>cost savings (ala the F-35)
What.
What.
There was even a notion that you could use the same plane across all branches of the military so the same supply chain could be used for all three and you could build them in higher quantities to spread the development costs over more aircraft. But then of course the aircraft got saddled with requirements from three different branches of the military at once which made it extremely difficult to design and build and thus very very expensive.
Sounds rather like the Space Transportation System. During design, it went from a compact inexpensive passenger shuttle with modest payload capability, to a complete pig of a ship. And all because the Air Force contributed cash on the condition that it be capable of classified high-payload-pass missions to polar orbits.
It is nothing short of a tragedy that fully-reusable compact shuttles with flyback boosters (like the Rockwell P333) lost out to the disposable-booster design that was eventually built.
Of course this is a problem when you have Congress breathing down your neck and looking for any excuse to cut your program. One big advantage of skunk works projects is that they keep you firewalled off from idea men.
A. The "light" F/A part of the heavy/light fighter model.
B. Meant to save costs by having one aircraft with shared parts (across the three models) fill virtually all roles.
It's not totally crazy on the face of it- The expensive but undefeated F-15 and the relatively cheaper F-16 successfully pulled it off in the 20th century.