs (including a vastly bigger wing).

Moreover, if you go back to history you'll see that LockMart's original preference (in CALF) was for a canard delta and that they switched to the quad-tail when the Navy came on board, because that was the only configuration that accommodated two widely different wing sizes (one big enough for the CV, the other small/light enough for a no-fold STOVL). And all that for less than 10 per cent of the planned build...

... The two X-32 prototypes featured a delta wing design, which was chosen to minimize production manufacturing costs. However, eight months into construction of the prototypes, the JSF's maneuverability and payload requirements were refined at the request of the Navy and Boeing's delta wing design fell short of the new targets. Engineers put together a new design with a conventional tail (narrowly beating out a Pelikan tail) with reduced weight and improved agility, but it was too late to change the prototypes. It was judged that they would be sufficient to demonstrate Boeing's technology.[3]

http://en.wikipedia.org/wiki/Boeing_X-32

LO and Modern Elmo,

I was able to go to some very informative briefs given by the JSF's chief designer at Fort Worth, where he set out the whole design evolution process.

There was a major change when the design went from a canard to a more conventional design, but we were told that the change was driven by predicted performance and structural efficiency across the required three variants. Yes, the wing was part of it, but only a part.

The canard was a better layout for the STOVL, but always had challenges with the control power required for carrier landings. (This was, incidentally, the reason for the late change to the X-32 design - the aircraft ran out of pitch control during carrier landings).

My own view was that Lockheed always really wanted to build an aircraft that looked like a single engined F-22 , to stay inside their design 'comfort zone'. And that's what they ended up with.

Best Regards as ever,

Engines

It's also true that the canard (CALF, early JAST) came out of Palmdale but that JSF came out of Fort Worth, where the view was that "the optimum location for a canard is on someone else's airplane". But I was told that it was the different wing/pitch control surface size which was the kicker. It gets very awkward with a high taper ratio if you want to keep the body design common.

So is the A400 delayed?

Not at all. Slippages are on schedule. :cool:

http://www.dfrc.nasa.gov/gallery/pho...96-43418-3.jpg

(1) Pro's and cons of "pure" delta wing versus non-delta?

(2) Pro's and cons of canards on either pure delta or non delta?

"So is the A400 delayed?"

If the latest rumours are to be believed then it will depend which type you are currently on as to whether this delay is likely to affect you :ok:

ME...
Depends what you're trying to do.

Canard/deltas are rather nice for agility and STOL (factors in Gripen, Typhoon and Rafale) while buying you the benefits of a delta wing (light, low drag, space to hang stuff that goes bang without too much interference drag).

Classic, cranked or double deltas are nice for low drag and high volume. What you tend to run out of is control authority because all you've got is the trailing edge... the leading edge is good for increasing lift to some extent (although the sweep tends to be too high - if you look at the XL it's got LE flaps outboard), but hard to use differentially for control. So the trailing edge... which doesn't have a lot of moment arm... has to provide for pitch and roll, and it gets a bit overloaded.

For instance, Boeing's delta JSF design, in its Navy version, was going to use vortex flaps above the leading edge to boost lift. But the more they looked at the Navy's bring-back requirement, the bigger control surfaces they needed, in order to rotate the wing to get high lift... and the actuator weights got out of hand.

So is it true that the MDD submission was canned because (a) it had a lot of foreign (i.e. BAE) design and (b) it was more likely to provide serious competition to Lockheed?

The X-32 being the more 'risky' option and the -35 the 'safe' version.

If the MoD cancels the F-35B buy I wonder if it can do a deal with the French? The UK can sell the French enough surplus Typhoons to equip several dedicated air defence squadrons and we can buy some French Rafales for our carriers.

Alice. Wonderland.
 

Hmmm.

All this from a country that once tried to navalise a naval aircraft.

F-4K anyone ?

And how should one pronounce '-4K' ?

Exactly.

Nowt wrong wit' FG1...as long as the nose wheel extension didn't stick down...

As the country that invented the angled deck, steam catapult, ski ramp and built the Buccaneer - an aircraft of beauty and strength, and the USMC seem somewhat enamoured of the Harrier the last 30-40 years....

Steel decks also came in handy in the pacific...

XV277,
Macs' big mistake was that they didn't think the customer was serious about not wanting a separate lift engine. It wasn't altogether logical given the fact that the overall complexity and number of flight-critical bits and pieces was certainly comparable to the LockMart solution, but the customer meant it.

Also, the Boeing design was different and risky, and offered a cheaper and simpler aircraft if it worked. LMT seemed low risk, in part because of its cousin relationship to the F-22.

Caspian,
Rafale is a very attractive jet for a small carrier, but my assessment is that you'd either have to buy into the French program (and help to fund an F4 program with some UK content) or start spending lots of money to Anglicize it. Your best bet would be to learn to love its quirks (like a Citroen 2CV or DS) including its magic jamming system and the What The Butler Saw machine in front of the pilot's nose.

<Nowt wrong wit' FG1...as long as the nose wheel extension didn't stick down...>

Certe loqueris . . . saepe vere !

No argument from this end about the Bucc. Wonderful machine.

There was a major change when the design went from a canard to a more conventional design, but we were told that the change was driven by predicted performance and structural efficiency across the required three variants. Yes, the wing was part of it, but only a part.

That's interesting. Could you tell us more? How did the canard affect performance?


So is it true that the MDD submission was canned because (a) it had a lot of foreign (i.e. BAE) design and (b) it was more likely to provide serious competition to Lockheed?

The X-35 was better than the X-32. No need for a conspiratorial view.


Macs' big mistake was that they didn't think the customer was serious about not wanting a separate lift engine.

Separate lift engine?