First, a disclaimer - new weapons programs generate critics, regardless of the merit of the program or how well it is executed. I distinctly recall massive criticisms of the M1 Abrams tank - it was too big and expensive, it was a gas hog, it's turbine powertrain was fragile and would never survive in combat, the high tech main gun would never work, tanks were obsolete, etc. Then it went into combat and
totally kicked ass - arguably the best tank ever. Turned out the only thing the critics had right was the 'gas hog' part.
So, that the F-35 program has many critics is not meaningful by itself. But, I know quite a bit more about aircraft than I do tanks, and I have friends that worked on the Boeing JSF entry - people that told me what was wrong with the Lockheed JSF entry over 10 years ago. So I can more readily judge the validity of the F-35 critics, and quite frankly many of their complaints about the F-35 ring true to my ears.
EVERY new engine program will push the start of the art - if it doesn't there really isn't much reason to spend billions on the development. Different programs push different aspects - fuel burn or TSFC, weight, thrust to weight, noise, etc. But they all push the limit. Further, military engines tend to accept more risk and push a little harder than commercial engines (it's worth noting both the GEnx and Trent 1000 engines on the 787 and 747-8 have been surprisingly reliable at EIS - something that wasn't the norm on past new commercial engines). But there is another side to that - I've spent over 35 years dealing with engines from "the big three" - Pratt, Rolls, and GE/CFM. All three have various strengths and weaknesses - to the point that if you tell me the problem, I can generally - with close to 90% confidence, say which engine company it is. Example problems:
Compressor Stability
Inclement weather
Fan flutter
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And the answers:
Compressor stability - Pratt
Inclement weather - GE/CFM
Fan Flutter - Rolls
As I noted in my earlier post 5159, tell me the problem is compressor blade rub/case distortion, and my answer would immediately be Pratt - they have a long history of that - and the other two don't. It's not that the F135 was beyond their models - it's that their models for case distortion simply are not as good as the other guys.
Oh, and don't fool yourself, Pratt may pay for the fix in the short term, but long term it's always going to come back to the taxpayer in the form of higher prices for future engines and spares. It always does
