At the center of the X-plane revival

By Ben Iannotta|February 2017

DAVID D. MCBRIDE

The first part of David McBride’s nearly four-decade career at NASA’s Armstrong (formerly Dryden) Flight Research Center in California centered on X-planes, but then in the early 2000s the pace of that work slowed. These days, McBride’s 550 civil servants and 600 contractors are preparing for a resurgence in X-plane flights for everything from quiet supersonic transportation to electric propulsion, all under NASA’s New Aviation Horizons initiative. As exciting as the X-planes are, they are not the only thing Armstrong does. The center leases an old B-1 assembly facility at Plant 42 in Palmdale from which it flies conventionally piloted science aircraft. I spoke to McBride by phone from his California office.

Perspectives

X-plane revival

We’ve had a quiet time in NASA aeronautics research over the last decade, since probably 2004. Over that 12 years, we have continued to work on maturing technologies through ground tests and wind tunnel and CFD work. Now it’s time to pull some of those technologies together, or they’re maturing to the point where we’re ready to go to flight. The only true way to validate aeronautics technology, in my opinion, is ultimately through flight. To date, there’s never been an airplane that has flown exactly as designed. That’s what Armstrong’s role is: to figure out what’s different from design to actual flight.

X-plane planning

What’s exciting now is we’re going back into that [X-plane] era with the New Aviation Horizons program that [President Barack Obama] announced last year. We’re kicking off with the X-57 Maxwell [electric research plane], which is going to be flown here soon, and the Low-Boom Flight Demonstrator that’s in the PDR [preliminary design review] phase, right now.

The promise of quiet supersonic flight

We believe we have the basic fundamentals of understanding of supersonic flight physics and aerodynamics and atmospheric flight conditions that we can design and develop a supersonic aircraft that would reduce the sonic boom to the ground to the point where it’s not a nuisance, but acceptable to the public, which would open the market for [passenger] supersonic flight.

Subsonic innovations

We’ve been working on things like flying the X-48 Hybrid Wing Body aircraft over the last decade in a subscale model. Now we believe, through the subscale model, we’ve validated some of the drag and noise benefits of the vehicle, and it’s ready to go build an efficient subsonic aircraft.

Optimal development process

I believe you need all three components: CFD, wind tunnel, and flight to get a better end product.

Why X-planes benefit from pilots aboard

In a lot of cases, it’s easier to have a pilot who understands aircraft dynamics and aircraft feel and can fly it. The human brain is still the best computer we have for flying an airplane. Having a man in the loop, in a lot of cases, is a cost savings. Something we’ve been doing for 70 years here at the center is testing handling qualities. Ultimately, as these aircraft, whether supersonic or subsonic, become transports for people, somebody has to evaluate the ride characteristics in turbulent weather, in adverse conditions, and say, “Yeah, that is acceptable for either a high-performance, high-g military type aircraft, or that’s a comfortable airline that you’d be happy to put grandma and your kids on.”

Future of “green” aviation

Green also means less fuel burn, which means less operating cost for the airline. Although jet fuel is cheap, today, it won’t stay that way forever. Operating cost and operating efficiency and the maintenance efficiency is always going to be a driver in selecting your next-generation airframe. Plus, if we take the lead in building them, and we hopefully build them here, it means jobs in the United States. That is very much in alignment with this next administration.

Earth sciences and climate change

NASA’s role isn’t to drive policy. What we do is we gather data. I believe that we are seeing changes in climate, and we are seeing adverse impacts to the country and to the world in regards to climate. NASA’s role is to gather data on that change, on the mechanisms for the change so the policymakers, be that Congress or the executive branch of the government, have the data to make appropriate decisions on how to make changes and apply resources of the country.

Science aircraft

Our role here at the center is complex systems integration to flight. We’ve supported NASA science with the integration and flight of the SOFIA [Stratospheric Observatory for Infrared Astronomy], which is the 747SP with a 20-ton, 2.7-meter infrared telescope that opens to the atmosphere. That airplane has a 20-year planned life on it. We’re about six years into that. It is now in routine flight operations. It flies three or four nights a week doing infrared astrophysics, both in the Northern and Southern hemispheres.

Testing space vehicles

We are working with supporting Sierra Nevada with Dream Chaser. They’re scheduled to be out here in the next couple months to do another approach and landing test. If there ever is another vehicle like the shuttle or like Dream Chaser is now, with wings and landing gear, it undoubtedly would be evaluated and tested here.

Cooperative education

Every year over the summer, we usually have about a hundred interns, co-ops, summer students that come through the system. Not all of them are [in Armstrong’s] Pathways Programs, but through all the different student intern programs. We work closely with AIAA in a lot of the student work that you all do, encouraging people to apply for the NASA internship programs here at the center and throughout the agency.★