Steve Trimble has a post up over at the Dew Line titled Top Ten List of F-35 Flaws and Fixes . I tried to leave what follows as a comment but I can't seem to get the DEW Line site's 'Captcha' feature to load on my laptop at the moment. Since I put a lot of thought into what Steve had to say, I wanted to at least get it committed to electrons someplace.
Steve,
I love ya’ man. I think you probably have the best instincts of any non-aviator journalist on a major stage out there and when you keep your distance from the “Ragin’ Hedge Baby from the Shires” you do your best stuff. I would suggest however that you start ‘tightening up’ the thoughts a little more before you start putting fingers to keyboard.
Problems with the ‘Ten flaws and fixes’ list:
First problem: I count at most 5 ‘flaws’ (ranging from minor to significant and all fixable), 3 ‘Risks’ and 2 (at least) development/maturation challenges. You might have characterized the descriptions and actions a little more accurately as well, but in the vernacular of the day, that shortcoming could be an ‘artifact’ of journalism’s deadlines and processes.
1. Bulkhead cracks: Flaw (Design – Correct!). But the description of the remedy as a ‘7-8lb patch’ is more accurately described as a structural ‘doubler’ – the use of which is an extremely common technique in aircraft structural design. When you take as much weight as possible out of a plane for the obvious reasons, sometimes you have to put a little back in here and there. If some Lockmart PR guy used ‘patch’ to describe it to you I’d blame him for the misnomer and urge you to try asking for the engineering terms when you feel someone is dumbing something down for you -- because someone may have dumbed it down for the guy telling you. A good rule of thumb is If it is described in a single syllable word, it’s probably not the correct terminology. BTW: A ‘patch’ is ad hoc and ‘slapped’ on, A ‘structural doubler’ is designed and has analysis and test behind it before it is ‘integrated’ into the design. BIG difference.
2. Vertical lift bring-back (VLBB): Risk (Incorrect). If LM defines it as “the F-35B has all the vertical thrust it needs to "bring back" the required load of weapons and fuel onto an amphibious carrier right now, but is concerned” – then there is a ‘risk’ that it MIGHT become a ‘flaw’. As you describe it, there are apparently both alternatives to mitigating that risk: weight control and increased thrust availability – so the Risk is apparently manageable and is being managed.
3. Auxiliary air inlet (AAI) doors: Flaw (Design – Correct!) No contest on this one because the program obviously wants to have the doors operating at 250kts. But if the program determines they can live with lower operating speed it is potentially a ‘nothing’ issue. There are no ‘solutions’ in life or aerospace: only ‘tradeoffs’. If the users insist LM needs to fix it, then as you point out the flaw is fortunately a relatively minor one that is easy to fix.
4. Parts reliability: Risk...and a rather broad brush assertion at that (So, Incorrect). Every system experiences birthing pains (think R&M ‘Bathtub Curve’). But if it is worth mentioning, then it is also worth mentioning that the program intends and has plans in place to extract high reliability out of systems via PBL support approaches and techniques over the life of the program.
5. Wing roll-off: Development/Maturation Challenge or Risk (Incorrect). As you wrote, it is “still on the list of concerns for the F-35C carrier variant”. Concern = Risk. I suspect this is a matter related to both the bigger wing of the C and the Navy’s fears after their F-18E/F adventures. The “squirrelly” bit can be true for all aircraft depending on their wing design, AOA and airspeed. I also suspect it has more to do fears of steep pressure gradient shift over the top of the wing (the F-18E/F problem) than anything else. Wing falloff in and of itself isn’t new or scary – it’s when you don’t know which way, when or how fast it is going to fall that gets meat-servo panties in a knot.
6. Driveshaft: Flaw (Minor Design – Correct) but also could be considered a Development/Maturation Challenge, since the program is still in SDD, the concept and system is unique/new/never-been-done. Since until the system is flown enough hours and in different regimes with real loads all the designer has to work with is simulations and estimates to start with, perhaps the effort in this area should be judged by what was reasonably probable to get exactly right, out of the box and is it 'tweakable' vs. against what is found to be needed? (and especially if this contingency was anticipated as a possibility they were prepared to deal with). After all, as I seem to have to frequently remind others elsewhere, SDD stands for System DEVELOPMENT and Demonstration.
7. Roll-post nozzle: Flaw (Minor Design – Correct) but could be viewed as a Development/Maturation Challenge as in 6 for the same reasons.
8. Lift-fan clutch: Flaw (Minor Design – Correct) but could be viewed as a Development/Maturation Challenge as in 6 for the same reasons
9. Generators: Flaw (Very Minor Design – Correct!) And evidently a new problem easily undone.
10. Price tag: Risk (Incorrect) Aircraft in work are tracking the cost curve predictions. The Royal Navy’s buy change has to be viewed as delta impacts on both the B and the C. Given higher commonality between the A and the B than the C (the C being more of an outlier in the design mix), the Royal Navy’s change is more boom for the Navy’s C model than bust for the Marine’s B model. Minor nit: The Marine’s B buy is not a reduction, but holds at the earlier assumed 340 number according to Defense News. The Marine’s ‘extra’ Cs are evidently coming out of the earlier presumed 340 number for the Navy’s C model. It’s a ‘wash’.
Kudos for framing the discussion with the positive ‘transparency’ point. Although there is no way the JSFPO or LM COULD conduct a program of this size and importance behind a veil, it’s good to give them credit for at least realizing it and using it as a philosophy.
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