SR-71B NASA 831 Over Sierra Nevada. Dryden's SR-71B, NASA 831, over the snowy Sierra Nevada Mountains of California. The Mach 3 aircraft are being flown as test beds for high-speed, high-altitude aeronautical research. Capable of flying more than 2200 mph and at over 85,000 feet, they are excellent platforms for research and experiments in aerodynamics, propulsion, structures, thermal protection materials, atmospheric studies, and sonic boom characterization (NASA Media Archives). Buy this as a superb wall poster, a canvas print or a framed print.