Originally kept under wraps as a US and UK secret Black Project, the Lockheed SR-71 Blackbird was a technological wonder. The fastest plane of all time (reaching an eye-melting 2,530km/h (2,193mph), it was also one of the highest-flying military aircraft ever made. The plane was so fast, it even broke both the sound and heat barriers and required a specialist fuel and titanium structure to fly. Devised after the U2 incident in 1960, the Blackbird demonstrated that the US needed a quicker and higher-fl ying reconnaissance aircraft that couldn’t be tracked by the USSR. The designers of the Blackbird described it as their hardest ever assignment, as the plane was so different and advanced compared with anything that came before. 32 were constructed in total and served as scouting aircraft for over 30 years. The details of a vast majority of these missions are still classified.