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From One Bay Area to Another: A Chat with Langley's X-43 Aerodynamicist Walt Engelund
03.26.04
 
Moving across the continent from the San Francisco Bay region to the Chesapeake Bay area has kept Walt Engelund from becoming too much of a land-lubber.

As the NASA Hyper-X / X-43 program's aerodynamics lead, Engelund has been staying busy these days as the hypersonic, scramjet-powered X-43A nears flight. Engelund, of NASA's Langley Research Center in Hampton, Va., directs and oversees the aerodynamics-related activities for the X-43A.

Walt Engelund, X-43A aerodynamics lead prepares for the next flight.Image on right: Walt Engelund, X-43A aerodynamics lead at work on the project. NASA Langley photo by Jeff Caplan.

Langley Research Center, rich in the aeronautical and space history of America, manages the X-43A program. The program began in 1996 with the high engineering purpose of reaching one of the pinnacles of aeronautics, airbreathing hypersonic propulsion.

"Nobody has ever flown anything like this before," says Engelund. "Even the casual observer can see that this is a very unique vehicle, so there's not a whole lot to draw from in terms of past experience. That makes it very challenging, but also very rewarding, knowing that we're doing something no one else has ever done," Engelund said. "I can imagine those that worked on the Apollo program or development of the Space Shuttle had similar feelings. What a great rush!"

Airbreathing hypersonic propulsion has been an elusive goal in atmospheric flight. Scientists and engineers have been studying scramjets, or supersonic combustion ramjets, as a way to accomplish this for almost 50 years, but always in a laboratory environment. "We've never actually flown one as an integrated propulsion system on a real airplane," said Engelund. "That's the trick. And when we do, to paraphrase Isaac Newton, it will be because we’ve stood on the shoulders of giants, many who spent their entire careers studying scramjets, but never actually got to the point of flying one. At the same time, there have been some naysayers and detractors who have said it can't be done, but we're going to prove them wrong."

Engelund spends his work time with wind tunnel testing, computer analysis, and computer model development. For pressure relief, mind-clearing and good exercise, avid cyclist Engelund cycles around the lowlands of the Chesapeake Bay.

Often, aerospace engineering disciplines need to interact with one another here and there. Aerodynamicists and propulsion engineers typically don't rub shoulders too often, but the fact that the X-43A is an airframe-integrated scramjet demands that aerodynamics and propulsion engineers work very closely together, almost on a day-to-day basis.

"That's one of the difficult things with this project," according to Engelund. "The engine and the airframe actually become one. It's a little more complicated than just keeping the pointy end forward. The aerodynamics and propulsion groups have to work very closely to fine tune the system to ensure the vehicle works exactly right."

The interesting process of developing the world's first airbreathing hypersonic vehicle includes the handing-over of the aerodynamics models to the flight control designers to let them develop an autopilot to fly the airplane. "We've been doing all of this on the ground, basing our analysis on models from wind tunnels and computers. Now it's time to go fly and see if we've got it right," Engelund said.

Pushing the frontiers of flight is a risky proposition. Engelund remembers watching the first X-43A go down before getting to test the scramjet. "That was a painful experience," Engelund relates. "Figuring out the complicated series of events that caused it was painful too. But, at the same time, it was a tremendous learning experience. And talk about team bonding! Enough can't be said about the group of people who have seen this thing through thick and thin since 1996."

Engelund, who has been at Langley for 17 years, earned bachelors and masters degrees in engineering from Old Dominion University in Virginia. Engelund says, "All in all it's been an amazing ride, and I just can't imagine how good it's going to feel when we get this thing in the air flying at Mach 7 under scramjet power!"

For more on NASA's X-43A, visit: http://www.nasa.gov/missions/research/x43-main.html

 
 
Gray Creech
NASA' s Dryden Flight Research Center