George,
You're right on the money about the USN and their attitude to a single engined design. And also right on the mark about the problems with a large single engine and its effect on the structure. However, single engined it was always going to be. To be fair, the F119 has performed tolerably well throughout the development programme. The powered lift system, despite the significant risks involved, has also performed well, in my view.
On the length of the aircraft - I know I've posted this one before but: the F-35B was not required to be compatible with an Invincible class ship except for a requirement to be able to conduct a ski jump takeoff from their runway and ramp. This requirement was left in to drive the ski jump STO capability. The requirement to be compatible with the Invincible class lift was left out of the final iteration of the JORD. In fact, there was a clear statement that the aircraft was not required to be compatible with the Invincible lift and hangar deck layouts. I've got a reasonably clear handle on this as I was the engineer responsible for monitoring how the LM team was handling the various shipboard compatibility requirements. I also had to brief various visiting UK senior officers on how limited the UK's shipboard integration requirements were. There were studies carried out into getting an F-35B down an Invincible lift earlier on in the programme, and I remember seeing a diagram of a scheme for small 'fold down' wing tips on the jet - these were canned well before contract award.
Given the extent of the subsequent airframe redesign in 03/04 to get the weight (and drag) of all three variants back inside the box, its my firm belief that if the guys at LM would have got an advantage from making the aircraft longer, they would have done it in a heartbeat. LM were looking hard at absolutely every option including new tails, revised fuselage layouts and many, many other ideas. I'd suspect that other constraints (LHD/LHA elevators? LHD deck parking?) may have had an effect on length and wingspan.
As LM found out, designing a supersonic, stealthy, STOVL aircraft about the size of an F-4 (hat tip to George K Lee for pointing this out) is a very hard thing indeed. Having an airframe design team whose last completed job was the F-16 didn't help. Ignoring offers of help from the UK also didn't help. Not having a Chief Designer DEFINITELY didn't help. Water under the bridge now, aircraft are deployed on USN LHDs as we speak.
Best Regards as ever to all those who take the kit into harm's way - fly safe, come home safe.
Engines