The SR-71 Blackbird was in service from 1964 to 1998 and was operated by the U.S. Air Force from United States and select NATO air bases. Capable of speeds in excess of mach 3+(2,200 mph+) and 85,000 feet, the Blackbird was the most capable platform for strategic reconnaissance. It's ability to launch to a specific target and return with the required intelligence in a matter of hours was unsurpassed by any other platform or country. The SR-71 was developed by the infamous Lockheed Skunk Works and the primary construction material was a Titanium alloy. The two Pratt & Whitney J-58-P4/32,500 lb. thrust engines had aerospikes at the inlet of the engine. The spikes moved in and out in order to control the airflow through the engine during the transition from subsonic to supersonic speeds. This feature, coupled with the afterburners unique design, allowed the SR-71 to cruise in continuous afterburner with a high degree of efficiency.