These are the Blackbirds. They were all invented by the Skunk Works. Kelly Johnson was the leader of the Skunk Works. All four of these aircraft were capable of going Mach Three, that’s three times the speed of sound. They were all capable of going the same exact speed . The Blackbirds all had a strict compressor inlet temperature limit of 427°C or 800°F. this limited the speed of the aircraft. In special conditions like war the wing commander could authorize the SR 71 to fly faster.. The A-12 is the only Blackbird that has one cockpit; all other versions have two cockpits. The A-12 could not take pictures while in a turn.. The YF-12 held to air-to-air 47 Falcon (GAR-9) missiles. It was not equipped with any Reconnaissance cameras. The YF 12 had a rounded nose because of the heavy nose radar. It lacked the continuous sharp side ridges chines. They ran all the way up to the front nose on the SR 71 and the A-12. A-12 only held cameras and was owned by the CIA. The M-21 was built to launch D-21 drones. Together they were called the MD 21M was her mother D was daughter 21 was just 12 turned around. YF-12 and M-21 where experimental aircrafts The Blackbird that flew the longest was the SR-71 it had a variety of cameras and sensors. It was constantly updated with the latest electronic countermeasures. The SR-71 flew from 1966 to 1990. She is still the fastest-manned aircraft in the world ~ written by Linda Sheffield