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High-Risk, High-Payoff Program

The eight-year, approximately $230 million NASA Hyper-X program was a high-risk, high-payoff research program. It undertook challenges never before attempted. No vehicle powered by an air-breathing engine had ever flown at hypersonic speeds before the successful March 2004 flight. In addition, the rocket boost and subsequent separation from the rocket to get to the scramjet test condition had complex elements that had to work properly for mission success. Careful analyses and design were applied to reduce risks to acceptable levels; even so, some level of residual risk was inherent to the program.

Hyper-X vehicle configuration
Image above: Hyper-X vehicle configuration. Credit: NASA
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Hyper-X research began with conceptual design and wind tunnel work in 1996. Three unpiloted X-43A research aircraft were built. Each of the 12-foot-long, 5-foot-wide lifting body vehicles was designed to fly once and not be recovered. They are identical in appearance, but engineered with slight differences that simulate variable engine geometry, generally a function of Mach number. The first and second vehicles were designed to fly at Mach 7 and the third at Mach 10. At these speeds, the shape of the vehicle forebody served the same purpose as pistons in a car, compressing the air as fuel is injected for combustion. Gaseous hydrogen fueled the X-43A.

Simplified Hyper-X flight plan, from air launch to experiment completion
Image above: Each of the Hyper-X research vehicles achieved test speed and altitude with the help of the NASA Dryden B-52B aircraft and an expendable booster rocket, as shown in this simplified flight trajectory. Credit: NASA
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NASA Langley Research Center
 Hyper-X logo
X-43A Flight Makes Aviation History
The first and second successful hypersonic flights of a scramjet-powered airplane.
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 U.S. Army infrared image of the Mach 6.8 flight of the second X-43A scramjet on March 27, 2004
High Risk, High Payoff
Though careful analysis and design minimized the risks, Hyper-X was a bold step.
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 Test a full-scale model of the Hyper-X vehicle at Mach 7 in a NASA Langley wind tunnel
The Record-Breaking Flights
During its third flight, the X-43A flew at about 7,000 miles per hour.
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 Still image of the Hyper-X vehicle in flight taken from an artist's animation
2001 Flight and Investigation
On the first Hyper-X flight attempt, the booster failed.
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 This graphic explains how air and fuel mix at supersonic speeds inside a scramjet engine
How Scramjets Work
In a scramjet, even the airflow through the engine remains supersonic.
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