Interview by Eric Hehs
This interview appeared in the April 1994 issue of Code One Magazine.
Marta Bohn-Meyer’s vitae reads like a flight engineer’s dream. Her career at NASA began in Langley, Virginia, as a cooperative education student during her sophomore year at Rensselaer Polytechnic Institute (Troy, New York). After graduating in 1979 with a bachelor of science degree from RPI in aeronautical engineering, she headed to NASA Dryden Flight Research Center in Edwards, California, where she began testing heat-resistant tiles for the space shuttle. Soon after, she became involved with laminar flow experiments on an F-111 and then on an F-14. As a flight test engineer on these projects, she flew in T-38 and F-104 chase aircraft. This work led to other laminar flow projects on the two F-16XL aircraft NASA acquired in 1989. Bohn-Meyer became the project manager for F-16XL laminar flow research in 1990.
When NASA received three SR-71s from the Air Force in 1990, Bohn-Meyer’s expertise and F-104 experience made her an easy choice for one of two flight engineer slots for the aircraft. She has the distinction of being the first female crewmember of NASA or the Air Force (and one of only two women) to fly in the triple-sonic SR-71.
In addition to her SR-71 duties, Bohn-Meyer is now in charge of the F-16XL No. 2 aircraft’s part in NASA’s high-speed research program. (The No. 1 aircraft went to NASA Langley last year.) She has over fifty hours each in the F-16XL, T-38, F-104, and in the F-18; twenty-five hours in the SR-71; and seventy-five hours in the F-14. Bohn-Meyer is an FAA-certified flight instructor. In her spare time, she and her husband fly their home-built Phoenix and Pitts Special biplanes in aerobatic competitions. Code One’s Eric Hehs visited Bohn-Meyer at NASA Dryden last fall to talk about NASA’s aeronautical research in general and the F-16XL’s part in that research.
Do NASA’s space programs overshadow its aeronautical research?
A lot of people don’t remember that the first A in NASA stands for aeronautics. NASA’s entire budget is on the order of $15 billion. The aeronautics part of that accounts for less than $1 billion. While aeronautical research is not the most glamorous NASA activity, the United States probably gets the highest return on this investment through better, more efficient airplanes.
The country still needs a flagship space program like the shuttle. And the program needs to be successful. The shuttle, however, is economically troubled. When we developed the space shuttle, we had a particular infrastructure in mind. That infrastructure was spread around a large geographic portion of the country so the entire program would be politically appealing. Any large program’s political acceptance may depend on this built-in inefficiency. Although it is very expensive, the shuttle works. Besides, it would probably be more expensive to try to streamline it.
Because the United States is so strapped economically, which is true for almost every other country in the world right now, I think we’re trying harder to identify programs that are truly in our national interest. We have to mature certain technologies. But we have to do that without spending too much money.
How does NASA select its aeronautical projects?
Sometimes it’s something we’re directed to do. Sometimes it’s internal advocacy. Sometimes people approach us because they know we have some expertise or skills in a certain area. The choice usually comes down to funding. Our management balances what we want to do with our manpower and resources. We do the things we must do first. The things we would like to do are done at a lower level. And the things that we don’t have funding to do fall through the cracks unless they are someone’s special project.
A good example of the latter involves one of our F-15s. An engineer who studied the Sioux City DC-10 crash determined that, had the pilot had access to the throttles through the airplane’s autopilot, he could have landed the airplane safely. The engineer developed a small-scale program in which the F-15’s engines were tied to the autopilot. The approach works. Some of our test pilots here have landed the F-15 on autopilot with throttles only. The project has been well-received by industry and by our headquarters. The technology may be incorporated in the next generation of commercial transports.
How does NASA’s approach to flight testing differ from industry’s approach?
We really don’t flight test; we do flight research. Rather than demonstrating that something will work and then moving on to a next step, we ask why something works and try to see what may make it work better. We try to understand the technology. We’re not profit motivated. We are schedule driven, but perhaps not as much as we should be and certainly not as much as our flight test counterparts in industry.
Have worldwide political changes affected NASA’s aeronautical research?
With peace breaking out, the military side of the house is being scaled down. We’re still involved with high-performance aircraft. But the civil sector has become more prominent. NASA has also become more involved in general aviation. There are very few general aviation manufacturers left in the United States. This may be another niche where we can introduce some new life into the economy. Taxpayers can see a return on their investment rather quickly in programs like these. Economic motivations are becoming more important.
Is NASA viewed as a catalyst for converting military technologies into civilian uses?
People familiar with our aeronautical research may see us this way. The aeronautics part of NASA does convert a lot of military technology into a civilian form. The military side, however, is concerned that we not convert their technologies too quickly.
It’s very important for us to stress that these aircraft, many of which are former military aircraft, are being used to promote technology. Most military airplanes have fairly wide flight envelopes, which give them a lot of room for a variety of military and civilian applications. Who would have guessed that the F-16XL would ever be used to develop a high-speed civil transport? As you know, it was first developed to carry a larger weapons load than its competitor, the F-15E.
Back to your original question: instead of looking for ways to convert military technology to civilian use, we are more likely to use military aircraft to solve problems in the civilian sector.
Does industry need help solving these problems because they involve higher-risk research?
Risk alone does not account for our involvement. It has more to do with our resources. While we have a better environment for high-risk research, it’s our test and fabrication facilities, highly trained people, and all those other research capabilities not typically found in one company. We are a focused organization. All we do here at Dryden is flight test and flight research. We don’t produce or design airplanes. We are best thought of as a national resource.
Does industry take full advantage of NASA’s aeronautical know-how as a national resource?
Yes, but at its own pace. Certainly with the high-speed civil transport we are doing as much as we can together and at a faster pace. Instead of NASA doing the design and then transferring that technology to industry, for example, we are assisting industry’s design effort for the HSCT-type aircraft.
In certain areas, industry has recognized that we can help. On the F-16XL, we have contracted companies to design a glove to our specifications. Our providing a test platform frees resources in these companies so they can concentrate on the design.
Explain the economic reasoning behind the high-speed civil transport program.
The aeronautics business in this country is in desperate shape. In the last ten to fifteen years, the United States has lost twenty percent of the market share for its large commercial transport aircraft to the Europeans, in particular to the Airbus. In 1975, we had eighty-five percent of the market share and, in 1990, the number was less than seventy percent.
NASA is being looked to as an organization that can help turn the US industry around, which is a big motivation behind the high-speed civil transport. We want to help rejuvenate our aerospace business so that we are more competitive in the world market. Airbus activities are supported by the governments of Europe. Our airframe manufacturers aren’t. We are trying to give them the help they need so that they can continue to compete with Airbus. We’re trying to leapfrog the foreign competition with new technologies.
What are some of the technical challenges for the high-speed civil transport?
We’re not looking at radical leaps in technology. We’re trying to go from a subsonic commercial airplane to a supersonic airplane in ten to fifteen years. You could build an airplane today that can carry 300 passengers and go Mach 2.4, but it wouldn’t be environmentally friendly. It would also weigh over 1.2 million pounds. That’s not a practical payload. The idea is to develop the technologies needed to drop the weight to 600,000 pounds, which is equivalent to some of today’s commercial airplanes. By the year 2005, we want an airplane that can go from California to New York in two hours, instead of the five hours it takes now. Everything indicates that we can do that. The question is, can we make it work for a reasonable cost?
The design will require some advances in composite and engine technology and some solutions to unique problems. For example, the Concord has to droop its nose for landing. The machinery it takes to droop the nose is very expensive in terms of weight. We are looking at synthetic vision as an alternative.
One reason the supersonic transport was killed in the 1970s was that it was too loud for communities. So, we’re looking at technologies to soften sonic booms. Unlike people here at Edwards, not everyone likes sonic boom noise. Researchers at NASA Langley are using the F-16XL No. 1 to evaluate concepts for high-lift leading-edge devices that will allow airplanes to come in slower, without the angles of attack of the space shuttle. These devices should also reduce noise and require shorter runways. Eventually, we would like to marry these high-lift techniques with supersonic laminar flow that we’re working on with the F-16XL No. 2.
Why use the F-16XL for this research?
The beauty of the F-16XL is that it has a planform very close to what we think the high-speed civil transport will have a seventy-degree-sweep wing with a crank at the mid span station at a roughly fifty-degree sweep.
Are the gloves being used on the F-16XL unique?
Although gloves have been around for some time, NASA first used a glove to investigate laminar flow in the late 1970s on an F-111 with a unique wing-the F-111 Transonic Aircraft Technology or TACT wing. The experiments consisted of nineteen flights on the F-111 TACT. We installed passive glove sections on both wings. The glove on the right wing was fully instrumented, and the left wing glove was added for symmetry. We obtained data over a range of angles of wing leading edge sweep an at Mach numbers from 0.8 to 0.85. We achieved significant amounts of laminar flow in the experiments.
The F-111 program led to an F-14 variable-sweep transition flight experiment in the mid-1980s. We gloved both wings of an F-14 and documented the effect of sweep on the transition location at 0.9 Mach. Because the glove limited the wing sweep to thirty-five degrees, the aircraft could not fly supersonic. However, we filled a large part of the database as far as what happens to laminar flow as wings are swept farther and farther back. NASA also had two hybrid laminar flow control experiments on a Lockheed JetStar in the mid-1980s. The program used the same basic equipment we’re using on the F-16XL-the same pumps, same turbo machinery.
Although supersonic laminar flow had been documented in fairly short runs on the Lockheed F-104 in the late 1950s, we achieved laminar flow over a significant portion of the wing of the F-16XL No. 1 in 1991. The active glove on the XL No. 1 didn’t work the first place we went to fly. It was designed for a particular point in the flight regime and it didn’t work there. It took us a couple more flights before we found a place in the flight envelope where the extent of laminar flow would be fairly significant. We’ve known how to make airplanes go fast for some time, but we’ve only recently learned what happens on the surface of a wing at high airspeeds.
How did NASA acquire the two F-16XLs?
They weren’t thrust upon us. It took a concerted effort on the part of people like Jim Smolka, who was at Fort Worth at the time but now works for NASA/Dryden, and Joe Bill Dryden. Ted Ayres, then deputy center director at Dryden, was also instrumental in getting the two XLs.
The airplanes had served their purpose and were either going to be destroyed or used by NASA. They were being stored in Fort Worth. We really didn’t know exactly what we were going to do with them when they first arrived, but we could see their potential.
How have the aircraft been used since they arrived?
We worked on the single seater, F-16XL No. 1, first because it was going to take the least amount of time to get it in flightworthy condition. The two-seater, F-16XL No. 2, arrived with a developmental engine that had to be replaced.
While we conducted the supersonic laminar flow experiment on XL No. 1, we worked with people in Fort Worth to get an F110-129 engine for the two-seat airplane. We had to do some product development work for the engine SPO (System Program Office) to get the engine.
The development work was a blast. We learned a lot about the airplane in the program. The F-16XL is an airplane to behold. With the new engine, it has some spectacular performance. It’s a shame that we didn’t have a chance to fly it for what it could do. We have some supersonic persistence that cannot be beat by anything else flying today. Except for the Concord, the SR-71 may be the only other airplane that has more supersonic persistence than the XL. We did supercruise quite accidentally early on. That is, we achieved Mach 1.1 at 20,000 feet with throttles in military power, no afterburner. The engine guys at General Electric were quite pleased. But we didn’t make a big deal about it at the time.
After the engine tests, we proceeded to turn this aircraft into a laminar flow experimental airplane. We installed a foam and fiberglass fairing, a passive glove, on the leading edge of the right wing. The glove allowed us to examine the aerodynamic fluid mechanics along the leading edge of a supersonic surface and to identify pressure distributions, whether the airflow is laminar or turbulent, and the noise environment. We studied all the things that affect our ability to maintain laminar flow.
We did not finish the experiment before we had to modify the left wing for a larger active-suction glove experiment for the high-speed civil transport program. The passive glove will stay on the right wing, and we will record data from it when we fly the new glove.
What will the new glove look like and what will it do?
The glove will look similar to the glove on the F-16XL No. 1. It will be foam and fiberglass fairing around a test section of a high-tech composite with a porous titanium skin. The glove will have a maximum thickness of about 2.5 inches. The wing’s S-shaped blend will be extended straight forward on the left side to match more closely the proposed wing for the high-speed civil transport.
The glove surface area will be more than twice that of the XL No. 1. The active (suction) section, the middle two-thirds of the glove, will have at least 2,500 laser-drilled holes per square inch and at least ten square feet of holes. The holes lead into a cavity beneath the wing surface. About twenty such cavities will be used to control the suction on the wing’s surface.
The glove is chemically bonded to the skin itself with common epoxy resins. We sand the paint off the airplane and put a couple of layers of fiberglass onto the composite skin of the XL. The fiberglass gives us a buffer region. When it comes time to take the glove off, the fiberglass keeps us from damaging the graphite polyamide skin of the airplane.
The airplanes had served their purpose and were either going to be destroyed or used by NASA. They were being stored in Fort Worth. We really didn’t know exactly what we were going to do with them when they first arrived, but we could see their potential.
Do you think laminar flow control will be commercially successful?
I believe it will be demonstrated successfully. I’m not so sure yet about commercial implementation. I am confident that, if we want to find a way to implement it, we will. The big question is can industry afford the investment in it as well as in some of the other technologies critical to a high-speed civil transport. Commercial success comes down to direct operating cost-all the things the airline industry uses to calculate the premium on a seat mile. Market surveys indicate people will pay ten percent more per ticket for the advantages offered by a high-speed civil transport.
How is NASA using its SR-71s?
The SR-71 program is part of our overall high-speed aeronautical research program. We’ve already used the airplanes in several experiments. One was to study an optical air data collection system-a system that uses laser light to produce airspeed and attitude data normally obtained by various tubes that measure air pressure. In another experiment, we placed a science camera in the nose bay. The camera can photograph celestial objects at wavelengths unobtainable for ground-based astronomers. We are planning to use the airplanes to study ways of reducing sonic booms. And we just completed four flights for Motorola. We used the SR-71 to simulate a satellite for their Iridium communication system.
How does the SR-71’s high-speed characteristics affect your work as a flight engineer?
Nothing is simple in the airplane. You have to wear these bulky pressure suits. Flying at thirty miles a minute, you’re making decisions much faster than you would in other aircraft. It requires 100 percent involvement. There’s not much time to enjoy the sights. The pilot stays busy flying the airplane. The flight engineer operates the experiment and handles the navigation, communication, and health monitoring. The workload is exactly the same as before, except the reconnaissance equipment has been replaced with research equipment.
At the end of the flight, you’re exhausted. We always have post-flight debriefs at a local restaurant with the maintenance folks and engineers. Everyone is happy. The FAA often shows up because they play a big part in coordinating our flights, which sometimes take us over five states.
How did you become interested in aviation and how do you explain your success?
When I was fourteen, my mother and father decided I needed a hobby. I was interested in horses and airplanes. The choice was easy for my father, who worked for Grumman as a flight test engineer. I started flying powered planes and soloed when I was sixteen, which was the minimum age. I’ve been working around airplanes ever since. I always liked hardware. One Christmas, my parents gave me the tools and parts needed to rebuild the engine of my 1967 Ford Falcon. I spent Christmas vacation in the garage.
I grew up in a family that was quite progressive, even by today’s standards. My parents had five children-three girls and two boys. But they did not treat the girls any differently than the boys. I had absolutely no fear doing what the boys did.
You make your opportunities into whatever they are. I was lucky to be in the right place at the right time with the right qualifications and enthusiasm.
Interviewed by Eric Hehs, Managing Editor/Code One