In great secrecy on December 22nd, 1964, one of the most awesome planes ever built was rolled out at Air Force Plant 42 in California, and took its first flight. On that very first flight it achieved a speed of Mach 3.4. This was the SR-71 Blackbird, a plane that played an honoured role in the Cold War

Wars are often started through uncertainty, when a potential aggressor is uncertain of the response. This makes intelligence extremely important; you need to know your enemy's capabilities. Behind the Iron Curtain NATO needed to assess the USSR's capabilities, and what aggressive potential it had. The US initially used the U2 spy plane, but it was becoming vulnerable to interception by missiles, and a successor was needed.

Kelly Johnson at Lockheed's "Skunk Works," created the SR-71. Its shape was designed to reflect radar beams, it was coated in radar-absorbent iron-ferrite paint, and its fuel was mixed to minimize exhaust trails. It could fly at over Mach 3 at 80,000 feet, and was able to outrun any enemy aircraft and missiles. It gathered massive reconnaissance on its many flights, identifying potential enemy positions and military assets. Its appearance was thrillingly exotic, and breathtakingly elegant. It became an icon.

It had ground-breaking technology. It was 85% heat-resistant titanium, with windows of quartz. During flights its exterior could exceed 500F, and when it landed, it had a long period to cool down before the crew could leave it or the ground crew could approach it. It leaked fuel on the runway at take-off because the tanks were designed to expand and seal with the heat once it was flying up to speed.

Its twin J58 engines needed vehicle-mounted starter engines to get them going, and moved to partial ramjet mode at high speeds and altitudes. It was soon breaking records for speeds and altitudes, though many remained long classified. It once established a New York to London record flight time of 1 hour and 54 minutes.

32 Blackbirds were built, and although 12 were damaged or lost in accidents, none was lost to enemy action, even though it was in harm's way many times. During the Vietnam war years, over 800 enemy missiles were fired at it, none successfully. It had missile attacks against it over Libya and North Korea, but it outran them all.

It served with the US Air Force for 32 years, from 1964 to 1998, and NASA operated the two last airworthy Blackbirds until 1999. Its missions helped keep the peace by keeping NATO apprised of possible enemy capabilities and deployment. It was finally superseded by reconnaissance satellites, but its career reminds us of the constant need to be on our guard, to be alert to possible enemy plans, and to construct defences to meet new offensive capabilities that our potential adversaries develop. The price of liberty is eternal vigilance, and the Blackbird performed an essential part of that vigilance. On the 55th anniversary of its maiden flight, we salute it.