Adolf Busemann

Editor’s Note:

Adolf Busemann is one of the most outstanding exponents of Riemann’s hydrodynamic method in this century. Although he is not well known outside the realm of supersonic hydrodynamics, his intellectual influence has penetrated deeply into all aspects of plasma physics; aerodynamics, and the theory of shock waves. The Intellectual history of this remarkable figure is recounted in this interview, which was conducted by Fusion editor-in-chief Dr. Steven Bardwell in the summer of 1979 when Busemann was 76. Busemann is currently professor emeritus at the University of Colorado. He holds many distinguished honors from various countries and is a member of the U.S. Academy of Engineering. Busemann’s research falls into three general areas which coincide with the three primary research laboratories in which he worked. The first of these was an independent institute near Gottingen University, where he worked under Ludwig Prandtl, leader of the German hydrodynamicist school; Busemann continued these researches in Dresden. This first period of his research concerned the formation and propagation of shock waves. The immediate context for the research was work on the aerodynamic problems of wing design and jet turbine construction for flight at supersonic speeds. The problem of supersonic flight had fascinated researchers and military thinkers since the first days of flight. But one outstanding feature of the problem had dominated all considerations: At velocities greater than the speed of sound, shock waves are generated. And these shock waves, because of the nearly singular nature of the air disturbances they generate, make it difficult to maintain stable, controllable flight at supersonic velocities. Even so, the fabled Mach 1 (the Mach number is the ratio of the speed of the aircraft to the speed of sound) was nearly reached by a German airplane using jet engines in 1945 — the ME-163, which reached Mach 0.86. Concentrating on the problem of the optimal design of turbine blades, Busemann discovered during the Göttingen-Dresden phase of his work some of the critical features of steady-state shock waves. The most famous of the results of this research was his development of the Busemann biplane, a configuration of two aircraft wings that completely eliminates drag at supersonic speeds (see Figure 1). Although this plane was never built, it had a tremendous impact on the design of supersonic aircraft, on the scientific understanding of aerodynamic drag, and on the general problem of the propagation of shock waves in two dimensions. The insight into Busemann’s method provided by his comments in this interview is quite striking: His primary motivation in the development of his theory was to eliminate the inefficiencies in turbines. To accomplish this end, Busemann realized that the properties of shocks upon reflection and turning were essential. This realization led to the experiments and the analysis of schlieren photographs of “dark spots” in the wind-tunnel flows. Using a quite intuitive geometric interpretation of the motion of the shock waves, Busemann realized that it should be possible to completely eliminate the trailing shock lines if a set of “interfering” shocks could be produced by a second wing. The Busemann biplane was the result. Out of this research, Busemann became interested in the focusing of shock waves as well as their destructive interference. This extrapolation of his work on aerodynamics was taken up in his work at the German rocket laboratory at Peenemunde just before and during World War II. Busemann’s comments on the Nazis’ science program are revealing. As can be seen, the results of the work that Busemann did during that period have had a tremendous influence on the course of inertial confinement fusion research. Busemann wrote several papers on the focusing of shock waves, partly as a study of how to avoid the concentration of shock waves in flight and how to design “shaped charges,” configurations of chemical explosives that focus the detonation of shock waves on a target. These papers have become essential ingredients in the design of advance fusion fuel targets in inertial confinement fusion (see Figure 2). The energy concentrating capabilities of these configurations, especially Busemann’s conical con figuration have led many researchers to expect that chemical explosives can be used to ignite a fusion reaction. In fact, a Polish team of scientists reported in 1978 that they had generated a significant number of fusion neutrons in an experiment using high explosives in Busemann’s conical configuration! After World War II, Busemann moved to the United States in 1947 and worked with NASA at Langley Field in Virginia. There, Busemann studied the aerodynamic forces and surface heating of the starting and landing of space vehicles, while his more famous colleague, Werner von Braun, designed the propulsion systems at NASA’s Houston research center. As a sideline of this work, Busemann directed a seminar on electrodynamics, in the course of which he made some critically important discoveries on the existence and properties of magneto hydrodynamic (MHD) vortices. These vortices, which he compares to their hydrodynamic analogues, have turned out to be a central feature in most high-energy plasmas. In the past two years, Busemann’s work in this area has received renewed interest because it is now thought that the fusion machine that can most closely approximate the “natural” plasma vortex configuration will be the easiest to control and heat to ignition conditions. These new machine signs like the spheromak and the reversed field pinch are all variations on Busemann’s MHD vortex.

Bardwell:

The Fusion Energy Foundation has done a considerable amount of historical research on Riemann and the Göttingen School of mathematical physics. Our work has shown over and over again that the work that the Göttingen school undertook was the most productive, containing the deepest insights into scientific questions of fusion, for example. More recently, we have done some very specific research on the role of shock waves and shock phenomena in laser fusion. Out of that work came our attempt to do a new appreciation of Riemann’s work. In doing that, we came across a whole series of researches that I think are largely unknown — in the United States, at least — by yourself, Karl Guderley, and the people in Germany in the 1920s, 1930s, and 1940s, researches that are not appreciated in this country at all. A lot of current research seems to be going through that same material again. What I would like to do in this discussion with you today is to get your insight into that history — why certain things were done, what was done, and the importance of those things today.

Busemann:

In the early years, in 1904, we already had a wind tunnel for studying supersonic speeds. We saw a lot of black things in the photos that were not always shocks. Sometimes it was when the humidity of the air was high; then there would be some black spots on the photographs, too. But the important thing was the shock. In supersonic situations, you cannot avoid getting shocks, no matter how low the angle of the tip [the wing]. This was already Prandtl’s main interest at Gottingen. He had lots of people working on high speeds during World War I. After the war was over, Germany wasn’t allowed to work on practical airplanes anymore. Of course, in turbines, too, you very often have supersonic speeds, at least in the first stages of the turbine — not in the later ones. But Prandtl’s researchers just wanted to get an idea of the compressible flow for any kind of application. The application for airplanes seemed out of reach or suppressed.

Bardwell:

Was there already research on supersonic flow in turbines say in the 1920s?

Busemann:

Yes. I worked as an engineer and had learned in college, of course, about steam turbines and things like that. They were already invented. Therefore, we wanted to see how to make them most efficient — how to get the most energy out, put the least into a reversed flow, and reduce energy losses. But Prandtl’s researchers were a little bit spoiled, because at the first Mach, at around 1.6, when two lines indicating pressure changes are going through each other, they stay straight — it doesn’t look like they interfere with each other. They were spoiled because that was where the lines should have changed their curvature from one side to the other, but near the turning point there was just no curvature at all. Therefore, when I came I wasn’t so spoiled. I said when this is not so linearized; finite disturbances have to interfere with each other. When one goes through the other one, it has to change its direction. And of course, the Mach number in the wind tunnel that I had at that time was already a little bit lower. There was already a visible curvature in a certain direction, and therefore when I came in I worked a little bit more on how to produce a picture predicting the interference of two crossing Mach waves.

Bardwell:

What year was that?

Busemann:

I got my doctorate in 1924, and then I went to work with Prandtl in 1925. I stayed with him until 1931, when he “sold” me to Dresden. Those were bad times. There was a young assistant there at Dresden who died before he was 33, and then there was a free opening. Those were pretty bad years. Some people didn’t know if they should change their subject of study. America also had very bad times then. But when you lose a war, you can’t be so much better. Even when Germany had just recovered in 1929-30 and therefore seemed kind of high up, America seemed to be very low. Because of the economy, Prandtl couldn’t keep so many people at his institute. The ones who could get other jobs. At a certain institution for aerodynamic research, they told three people, “One of you has to go. You select him.” The workers came back and said, “Well, we would rather take two thirds of our salaries and stay on here.” Perhaps one of them was a boy with a rich father, and they asked him to ask his father for help. They were bad times.

Bardwell:

When did you go to Dresden?

Busemann:

Prandtl couldn’t keep everybody at Gottingen, so I went to Dresden. I had already agreed to a 10 percent smaller salary there. And then all of a sudden, one year or another, the governor of Saxony said that everyone had to give up one tenth of his salary. So I lost not only my voluntary 10 percent at Göttingen, but another 10 percent. One or two people said it was illegal. But they said it couldn’t be helped; it was the government’s order. So I lost 20 percent. Surprises like this don’t go so well when you can’t afford to live on less than the total amount of your salary.

Bardwell:

Was there a laboratory there in Dresden?

Busemann:

In Dresden there was a laboratory for applications of aerodynamics for engineering turbines and things like that. And although you weren’t supposed to say it, it was for airplanes, too. While I was at Dresden I got invited to the Volta meeting [the 1935 European meeting in Italy that laid the foundation for supersonic aerodynamics]. And there we could say that Dresden was working on applications to aviation — but for 100 years in the future. But it didn’t take long — just 10 years later Germany had a war.

Bardwell:

Were you thinking of those turbines for jet engines, or was it still the aerodynamic question of wing design?

Busemann:

We had supersonic wing shapes, to have less drag and lots of lift. That was the subject I got to talk about at Volta, since I had worked on that. They invited all the people who had worked on high speeds to the meeting in Volta, Italy in 1935. The subject was high-speed subsonic and supersonic flight. And they invited all the winners of the Schneider Cup to talk about how they had built their airplanes for this special use and what their thinking was about engine changes, the wings, and things like that.

Bardwell:

Did Germany have an entry in the Schneider Cup race?

Busemann:

No. We were not allowed to enter. The first race was in 1913, I think, and the last one was in 1931. But during the First World War, there were no Schneider Cup races. I don’t know whether Germany had a chance to take part between 1913 and 1914; and in 1918, they told Germany in the peace treaty, “no more airplanes anymore for you.” We would supposedly only try to make war with them, to shoot things and throw things at other countries. Prandtl, Ackeret, and I were invited to Volta. Ackeret was another pupil of Prandtl. He is now 80 years old. He’s alive in Switzerland. [Ackeret died March 27, 1981 at the age of 83.] He talked about wind tunnels. Prandtl talked about the experience of the early years. I talked about lift at supersonic speeds. And von Karman [Theodor von Karman, a Hungarian scientist working in Germany who emigrated to the United States before World War II] talked about drag at supersonic speeds. I had the Busemann biplane. The idea was, when you are interested in getting no lift, you can use two surfaces and send the waves back, and they cancel each other out in between. You can have this cancellation at lower Mach numbers, at higher concentration of shock waves, so that you can have a finite volume of parameters that makes no wave drag. Of course, it makes a lot of friction drag, especially when you have four surfaces instead of two — the outside and the inside. The friction drag is at least doubled. And when you have separation, you may have more than just friction drag; therefore, you have to be very careful about it. That was von Karman’s idea; it was his business to talk about that.

Bardwell:

What about your work on the conical focusing of shock waves?

Busemann:

During the war, I wanted to write a book about my new ideas, but I wasn’t allowed to do it, since I was so much involved in secret things, than even when I didn’t intend it, they might just pop out. I gave the introduction to a secret meeting about shaped charges. The Academy [German Academy of Sciences] wanted one speaker, as a member of the Academy, and they chose me. These [pointing to one of the view-graphs he used in his talk] are steady flows, and I made another view-graph to represent non-steady flows. I wanted to publish this, but they didn’t allow me. In this non-steady flow, if you want to put it on two- dimensional paper, you can put the time in one direction and then there’s only one direction left. Therefore, you can study non-steady pipe flow created by pistons on both ends. I extended my studies to non-steady waves going through a conical pipe. This focuses the pressure. (That’s what people like — to make shaped charges, so that they can put them on a jeep or something, and then it really makes a hole.)

Bardwell:

This is the Idea the Russians use extensively in their work on fusion. This idea of the conical focusing of shock waves comes from you. Is that right?

Busemann:

Yes. Since I had only one direction left, I could only make a circle — a cylindrical one or spherical one, so that I didn’t have to make changes except on one radius. It is usually nicer to have one dimension, or three dimensions, or something odd-numbered. If it’s even numbered, the mathematics of it is sometimes a bit harder. Therefore, when I make a steady flow, I can make it only two dimensions. I make the drawing on a plane, and then I can show the space in one direction only, and there must be an identical thing around in however many directions you may wish [That is, it must be independent of the other coordinates]. Therefore, I could make it spherical, and that was what they liked best.

Bardwell:

When did you start that work?

Busemann:

After I was through with the work on the steady flow one, I started work on non-steady flow in Dresden.

Bardwell:

You had a paper in 1942 or 1943 on self-similar solutions to spherical shock waves?

Busemann:

Yes. That was my introduction lecture at the secret meeting I mentioned, since I wasn’t working on explosives, but on non-steady gas dynamics.

Bardwell:

So it was in the late 1930s in Dresden that you started on this research on shaped charges?

Busemann:

No. Just on non-steady gas dynamics. The steady dynamics were now finished — at least what you could put down in two dimensions — and the other ones had to wait until they invented movable wings. For non-steady dynamics, you’d have to open the wing up and close it, and how can you do that on an airplane? And you’d have to make hinges on it, doing that when you have no lift. But, you see, the flow that I drew on that biplane is not unique. It. can be what I’d like it to be. It can be at the same time a choked thing; and then it would spill the air around on the sides instead of going through the middle. When the flow in the inside is not exactly what I want it to be, then it doesn’t go through — the same amount of fluid doesn’t go through, but comes back. You see, when we choke the flow for a while, then the airplane goes through sonic speeds. Then the flow goes around, and it doesn’t come back to this one [pointing to one wing of the biplane] unless it starts from the sides where there is an opening and then goes around; and it doesn’t come back to this one [pointing to the other wing in the biplane] unless it starts from the sides where there is an opening, and then goes slowly through the middle. The people in Rome [at the 1935 European conference] were very much interested to see how you could get that thing that you want stable, or to come back to that when something else came up. That was resolved by using very nice shapes, but the flow doesn’t always do this — you have several solutions for the same thing. You choke the flow in one place, and then you have a minimum cross section there. And at sonic speeds, you cannot reduce your cross section anymore. Therefore, you have to throw something around on the right side; there is a shock coming, and this shock will never disappear unless you give it a chance. When you have an airplane that goes from subsonic to supersonic speeds, you have to learn to make the dynamics stabilizing. The Ronan’s worked very hard on this one: right after 1935, they tried it out at their new center for supersonic wind tunnels — how to get the design of flow. From 1935 to 1945, the Italians were very much interested in getting higher speeds. They wanted not to be second, but to be among the first to work on supersonics. Especially after this 1935 meeting, supersonics was a little bit closer to human possibility — in spite of the fact that at the meeting itself, they were still talking as if the future were far away. They made the Busemann biplane at their workshop; they made a picture of the Busemann biplane with kind of swastika propellers on it — you see, at high speeds, you get a better thing when you go Mach, and therefore the propellers, which were usually straight, were bent like birds’ wings. I didn’t have to invent it — I had seen enough of it already. And only the man from NACA [National Advisory Committee for Aeronautics the predecessor to NASA], Richard Whitcomb made it not two but one. He made supersonic speeds with changed angles, but not forward — not symmetric, but asymmetric. The body goes in the proper direction as the flow goes, but the wing is tilted over. You would have to find out from the pilot whether he thinks it is stable enough and would not kill him. But he could show in the wind tunnel that it works, and when you make it symmetrical you know it works yourself — when you go backward especially. When you go forward, it probably goes one way or the other, and you are dead. But when you make it backward, you know that it has certain stability. When you make this straight, you get more drag than this one. When you go in another direction, you get much less; therefore, it was not necessarily so that it was stable. This man Whitcomb, he made it so, and then he had no trouble in the middle to say what the flow was supposed to do. He made his plane body go through the velocity of sound with the optimum shape, to get through the worst drag. Sometimes the plane had to fall down, since the engine and its propellers didn’t have enough thrust to get through them. Therefore, they went up to 0.9, and then they fell through Mach 1, but using gravity, and they landed on top of the propeller. Really, it was a very difficult time, but very interesting subject they were working on. And in Italy in the 1930s, our meeting was not only to show off that the Italians had the better airplane. During the meeting we went to that new center of research that the Italians had built in Guidonia near Rome. They had one part where they invited the winners from the Schneider Cup, and the other part was for the scientists who had worked on building wind tunnels. In the practical part, the people showed off what they did in their Schneider Cups. They were the winners, and they were invited to show how they came to their ideas. The second part was the more scientific part, where things were so far from practical that we would all be dead before they would be used.

Bardwell:

So it was in the late 1930s that they were working on these supersonic wing designs and the rest in their wind tunnel. Were you still at Dresden then?

Busemann:

Yes, and I built my wind tunnel. But then, when Hitler didn’t care about the conditions of the peace treaty and started to fly again, there was a new center in Braunschweig. There I built my own wind tunnels. I came to Braunschweig in 1936. Then I had a really different, transonic kind of a tunnel, with a very large diameter, and a supersonic tunnel with a small cross section. And I also had a rocket test facility in the country. It was in the country, because a lot of people who invented rockets died from the explosions; therefore, we couldn’t build in the neighborhood of the town. But I had to go there a couple of times every month to see what they were doing. Therefore, my problem was at that time not only wind tunnels, but rocketry, too. It was then that I got to know von Braun. We Germans talked to each other so that we didn’t spend a million reichsmark on the same experiment. When they had experience, they told me about it, and when we wanted a new experiment, we told each other. Of course, it is sometimes very good for two different people to test the same thing. But we were not supposed to do that.

Bardwell:

What was the motivation for the research you did on self-similar solutions in spherical geometry?

Busemann:

The similar solution was, I had no more than two dimensions.

Bardwell:

But did this come out of research for explosive design, or for jet engines? I am thinking of the paper by Guderley, for example, that appeared at the same time as your paper in the Luftfahrtforschung on cylindrical focus?

Busemann:

Zylindrische Verdichtungschicht. Yes, sometimes we had real vortices; sometimes we had questions in our wind tunnel — there was not an understandable way of how the flow went around certain bodies we put in there. Sometimes we had people during the war who wanted to build a new kind of airplane for the Germans, and then we had real problems. They were, of course, secret, and we couldn’t talk about them. But they needed our wind tunnels, because they did not have wind tunnels for all speeds in their own factories. And then they came to us. Guderley was very good at applied mathematics. I talked to him, and I could use him for a lot of problems. I was more in mechanical engineering work than elasticity. When I earned my doctor’s degree and came to Prandtl, I learned to have ideas about the flows, so that I had it in my head and didn’t need wind tunnels for everything. In that way, I learned to construct them; but, of course, you cannot construct wind tunnels in three or four dimensions on your drawing board. Therefore, it was a little bit oversimplified when we did it in two dimensions. But we had ideas about what would happen at the end of the airplane, when the air can go around it instead of the other way. Then there were the vortices that Prandtl needed in order to explain the drag related to the lift.

Bardwell:

There’s a lot of work that was done on the focusing of shock waves — cylindrical spherical focusing. What was that directed toward? In fusion research, this is really the key problem. Can you concentrate the compression from a shock wave? Can you use reflections to amplify it? Can you bring it down to a point? And that work was already going on in the 1940s in Germany. To me, that’s fascinating, because the basic problem today was researched 25 or 30 years ago in tremendous detail.

Busemann:

At that time our idea was more to get rid of strong shocks, not to make them stronger. It was only my cone that couldn’t help but to get stronger and stronger all the time.

Bardwell:

But nobody looked at that for compression research?

Busemann:

We sometimes were interested in finding out how difficult it was to live with these detached strong shocks, to see whether to make a wedge or something. We wanted to know whether that really helps to reduce the drag, or whether these things have a boundary layer separation as a part of what happens there, too, so that the drag looks much higher than it really should be by itself. We did a lot of things in our workplaces with just mathematics and thinking, but when there was a problem that really had to be solved; we could get enough money to put it in the wind tunnel. That was usually a little bit more expensive. On the other hand, when anybody didn’t have a problem to work on, he would be drafted.

Bardwell:

Did anybody think at that time of something like a fusion reaction — of using the very high densities of high temperatures that these focused shock waves could generate?

Busemann:

Not for fusion, but we thought about making the explosions a little more concentrated, so that when somebody had a big shield, any bullet would make a big hole in it. But, of course, every day it was different, and there could be a change. If anybody who worked on these problems was not important anymore, he would have to go to the war. And then we would have to change our subject to something that Hitler thought was important. But he really had few ideas that we thought were important overall. Only when the Americans came over there flying higher up and we had no guns that could shoot that high, only rockets that could fly that high, did Hitler call for a meeting. His people came to ask us to improve the bullets and the cannons, to kill the enemies that were flying so high. And then afterwards they said to Hitler, “Yes, we can make it.” “And how long will it take?” Hitler would ask. “Three years,” they said. “Oh! Three months, that’s all I can give you,” Hitler would say. So they had to pretend that they could find something in three months. He was a crazy guy. Therefore, it was very hard to have a certain group of people working for you and keep them together.

Bardwell:

So that work was mostly for the design of supersonic airplanes?

Busemann:

There were people in Munich or Nuremberg who worked on supersonic airplanes. Oh, there was also this thing called a buzz bomb that flew with a high velocity. And the one that flew with really supersonic speed was, of course, von Braun’s. In order to try out Hitler’s bombs, they had to have an airplane to put them underneath.

Bardwell:

The same idea today is the Cruise missile…

Busemann:

We were really interested in having a good picture of what goes on in supersonic flight, or what happens when you get closer to the velocity of sound — what makes you unstable, or gets the lift down or the drag so high that nothing can help you. But in order to keep my people paid, I had to adjust them to what Hitler thought was important. Therefore, when those people couldn’t make any kind of gun with the necessary range, Hitler asked whether von Braun could make a rocket that would go high enough to kill the airplanes that were coming and throwing bombs. We even had this silly thing — the buzz bomb — that had a gasoline engine that went putt, putt. It made a lot of noise, because it opened and closed in alternation. Its path was controlled by its tail, and when the tail got stuck on one side, it made a circle. And the circle was exactly the total length at which distance it was supposed to explode the bomb. So it fell on the people who sent it up! The silly tail was supposed to steer the thing to the right point, but it very often got stuck on the left-hand side. It made an exact circle and boom! That was the buzz bomb. And from Belgium, where they tried to launch the bombs against London, they made the circle so large that it was just the distance from where they were to London. There were lots of things we had to do during the war. And they threw out even von Braun because von Braun said: “When you send a bomb against a foreign country, an enemy country, you have to put it on the target — you cannot just throw it, because London is too big — a 10-mile radius circle is too big. It is illegal to kill people too; you should kill things that are made for the war.” Therefore, von Braun tried to make guidance on the bomb, and after one year when the guidance didn’t work, Hitler said, “He’s delaying the thing,” and sent him away. Hitler put in another man, the man who made the trains for Russia. (The Russians had a different kind of track, and therefore this man had to make trains that worked only on the Russian track, or that could change from one track to the other.) This man got the job to make the bombs ready in three months; they said von Braun was not interested in wars, because he was so slow. Under Hitler, you really could get into trouble without doing anything bad. People would finger you because of something you did for a different reason. At that time, our publications were often secret. Therefore, I cannot always find the work I did at that time — unless my papers were in a big box that the Americans found so that they were not burned.

Bardwell:

I think that much of that research is still secret in the United States.

Busemann:

Some was translated after the war.

Bardwell:

But it’s still secret here. You say that most of your work was done not for research on shaped charges, however, but mostly for aerodynamic research? Yes, the part I did on it. But when I was supposed to give an introductory talk on these shaped charges, I just demonstrated the things you can do with the waves that go in focus.

Bardwell:

Did you come to the United States in 1945?

Busemann:

No. I was on the English list. The English soldiers saw that America was getting all the German scientists, and they knew that the British needed some too. So they put me as one of the first scientists on the British list. But the people in Britain said, the thing that we need is not chiefs — what we need is Indians to help. During the war they had a lot of women and others who wanted to help, but they went home after the war and didn’t work in the laboratories anymore. After six months, there I was in several different places just talking about results that we got during the war. They brought me to a lot of universities, but nobody wanted me. So I finely asked my American friends whether there was still a chance to come to America. And then, because I did that by going to the American embassy, I was — what do they call it in England when they don’t trust you anymore? A persona non grata. I was sent back home to Germany the same day, when they found out through the Secret Service that I had contacted the Americans. While in England, I had wanted to raise a little bit of money. I had three girls almost at the end of school — college age — and, of course, we had lost all of our savings in the inflation right after the war. I just wanted to tell them, look; in America I could get a job for more money. They actually told me they tried very hard to “sell” me, but nobody wanted me; no university, no other place of research. So the British allowed me to go away, but they called me, of course, a persona non grata.

Bardwell:

So you came to the United States in 1946?

Busemann:

In 1947, I was in England from 1946 until February 1947. Then they sent me home, and in May 1947, the U.S. Occupation forces picked me up to be transported to America. I came to NASA, since both the Navy and the Air Force was fighting over who would get me — neither got me.

Bardwell:

In some of the research I’ve done in plasma physics, your work in magneto hydrodynamics in the 1950s on vortex formation is very important. How did that work start — the work you did on plasma or magneto hydrodynamic vortex motion? That work seems very different from aerodynamics.

Busemann:

Yes, but it was a new subject, and in research you have to keep up to date when you are a senior research man. Therefore, I had seminars with people who worked on this problem. You see, at first I was an e1ectrical engineer, because when Germany lost the First World War, I took every subject that I thought was important for Germany. Therefore, I studied electrical engineering too, including electrical physics. My physics teacher in the Technische Hochschule university was very nice to me and taught me everything about relativity, which was new at that time. I studied it in 1923-24. I had learned fluid dynamics more from electricity, and, therefore, when they started this magneto hydrodynamics, I would go back and do it the proper way. I mean that electricity is not a real flow, but for magnetism, you need electricity. And that was my old subject, which I used to compare hydrodynamics with electricity. Therefore, it was easy for me to be the boss of the magneto hydrodynamics seminar in Langley Field. You see, when you begin a new subject, the young people have no prior experience; they’ve learned it only from books, but I could compare it with the things I had learned before and played with already, so I could be an important man in this seminar.

Bardwell:

What relation do you see between the research on vortex motion and shock waves?

Busemann:

The electricity had no shocks. I don’t know; we never made a real application. There were other NASA centers that were working on magneto hydrodynamics. I worked on magneto only for a short time, and then I came to Boulder in order to make this a center of excellence in aerospace. Well, the space things were so important that we worked on vortices only on the side. We had to make real space progress.

Bardwell:

Did you work with von Braun on space rockets and that kind of thing?

Busemann:

No. He was in another area. I was in Langley Field, where we did see supersonic parts and things like that where they built the equipment for Langley. Magneto was just a side subject that we worked on. You see, when you work on the same chapter day and night, you get yourself into a corner. Sometimes you are better off if you leave it and come back after a week and you say, why didn’t I see this before? Of course, when it’s a very important subject, and has to be done by October, say, you can’t go into something else at night. At Langley we sometimes had to work on a certain problem that they gave us, and sometimes in between we had a little bit of time off, so that we were not stuck on the same old thing. Very often NASA asked us to tell them about supersonics or about how to get out to space. The different space research centers didn’t get money for everything. They had a special subject matter in which they had to prove they could work well. We worked in this aerodynamics business, what goes into space and gets out of orbit into the atmosphere. As for rockets, of course, it was von Braun’s problem. He worked on that one at a special center in Houston. Some guidance people were somewhere else — at the Ames Research Center, I think. But when von Braun had a question about supersonic drag or lift or whatever, or whether the proper flows would come automatically or had to be readjusted, of course he would direct the question to the Langley Center.

Bardwell:

How long were you at NASA?

Busemann:

I was with NASA from 1947 to 1964, and then I came here, to the aerospace section of the University of Colorado. My problem was that because I had secret information, I was not allowed at Langley to tell the Germans to give me my earned retirement pension. They told me that I couldn’t be dependent on a foreign government. I was to be retired from Langley Field not later than age 70, but before I reached their retirement age, I accepted the invitation of the University of Colorado to come and hold a “lifetime” job.