I'm not sure exactly what you are trying to say here but the air was bled
off the fourth stage compressor section and ducted to the afterburner
section where the fuel came out the afterburner nozzles and all the
combustion took place in the AB. The J58s were not ramjets but more of a
hybred. Pratt called them "dual cycle turbo-ramjets". It isn't true that
"the faster it flew the faster it could go", like all aircraft it has all
sorts of limits only one of which is temperature. I have the flight manual
for the SR-71 minus the recon and defensive systems.

It is my favorite aircraft too but I can't help objecting when someone calls
an aircraft "invulnerable". It is the same as calling a ship "unsinkable".
Most of the unsinkable ships can be found on the bottom of the ocean.

Mike
MU-2


"Jay Honeck" wrote in message
news:5fSnc.66286$kh4.3904147@attbi_s52...
The Blackbird used afterburning in all supersonic flight.

The Blackbird used afterburners to accelerate for takeoff, and to achieve
supersonic flight, not unlike the Concorde.

At speeds above 2000 mph, however, the J-58 engines became ramjets, and
operated in supercruise, enabling Mach 3+ flight for anywhere from 2500 to
3300 miles without refueling.

The unique thing about the Blackbird was that the faster it went, the
faster
it could go. The only thing limiting its top speed was heat -- the
engines
and airframe aerodynamics would have allowed even higher speeds, except
that
critical things started to melt.

Still, it flew faster than a rifle bullet for hours on end -- a truly
remarkable aircraft.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"