SR71 Blackbird Engine

The SR71 was fitted with Pratt & Whittney J-58 engines. The J58 engine has 32,500 lbs. of thrust, enough to drive the largest ocean liners. They are the largest of their kind and used to be the most powerful in the world. The engine is one part of a propulsion system, which includes an inlet, and an ejector, each producing thrust. In order for the system to work properly over a long period of time, the inlet must capture the onrushing air properly. To do this, a large spike is placed in the inlet and moves forward and back as conditions change. When the air is not captured properly, an event called an unstart occurs. An unstart is best described as a violent yaw where the aircraft pulls to the side where the engine has unstarted. To correct the problem, the pilot must push the spike totally forward and adjust it to capture the air properly, this is called a manual intake. The J58 engines operate as ordinary jets at low speeds, switching to become ramjets at high speeds above 2,000 mph

Thanks for the Info Matzos