High Quality Content by WIKIPEDIA articles! The Pratt & Whitney J58
(company designation JT11D) was a variable cycle turbojet aircraft
engine used on the Lockheed A-12, and subsequently on the YF-12 and
SR-71 Blackbird aircraft. It was essentially a hybrid turbojet/ramjet
engine. The J58 was initially developed for the US Navy to power the
planned version of the Martin P6M jet flying boat. Upon cancellation of
this aircraft, it was selected by Convair and Lockheed for their
supersonic projects. Other sources link its origin to the USAF's
requirement for a powerplant for the WS-110A, the future XB-70 Valkyrie.
The J-58 produced 32,000 lbf (142 kN) of thrust. It was the first engine
to be able to operate on afterburner for extended periods of time, and
the first engine to be flight-qualified by the United States Air Force
for Mach 3
