Well, supersonic flight is not a trivial matter. I flew the F104A
equipped with the J79-19 engine. Minutes after takeoff the fuel was
down to wehere the aircraft had a 1:1 thrust to weigth ratio. With
18,900 pounds of thrust (engine was later de-rated for longevity) the
Zipper would exceed its thermal limit quite handily. The problem as I
saw it was the windshield and canopy. M2.0 in the stratosphere in a
standard atmosphere (-57F) gave us an inlet temperature of 100C. M2.0
was also the USAF limit of lateral stability. Yes, we went faster now
and then - some went faster than others (I had a wife and 2 kids' 2.2
was enough for me). 2.4 is the limit for an aluminum-fuselaged aircraft
- above that you risk de-tempering the alloy and subsequent loss of
strength. The F106 on display at the USAF Air Academy is one such
aircraft - it and its engine were expended to establish a speed record
around (ISTR) M2.45. The idea of rebuilding an A10 to make a supersonic
interceptor out of it is so far from being even remotely practical that
only total unfamiliarity with what would be required could excuse such
a concept. Sorry for the bluntness - but it's true.
Walt BJ