I guess I'm the only one here old enough to know all the details.

Yes, MacNamara tried to apply the principles of the civilian auto-industry to the military services. He reasoned that instead of the Navy and Air Force demanding different aircraft to meet their mission requirements, with multiple developmental costs, one-size-could-fit-all. Development costs would be reduced perhaps by two-thirds, and logistical support would be greatly reduced. Divert to someone else's airfield? They should have parts if you need them.

He ordered the TFX to be evaluated by the USAF and Navy.

He was also in charge when the services standardized the designation system for aircraft. The USAF system was what it is now. But the Navy system was very confusing. If you look at WWII aircraft, Corsairs built by different companies were either F4U-(letter-suffix), or FG-1, or (cloudy on this one, F2-something,I think). The designation reflected the manufacturer as well as the role.

This will play-in momentarily.

Remember: at this time, the Big Generals in the Air Force were mostly bomber guys who rose to power during or after WWII. They dictated a lot of the design requirements for aircraft. (Re: Robert Coram's book about John Boyd).

To them "fast" was the prime design requirement of a fighter, and stations to bolt the weapons to.

They were used to side-by-side seating, so they wanted the cockpit that way (because they envisioned it having a dual-role as a penetrating nuke bomber, and because the Navy wanted a two-seat jet).

Due to the standardizing of nomenclature, the question must have come up: what to call it?

It was intended to have an air-to-air role and air to ground role. They didn't want to designate it "B-111," nor "A-111." (Politics probably came into play as the Air Force was lobbying for money for the B-70. Another "B" airplane would have reduced their arguments). They did designate the SAC airplanes as FB-111, because they were heavier (more gas), had longer wings (and possibly fuselage) and had no intended air-to-air capability.

I think the powers that be (powers that were?) equated Afterburners with Fighter. So there you had it: F-111.

Reality:

Side-by-side is no way to build for max performance...and that's what a fighter must be. Lots of profile drag. More drag means more power required to hit design top-speed.

That means more fuel to hit required range.

That means more wing to support the weight of that fuel.

That means heavier landing gear...

The F-111 is an awesome low-level bomber. It can haul a$$ like nothing else I have seen. It can easily do Mach 1.1 to maybe 1.3 at 300 ft. From the even older guys, the only thing faster on the deck was the F-105 (which, I'm told, could hit 1000 kts indicated at 200 AGL!!)

But it was never a fighter. The radar really had no capability against airplanes. Cockpit visibility was crap to the rear or right (had to ask the WSO). Yeah, they put AIM-9Ps and later 9Ms on it..."for Self-defense." But the Vaark turned so poorly, that (I was told by a former vaark-driver) that it was illegal to perform a loop. I know a guy who said he did one: he had to get supersonic, and keep it in burner the whole way around.

That's not a fighter.

The Navy knew this, and went through the motions of carrier-testing it. But some Admiral, testifying before Congress, was asked why it wasn't suitable for the Navy. The Congressman/Senator asked "What if we put bigger engines on it?"

And the Admiral stated "All the thrust in Christendom wouldn't make that airplane a fighter!!"

Interesting segue: todya, the most expensive fighter contract in history is supposed to fly for the Air Force, Navy and Marines. One-size-fits-all.

Except, each model is a little different.

And it is uglier than the airplanes it is supposed to replace. Sorry, the F-35 is not a very good-looking airplane. The F-16 and F-18 are.