Summary and Key Points: NASA’s X-43A hypersonic research vehicle, first flown aboard a B-52 in 2001, achieved unprecedented speeds of Mach 9.64 (6,363 mph) at an altitude of 110,000 feet, setting a world record for air-breathing aircraft.
-Powered by an innovative scramjet engine, the 12-foot X-43A demonstrated significant potential for efficient hypersonic propulsion by using external airflow rather than onboard oxygen.
-Despite its success and plans for follow-on programs (X-43B/C), NASA ultimately canceled the project due to shifting priorities.
-However, the groundbreaking achievements of the X-43A continue to influence current hypersonic programs, notably the Air Force’s ongoing X-51 Waverider development efforts.
NASA’s X-43A: The Fastest Aircraft You Never Heard Of
The first captive-carry flight of NASA’s X-43A hypersonic research vehicle occurred on April 28, 2001, aboard a B-52 over the Pacific Test Range. A Pegasus booster rocket was attached to the X-43A and carried on the B-52’s wing pylon.
Despite all the talk about how the United States is lagging behind China and Russia in hypersonics, the US has been flying hypersonics for longer than anyone and holds the record for an air-breathing aircraft with speeds of Mach 9.64, or 6,363 mph at 110,000 feet altitude.
The NASA aircraft was awe-inspiring because the SR-71 Blackbird cruised at Mach 3.
The X-43A Is Built
The X‑43A was a 12-foot long, 5-foot wide lifting-body design jet aircraft designed to be flown once and not recovered. It was one of NASA’s “better, faster, cheaper” programs developed by the space agency in the late 1990s. The aircraft weighed about 3,300 pounds, and the program cost $230 million.
The X-43A was powered by a scramjet, a supersonic combustion ramjet integrated with its lower fuselage, designed for speeds up to Mach 10. This aircraft was the first hypersonic (Mach 5+) research program since the X-15 in the 1960s. NASA built three X-43A aircraft, the first two designed to fly at Mach 7 and the third intended to fly at Mach 10.
The first aircraft was destroyed when the first stage of the winged Pegasus booster rocket failed. In 2004, tests commenced, and the X-43A reached speeds of Mach 6.83. The final X43A flew on November 16, 2004, and set a speed record of Mach 9.64 (6,363 mph) at about 33,500 meters (110,000 feet).
How Do Scramjets Work?
According to NASA, “A scramjet (supersonic-combustion ramjet) is a ramjet engine in which the airflow through the engine remains supersonic. Scramjets-powered vehicles are envisioned to operate at speeds up to at least Mach 15. Ground tests of scramjet combustors have shown this potential, but no flight tests have surpassed the Mach 9.6 X-43A flight.”
Because scramjets use external air for combustion, they are a more efficient propulsion system for flight within the atmosphere than rockets, which must carry all their oxygen. Scramjets are ideally suited for hypersonic flight within the atmosphere.
NASA planned to build an X-43B, an ambitious project in which the aircraft would fly at supersonic speeds at lower altitudes and then use scramjet propulsion at higher speeds and higher altitudes. The planned “Hyper X” aircraft, the X-43C, was slated for the late 2000s and was scheduled to demonstrate the operation of a solid hydrocarbon-burning scramjet engine at speeds between Mach 5 and 7 sometime around 2008. However, the project was canceled.
Why Did NASA Cancel the X-43 Project?
The X-43 project was canceled due to a shift in NASA’s strategic goals following the announcement of the “President’s Vision for Space Exploration.”
The Air Force has continued testing hypersonic aircraft with the X-51 “Waverider” program.
The X-51 Waverider can fly 600 nautical miles in 10 minutes after being released from a B-52 mothership, like the X-43A.
X-Planes: A Photo Essay Beyond the X-43A
This photo shows the X-29 during a 1991 research flight. Smoke generators in the nose of the aircraft were used to help researchers see the behavior of the air flowing over the aircraft. The smoke here is demonstrating forebody vortex flow. This mission was flown September 10, 1991, by NASA research pilot Rogers Smith.
X-29.
The No. 1 X-29 advanced technology demonstrator aircraft banks over desert terrain near NASA’s Ames-Dryden Flight Research Facility (later redesignated the Dryden Flight Research Center), Edwards, California. It was flown in a joint NASA-Air Force-Defense Advanced Research Projects Agency program from December 1984 to 1988 investigating handling qualities, performance, and systems integration on the unique forward-swept-wing research aircraft. Phase 2 of the X-29 program involved aircraft No. 2 and studied the high-angle-of-attack characteristics and military utility of the X-29. Image Credit: Creative Commons.
About the Author:
Steve Balestrieri is a 19FortyFive National Security Columnist. He served as a US Army Special Forces NCO and Warrant Officer. In addition to writing for 1945, he covers the NFL for PatsFans.com and is a member of the Pro Football Writers of America (PFWA). His work was regularly featured in other military publications.
