YF-twenty-WHAT?

[Jackonicko]

So if the LWF contenders were YF-16 and YF-17, AX contenders were YA-9 and YA-10, and ATF were YF-22 and YF-23, then do you think the JSF demonstrators should really have been X-32 and X-35?

[DaveW]

The answer to this question given at the time was:

The JSF Concept Demonstration Program is not meant to be a competitive fly-off. The Boeing JSF X-32 and Lockheed Martin JSF X-35 are not prototypes – they are technology demonstrators, hence the "X" designation, as opposed to the "Y" designation used for aircraft such as the YF-22 and the YF-23 (prototypes for the F-22).

Doesn't explain why the winner became the "F-35" though. This thread may explain why it wasn't the "F-24", however; perhaps that designation was already taken.

Thinking further: You could imagine a scenario where the DOD didn't wish to invite rampant speculation about existence of a missing aircraft if the JSF designation had been announced as "F-25"; remember the fuss when there was a gap between F/A-18 and F-20 (Tigershark)?

So why not leap straight to 35, and leave lots of other handy holes in the system to be filled within the black world? There you go - problem solved

[John Farley]

At least 1 of the YC-15s

I think you will find there was only one.

It was 'SC1' (whereas the YC-14 was the 'P1127') of that competition