Pratt & Whitney J58
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J58-In-Thrust-We-Trust-Power.jpg
Pratt & Whitney J58 uniform patch
The Pratt & Whitney J58 (also known as the JT11D) was the jet engine used on the Lockheed SR-71 "Blackbird".
The J58 was started using a AG330 engine starter cart, which were basically two Buick Wildcat internal combustion engines with a common driveshaft. The cart operators had to get the J58 spinning to 3,200 rpm in order to start.
The J58 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 U.S. Air Force for Mach 3. Another unique feature of the J58 were conical spikes in the variable-geometry inlets, which were automatically moved fore and aft by an Air Inlet Computer. The spike altered the flow of supersonic air, keeping air entering the engine at a subsonic speed. This feature also provided about 80% of the engine's thrust (at Mach 3.2), with the turbine only providing 20%, making the J58 a ramjet at higher speeds. At lower speeds, the J58 operated as a turbojet.
The engine and aircraft operated at such high speeds and temperatures that a new jet fuel formulation had to be invented, JP-7.
External link
- The heart of the SR-71 : the J-58 engine (http://aerostories.free.fr/technique/J58/J58_01/page8.html)