Built with the goal of outpacing any missile launched at it, the SR-71 Blackbird has been the fastest air-breathing, manned aircraft since 1976. Blackbird's unique aerosol made it impossible to be tracked by radar, making it a perfect spy plane. Customised windscreen, special fuel and external fuel tank make it one of the most amazing aircrafts of the modern era.
The speed limit of the airplane is determined by its engine temperature. According to a BBC report, the 'reconnaissance aircraft' will clock its fastest speed when the temperature of its engine indicates 427C (800 F). The makers of the Blackbird had developed a special fuel, JP-7 that could extinguish even a cigarette. The purpose was to prevent any chances of explosion in the plane as the original fuel used was highly inflammable. Another unique feature of this jet plane was that the fuel tank was a part of its external skin. The fuel was allowed to leak from below the plane and the leak was measured in Drops Per Minute (DPM). Blackbirds were used to collect photographic evidences by the US airforce to track the Yom Kippur War in the early 70s. Colonel Rich Graham, one of the few pilots to have flown the airplane, in an interview to the BBC, narrates that the Blackbird had provided evidences of the ceasefire or the lack of it between the Arab states and Israel to the American president, which, according to him, helped end the war. The high altitude reconnaissance US Air Force jet provided 25 years of service flying missions over potential trouble hotspots around the world. The Blackbird served the US airforce between 1964 and 1998. A total of 32 such spy aircrafts were built, out of which 12 were lost in accidents and none lost to enemy action.