Sorry, guys, I could have checked this myself before asking. Some
early versions of the airplane were in fact configured with a weapon's
bay. You'll find this writing at aerospacewed.org. (It also suggests
another of Mx's statements is in error).

The first units built were 15 A-12 strike models configured for both
reconnaissance and attack missions. These single-seat aircraft were
delivered to the CIA beginning in 1962, although one was modified for
use as a two-seat trainer and two more gained a second seat for a
launch officer to operate a D-21 unmanned drone. These early aircraft
could carry a centerline pod containing a 1-megaton nuclear bomb or
the D-21 recon drone armed with cameras, infrared sensors, and other
equipment. Three new two-seat aircraft were also built as YF-12A high-
speed interceptors, but these were primarily employed as research
aircraft in conjunction with NASA. The A-12 aircraft were flown by the
Air Force on behalf of the CIA until the more advanced SR-71, a
dedicated reconnaissance model, became fully operational in 1968. The
SR-71 featured an improved airframe, increased fuel capacity, and
better aerodynamic performance but lacked the weapons bays of earlier
models. The SR-71 was also equipped with in-flight refueling
capability to compensate for the design's high fuel consumption and to
extend its range.




On Nov 17, 6:21 pm, quietguy wrote:
On Nov 17, 3:55 pm, Tina wrote:

The following text is from Brian Shul's Sled Driver, his memoir of
flying the SR-71. It's a great read, and most of us has seen parts of
it before. If and when you read it, I'd appreciate your thoughts about
this. how is it such an airplane had been resticted to recon? Had any
been configured as a first strike weapon? I suppose some may have and
we'd never know.

I'd wonder the same thing about the U2.

Google "Lockheed YF-12A" and you'll find some material on the USAF
interceptor version. Not everyone believes that the Air Force was
serious about it; it may have been just a cover program for the SR-71,
the two-seat USAF version of the CIA's single-seat A-12.

As for an armed version of the U-2, google "sitting duck". Before its
first operational flight it was already clear that it was just a
matter of time before one got shot down; that's why the CIA started
the A-12 program in 1959, before the first of the two U-2 shoot-down
incidents.