The Lockheed NF-104A was an American mixed power, high-performance, supersonic aerospace trainer that served as a low cost astronaut training vehicle for the X-15 and projected X-20 Dyna-Soar programs. Three aircraft were modified from existing Lockheed F-104A airframes and served with the Aerospace Research Pilots School between 1963 and 1971, the modifications included a small supplementary rocket engine and a reaction control system for flight in the upper atmosphere. During the test program the maximum altitude reached was over 120,000 ft (36,600 m). One of the aircraft was destroyed in an accident while being flown by Chuck Yeager which was later featured in The Right Stuff motion picture, the surviving NF-104As being retired from service.

The North American X-15 rocket-powered aircraft/spaceplane was part of the X-series of experimental aircraft, initiated with the Bell X-1, that were made for the USAF, NASA, and the USN. The X-15 set speed and altitude records in the early 1960s, reaching the edge of outer space and returning with valuable data used in aircraft and spacecraft design. It currently holds the official world record for the fastest speed ever reached by a manned rocket powered aircraft.

During the X-15 program, 13 of the flights (by eight pilots) met the USAF spaceflight criteria by exceeding the altitude of 50 miles (80.47 km, 264,000 ft), thus qualifying the pilots for astronaut status. The USAF pilots qualified for USAF astronaut wings, while the civilian pilots were later awarded NASA astronaut wings.Of all the X-15 missions, two flights (by the same pilot) qualified as space flights per the international (Fédération Aéronautique Internationale) definition of a spaceflight by exceeding a 100 kilometer (62.137 mi, 328,084 ft) altitude.

The Lockheed U-2, nicknamed "Dragon Lady", is a single-engine, very high-altitude reconnaissance aircraft operated by the United States Air Force and previously flown by the Central Intelligence Agency. It provides day and night, very high-altitude (70,000 feet / 21,000 meters), all-weather surveillance. The aircraft is also used for electronic sensor research and development, satellite calibration, and satellite data validation.

SR-71 (1964)
Crews flying the SR-71 at 80,000 ft (24,000 m) faced two main survival problems: 1) with a standard pressure demand oxygen mask, human lungs cannot absorb enough of 100% oxygen above 43,000 ft (13,000 m) to sustain consciousness and life, and 2) the instant heat rise pulse on the body when exposed to a Mach 3.2 air flow during ejection would be about 450 °F (230 °C). To solve these problems, the David Clark Company was hired to produce protective full pressure suits for all of the crew members of the A-12, YF-12, MD-21 and SR-71 aircraft. These suits were later adopted for use on the Space Shuttle during ascent.

“On December 10, 1963, while testing an NF-104A rocket-augmented aerospace trainer, he narrowly escaped death when his aircraft went out of control at 108,700 feet (nearly 21 miles up) and crashed. He parachuted to safety at 8,500 feet after vainly battling to gain control of the powerless, rapidly falling craft. In this incident he became the first pilot to make an emergency ejection in the full pressure suit needed for high altitude flights.” (from the biography of Gen. Yeager)

Powers was discharged from the Air Force in 1956 with the rank of captain. He then joined the CIA's U-2 program. U-2 pilots flew espionage missions using an aircraft that could reach altitudes above 70,000 feet, making it invulnerable to Soviet anti-aircraft weapons of the time. The U-2 was equipped with a state-of-the-art camera designed to take high-resolution photos from the edge of the stratosphere over hostile countries, including the Soviet Union. U-2 missions systematically photographed military installations and other important sites.

The suit also enables the wearer to travel longer distances horizontally; glide ratios of 2.5:1 are commonplace.

and pressure that can boil blood.