NF-104A "NF-756" with instructor pilot Dean F. Vikan wearing the high-altitude "David Clark AP22S-2" full-body pressure suit

The F-104 Starfighter fitted with an additional rocket engine was also regularly used in zoom climb research for future space flight.
On May 7, 1958, the aircraft reached an altitude of 91,249 feet (27.81 km) in a zoom climb at Edwards Air Force Base, CAL.
The Mach 2 mission took the airplane so high that the standard F-104’s jet engines routinely exceeded their temperature limits and had to be shut down.
Sometimes the engine simply flamed out for lack of air. Then the pilot steered the aircraft like a returning spaceship to a lower altitude,
where he would restart the engine.
It was on one such "zoom climb" flights that test pilot Chuck Yeager was nearly killed flying a heavily modified F-104 on December 10, 1963
Without engine power, the cockpit would de-pressurize on these missions. Consequently, for protection against the rarified atmosphere,
the pilot wore a full-body pressure suit. Properly outfitted with an airtight helmet and suit the pilot received breathing oxygen without ill effects.

copyright © Chris Baird