With the same intensity of how incredibly marvelous the invention of the A-12 was, it was just incredibly difficult to make these engines.
A-12 was first A= stood for Article or Archangel.
But, the crews named her Cygnus.
The U2 had been known as an angel.
YF-12 was the next three that were produced, the project was canceled. Y =experimental F fighter or interceptor. One YF 12 continued to fly for NASA until 1979.
The MD-21 was flown FIRST on the same day as the FIRST SR-71 on Dec 22, 1964.
S= strategic R= reconnaissance. RS-71 was supposed to be the name. It stood for reconnaissance strike. The number 71 in the SR-71 Blackbird designation signifies its place in a sequence that continued the pre-1962 bomber aircraft series. It followed the experimental XB-70 Valkyrie, which was proposed for a reconnaissance and strike role.
It was Gen. Curtis Lemay who changed the name not President Johnson.
M stood for mother 21 was 12 backwards
The J58 turbojet engines, which would enable the A-12 and following Blackbirds to fly so high and fast.
Kelly Johnson said we’re going to fly so high and so fast that they’re not going to be able to see us much less stop us.
The engines: J-58 -were not simply turbojets. They were complex, hybrid, turbojet engines that changed their operating mode as the aircraft accelerated.
The core engine was a turbojet. It was integrated into a larger variable geometry nacelle system that allowed it to function more like a ram jet at high speeds.This allowed the inlets' spikes to move up to 26 inches.
The move that was controlled by a computer was precisely managed. The series of shockwaves was generated as the aircraft accelerated to its cruising speed. The goal was to keep the terminal shockwave when the air changed from supersonic to subsonic. In other words, the engine needed to adapt to how fast it was going. The engine could only function with subsonic air.
If the shockwave moved out of position, it would cause an unstart.
Here is a step-by-step explanation of how the engines transitioned between modes:
Takeoff and low-speed flight: At speeds below Mach 2, the J58 functioned like a conventional turbojet. Air entered the inlet and was compressed by the nine-stage axial compressor, mixed with fuel in the combustion chamber, and exhausted out the rear. The afterburner could be used for additional thrust.
Transitioning to high-speed cruise: As the aircraft accelerated past Mach 2.2, a system bypass valve began to open. These valves redirected air from the fourth stage of the compressor through six large ducts that ran along the outside of the engine.
High-speed cruise (Mach 3+): At the SR-71's cruising speed of Mach 3.2, the internal turbojet provided only about 17% of the total thrust.
The engine's purpose at this point was to keep the airflow at a constant, high pressure. The remaining 83% of the thrust came from the compressed air being directed through the bypass tubes and into the afterburner. The very high-speed air was compressed by the aircraft's forward motion, and the engine's spike and cowl further directed and compressed it.
The air rushing around its engine core thus created a powerful ramjet-like effect.
This dual cycle design was the black magic. If you will, that allowed the SR-71 to fly continuously at high supersonic speed, the first aircraft ever to do that.
The engines were originally designed in 1956 for a Navy aviation project that was canceled, the engines had to undergo major modifications to turn them into the most powerful air-breathing propulsion devices ever made.
Just one J58 had to produce as much power as all four of the Queen Mary’s ( ocean liner produced in 1936 ) huge turbines—160,000 horsepower or over 32,000 pounds of thrust.
To crank it up, two Buick (later, Chevrolet) racecar engines on a special cart were used.
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