Also amazing, was the materials engineering. SR71 ushered in the use of widespread Titanium in the airframe, which was needed to stand up to the heat (friction

Also amazing, was the materials engineering. SR71 ushered in the use of widespread Titanium in the airframe, which was needed to stand up to the heat (friction) at Mach 3+. Because of the severe heat-cycling, the engineers ultimately figured out an unorthodox solution to manage thermal expansion: The fuselage panels were manufactured to fit only loosely on the ground. Proper alignment was only achieved when the airframe heated up and expanded several inches. Because of this, and the lack of a fuel sealing system that could handle the thermal expansion of the airframe at extreme temperatures, the aircraft would leak JP-7 jet fuel on the runway. At the beginning of each mission, the aircraft would make a short sprint after takeoff to warm up the airframe, then refuel before heading off to its destination. http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Airframe http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Airfra...