SR-71 and The Evolution of the American Spy Plane

Since the early days of spy planes - around the World War I era-, the name of the game had been unarmed  "Hot Passes" (relatively low, extremely fast passes) to get a glimpse of enemy installations. However, with the invention of fighter jets and Surface to Air Missiles (SAMs) came the need for changing tactics. In the Vietnam war, experimentation was conducted with lightly armed "recognizance and fast-attack" aircraft. Basically, the idea was that these planes would spot enemy emplacements, mark them with smoke rockets (take some other pot shots at them? Couldn't find much information on this) and allow more advanced jet aircraft to take out the targets. On paper, this was a great idea, use small, cheap aircraft for routine patrols (basically civilian single-engine propeller aircraft) and save the big expensive "fast movers" for actual targets. In practice though, the whole program was a disaster. These planes usually operated very low making them easy targets for everything from SAMs and jets to small arms fire. The US military lost several planes like this. It was clear that a new strategy was needed. A top-secret program from the 1950s  was rekindled for use as a spy plane. This was the U2. The U2 program represented a fundamental change to the modern battlefield. The U2 could fly at up to 88,000 feet (well into the stratosphere) and used cameras that were more powerful than those of many space programs of the time. This, coming at a time before clear satellite imagery for military use, was unheard of. This allowed the US to conduct reconnaissance over enemy countries while out of reach of enemy interceptors... At least for a few years. The Soviets became increasingly irate about American spy planes (as they were now called) conducting uninhibited operations over their airspace. However, a boiling point was reached when American Aircraft disproved the bomber and missile gaps during the cold war. The Soviets accelerated their Ultrahigh altitude interceptor program. This encompassed missiles that could be fired up to these high altitudes and strike American planes. On May first of 1975, Col. Garry Powers was conducting a reconnaissance mission over the USSR when he was discovered by Soviet Radar. When two intercept attempts failed due to the fighter aircrafts altitude limitations, They resorted to missile defenses, striking down the aircraft on the third shot. The incident was nonfatal however it made it clear that America needed a new solution to this problem. The Soviets had countered their high altitude advantage. American companies competed for a new military contract that called for a plane that could provide a new advantage to the United States. Lockheed Eventually won the contract with their proposal of the XR-71 (SR-71), a High Altitude, High-Speed aircraft that could easily circumvent enemy defenses. The Sr-71 could not only fly higher than the U2 but it also flew at speeds of over Mach 3 (compared to the ~500 mph speeds of the U2) with help from the hybrid turbojet ramjet engines. This was astronomical. The plane could not only comfortably take pictures from over sixteen miles in the air, but also do so at speeds that were faster than any defenses that the Soviets Could throw at it. To give some insight into the sheer speeds of the airplane, a routine training flight for these crews, with the help of a refueling tanker, was a lap around the continental United States which could easily be completed in under four hours. Ultimately the program was shut down due to cost and advancements in spy satellites but it is clear that this is one of Americas most badass planes to date.