rangerj
The F-4 Phantom was originally designated the F-110. That wasa back in the day of the Secretary of Defence Robert Macnamera and "universal one size fits all" weapon systems. So the F-4 and the F-111 were supposed to be used by the USAF, the Navy, and the Marines. The F-4 worked out, but the F-111 was to heavy and large for carrier operations so the Navy and Marines never went fully operational with the F-111. The A-7 also fit into this program.
The a/c that became the F-4C was origially the F-110 Spectre. There had been a YF-110, so the names was "in use" hence the skip to F-111.
The other missing birds are
F-107 the "Ultra Saber"
F-108 Rapier, North American's escort for the XB-70.
F-109 the Bell D-188 that never left the drawing board.
Convair had sorted the F-111 design out before Macnamara started monkeying with the process. They had designed the bird to what they expected the AF to want, based on their prior experience.
So, when they had to make the bird carrier-capable, they really wound up with a different a/c. This was labled F-111B for USN/MC use and F-111A for AF use. The Bravo had longer wings to increase lift, too. Only a coule of feet, but enough to reduce the commonality quotient.
Mac also came up with the notion that no military service need more than one plane type, no matter what mission type was being flown. Mac had previously convinced Ford that the Edsel, coupe, sedan, and wagon, would take over the auto indusrty, too (that's why he was available to be SecDef).
So Convair had another problem, how to pile external stores on what had been meant to be a fighter-interceptor. They had a leg up, in the heavier F-111B airframe, which had enough frame oomph to carry al lthe hydraulics for pivoting stores pylons (which Convair resisted no small amount).
In the end, the Bravo was too big, too heavy, too slow (engines designed for the lighter weight)--while also too fast for best carrier landings, and only just adequate landing gear. The "parts commonality" was down to 20-30%, so Convair saved no money, which raised the unit price, and lengthened the delivery times. So, around a billion over budget, DepNav pulled the plug. And, this was not unknown in the industry. So, Grumman just happened to have a desinged from the get-go carrier-ready a/c with variable geometry wings. And, designed around AIM-54, which the AF no longer had a good a/c for.
Most of which I was a bystander to, as my dad was on the USN audit team working at Convair.
Convair converted al lthe Bavos to be strike fighters, which were designated FB-111.
Mac passed into history, and the AF got the figher they actually wanted in the F-15, and as a bonus, Convair also got them the F-16. That latter light fighter competition also got us Northup's F-17, and the Mac-Doug F-18.
And now, I may have "jet fatigue"
