To allow for thermal expansion at the high operational temperatures the fuselage panels were manufactured to fit only loosely on the ground. Proper alignment was only achieved when the airframe heated due to air resistance at high speeds, causing the airframe to expand 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 onto the runway before it took off. The aircraft would quickly make a short sprint, meant to warm up the airframe, and was then refueled in the air before departing on its mission. Cooling was carried out by cycling fuel behind the titanium surfaces at the front of the wings (chines). On landing after a mission the canopy temperature was over 300 °C (572 °F), too hot to approach. Non-fibrous asbestos with high heat tolerance was used in high-temperature areas.[15]
[edit] Stealth
http://en.wikipedia.org/wiki/SR-71_BlackbirdGod Bless those "Skunk Works", my father in law, now 84 was with the Westinghouse Division, after the Army, that helped develop internal gyroscopes in ICBM's in essence creating real time ground mapping radar. Predecessor to the Smart Bomb, and GPS.
The SR-71 is only posted to the public at Mach 3.2, although, Mach 5 was rumored, maybe that's where "Speed Racer" got the name for his car....
However, I asked him about Area 51, several times, and he gets a funny sheepish grin on his face, and says "There's nuthin out there but desert"
His generation did things, and knows things they will take to the grave. The Original Homeland Security.