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Exploring the Hypersonic Realm
Nov. 2004
The Pegasus rocket that powered NASA’s X-43A scramjet to almost Mach 10 test conditions leaves a bright arc in the Pacific sky during the boost phase. The X-43A team shattered a speed record Nov. 16 for the second time this year when the aircraft successfully reached speeds approaching Mach 10.

Image Right: The Pegasus rocket that powered NASA's X-43A scramjet to almost Mach 10 test conditions leaves a bright arc in the Pacific sky during the boost phase. NASA Photo by Carla Thomas
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The team celebrated the first flight of an integrated airbreathing supersonic combustion ramjet (scramjet) engine during a March 27 mission in which the X-43A separated from a rocket booster and flew at about 5,000 mph, or Mach 7. Researchers reported that initial data from the Nov. 16 flight shows the scramjet-powered research vehicle successfully flew at an altitude of about 110,000 feet, at speeds of about Mach 9.6, or 6,500 mph.

Dryden X-43A project manager Joel Sitz said the X-43A team has completed its job.

"We've given industry and government a lot of confidence to go forward with hypersonic flight and hypersonic airbreathing propulsion. I think that technology definitely has a future, and we definitely opened that door. We completed 100 percent of the goals this program had set out to achieve," he said.

The high-risk, high-payoff flight with the revolutionary engine technology took place in restricted airspace over the Pacific Ocean northwest of Los Angeles. The flight was the final and fastest of three unpiloted flight tests in NASA's Hyper-X program. The program was designed to explore an alternative to rocket power for space access vehicles.

"This flight is a key milestone and a major step toward the future possibilities for producing boosters for sending large and critical payloads into space in a reliable, safe, inexpensive manner," said NASA Administrator Sean O'Keefe. "These developments will also help us advance the vision for space exploration, while helping to advance commercial aviation technology."

NASA's associate administrator for the aeronautics research mission directorate, J. Victor Lebacqz, congratulated the team.

"The work of the Langley-Dryden team and our Vehicle Systems Program has been exceptional," Lebacqz said. "This shows how much we can accomplish when we manage the risk and work together toward a common goal. NASA has made a tremendous contribution to the body of knowledge in aeronautics with the Hyper-X program, as well as making history."

NASA's B-52B launch aircraft cruises to a test range over the Pacific Ocean carrying the third X-43A Image Left: NASA's B-52B launch aircraft cruises to a test range over the Pacific Ocean carrying the third X-43A vehicle attached to a Pegasus rocket on November 16, 2004. NASA Photo by Carla Thomas

While congratulating the X-43A team on the mission, Lebacqz also explained what the X-43A flights mean for future NASA hypersonic research.

"We have a lot of data to look at now from two successful flights, a lot of wind tunnel data leading up to the flights, and CFD (computational fluid dynamics) data. We'll talk with our industry partners. We'll work our way through what we think we've learned to see what next steps might be, and talk about some foundational technology we might what to do," he said.

Randy Voland, a senior research engineer from Langley Research Center, Hampton, Va., explained "foundational technology" as smaller projects that can later lead to larger ones. In the case of possible follow-on research to the X-43A, foundational research could include ground tests of new engine technology that could later be integrated into a flight research vehicle that could take off under its own power and fly into the hypersonic realm, he said.

Sitz has a vision of what he thinks should happen next.

"The next step I'd like to see at NASA is to take a turbine engine and a ramjet or scramjet engine and combine those propulsion cycles and put some hardware together and start testing it," he said. "Maybe in a couple of years we could put an airplane around that technology. There are a lot of paths you can take from this point, and they all lead forward."

Laurie Marshall, Dryden X-43A chief engineer, explained the significance of the latest record flight.

"It was a phenomenal flight that looked just like some of the mission simulations we practiced. The data was captured longer than we predicted and we have quite a lot to look at for quite a long time," she said.

Voland agreed with Marshall and elaborated on the issue of data acquisition."This data set dwarfs all previous (Mach 10) data," he said. "Mach 10 research on the ground is measured in miliseconds; this time, the engine was open for 20 seconds (10 seconds during which fuel was fed into the engine), which dwarfs all Mach 10 data combined. Hopefully, we'll go beyond this (in future experiments). We can really do this stuff, and the vehicle works the way we thought it would."

Dave McAllister, X-43A operations manager for flight three, expressed officials' gratitude to the families of X-43A team members for the greatest sacrifice: the absence of loved ones during the long days and weeks and even longer weekends and holidays required to keep the project moving forward.

Supersonic combustion ramjet engines promise more airplane-like operations for increased affordability, flexibility and safety in ultra-high-speed flights within the atmosphere and for the first launch stage into Earth orbit. The advantage to scramjets is that once they are accelerated to about Mach 4 by a conventional jet engine or booster rocket, they can fly at hypersonic speeds, possibly as fast as Mach 15, without carrying heavy oxygen tanks, as rockets must.

The design of the engine, which has no moving parts, compresses the air passing through it so combustion can occur.

NASA Deputy Administrator Frederick Gregory congratulated the team after the flight.

"This is a very, very exciting time," he said. "It was a privilege to come out and see the B-52 launch a hypersonic vehicle for the last time. It was a very significant mark for NASA and those who support the effort. It really demonstrates a capability to do things people said were impossible. I'm proud of the team, and I congratulate them."

Hyper-X Program Manager Vince Rausch also was pleased with the X-43A's performance.

"It was really great to see that we once again made aviation history. We are absolutely elated. We had a great team at both centers (Dryden and Langley) and with our industry partners," he said.

The X-43A, atop the modified Pegasus rocket booster, took off from Dryden, attached beneath the wing of Dryden's historic B-52B launch aircraft. The booster and X-43A were released from the B-52B at 40,000 feet and the booster's engine ignited, taking the X-43A to its intended altitude and speed. The X-43A then separated from the booster and flew on scramjet power for a brief flight at nearly Mach 10.

Langley and Dryden jointly conduct the Hyper-X program. It is headquartered at NASA's aeronautics research mission directorate, from the Agency's Washington, D.C., headquarters. ATK-GASL (formerly Microcraft Inc.) of Tullahoma, Tenn., and Ronkonkoma, N.Y., built the X-43A aircraft and the scramjet engine, and The Boeing Company Phantom Works, Huntington Beach, Calif., designed the thermal-protection and onboard systems. The booster is a modified first stage of a Pegasus rocket built by Orbital Sciences Corp., Chandler, Ariz.

For more information about the Hyper-X program and the flights of the X-43A, visit

For information about NASA and Agency programs, visit

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Jay Levine
X-Press Editor