Portions of the inner wing & fuselage surfaces are longitudinally corrugated rather than smooth, to allow the titanium to return to shape after enduring the heating & cooling cycle of every flight (a smooth surface would've buckled).
The Blackbird is, without a doubt, the most advanced airplane ever built in relation to the technology available at the time. It broke all aviation records, it flew incredible missions, and it became the stuff of legend.
The final of 12 ordered by the CIA "Oxcart" is seen in production at the Skunk Works plant in Burbank, California (June Equipped with twin Pratt & Whitney engines, the reached speeds of Mach mph) at feet. Its service ceiling was
Blackbird and parked together in a hangar at Lockheed Martin Skunk Works in Palmdale, California. The now resides at the National Air and Space Museum Steven F. Udvar-Hazy Center near Washington Dulles International Airport.