Category Archimedes


The story recounted here was, in sum, about the success and the failure of Leonard Bairstow. The whole story turned on the scientific and technological significance of the key instrument for aeronautical research: the wind tunnel. Bairstow made full use of it, defended the validity of the data from it, and argued for the continuation of model research in it. He further promoted the attempt to standardize the performance of wind tunnels all over the world and to accord the NPL a central role. For all these efforts to connect the inside and the outside of the laboratory, I compared him to a laboratory director in Latour’s Science in Action and Pasteur in Pasteurization of France.

At first, Bairstow was exceptionally successful. His prewar stability research was applauded at home and abroad. Despite an American request, the British regarded it too important to disclose. Through such accomplishment, Bairstow attained fellowship in the Royal Society, served on the Air Board, and became Professor of Aeronautics at Imperial College. He became an extremely powerful figure in the British aeronautical community.

Bairstow’s position would have been further enhanced had the NPL model of wind tunnel research been standardized around the world. That was one object of the decade-long International Trials project. During this project, however, it turned out that Bairstow’s previous argument for ignoring the scale effect was called into question. Prandtl’s new aerodynamic theory challenged Bairstow’s position. French use of the Prandtl correction sparked a scientific debate on the validity of Prandtl’s aerodynamic theory. Acceptance of the Prandtl correction implied criticism of Bairstow, who had insisted on the negligibility of the scale effect.

While Bairstow served as an excellent middleman between theoretical scientists and practical engineers in conducting model research on stability, he failed to be such a middleman between Teddington and Famborough. He might have been more sensitive and generous to the full-scale experimenters at Famborough, initiating a theoretical and experimental research program on scale effect. Instead, he defended his model research like a lawyer at court by pointing out possible weaknesses in full-scale testing. Perhaps the wartime emergency and the position of the Air Board prevented him from taking a more discreet stance on this matter. In any event, he left himself open to later criticisms and repudiation. In the end, the renamed Scale Effect subcommittee approved the desirability of constructing a new variable-density wind tunnel developed by American engineers. This was a clear judgment that Bairstow had been wrong.

If we take Latour’s argument seriously, we could pose a question. Why did Prandtl’s theory prevail in the postwar world? From 1904, when he arrived at Gottingen, to 1918, the year of armistice, Prandtl succeeded, like Bairstow, in conducting aerodynamic research and expanding his research facilities. But after the war, he was placed in severely limited conditions on poor financial and material bases and with almost no communication with foreign investigators. Yet his aerodynamic theory soon won over aeronautical engineers all over the world. It was mainly not through Prandtl’s own effort but through the efforts of foreign engineers, and his disciple in the case of the United States, that his theory was accepted worldwide. In this connection, we could turn our attention to the RAE engineers who championed the introduction of Prandtl’s theory in Britain. In arguing for the validity of the German theory and specifically promoting the application of Prandtl correction, they succeeded in restoring the position held by their colleagues at Famborough in the wartime scale-effect controversy.64


Vandervoot Walsh, an assistant professor of architecture at Columbia wrote in 1931: “I suspect most engineers believe that the correct method of designing an airport is to let them lay the whole thing out, insuring its practicability: and then, if there is any money left, to call in an architect to spread a little trimming around on the outside of the buildings to make them look pretty.”54 Walsh felt that engineers believed that they could design an airport without an architect. The architect, suggested Walsh, did not share the same conviction about his own skills; the architect “understood” he could not design an airport without the help of an engineer.

Walsh was hardly arguing that an architect was superfluous, rather his article was a strongly-worded declaration of the architect’s rightful place in the design process. The value an architect provided was not in the “trimmings”; in fact, using an architect in this way was surely a waste of money according to Walsh. “Flying will never become generally popular until airports become more than merely practical and safe. They must affect the human emotions, establishing a mental state of ease through a feeling of comfort, safety and other emotions producing pleasure.”55

By the beginning of the 1930s, airport engineers embraced the idea that airport design should pay consideration to psychological factors. They agreed with the architects that the physical appearance of the airport help convey the image of permanence while disguising the very real discomforts and hazards of aviation. The question was to what degree and at which phase of the design process should they be incorporated. Further, there was no established mechanism for coordination between engineers and architects. As Walsh wrote, “practically no engineers have the training which architects have in the technique of keeping the planning in a very plastic condition, capable of quick changes as new and better ideas pass through the mind.”56 On the other hand, few architects understood the dynamics of airplanes and aircraft movement. Architects emphasized in their airport designs the idea of maximizing the functionality of the buildings; airport engineering design emphasized the functionality of the airplane.

It is important to keep in mind that airport design was more complicated than the design of a single facility. What becomes clear is that despite the assertions of the architect, both the architect and engineer were vitally interested in the problems of transfer. However, for the architect “transfer” was a local, small-scale phenomenon – how to get passengers between airplane and car, train, or bus. For the engineer, the problem of transfer was how to get passengers in and out of the air so that they could get from one airport to another.

There was no real resolution of competing claims for technical expertise over airport design in 1931 and 1932, just an acceptance that the amount of money being spent and the increase in passenger traffic had dictated a much more complex set of solutions to the problems of airport design. There was a consensus that airport design had to address two fundamental problems – takeoff-and-landing and transfer. As the matter of take-off and landing still was seen as the more pressing of the two problems, the engineers enjoyed the upper hand; but their visibility, if not their influence, was waning. Architects spoke more eloquently and effectively and captured public imagination. Architects proved much more adept at embedding the rhetoric of the American cultural ideals of progress and modernity in their descriptions of airport design. Again, Vandervoot Walsh provides a good (if lengthy) example:

Since we must admit that one of the grandest achievements of the human race is its newly acquired power to fly, then no airport is worthy of its existence if it does not express in its form the poetry of this great event. … There are others who say that the days of story-telling in archi­tecture are over, that all buildings have essentially become machines – cold, inhuman, efficient, doing their work with precision and speed. Let us hope, though, that the builders of airports will have a bigger vision than this, that engineers will realize that with human beings there is a spirit as well as body that must be satisfied. And that they will be willing to cooperate with architects to make these places of embarkation into the skies worthy of the great science of aviation.57

The reduced visibility of airport engineers was not really due to a lack of poetry but rather the fact that their profession was undergoing significant change. In 1931, Archibald Black expressed his concern for the “vanishing airport engineer” in a brief polemic published in The American City. Black was correct when he noted that there were fewer airport engineers but what was disappearing was the airport engineer who functioned in the same manner as the medical general practitioner – student of all the major airport systems but true expert in none. That airport engineer was about to be replaced by a new type – one more fully engaged in the technological problems of making an individual airport system function within a national system of airports and air transportation. That change was a direct consequence of the new involvement of architects in airport design.58



The field of aerodynamics is frequently characterized as an applied science. This appellation is simplistic, and is somewhat misleading; it is not consistent with the engineering thought process so nicely described and interpreted by Vincenti.1 The intellectual understanding of aerodynamics, as well as the use of this understanding in the design of flight vehicles, has grown exponentially during the twentieth – century. How much of this growth can be called “science”? How much can be called “engineering”? How much falls into the grey area called “engineering science”? The purpose of this paper is to address these questions. Specifically, some highlights from the evolution of aerodynamics in the twentieth-century will be discussed from an historical viewpoint, and the nature of the intellectual thought processes associated with these highlights will be examined. These highlights are chosen from a much broader study of the history of aerodynamics carried out by the author.2

For the purpose of this paper, we shall make the distinction between the roles of science, engineering, and engineering science as follows.

Science: A study of the physical nature of the world and universe, where the desired end product is simply the acquisition of new knowledge for its own sake.

Engineering: The art of applying an autonomous form of knowledge for the purpose of designing and constructing an artifice to meet some recognized need.

Engineering Science: The acquisition of new knowledge for the specific purpose of qualitatively or quantitatively enhancing the process of designing and constructing an artifice.

These distinctions are basically consistent with those made by Vincenti.3

There is perhaps no better example of the blending of the disciplines of science, engineering science, and pure engineering than the evolution of modem aerodynamics. The present paper discusses this evolution in five steps: (1) the total lack of technology transfer of the basic science of fluid dynamics in the nineteenth century to the design of flying machines at that time (prior to 1891); (2) the reversal of this situation at the beginning of the twentieth century when academic science discovered the airplane, when the success of Lilienthal and the Wright brothers


P Galison and A. Roland (eds.), Atmospheric Flight in the Twentieth Century, 241-256 © 2000 Kluwer Academic Publishers.

proved the feasibility of the flying machine, and when academicians such as Kutta and Joukowski developed the seminal circulation theory of lift and Prandtl introduced the concept of the boundary layer, all representing the introduction of engineering science to the study of aerodynamics (1891 – 1907); (3) the era of strut and wire biplanes, exemplified by the aerodynamic investigation of Eiffel, who blended both engineering science and engineering in his lengthy wind tunnel investigations (1909 – 1921); (4) the era of the mature propeller-driven airplane, characterized by the evolution of streamlining, representing again both engineering science and engineering; (5) the era of the modem jet propelled airplane, including the revolutionary development of the swept wing (see also the companion paper in this volume, “Engineering Experiment and Engineering Theory: The Aerodynamics of Wings at Supersonic Speeds, 1946 – 1948,” by Walter Vincenti). In the final analysis, we will see that the naive “engineering versus science” alluded to in the title of this paper fails to hold up, because the evolution of aerodynamics in the twentieth century was characterized by a subtle integration of both.


Part of the reconciliation between airport engineers and architects was stimulated by their mutual confidence in the utility of city planning in the design process. In a commentary on a paper presented by Donald Baker at a major meeting in 1928 of the American Society of Civil Engineers’ City Planning Division, John Nolen, one of the nation’s preeminent city planners, wrote: “As an outstanding feature of modem transportation the airport has an effect upon the city or urban community as a unit. To choose a site without consideration of all the elements of the community composition may mean that either the city may be injured by the location given over to the airport, or, in turn, the airport may not be so situated as to serve the city economically; or still worse, it may be so placed that it cannot develop business either from the city or serve as an adequate and safe stopping point on an airway for traffic from outside.”59

What Nolen and others were suggesting was a new way of understanding the specialized contributions of engineers and architects. In the minds of city planners, neither the engineering nor the architectural treatment of an airport facility

constituted the only issues guiding airport development. Good airport design, according to Nolen, necessarily incorporated “mastery not only of the physical conditions, but also a firm grasp on their financial and economic relations under appropriate statutes, laws and regulations.”60

City planners believed their endeavors to constitute a “scientific profession,” derived from a fundamentally different basis from that of engineering or architecture. John Nolen, wrote that “successful town planning cannot be the work of a narrow specialist, or of a single profession. The call is for versatility, special knowledge and cooperation. For town planning is engineering plus something; architecture plus something; or landscape architecture plus something….”61 Nolen was keenly interested in airports. He wrote several papers about city planning and airports, was an active public speaker on the subject, and most importantly was hired by several cities to design their airports. Nolen’s philosophy of city planning was that excellent results could only be achieved if social and economic factors were considered as seriously as demographic, aesthetic, and technical criteria. This produced a strikingly different outlook on airport design than existed in the aviation community. For example, when Commerce Department officials were in the midst of their crusades to persuade American cities to build airports, John Nolen stated unequivocally to a meeting of the Aeronautic Section of the Society of Automotive Engineers that the locations of the nation’s most important airports had already been determined. Simple “boosterism” was not particularly useful to Nolen’s way of thinking.62

Most city planners shared Nolen’s assessment. Airports were like bridges, connecting formerly-separated regions and like real bridges, they had the potential to alter the economic geography of the nation. The “bridge” had little value if it was not integrated with all other modes of transportation. The third part of airport design then, was identified as connecting the airport with the local systems of ground transportation.63

By the mid-1930s, engineers, architects and city planners were all engaged in the problems of airport design. Each profession viewed the technological possibilities of an airport from very different perspectives. This might have resulted in vigorous professional competition yet, instead the engineers, architects and city planners came to embrace each other (albeit warily) in a way that resulted in a synthesis of airport design concepts. There were several diverse factors contributing to this result including the full integration of radio into airport technology; the introduction of an entirely new type of aircraft, the so-called “modem” airliners; the political and economic circumstances of the 1930s that led to the Roosevelt Administration’s dramatic increase in federal investment in airports; and an abiding American fascination with aviation and its seductive promise of speed. How these factors helped bring together these three groups of professionals is perhaps best shown through a brief recounting of the development of LaGuardia Airport in New York.


To understand the relationship of science and engineering to aerodynamics in the twentieth-century, we need to examine briefly the completely different relationship that existed during the nineteenth-century.

The history of aerodynamics before the twentieth-century is buried in the history of the more general discipline of fluid dynamics. Consistent with the evolution of classical physics, the basic aspects of the science of fluid dynamics were reasonably well understood by 1890. Meaningful experiments in fluid dynamics started with Edme Mariotte and Christiaan Huygens, both members of the Paris Academy of Science, who independently demonstrated by 1690 the important result that the force on a body moving through a fluid varies as the square of the velocity. The relationship between pressure and velocity in a moving fluid was studied experimentally by Henri Pitot, a French civil engineer in the 1730’s. Later in the eighteenth-century, the experimental tradition in fluid dynamics was extended by John Smeaton and Benjamin Robins in England, using whirling arms as test facilities. Finally, by the end of the nineteenth-century, the basic understanding of the effects of friction on fluid flows was greatly enhanced by the experiments of Osborne Reynolds at Manchester. These are just some examples. In parallel, the rational theoretical study of fluid mechanics began with Isaac Newton’s Principia in 1687. By 1755 Leonhard Euler had developed the partial differential equations describing the flow of a frictionless fluid – the well-known “Euler Equations” which are used extensively in modern aerodynamics. The theoretical basis of fluid mechanics was further enhanced by the vortex concepts of Hermann Von Helmholtz in Germany during the mid-nineteenth-century. Finally, the partial differential equations for the flow of a fluid with friction – the more realistic case – were developed independently by the frenchman Henri Navier in 1822 and the englishman George Stokes in 1845. These equations, called the Navier-Stokes equations, are the most fundamental basis for the theoretical study of fluid dynamics. They were well-established more than 150 years ago.

Thus, by the end of the nineteenth-century, the basic principles underlying classical fluid dynamics were well established. The progress in this discipline culminated in a complete formulation and understanding of the detailed equations of motion for a viscous fluid flow (the Navier-Stokes equations), as well as the beginnings of a quantitative, experimental data base on basic fluid phenomena, including the transition from laminar to turbulent flow. In essence, fluid dynamics was in step with the rest of classical physics at the end of the nineteenth-century – a science that was perceived at that time as being well-known, somewhat mature, with nothing more to be learned. Also, it is important to note that this science was predominately developed (at least in the nineteenth-century) by scholars who were university educated, and who were mainly part of the academic community.

The transfer of this state-of-the-art in fluid dynamics to the investigation of powered flight was, on the other hand, virtually non-existent. The idea of powered flight was considered fanciful by the established scientific community – an idea that was not appropriate for serious intellectual pursuits. Even Lord Rayleigh, who came closer than any of the scientific giants of the nineteenth-century to showing interest in powered flight, contributed nothing tangible to applied aerodynamics. This situation can not be more emphatically stated than appears in the following paragraph from the Fifth Annual Report of the Aeronautical Society of Great Britain in 1870:

“Now let us consider the nature of the mud in which I have said we are stuck. The cause of our standstill, briefly stated, seems to be this: men do not consider the subject of ‘aerostation’ or ‘avia­tion’ to be a real science, but bring forward wild, impracticable, unmechanical, and unmathematical schemes, wasting the time of the Society, and causing us to be looked upon as a laughing stock by an incredulous and skeptical public.”

Clearly, there was a “technology transfer problem” in regard to the science of fluid dynamics applied to powered flight. For this reason, applied aerodynamics in the nineteenth-century followed its own, somewhat independent path. It was developed by a group of self-educated (but generally we//-educated) enthusiasts, driven by the vision of flying machines. These people, most of whom had no formal education at the university level, represented the early beginnings of the profession of aeronautical engineering.

For example, this community of self-educated engineers was typified by the following: George Cayley, who in 1799 enunciated the basic concept of the modem configuration airplane; Francis Wenham, who in 1871 built the first wind tunnel; Horatio Phillips, who in 1884 built the second wind tunnel and used it to test cambered (curved) airfoil shapes which he later patented; Otto Lilienthal (who did have a bachelors degree in Mechanical Engineering), who carried out the first meaningful, systematic series of experimental measurements of the aerodynamic properties of cambered airfoils,4 and later designed and flew extensively the first successful human-carrying gliders (1892 – 1896); and Samuel Langley, 3rd Secretary of the Smithsonian Institution, who carried out an exhaustive series of well-planned and well-executed aerodynamic experiments on rectangular, flat plates,5 but who had two spectacular failures in 1903 when a piloted flying machine of his design crashed in the Potomac river.

Langley clearly stated the prevailing attitude in his Memoir published posthumously in 1911.6

“The whole subject of mechanical flight was so far from having attracted the general attention of physicists or engineers, that it was generally considered to be a field fitted rather for the pursuits of the charlatan than for those of the man of science. Consequently, he who was bold enough to enter it, found almost none of those experimental data which are ready to hand in every recognized and reputable field of scientific labor.”

Langley considered himself one of the bold ones. This is particularly relevant because in the United States at the end of the nineteenth century the position of Secretary of the Smithsonian was considered by many as the most prestigious scientific position in the country. Here we have, by definition, Langley as the most prestigious scientist in the United States, and he is turning the tables on the scientific community by devoting himself to the quest for powered flight.

However, the prevailing attitude abruptly changed in the space of ten years, beginning in 1894.


On Sunday, November 25, 1934, a front page article in the New York Times was headlined: “LaGuardia Won’t Land in Newark and Insists Liner Fly Him to City Airport From Rival Field.” “My ticket says New York, and that’s where they brought me,” said the beaming new mayor as he got off the TWA plane at Floyd Bennett Field.64 The whole incident was a carefully planned publicity stunt by Fiorello LaGuardia and his staff who wanted to announce dramatically his intentions to build a major airport in (not near) New York City. Five years later, 325,000 people joined the mayor to dedicate New York City Municipal Airport (renamed LaGuardia one month later) and another 1.5 million people plunked down a dime to inspect the airport operations during subsequent years, lured by the opportunity to see the world’s most modem airport.65

LaGuardia was seen as a kind of “crown jewel” in new national airport plans developed through the joint efforts of the Bureau of Air Commerce and WPA engineers. Describing the development of the LaGuardia, Fortune magazine noted that: “There is no such thing as an ideal airport. It doesn’t exist because the ideal geographic location for it doesn’t exist inside or adjacent to the metropolis it is intended to serve, symmetrical in all directions, possessing full wind coverage, and free from obstructions in its entire periphery. Most airports are a compromise.”66

Still, the site Mayor LaGuardia found in Queens on North Beach, the old Curtiss Airport, was considered nearly ideal. It fit into the city’s massive highway and parkway constmction program; it was on the water; the weather conditions were favorable; and the travel time into the city was projected to be nearly identical with Newark’s. Aero Digest added that “Instead of fitting the airport to its surroundings, handicapped by the terrain or the nearness of buildings, it was possible there to plan runways of ample length to meet the increasing requirements of the modem airliner and a rapidly-expanding air transport industry.”67

The WPA, under the direction of Brehon Somervell, had overall responsibility for the project. The main plans originated with the engineers, architects, and planners of the Design Section of the WPA Division of Operations, but the engineers of the city’s Dock Department were full partners in the effort. For the landfill portion of the project, a special board of consulting engineers from the Army Corps of Engineers was brought in. Private airport engineering firms were also consulted. Bureau of Air Commerce engineers laid out the field design, including lighting and other electrical signal device plans. WPA engineers conducted all the soil borings and topographic surveying. Delano and Aldrich were hired to design all the buildings and develop a landscaping plan.68

There were many contemporary descriptions of the various systems of mnways, drainage, heating, lighting, fire prevention, as well as of the designs for the administration and passenger terminal buildings plus the hangers. Above all, however, the greatest attention was accorded to the control tower and radio equipment. “The electrical wiring and controls in this room comprise one of the most intricate and efficient systems ever installed,” wrote Samuel Stott. There were 21 receiver units which were described as “elaborate as that of any airport in the World, and considerably more flexible.”69

LaGuardia Airport is significant not because the individual technological components represented the “newest” or the “best” of their class (although some were) but because it was the first to integrate these systems (and to do so in the design phase, rather than after the airport was built). This level of integration was only possible through the combined efforts of engineers, architects, and city planners as well as a host of federal, state, and local officials. The potential for chaos was quite high but all agreed that one entity had to have final say.

In the case of LaGuardia, the temptation is to identify the airport’s namesake, the mayor, as a driving, dictatorial force that brought about cooperation by coercion. Fiorello LaGuardia was certainly the local power behind the New York airport’s creation. The mayor assumed day-to-day responsibility for oversight of the airport (it was perhaps one of his proudest boasts that his rival Robert Moses, head of the New York Parks Department, had nothing to do with the airport). But LaGuardia Airport was not simply a local project. President Roosevelt was equally interested in the construction of this airport as were a bevy of federal officials. They saw New York’s new airport as the first of many major new metropolitan airports which would form the crucial links in the nation’s air transportation system. Right on its heels was the construction of Washington National Airport. Newark, Chicago, Los Angeles had all undergone major transformations compliments of New Deal relief dollars. All of these projects (and several hundred others) turned to the federal government for more than money. The airport sections of the WPA and the Bureau of Air Commerce working in tandem were, in fact, the main organizing force behind a national system of airports. It is these organizations that truly coordinated the design and construction of LaGuardia.

Airports were not islands unto themselves. They were part of a national system of airports. Air transportation was about the purposeful movement between geographically separate locations. Creating one “perfect” airport was of little value unless there were many others just like it. The federal airport engineers, especially W. Sumpter Smith, Jack Gray and Alexis McMullen, helped communities throughout the nation coordinate their efforts with each other. The federal engineers tapped into the new professional identity of engineers, architects, and city planners. During the opening decades of the 20th century the professional associations representing these three groups fashioned strong bonds that transcended local associations. The Commerce Department under the Coolidge, Hoover and Roosevelt Administrations all encouraged associational activities (albeit for different reasons and under different names).

No one wanted airplanes to crash but until the mid-thirties this happened with shocking regularity. Federal aviation officials used the fear-and-safety factor as initial leverage to promote the coordination of efforts among design professionals. All three groups were responsive to this appeal. However, it was also used to extract funds from Congress for the development of a radio-based air traffic control system. That system helped make the Bureau of Air Commerce, and its successor agency the Civil Aeronautics Authority in particular, the focal point for every airport project.

For small communities this was often the only technical consultation accomplished. For major airport projects like LaGuardia or Washington, the participation of the Bureau of Air Commerce representatives was considered vital. The centrality and importance of the federal leadership initiatives in airport development became apparent during the Congressional hearings for new civil aeronautics legislation in 1937 and 1938. Members of Congress were taken aback by the emphatic pleas of aviation advocates to strike out the airport exclusion clause of the Air Commerce Act of 1926.

Despite considerable trepidation, Congress was ultimately responsive to these concerns and the resultant Civil Aeronautics Act of 1938 expanded federal authority over the airways to include the development and operation of air navigation facilities at airports. Following the completion of the National Airport Survey in the spring of 1939, it was clear that a new era had begun. “Normal” airport design meant a process undertaken by several different types of technical specialists whose work on a specific local technological system was coordinated by the federal government (specifically the new Civil Aeronautics Authority) with responsibilities for the creation and maintenance of a national system. The role of the Federal government has endured to this day, as has the core design concept of both the airport and the network of airports and the tripartite relationship of airport engineers, architects, and city planners.


Between 1891 and 1896, Otto Lilienthal in Germany made over 2000 successful glider flights. His work was timed perfectly with the rise of photography and the printing industry. In 1871 the dry-plate negative was invented, which by 1890 could freeze a moving object without a blur. Also, the successful halftone method of printing had been developed. As a result, photos of Lilienthal’s flights were widely distributed, and his exploits frequently described in periodicals throughout Europe and the US.

These flights caught the attention of Nikolay Joukowski (Zhukovsky) in Russia. Joukowski was head of the Department of Mechanics at Moscow University when he visited Lilienthal in Berlin in 1895. Very impressed with what he saw, Joukowski bought a glider from Lilienthal, one of only eight that Lilienthal ever managed to sell to the public. Joukowski took this glider back to his colleagues and students in Moscow, put it on display, and vigorously examined it. This is the first time that a university-educated mathematician and scientist, and especially one of some repute, had become closely connected with a real flying machine, literally getting his hands on such a machine. Joukowski did not stop there. He was now motivated about flight – he had actually seen Lilienthal flying. The idea of getting up in the air was no longer so fanciful – it was real. With that, Joukowski turned his scholarly attention to the examination of the dynamics and aerodynamics of flight on a theoretical, mathematical basis. In particular, he directed his efforts towards the calculation of lift. He envisioned bound vortices fixed to the surface of the airfoil along with the resulting circulation that somehow must be related to the lifting action of the airfoil.

Finally, in 1906 he published two notes, one in Russian and the other in French, in two rather obscure Russian journals. In these notes he derived and used the following relation for the calculation of lift (per unit span) for an airfoil:

L = pVT

where L is the lift, p is the air density, V is the velocity of the air relative to the airfoil, and Г is the circulation, a technically-defined quantity equal to the line integral of the flow velocity taken around any closed curve encompassing the airfoil (Circulation has physical significance as well. The streamline flow over an airfoil can be visualized as the superposition of a uniform freestream flow and a circulatory flow; this circulatory flow component is the circulation. Figure 1 is a schematic illustrating the concept of circulation.) With this equation, Joukowski revolutionized theoretical aerodynamics. For the first time it allowed the calculation of lift on an airfoil with mathematical exactness. This equation has come down through the twentieth-century labeled as the Kutta-Joukowski Theorem. It is still taught today in university-level aerodynamics courses, and is still used to calculate lift for airfoils in low-speed flows.

The label of this theorem is shared with the name of Wilhelm Kutta, who wrote a Ph. D. dissertation on the subject of aerodynamic lift in 1902 at the University of Munich. Like Joukowski, Kutta was motivated by the flying success of Lilienthal. In particular, Kutta knew that Lilienthal had used a cambered airfoil for his gliders, and that, when cambered airfoils were put at a zero angle of attack to the freestream, positive lift was still produced. This lift generation at zero angle of attack was counter-intuitive to many mathematicians and scientists at that time, but experimental data unmistakenly showed it to be a fact. Such a mystery made the theoretical calculation of lift on a cambered airfoil an excellent research topic at the time – one that Kutta readily took on. By the time he finished his dissertation in 1902, Kutta had made the first mathematical calculations of lift on cambered airfoils. Kutta’s results were derived without recourse to the concept of circulation.


Figure 1. The synthesis of the flow over an airfoil by the superposition of a uniform flow and a circulatory flow.

Only after Joukowski published his equation in 1906 did Kutta show in hindsight that the essence of the equation was buried in his 1902 dissertation. For this reason, the equation bears the name, the Kutta-Joukowski Theorem.

This equation became the quantitative basis for the circulation theory of lift. For the first time a mathematical and scientific understanding of the generation of lift was obtained. The development of the circulation theory of lift was the first major element of the evolution of aerodynamics in the twentieth century, and it was in the realm of science. The objective of Kutta and Joukowski – both part of the academic community – was understanding the nature of lift, and obtaining some quantitative ability to predict lift. Their work was not motivated, at least at first, by the desire to design a wing or airfoil. Indeed, by 1906 wings and airfoils had already been designed and were actually flying on piloted machines, and these designs were accomplished without the benefit of science. The circulation theory of lift was created after the fact.

Contemporary with the advent of the circulation theory of lift was an equally if not more important intellectual breakthrough in the understanding and prediction of aerodynamic drag. The main concern about the prediction of lift on a body inclined at some angle to a flow surfaced in the nineteenth-century, beginning with George Cayley’s concept of generating a sustained force on a fixed wing. In contrast, concern over drag goes all the way back to ancient Greek science. The retarding force on a projectile hurtling through the air has been a major concern for millenniums. Therefore, it is somewhat ironic that the breakthroughs in the theoretical prediction of both drag and lift came at almost precisely the same time, independent of how long the two problems had been investigated.

What allowed the breakthrough in drag was the origin of the concept of the boundary layer. In 1904, a young German engineer who had just accepted the position as professor of applied mechanics at Gottingen University, gave a paper at the Third International Mathematical Congress at Heidelberg that was to revolutionize aerodynamics.7 Only eight pages long, it was to prove to be one of the most important fluid dynamics papers in history. In it, Prandtl described the following concept. He theorized that the effect of friction was to cause the fluid immediately adjacent to the surface to stick to the surface, and that the effect of friction was felt only in the near vicinity of the surface, i. e., within a thin region which he called the boundary layer. Outside the boundary layer, the flow was essentially uninfluenced by friction, i. e., it was the inviscid, potential flow that had been studied for the past two centuries. This conceptual division of the flow around a body into two regions, the thin viscous boundary layer adjacent to the body’s surface, and the inviscid, potential flow external to the boundary layer (as shown in Figure 2), suddenly made the theoretical analysis of the flow much more tractable. Prandtl explained how skin friction at the surface could be fundamentally understood and calculated. He also showed how the boundary layer concept explained the occurrence of flow separation from the body surface – a vital concept in the overall understanding of drag. Since 1904, many aerodynamicists have spent their lives studying boundary-layer phenomena – it is still a viable area of research

today. This author dares to suggest that PrandtTs boundary layer concept was a contribution to science of Nobel prize stature. Perhaps one of the best accolades for Prandtl’s paper was given by the noted fluid dynamicist Sydney Goldstein who was moved to state in 1969 that: “The paper will certainly prove to be one of the most extraordinary papers of this century, and probably of many centuries.”8

As in the case of Kutta and Joukowski, Prandtl was a respected member of the academic community, and with the boundary layer concept he made a substantial scientific contribution to aerodynamics. This was science; the boundary layer concept was an intellectual model with which Prandtl explained some of the fundamental aspects of a viscous flow. However, within a few years this concept was being applied to the calculations of drag on simple bodies by some of PrandtTs students at Gottingen, and by the 1920s, research on boundary layers had become focused on acquiring knowledge for the specific purpose of drag calculations on airfoils, wings, and complete airplanes. That is, boundary layer theory became more of an engineering science.

In retrospect the beginning of the twentieth-century was the time of major technological breakthroughs in theoretical aerodynamics. These events heralded another breakthrough – one of almost a sociological nature. Wilhelm Kutta, Nikolay Joukowski, Ludwig Prandtl were all university-educated with Ph. D.s in the mathematical, physical, and/or engineering sciences and all conducted aerodynamic research focused directly on the understanding of heavier-than-air flight. This represents the first time when very respected academicians embraced the flying machine; indeed, the research challenges associated with such machines absolutely dictated the direction of their research. Kutta, Joukowski, and Prandtl were very much taken by the airplane. What a contrast with the prior century, when respected academicians essentially eschewed any association with flying machines, thus


Figure 2. PrandtTs concept of the division of the flow field into two regions: (1) the thin viscous boundary layer adjacent to the body surface, and (2) the inviscid (frictionless) flow outside the boundary layer.

causing a huge technology transfer gap between nineteenth-century science and the advancement of powered flight.

What made the difference? The answer rests in that of another question, namely, who made the difference? The answer is Lilienthal and the Wright brothers. Otto LilienthaTs successful glider flights were visual evidence of the impending success of manned flight; we have seen how the interest of both Kutta and Joukowski was motivated by watching Lilienthal winging through the air, as seen either via photographs or by actual observation. And when the news of Wilbur’s and Orville’s success with the Wright Flyer in 1903 gradually became known, there was no longer any doubt that the flying machine was a reality. Suddenly, work on aeronautics was no longer viewed as the realm of misguided dreamers and madmen; rather it opened the floodgates to a new world of research problems, to which twentieth-century academicians have flocked. After this, the technology transfer gap, in the sense that occurred over the previous centuries, began to grow smaller.


On 12 November 1975, ten lawyers from nine different law firms appeared in U. S. District Court, Southern District of New York. They represented twenty clients – nineteen of the largest aerospace firms in the United States and a curious legal and business entity known as the Manufacturers Aircraft Association, Inc. (MAA). All the aerospace firms were members of the MAA; some had been members since the MAA was founded in 1917. All ten lawyers agreed with the court’s finding that the MAA violated Section One of the Sherman Anti-Trust Act of 1890. The MAA was, in short, “a contract, combination… or conspiracy in restraint of trade or commerce.”1 On behalf of their clients, the assembled lawyers agreed to “wind up the affairs and terminate the existence” of the MAA.2 They further agreed to “terminate and cancel the Amended Cross License Agreement,” the legal instrument defining the purpose and operation of the MAA.3

The consent decree captures none of the historical irony hanging over this decision. The federal government had directed aircraft manufacturers in 1917 to enter into a cross-licensing agreement and to form the MAA to administer the agreement. In spite of protests at the time and repeated challenges in the 1920s and 1930s, the Justice Department consistently found that the cross-licensing agreement did not violate the Sherman Anti-Trust Act. In 1972, however, that same Justice Department brought suit in District Court, arguing, in effect, that it had been mistaken for 55 years. During that time, the United States aircraft manufacturing industry had been arguably the most successful in the world, dominating a market in which other nations, beyond the reach of the MAA, were free to compete. Half the companies represented in District Court had joined the MAA since its founding, a membership pattern suggesting openness and inclusivity, not combination and conspiracy. The MAA had been good for its members and good for America.4

Still more ironically, termination of the cross-licensing agreement had no discernible impact on American aircraft development. The MAA went out of business in 1975. All the patents licensed by the MAA and controlled by its members were made available to any applicant. The Court arranged to adjudicate disputed royalties arising from the new dispensation. Yet American aircraft manufacturers went right on dominating the free world market for this product, just as they had done under the protection of the cross-licensing agreement. In fact, the termination of the MAA coincided with the introduction of the European Airbus,


P Galison and A. Roland (eds.), Atmospheric Flight in the Twentieth Century, 323-345 © 2000 Kluwer Academic Publishers.

which, in the words of author John Newhouse, appeared at first “to be an even more dismal failure than most of Europe’s other jet transports had been.”5 The Airbus went on to be more competitive, but the United States still dominates the world market for commercial airliners more than twenty years after the dissolution of the MAA.

The many ironies of this case have attracted scholars of patent law, economists, and even sociologists.6 They have not, however, stimulated much study by historians of technology, not even historians of aviation. In most histories of American aviation, patents are noted by their absence.7 Even in my own study of the National Advisory Committee for Aeronautics (NACA), patents find little place after the cross-licensing agreement of 1917, which the NACA brokered.8 The NACA formed a patents committee in 1917, but discharged it with thanks when the cross-licensing agreement was signed. The Air Commerce Act of 1926 directed the NACA to form a patents committee, but the following year the NACA converted it to a committee on “Aeronautical Inventions and Design.” Congress may have thought of aviation development in terms of patents, but the NACA did not. Even in the 1930s, when the NACA found itself under congressional pressure to be of greater service to industry, it was proprietary information, not patents, that proved the sticking point.

The importance of aircraft patents to economists and legal scholars and their apparent irrelevance to aviation historians raises several nagging questions. Have historians simply overlooked the importance of patents in aviation history? If, as historians seem to believe, patents were not important, why was there a patent pool? And why did the Justice Department believe that the patent pool restrained trade? Finally, if patents do not shape an innovative industry, such as aircraft manufacture, what do they achieve? And what, then, does drive innovation in aircraft manufacture?

This paper will attempt to answer those questions. It will first summarize the history of aircraft patents in the United States. Then it will explore the theory of patents and the application of that theory to this particular case. Next it will seek the reasons for the success of the American aircraft industry, looking especially for ways in which patents might have played a role. In conclusion, it will attempt to explain the invisibility of patents in previous accounts.


In this and the subsequent sections, specific examples of important advances in aerodynamics will be examined, primarily from the point of view of the relative roles of science, engineering science, and engineering. The state of the art in aerodynamics has grown exponentially since the turn of the century; we can not do justice to the whole story in this limited paper. Instead, only a few specific examples from each era will be considered. In the present section, we examine some developments in aerodynamics contemporary with the hey-day of the strut-and-wire biplane exemplified by the British S. E.5 from World War I (Figure 3).

With Wilbur Wright’s flying demonstrations in Europe, which began on August 8, 1908, the world truly discovered the existence of the successful airplane. With this “discovery”, the attitudes surrounding the value of scientific and engineering work in aerodynamics changed radically. Almost overnight it became fashionable, indeed critical, to learn more about the laws of nature that sustained these flying machines in the air, and to develop engineering techniques that could lead to improved aerodynamic design. We have already discussed how academic science met the flying machine at the turn of the century. Now, with Wilbur’s dramatic demonstration that the airplane was indeed an established reality, the world of professional engineering suddenly had a new and very exciting discipline to develop.

This technical awakening was accompanied by the sound of new wind tunnels revving up throughout Europe. Nowhere was this as dramatic as in the shadow of the Eiffel Tower in Paris. In 1909, Gustav Eiffel designed and built a large wind tunnel on the Champ de Mars adjacent to the famous tower he had erected 20 years earlier. Indeed, Eiffel was soon to become France’s first great aerodynamicist on the strength of his wind tunnel experiments. Today, the name of Eiffel rarely crosses the lips of practitioners and students of aerodynamics. In fact, most people in general do not associate Eiffel’s name with aerodynamics at all. However, his contributions to


experimental aerodynamics were as important in the history of technology as were his structural innovations embodied in the design and construction of the Eiffel tower. At the beginning of the twentieth century, Eiffel pioneered some of the experimental techniques which we still use today, and in the process he was the first to quantitatively measure some of the most basic aerodynamic aspects of a complete airplane configuration.

The wind tunnel experiments at the Champ-de-Mars laboratory conducted during 1909 and 1910 led to five substantial contributions:

1. First, there was the wind tunnel itself, an innovative design using a free jet in a hermetically-sealed chamber. This was pure engineering.

2. Eiffel found that drag measurements made in his wind tunnel agreed with earlier measurements he made by dropping aerodynamic shapes from his Tower. Eiffel finally proved experimentally once-and-for-all the basic principle of the wind tunnel that had been first stated by Leonardo da Vinci more than four centuries earlier, namely that “the same force as is made by the thing against the air, is made by air against the thing.” Some doubt about this persisted until the twentieth century, even though wind tunnels had been in use since their invention by Francis Wenham in 1871. Eiffel proved the validity of the wind tunnel principle. This was science.

3. He was the first to make detailed measurements of the distribution of pressure over the surface of an aerodynamic body, proving conclusively that the aerodynamic lift on a wing was due to the presence of lower pressure on the top surface and higher pressure on the bottom surface. Moreover, he proved conclusively that the majority of the lift on a wing is derived not from the higher pressure exerted on the bottom of the wing, but rather from the lower pressure exerted on the top of the wing. This was engineering science.

4. Eiffel pioneered the general principle that the net resultant aerodynamic lift on a body is due to the integrated effect of the pressure distribution exerted over the surface, and he was the first to prove it. Using his measured pressure distributions on one hand, and his direct measurements of lift using a force balance on the other, he was able to state: “The direct measurement of pressure has given us a result to which we attach great importance; viz., the summation of the observed pressures was equal in every case to the reaction weighed on the balance.9 This was engineering science.

5. Eiffel was the first to conduct wind tunnel tests using models of complete airplanes, and to show conclusively the correspondence between such tests and the performance of the real airplane in actual flight. This was pure aeronautical engineering.

Perhaps the most important contribution Eiffel made to aerodynamics was as follows. Over the course of his earlier aerodynamic work, Eiffel had measured the drag of spheres. However, in experiments at Prandtl’s laboratory at Gottingen, the data showed sphere drag to be more than twice as large as Eiffel’s measurement. Eiffel was angered by a German insinuation that he had made a mistake, and in 1914 he carried out a definitive series of drag measurements on spheres in a new laboratory at Auteuil, a suburb of Paris. Testing spheres of various sizes, he found out that for each size, there was a velocity above which the drag decreased markedly – by slightly more than a factor of two. Every student of aerodynamics today recognizes this variation, and knows that the sudden decrease in drag is associated with a transition of the flow inside the boundary layer from laminar to turbulent at a value of the Reynolds number of about 300,000. Prandtl was the person who eventually explained why this phenomenon occurs. But Eiffel was the person to first observe and publish the phenomenon. This was a purely scientific contribution.

The period during and just after World War I saw major advances in the theoretical calculation of airfoil and wing aerodynamics. Based on the circulation theory of lift, Prandtl conceived a theoretical model of the aerodynamic properties for a finite wing (a real wing with wing tips, in contrast to the two-dimensional aspects of an airfoil shape). Labeled “Prandtl’s lifting line theory”, this model allowed the calculation of lift and induced drag (a pressure drag due to the influence of vortices generated at the wind tips and trailing edge of the wing). This is a rational, engineering-oriented theory that could be applied to the wings of real airplanes. It is still used today. In a similar vein, one of Prandtl’s colleagues, Max Munk, after immigrating to the United States after the war and going to work for the National Advisory Committee for Aeronautics (the NACA), derived the first practical theory for the calculation of the lift of airfoils of any arbitrary shape, as long as the airfoils are relatively thin. Prandtl’s lifting line theory for finite wings, combined with Munk’s thin airfoil theory, represented major contributions to applied aerodynamics. This was one of the first important examples of engineering science in the twentieth century. However, again emphasis is made that these theories were after-the-fact; airfoils and wings, albeit not optimum, were being designed successfully based on empirical experience and routine wind tunnel testing long before these theoretical tools became available.


The story began where it ended, in court. On 13 January 1914, the United States Circuit Court of Appeals ruled that Glenn Curtiss and his colleagues had infringed the basic patent of Wilbur and Orville Wright.9 The implications for the nascent American aircraft industry were profound. If Curtiss, a prolific inventor and tireless entrepreneur, could not break the Wright patent, no one could. Curtiss himself and his associates could fall back on their own stock of pioneering patents, mostly in seaplanes. But other builders faced the prospect of crippling royalty payments to both Wright and Curtiss. The conflict reached crisis level in December 1916, when the Wright-Martin Company, holder of the Wright patent, announced that manufacturers would have to pay a royalty of 5% on each aircraft sold, with a minimum annual payment of $10,000 per manufacturer.10

This crisis sprang from a patent phenomenon that is rare but not unprecedented. The Wrights held a foundational patent that the courts interpreted broadly. To understand how they got that patent and why the courts might be inclined to construe it generously, it is necessary to briefly retrace their steps.

In 1899, when Wilbur and Orville Wright entered the race to fly, they discovered a crowded field. Most inventors around the world were taking the same path to heavier-than-air flight.11 They were trying to move airfoils through the atmosphere fast enough to generate lift greater than the combined weight of their airframe, engine, and pilot. None had yet overcome the fundamental dilemma: simply enlarging the engine added power and speed, but at the cost of more weight.

The Wrights embraced a different model. They emulated Otto Lilienthal, a German inventor who was conducting glider experiments (what would now be called hang gliding) in an attempt to learn how to actually fly. Like the Wrights who followed him, he was more concerned with what to do aloft than how to get there. The Wrights’ first round of experiments revealed that most other researchers were on the wrong track, producing flawed data. Thus, the Wrights began at the beginning. They built their own glider and learned to control it in flight by applying lessons from bird-watching. Only then did they turn to propulsion. They designed their own engine and their own propellers, relying on data from their own wind tunnel. The resulting airplane, the one that first achieved sustained, powered, human flight in 1903, was a product of their native genius and no small measure of what Alfred North Whitehead would call scientific method.12 They had broken a large problem down into component parts and had solved them one after another using observation, experiment, and theory.

Recognition of the Wright achievement came slowly. The world at first paid little attention to the 1903 flight at Kitty Hawk, NC, and to the follow-on flights in Dayton, Ohio. The brothers filed their first patent application in 1903, but received their foundational patent only in 1906.13 Still, that was early enough to preempt the field. They claimed that the method they had developed for controlling the airplane in flight – wing-warping, which created differential lift on opposite sides by actually twisting the wings – was fundamental to all flight. The courts agreed. Even when Glenn Curtiss introduced an airplane with a superior method of lateral control, the ailerons still used on aircraft today, the courts refused to budge from their commitment to the Wrights, for the Wrights had specifically anticipated ailerons in their patent. Curtiss had behind him the resources and prestige of Alexander Graham Bell and the Smithsonian Institution, both of whom had reason to challenge the Wright stranglehold. But nothing would avail. In case after case, the courts held for the Wrights, leading up to the climactic decision of 1914.

By this time, the matter of aviation development was slipping from the hands of lone inventors and into the board rooms of nascent manufacturers. Orville Wright, demoralized after his brother’s premature death in 1912, sold his interests in 1915 to an entity called the Wright Company, soon to become Wright-Martin Corporation. Curtiss had his own company and thirty important patents on seaplanes; his patents stood in spite of the fact that all of his airplanes infringed on the Wright master patent. With the outbreak of World War I in Europe and the prospect of lucrative government contracts, other aircraft manufactures were attracting capital and coming under the sway of major investors. An Aircraft Manufacturers Association formed in February 1917, but its prospects were dimmed by the refusal of Wright-Martin to join. Jacob Vander Meulen and others have seen in the Aircraft Manufacturers Association an attempt to bring Progressive-era associationalism to aviation. It was, in short, a bid for the middle ground between “the chaos of laissez faire… and the tyrannies of business monopoly and statism.”14 Manufacturers that found such an association congenial might also be expected to embrace patent pooling, a technique that navigated between the treacherous shoals of commercial pirating on the one hand and monopoly extortion on the other.15

Serious movement toward a patent pool, however, was not likely to issue from such voluntarism, at least not when a critical player such as Wright-Martin refused to participate. Instead, government had to intervene forcefully to impose an associationalist model on the entire community.16 Responding to the Wright-Martin royalty claim of December 1916, the Army and Navy both asked the NACA to resolve the aircraft patent stalemate. At the Committee’s request, Congress appropriated $1,000,000 to buy out the existing patents.17 With that leverage in hand, the NACA on 22 March 1917 convened a meeting of its newly-formed patent committee and representatives of the major aircraft manufacturers. They agreed to a cross-licensing agreement that would ultimately pay the Wright and Curtiss interests $1 million each, twice what Congress had appropriated.

Before the agreement could be consummated, the United States entered World War I. Realizing that orders for aircraft would skyrocket, the principals held out for greater royalties. A second round of negotiation ensued, this one including W. Benton Crisp. He was a lawyer for the Curtiss interests who, not coincidentally, had brokered a comparable cross-licensing agreement in the automobile industry that had gotten Henry Ford around the foundational Selden patent. With Crisp’s help, a new agreement was reached that doubled the payments to the Wright and Curtiss interests. The NACA committee on patents submitted its report on 12 July 1917 and the cross-licensing agreement was signed twelve days later.

The specific terms of the agreement warrant close scrutiny.18 All aircraft manufacturers who were party to the agreement were to pay to the MAA $200 for every aircraft they produced, plus royalties to be determined on licenses issued after the agreement was adopted. Of that $200, $175 would be distributed between Wright-Martin and Curtiss until they had each received $2 million on their foundational patents. The remaining $25 per airplane went to administrative costs of the MAA. A Board of Arbitration within the MAA would determine the royalties to be paid on future patents. Significantly, “engines and their accessories” were excluded from the agreement.19

Eight companies signed the cross-licensing agreement on 14 July 1917. They were Aeromarine Plane and Motor Company, Burgess Company, Curtiss Airplane and Motor Corporation, L. W.F. Engineering, Standard Aero Corporation, Sturtevant Aeroplane Company, Thomas-Morse Aircraft, and Wright-Martin Aircraft Corporation.20 These were also the charter members of the Aircraft Manufacturers Association, which had formed on 13 February. Day ton-Wright joined the cross­licensing agreement a few months later. By this time more than 283 companies had formed in the United States to produce aircraft or components other than engines.21 How many were still viable in 1917 and how many individual, unincorporated concerns were manufacturing aircraft is impossible to determine. It is nonetheless clear that these charter eight were the cream of the crop in 1917. They made up less than half of the group that attended the meeting of the AMA in Washington on 22 March 1917.22

“Aircraft trust,” howled critical newspapers when the agreement was announced.23 A patent attorney who protested on behalf of the American Aeronautical Society later described the agreement to Congress as “a most pernicious undertaking, detrimental to the interests of inventors and independent manufacturers, operating to stifle invention and thereby to retard the development of the art of aviation.”24 Another Congressional witness reported in 1918 that the MAA was “condemned by every airplane manufacturer outside the beneficiaries.”25

Suspicions about the agreement followed two tracks. One group protested that the major manufacturers were conspiring to drive out the small operations. Another group saw a “Detroit conspiracy,” an attempt by the automobile industry to comer the wartime market for engine manufacture and parley that into a foothold in airframe manufacturing as well.26 The latter suspicion was fed by the merger in 1916 of the American Society of Aeronautical Engineers and the Society for Automotive Engineers,27 by the role of Crisp in transferring his experience from the Selden patent fight, and by the subsequent role of Detroit manufacturers in wartime production.

At the request of the Secretary of War, the Comptroller of the United States reviewed the cross-licensing agreement to determine if it violated the anti-trust laws. The Comptroller certified that it did not.28 This satisfied the government and allowed the aircraft manufactures to get on with the business of producing planes for the war. That production, however, proved disappointing, by any standards. The government spent over $1 billion for aircraft in World War I but only 960 aircraft reached the front, not a single fighter among them.29 The reasons for this dismal performance had more to do with corruption and mismanagement than with patents. Nevertheless, “aircraft trust” became a familiar refrain in what NACA Chairman Charles D. Walcott called the “hymn of hate” spewing from critics of the establishment after World War I.30

By the middle of the 1920s, other voices had joined the chorus. Billy Mitchell and the advocates of a separate air force held the “air trust” partly responsible for the inadequacies of military aviation in the United States. Advocates of commercial operation believed the government was providing insufficient support for the nascent industry. Some observers believed that air safety required government regulation. And other observers believed that the government should transfer air mail operations to the private sector. Congressional critics of government policy formed the Lampert Committee in 1924 to study this array of problems and make constructive suggestions. Distrustful of the politics of this group, the Coolidge Administration appointed its own Morrow Board to make an independent appraisal. The battle of the boards produced a political stalemate, but a legislative landslide. In short order Congress passed and President Coolidge signed the Air Mail Act of 1925, the Air Commerce Act of 1926, and the Air Corps Act of 1926.

Among them, these new laws established the legal structure that would carry American aviation to the Second World War. All of them recognized the need for government support, but none of them explicitly endorsed the belief that an “air trust” existed or that the patent pool was an illegal combination in restraint of trade. Quite the contrary. An amendment of the cross-licensing agreement dated 31 December 1928 essentially validated the original pact. It, and two supplementary agreements which had preceded it in 1918 and 1923, changed the proportion of MAA income that went to the association and the two major patent holders, but it did not substantially alter the fundamental deal struck in 1917.31 The 1928 agreement was the one overturned in 1975.

By the time the cross-licensing agreement was amended in 1928, American aviation had turned a comer. Charles Lindbergh had crossed the Atlantic Ocean in May 1927, claiming the Orteig Prize first offered in 1919 and more importantly stimulating a buying spree of aviation stock. Before the market crashed in 1929, new purchases had pushed aviation securities over the $1 billion mark.32 Approximately 95% of that value disappeared in the early years of the Depression, but not before the wave of capital had financed an increase in infrastructure. With the new resources, aircraft manufacturers not only survived the Depression, they also created the so-called “airframe revolution.”

The all-metal, stressed skin, monocoque airliner with twin cowled engines and retractable landing gear was not exactly invented in the United States. The various innovative components were invented, sometimes simultaneously, in several countries including the United States. But American airframe manufacturers, especially Boeing and Douglas, combined these features in designs that transformed commercial aviation. Relying on the infrastructure purchased with the capital investment of the late 1920s, Boeing introduced the 247 in 1933 and Douglas followed with the revolutionary DC-2 and the classic DC-3 shortly thereafter. The DC-3 went on to be the most famous and most durable airliner of all time. Along with its imitators, it made possible the growth of a viable commercial airline industry in the United States.

The technical innovations that made these airplanes the best in the world came in part from the manufacturers themselves, but also increasingly from university and government laboratories. The Guggenheim Fund for the promotion of aeronautics, for example, supported laboratories at MIT, the California Institute of Technology, and other universities around the country.33 The National Advisory Committee for

Aeronautics supported what it called “fundamental research,” benefiting both the military services and the commercial industry.34 Patents contributed to this development, but the role of government especially made patents difficult to rely on. The government often insisted that developments supported by its funding be made freely available to all, or at least licensed for government purposes. Similarly, the NACA agreed to respect proprietary information whenever possible in conducting research for industry, but in its own work on the famous NACA cowling, for example, it declined to patent.35

The outbreak of World War II only accelerated these trends. Aircraft production went from less than 6,000 in 1939 to more than 96,000 in 1944.36 In some cases, designs from one manufacturer were handed over to another for production. Existing patents were licensed as necessary, not only to other aircraft manufacturers but to automobile manufacturers as well.37 As Robert Ferguson discovered in his study of aircraft manufacturing in World War II, patents and even proprietary knowledge hindered the flow of information but little. More intractable were the incompatibility of “technological cultures” in the different companies, “that is, the unique methods and traditions of practice for designing and producing aircraft that existed within each firm.”38 Some companies, for example, moved airframe components to the workers in assembly-line fashion, while others moved workers about the shop floor. Similarly, tooling varied greatly from company to company and existed beyond the reach of the cross-licensing agreement. Ferguson found that the MAA and the patent pool provided “an adequate legal and financial infrastructure” for the exchange of ideas, but new institutional arrangements were needed to provide an “organizational framework for sharing proprietary technologies.”39 A National Aircraft War Production Council was created to fill this need.

After World War II, the American aircraft industry did not return to its pre-war status. The creation of a separate air force, the elevation of strategic bombing to the first line of defense, the outbreak of the Cold War, the advent of rockets and missiles, and the commitment of the United States to a qualitative and quantitative arms race with the Soviet Union all combined to transform the aircraft manufacturing industry into the aerospace industry. Bulwark of the military – industrial complex and mainstay of the U. S. balance of payments, the aerospace industry grew to enormous proportions without a comparable growth in the number of companies. The dollar value of aircraft shipments doubled between 1958 and 1992, from $31.3 billion to $63.0 billion (both in 1992 dollars), while the number of companies rose in the same period only from 113 to 151 40 The trend was even more striking among major airframe manufacturers, where mergers in the 1990s of Lockheed Martin, Northrup Grumman and Boeing/McDonnell Douglas accelerated the concentration of the industry.

As aerospace business grew, those fewer and fewer manufacturers grew larger and larger. Their ideal business formula was some combination of military and commercial production. This allowed companies to conduct research for the government and then convert that knowledge into commercial products.41 Very often the research conducted for the military services set higher standards for quality and reliability than would have been warranted by market forces; the resulting technologies nevertheless found their way into commercial products. Patents played little role in this enterprise, in part because the government insisted on licensing the knowledge gained with its funds; in part because the success of the companies was predicated more on design, production, and marketing than it was on invention; and in part because the firms preferred the secrecy of proprietary knowledge to the disclosure of patenting. For whatever reason, the American formula worked. In 1975, when the MAA disappeared, the U. S. aerospace industry controlled 67% of the international market.42