Century Series: F-108, F-109, F-110, F-111

century series fighters

Century Series: F-108, F-109, F-110, F-111 - Why was the TFX changed to F-111A?, by phantomphan

In 1963, the USAF was taking delivery of what was originally to be the F-110A Spectre. The air force was told to drop the century series numbering. The USN and USMC also had to simplify
their systems. So the navy's F4H-1 became F-4B. The F-110A became the F-4C Phantom II.


Why was the TFX later designated F-111A? The F-111 is not included in the immortalized Century Series of fighters. F-100 thru F-106. There was a F-107 prototype produced in the early 60's by North American Aviation. What happened to the F-108 and F-109? Regarding the F-117A, the air force apparently came up with that designation to confuse plane spotters who routinely use radios tuned to mil frequencies. Seems that the air force was flying there MiG's from the Tonopah Range also and they were given a three digit designator instead of a controller calling a Mig-21 a Mig-21. Maybe around the time of the F-111A that was the situation also. Any ideas?

Century Series: F-108, F-109, F-110, F-111 - Century Series Designations., by max_g_cunningham

The F108 and F109 were designations for experimental prototypes t
hat were never put into production. 

One of those was a experimental podded jet, that operated in VStol, by method similar in principle to the tilt rotor. It never got past the mock-up stage, and that's probably a good thing. 

Don't forget the YF-12 Fighter interceptor version of the blackbird, equipped with the progenitor of the Phoenix missile system. One of those designations, was the proposed mach 3 escort fighter to accompany the B-70 Valkyrie. That particular fighter was cancelled, shortly after the infamous U2 loss over Russian airspace

because
the B70 program itself was gradually called into question, and more importantly, around the same time, Lockheed had already demonstrated the A11 prototype, of the A12, and a little later, the YF12 derivative, which wholly eclipsed the sheer performance capability of the original Valkyrie, and specifically it's proposed twin engined escort fighter, the "Rapier." The Lockheed Blackbird family of A12 YF12, and SR-71 versions later went on to set reco
rds w
ell in excess of Mach 3. Mach 3.35
being about the best I've ever heard of, (unofficial) for the A12, and/or SR71, It's speculated that the A12 version the fastest and highest flying, routinely achieved cruise altitudes in excess of 90,000 ft. 8)

By comparison, the vaulted MiG25 is/was actually more of a mach 2. M2.8 (1800-2000mph*) class airframe, than a true sustained, mach 3+ capable machine.

The very best performance posted for the XB70 was somewhere around mach 3.02, at/or around 72,000ft, and it didn't demonstrate and sustain that performance anywhere nearly as long as the Blackbirds would routinely operate. The XB70s had serious structural problems, which had improved, by the time the 2nd prototype was tested, but were still never as well developed and proven, in reliability, not to mention anywhere close in terms of ultimate sheer performance, to the degree that the Blackbirds had around the same timeframe, routinely demonstrated in secret. Interestingly enough though, the basic aerodynamic configuration of the XB70, (it still looks unearthly futuristic to this day) was wind tunnel tested out to Mach 4, and it may have been possible, with further development and advancements in several technologies, to eventually, achieve those speeds, the problem, always being time, and costs.

The Blackbirds also, one can wonder, and speculate on what more improved versions could achieve, with continued aerodynamic and propulsion systems development. Even in the case of the B58 Hustler, which lightly loaded, in it's day, could outclimb an F4, consider the "what ifs",,, equipped with contemporary 28,000 thrust class engines. I find it all a little ironic with the current hoopla, from NASA over the recent unmanned speed record.


Don't forget Pete Knight's piloted record in the advanced version of the X15,  back in 1967.