Glad, LO,
Thanks for coming back - perhaps a short response can help.
Glad, what I didn't make clear was that the 'weight growth' I was referring to was the 'Design To' weight - that's the target weight for the concept you've arrived at. The problem the DoD faced was that these weights were going up all the time as the desired aircraft got bigger and more complex. The F-22 is a decent example of that problem.
By contrast, the 'weight growth' problem with the F-35 was more to do with a failure to keep close enough to the 'design to' weight - and it took the USN weight experts to tell LM that the aircraft was badly overweight.
LO, I agree that the 'single engined single seat will cut costs' argument might appear simplistic, but I'm probably guilty of expressing the DoD's thought process in a simplistic way. They had done a fair bit (actually a hell of a lot) of work that underpinned their conclusion that any twin engined aircraft the USAF or USN came up with would be too big ever to be affordable. The single engined concept was made possible by advancing technology (i.e. F135) that allowed an aircraft of the desired weight with a single engine.
LO, not sure I quite understand your reference to a 3000 foot runway and the special concrete for the F-35B. The aircraft can operate off a 1,500 foot runway with the specified load for that mission, and the special concrete is for a specific VTOL training pad. There are a number of techniques that can significantly reduce the thermal footprint of the B, including a creeping landing. (JF may be able to help here - I think that this was a technique used on Mexepads in the 60s). However, happy to be corrected. And the F-35B's replacing the AV-8Bs first, as far as I understand the programme.
Best Regards as ever to those who have to do the hard sums for real,
Engines