Key Points – NASA’s X-43A hypersonic research vehicle, part of the “Hyper-X” program, still holds the world record for an air-breathing aircraft, achieving a speed of Mach 9.64 (6,363 mph) in its final flight on November 16, 2004.
-The 12-foot-long, unmanned aircraft was powered by a revolutionary scramjet engine and launched from a B-52 mothership via a Pegasus booster rocket.
-Despite the program’s success in demonstrating scramjet viability and setting speed records, follow-on projects like the X-43C were canceled due to a shift in NASA’s strategic goals.
-However, the research has informed subsequent hypersonic programs like the Air Force’s X-51 Waverider.
X-43A in 1 Word: Cancelled?
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.
About the Author:
Steve Balestrieri is a National Security Columnist. He served as a US Army Special Forces NCO and Warrant Officer. In addition to writing on defense, 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.
Fighter Jet Fails
Russia’s Su-57 Felon Stealth Fighter Is a Waste of Rubles
