The SR-71 Blackbird

The CIA A-12 Blackbird Program


The A-12 started out as an USAF interceptor to replace the cancelled F-108A Rapier. In October 1962, CIA authorized the Skunk Works to study the feasibility of modifying the A-12 to carry and deploy a reconnaissance drone for unmanned overflight of denied areas. The project was codenamed TAGBOARD.

1 Feb 1975

The Cold Wall Experiment

The Cold Wall Experiment

Author: SR Admin  /  Categories: NASA YF-12  /  Rate this article:

Because air friction subjected the plane to extreme heat during flight, the YF-12 was also used to study high-temperature phenomena unrelated to the plane itself. Perhaps the most significant of these studies was the Cold Wall Experiment, which involved exposing a cooled cylinder to the friction and heat of a Mach 3 environment.

The cylinder, which was hollow, equipped with sensors, and mounted beneath the aircraft, was cooled with liquid nitrogen and insulated from the heat that was generated during flight. When the plane neared Mach 3, a primer cord was used to blow the insulation from the frigid cylinder. Temperature, pressures, and friction readings from the cylinder in flight were compared with information developed from theoretical analysis and wind-tunnel simulation. The findings were a major achievement in fluid dynamics research.


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