Monday, November 2, 2015

F-35 Tidbits

Here’s a quick update on the F-35, courtesy of GAO (1).

Software.  First, a refresher on the F-35 software development.  Software is being developed and delivered in blocks with each block adding new capabilities and moving the aircraft closer to full operation.

1&2     A  Training
2B       Initial Warfighting Capability;           Marine IOC
3i         Extension of 2B;                                Air Force IOC
3F       Full Warfighting Capability;              Navy IOC

Engines.  Engine reliability is still a major issue.

“Data provided by Pratt & Whitney indicate that the mean flight hours between failure for the F-35A engine is about 21 percent of where the engine was expected to be at this point in the program. The F-35B engine is about 52 percent of where the engine was expected to be at this point.”

Look at those percentages.  That is some awful reliability!  Who’d have thought that the B version would have the more reliable engine?

Cost.  As of Dec 2014, GAO reports the total program cost estimate as,

Development             54.9B
Procurement              331.6B

Unit Cost                    $159M per aircraft

So there you have it.  With all the proclamations about $80M aircraft, the actual unit cost is $159M.  That’s a little different than what the program managers and LM are telling us, huh?

Concurrency.  This is a stunning bit.  We’ve thoroughly documented that the practice of concurrency (production of an item while it’s still being designed and tested) inevitably adds cost as products have to be reworked multiple times to fix and modify problems uncovered during testing.

“As of June 2014, DOD estimated that at that point about $1.7 billion in funding was needed to rework and retrofit aircraft with design changes needed as a result of test discoveries.”

$1.7B required for concurrency corrections??!!  The report doesn’t state how many aircraft are affected but let’s say there are 100-200 that have been produced or are in production at this point that are affected, so that works out to around $9M - $17M per aircraft for concurrency fixes.

Is that the end of the concurrency costs?  Well, no.

“… with more complex and demanding testing ahead and engine reliability improvements needed, it is almost certain that the program will encounter more discoveries.”

So, the concurrency costs will continue to add up.  I hope the F-35 supporters add these costs into the production costs as they make their claims about how cheap the F-35 is.

Finally, bear in mind that this aircraft hasn’t even come close to working through all its test points.  There are lots more problems to come.

(1)GAO, “F-35 Joint Strike Fighter”, Apr 2015, GAO-15-364


  1. I be honest I don't really understand that. The "B" engine is the same engine. Its not a different engine.

    It just has a load more "bits" on it ?

    Its a very weird thing, "energetically" speaking the F35B generates twice the thrust from the same engine anyway ( this "should" be impossible ).

    I know I'm bound to say this, but I think reactivating the F136 engine would be a good idea.

    1. The quote does not say the B engine is more reliable than the A engine. It says the B engine is closer to where it was expected to be. That's not the same thing.

    2. Um, if the A is farther away from its goal than the B, that would make the A less reliable because it's failing more often. You're trying to put together some kind of subtle, semantic difference but I'm not seeing it.

    3. The B's goal timeline may have been less aggressive.

    4. Rechecking the referenced report, the data shows the B engine to have a MTBF of around 50 hrs versus the A engine of around 25 hrs. Thus, on an absolute basis the B is demonstrating twice the reliability of the A.

      The two engines do have different performance timelines (your point, I think) but even if the A's timeline were the same as the B's, it would still have half the reliability.

      There's no way around it, the A engine is less reliable.

      Now, depending on how many B engines there are in the data pool, the data may not be statistically significant but there is nothing to indicate that's the case.

    5. Hmm. odd. I don't see why the A engine would be less reliable. I thought they were essentially the same engine, with the addition of the lift fan in the B.

    6. Odd, indeed! Maybe the B engines aren't being used as "hard". The B aircraft are newer and I seem to recall they may have somewhat lower g-limits at the moment (more restricted flight envelope for the time being??). That's the only speculation I can even remotely come up with.

    7. You guys missed the bit that the failure rates are weighted:

      "The program uses various measures to track and improve reliability, including the mean flying hours between failures (design controlled).9"

      "9 This specific metric tracks failures that are directly attributed to design and are considered fixable with design changes."


    8. From DOTE FY14 report:

      "The reliability metric that has seen the most improvement
      since May 2013 is not an ORD requirement but a contract
      specification metric, mean flight hour between failures
      scored as “design controllable” (which are equipment
      failures due to design flaws)."

      Also, the PO imposed aircraft operating limitations (AOL) on all variants of F-35 aircraft (As, Bs, and Cs); given the different testing requirements (Block 2 versus Block 3F) makes it very difficult to compare engines in the program.

      Besides, who uses the mean flight hour between failures in lieu of the more readily understood MTBF and MTBCF standards?


    9. Not the same engine, its based on the A, C engine but has to develop more power to run shaft to lift engine. Known as the F-135-600 with the main difference a 2 stage power turbine ( instead of 1) and of course the shaft connections

    10. " Known as the F-135-600 ..."

      Would you anticipate that the difference would confer a greater degree of reliability on the B? I'm nowhere near knowledgeable enough to assess that.

  2. Every time I try to get positive on the F-35.... *sigh*. I'd say cancel it but then what? Keep updating hornets while we hope to God we can build a 5th gen fighter? Its an option. Maybe the best one. But it means we've thrown out how many billions again?

    1. "Every time I try to get positive on the F-35.... *sigh*."

      You're still trying to be positive about this flying dog pile??! I admire your enthusiasm, if somewhat misguided. :)

    2. This comment has been removed by the author.

    3. Well, yes.

      It is my Official Opinion ( :-) ) that I'd like to see the Navy develop a large interceptor/air superiority fighter on the lines of a Tomcat. It should be big enough to have tons of range and loiter time, be able to hoist lots of weapons, and be fast enough to ingress/egress as needed. Think of something roughly akin to a navalized Flanker.

      Throw in Superhornet levels of stealthyness, and the 'standard' improvements today: Big AESA; a gun; thrust vectoring, etc. Aim for near Superhornet levels of maintainability. Then call it good. Maybe add in some level of sensor fusion as that matures, but don't worry about it too much for now.

      I have a strategy into which that type of plane fits in. I also think that when you build a plane to be good at those sort of A2A things (with good thrust, range, etc.) you bake in alot of the things you need to be a decent strike aircraft. Not all of them to be sure, but many.

      Alas, the Navy, Airforce, and OSD have gone in a completely different direction. And we need a fighter. The SH can be modified to last longer, but its already 20 years old, IIRC. We're likely facing the end of the ability to keep it relevant as the front line guy. Besides, it was optimized for close range Balkans type strikes, not the modern A2/AD environment.

      So, yes. I keep hoping that the F-35C with its 600nm combat radius, stealth level, and BVR suite could be made to work. We've already dumped billions into it. Its (theoretically) closer to production than cancelling it and starting anew. And I don't trust the MIC/Congress/etc. to not take the F/A-XX and turn it into a trillion dollar starfighter that will follow a similar path as the F-35 anyway. Thereby wasting billions more without giving us a single fighter.

      I do have major worries. (This thing looks like its going to make the F-14 look like a Camry in terms of maintanance with the troubles with ALIS). But there it goes. Part of me wishes they'd ditch all the sensor fusion/ESP helmet and just put in a HUD to interface with the AESA, allow it to launch Meteors, and call it good. At least we'd get *something* out to the fleet that has some redeeming qualities.

      If you do cancel it, nail LM's posterior to the wall and demand the tech they've gotten out of this mess get discounted to the rest of the fleet.

      What a mess. I think I'm going to go look at pictures of kittens.

  3. So basically double the promoted costs and that's before the various concurrency costs, which I have no doubt will drive the unit costs up when the full extent of the problems are discovered.

  4. They eventually cancelled the F-22 due to cost, so why can't they cancel the F-35?

    Seriously, besides the vested interests, surely even Blind Freddy can see they'd be better off with starting up the F-22 line again (several billion to restart the F-22 is cheaper than several TRILLION for the F-35, and the F-15 Silent Eagle is a pretty awesome plane too.

    Since the policiticians and higher up military leaders are being paid off by military companies, surely it would be cheaper also to offer these same politicians massive bribes, I'm talking billions. Because even 20-30 billion in bribes is cheaper than 1.5 TRILLION bucks.

    1. Attempting to fix one wrong with another wrong is not the way to go, however, your point about the F-15SE and F-22 restart offers viable alternatives. Add in the Advanced Super Hornet and we'd have a fair capability to buy us time to make a next generation aircraft (assuming we wouldn't just repeat the mistakes of the past - a major assumption).

    2. I just saw the FA article on the Israelis requsting the SE. Its a neat aircraft. Advanced SH; new Viper, and SE might be much more affordable alternatives to us keeping a viable airforce in place.

  5. My understanding is that the P&W F135 engine is is basically a 15% throttle pushed F119 and to maximize the thrust to cope with the F-35’s weight growth, the rotars rub in tip clearances were tightened.

    What was not envisaged is that the bending loads on the engine from the high G's and the F-35's fuselage structure. The weight having to taken out from the fuselage structure due weight issues. This resulted in the catastrophic engine failure last year due to a fractured engine rotor caused by rubbing.

    Throttle Push
    “The way the engines OEMs create the different variants is by injecting more and more fuel into the combustor. This means the combustor temperatures increase and the fuel-air mixture has higher temperatures when hitting the turbines. This means more horsepower gets generated in the turbines, which drives the compressors and fan harder. The engine spins faster, pumps more air through and thereby generates more thrust. Stretching an engine like this is called “throttle push”.
    There is, of course, a limit to how far this can be done and there are drawbacks for creating stronger variants with throttle push. The hotter temperatures in the core (both compressors and turbines get hotter at higher RPMs) will shorten the time-on-wing for the engine.”
    Leeham News – Bjorn

    So now the F135 tolerances must have been relaxed giving less power/thrust and still left with the throttle push resulting in shorter life for engine and higher maintenance.


    1. Nick, nice explanation. Good contribution! Thanks.

  6. The GAO report has sadly been outdated as the Block 3F is no longer the 'Full Warfighting Capability' as necessary software has been pushed out into Block 4/4F.

    Some highlights from Breaking Defense.

    "The Block 4 software upgrade at its core is essential to the aircraft reaching its “full warfighting capability,” Maj. Gen. Jeffrey Harrigian, the Air Force’s F-35 integration director, told Congress October 21st.

    The Air Force F-35A model will reach Initial Operating Capability (IOC) in December 2016, but it won’t have all the advertised features — i.e. full capability — at that time. The modernization effort will cost $2.6 billion in R&D through 2020 alone.

    With wish-lists coming from three US armed services and eight foreign partners — seven if Canada drops out (more on that below) — the upgrade package has swollen beyond what’s feasible or affordable, Bogdan said.

    The basic issue with the requirements list is that “it grew over time as threats evolved,” Harrigian told reporters. “It grew to, frankly, an unacceptable list that we are now working through to determine what no-kidding capabilities…do we need to have on this airplane to ensure we stay ahead of the threat.

    By December, the requirements document will be ready for review by the Air Force Requirements Oversight Council and the Joint Requirements Oversight Council. The AFROC and JROC, in turn, should be done with the requirements sometime in the spring. There will also be a “parallel” review by the nine-nation JSF Executive Steering Board (JESB), Bogdan added, though he didn’t specify dates. The modernization effort actually kicks off the following year, in October 2017 (fiscal year 2018)."


    1. Nick, good addition! I thought about including the Block 4 issue but decided it would just confuse the post. You're right, though. Software creep is killing this program just as much as any other aspect.

      Good comment.

    2. USN lukewarm to the F-35C.

      In Rear Admiral Michael Manazir's testimony to the readiness subcommittee of the House Armed Services Committee Tuesday he wants two or three more squadrons of F/A-18E/F's.

      "Manazir said it would not make sense for the Navy to accelerate its purchases of F-35 C-model jets instead since work had not been completed on the required Block 3F software needed for the jets to carry all the weapons required by the Navy." Highlighting the problems with software as outlined above, not wanting to spend limited budget on what will be in effect more training/R&D aircraft.

      Yesterdays contract award of $5.37B to LM for 55 aircraft, lot 9, reflected this as only included 2 for the USN F-35C, presume minimum buy without upsetting Congress.


  7. "The modernization effort will cost $2.6 billion in R&D through 2020 alone"
    And we have the LCS...

    Look ! Cute Kitten pictures!


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