More than any other single individual, Ezra Kotcher would be responsible for the design and development of the airplane that would ultimately prove the validity of this observation. After graduating from the University of California in 1928, he had gone to work as a civilian at Wright Field. As senior instructor at the Army Air Corps Engineering School throughout the 30s, he was required to remain abreast of the latest developments in a remarkably wide range of increasingly esoteric aeronautical disciplines and he established a reputation as one of the few truly brilliant engineers who were then working at Wright Field. He first became interested in the subject of transonic aerodynamics in the mid-30s and, very early on, concluded that overcoming all of the problems associated with the sonic barrier was really just a matter of acquiring valid data concerning transonic conditions. Given the wind tunnel limitations of the time, he also concluded that the only way to acquire that knowledge would be by means of specially designed research aircraft and, given the limitations of even the highest performance fighters of the day, he realized that such airplanes would require unconventional propulsion systems. In August of 1939, nearly two years before the AAF became aware of turbojet and other reaction propulsion developments abroad, Ezra Kotcher submitted a report to the Kilner-Lindbergh Board in which he recommended the establishment of a comprehensive transonic flight research program which would permit the correlation of wind tunnel and actual flight performance data. He also suggested that gas turbine or rocket propulsion systems would have to be developed to support such an effort because of the compressibility limitations on prop-driven aircraft at high speeds. A truly bold proposal but, in 1939, his was a voice in the wilderness. With war imminent, Air Corps leadership was totally focused on immediate production problems and long-term research proposals such as he was recommending were relegated to the back burner.

Nevertheless, Kotcher was persistent and, called to active duty and assigned to the Engineering Division at Wright Field after the U.S. entered the war, he continued to press for a dedicated transonic flight research program. He also remained perhaps the staunchest proponent for rocket propulsion within the AAF. His arguments finally began to win converts only after combat pilots started encountering the effects of compressibility in existing prop-driven fighters and the enormous potential of turbojet propulsion finally became apparent. And they became even more compelling after intelligence sources began to reveal that German turbojet and rocket propulsion projects were in advanced stages of development. Against this backdrop, in early 1943, Kotcher’s boss and chief of the Engineering Division, Brigadier General Franklin O. Carroll, asked Theodore von Karman if he believed an aircraft capable of flying at Mach 1.5 could actually be built. After pondering the question for a few days, Karman not only replied in the affirmative, he also provided Carroll with very preliminary design data for such a vehicle. Kotcher and other representatives from the Engineering Division conducted a series of conferences with Karman and his colleagues at the California Institute of Technology throughout the remainder of the year and ultimately issued them a contract to develop theoretical methods for predicting pressure and velocity distribution over aerodynamic bodies at subsonic and supersonic speeds as well as a means by which such theoretical predictions could be correlated and compared with real-world experimental data. Kotcher finally had his opening and, over the next couple of years, in addition to serving as project officer for a number of advanced programs which focused on the development of radical new technologies, he was also assigned the job of shepherding a nascent high-speed research aircraft program for the AAF which, from its very inception, aimed at achieving supersonic flight (i.e., flight beyond the so-called "sonic wall").

By early 1944, Kotcher and other representatives of the Engineering Division had already entered into discussions with the Douglas Aircraft Company concerning its interest in submitting a design proposal for a supersonic airplane which could attain speeds of up to 1,500 mph. Douglas design engineers expressed confidence that they could tackle such a project. Meanwhile, Kotcher had also inaugurated an in-house comparative study to examine the merits of rocket versus turbojet propulsion for a transonic research airplane. He asked the Design Branch of the Aircraft Laboratory at Wright Field to prepare design studies for two different configurations. The first was to be designed around a 4,000-pound thrust General Electric TG-180 axial flow turbojet which was then under development and the other around a 6,000-pound thrust liquid-fuel rocket engine which had been proposed for development by the Aerojet Engineering Corporation. Completed in April, the so-called "Mach 0.999" study confirmed Kotcher’s predilection for rocket propulsion. The rocket engine would provide more thrust--and, hence, higher speed--and far better high-altitude performance than any turbojet then under development. It would enable test pilots to make their high-speed runs for up to two minutes in level flight at pressure altitudes which would impose lower air load stresses, rather than in risky dives into the dense lower atmosphere which would, at best, afford roughly 20-30 seconds of useful data. Interestingly enough, the general configuration of the "Mach 0.999" rocket airplane bore a striking resemblance to the research aircraft which would ultimately appear on the ramp. Incorporating a 6,000-pound thrust rocket engine, it was a mid-wing design, with conventional tail surfaces, a bullet-shaped fuselage, and a smoothly faired cockpit canopy.

John Stack, along with a number of his colleagues at Langley, had been concerned with compressibility phenomena since the late 1920s and, in the early 30s, he had even conceptualized a modest, prop-driven compressibility research air-craft which he estimated would be capable of achieving more than 560 mph. It was the "choking" problem caused by shock wave formation in the wind tunnels, however, which ultimately drove Stack and his colleagues to the conclusion that, if they were ever going to understand the transonic region, it would be necessary to design and develop a specially instrumented full-scale airplane that would be capable of safe operation in that speed range. By the spring of 1942, Stack had convinced Langley management of the need for such an airplane but, when he proposed the idea to Dr. George W. Lewis, the director of NACA research, he did not get an enthusiastic reception. Nevertheless, Lewis was not averse to some kind of low-priority effort to at least identify the most desirable design features for such an aircraft and, by the early summer of 1943, a small team under Stack’s direction had completed a preliminary design study for a small turbojet aircraft which they estimated would be capable of safely probing the region between Mach 0.8 and Mach 1.0. By this time, the real-world problems posed by compressibility had become so commonplace that the NACA had established a Compressibility Research Division at Langley under Stack’s direction. Even George Lewis was finally convinced of the need for a transonic flight research program when first the military and then the aircraft industry began to show a strong interest in it. In late December 1943, for example, Robert A. Wolf, a Bell Aircraft Corporation engineer who had been involved in the design and development of America’s first jet airplane, the XP-59A, explained the urgency of the need for valid transonic data because jet fighters would soon encounter the same compressibility effects in level flight which current fighters were then encountering in max-power dives. A turbojet transonic research airplane, he argued, was both feasible and absolutely essential. Lewis responded that the NACA was giving the matter "our very serious consideration."

In early February 1944, Lewis informed the engineer-in-charge at Langley that he was establishing a special High-Speed Panel which would coordinate transonic research activities at all three of the NACA’s laboratories. The panel met for the first time at Langley on March 2-3. Stack and Eastman Jacobs, another long-time and very articulate proponent for a research airplane program, were among the Langley representatives. Lewis informed them that he wanted the panel to be the most forward thinking group in the NACA and, in the discussions which followed, Jacobs even went so far as to argue the benefits that could be gained from a special supersonic research airplane. The panel concluded, however, that such an effort was currently far too ambitious and it shifted its focus toward the development of a more conventional turbojet-powered airplane which would be limited to speeds in the low transonic range. Several of the members argued in favor of procuring a small, fighter-sized aircraft powered by four Westinghouse 19XB jet engines (providing a combined 6,440 pounds of thrust) and Lewis suggested that this recommendation be submitted to the AAF for review.

Thus, by early 1944, the dogged persistence of men like Kotcher and Stack within the AAF and the NACA, along with similar efforts by like-minded men such as Captain Diehl within the Navy, had brought their respective agencies to the point where each had independently concluded that the procurement of some kind of research airplane was essential to unraveling the mysteries of transonic flight. Each also knew that the best way to proceed would be by combining forces. The military ser-vices realized that the NACA had the charter for conducting flight research in the United States and that they would require the agency’s technical expertise. And, for its part, the NACA was pain-fully aware that it did not have the funding or the authority to procure a research airplane. The presumption was that the military would purchase the airplane based on specifications developed by the NACA and then the NACA would conduct the flight research program and collect and reduce the data. Thus the stage was set for a meeting of the minds.

That meeting occurred at a conference between AAF, Navy and NACA representatives held at Langley on March 16, 1944. During the course of two sessions, one chaired by Captain Diehl and the other by Colonel Carl Greene, the AAF Materiel Command’s liaison officer at Langley, the conferees discovered that, although all three organizations agreed on the need for a joint NACA-military transonic research airplane, there was little agreement concerning the basic design features for such a craft or even the specific goals for a flight test program. Basically, Stack made a pitch for the NACA’s turbojet-powered airplane and a program aimed at collecting data at speeds approaching Mach 1. Although interested in dispelling the myth of an impenetrable sound barrier, the Navy tended to follow Stack’s lead and favored a cautious approach utilizing jet propulsion in a gradual, step-by-step program directed toward the acquisition of transonic data. The AAF, however, argued for a much bolder approach: a major developmental effort, employing unconventional propulsion if necessary, directed toward attaining speeds in excess of Mach 1. As the discussions proceeded, the prospects for a single, concerted effort evaporated because of a fundamental disagreement over means and ends. In the end, the Army and Navy representatives indicated that they would recommend that their respective services should each furnish a different airplane. The research aircraft program was to be an entirely new type of enterprise and the differing views that were laid on the table at this conference were just the first of many to follow.

An indication of the AAF thinking at this time may be found in a March 29 memo from General Carroll to Major General Oliver P. Echols, the Assistant Chief of the Air Staff for Materiel, Maintenance and Distribution, in which Carroll sought approval to proceed with the development of "a purely experimental airplane" to support the NACA’s research efforts. This memo was, in fact, drafted by Kotcher and, after detailing the problems with wind tunnels and the progress of the ongoing Cal Tech and Douglas Aircraft supersonic flight studies, he described an airplane which was obviously based on the Mach 0.999 design study that was then nearing completion:

While he had certain reservations concerning the purchase of an aircraft that did not strictly meet a military requirement, Echols agreed with the proposal "in general" as well as the overall effort "to support the National Advisory Committee for Aeronautics in all high speed investigations." Carroll interpreted this as a "yes" and, on April 15, the Engineering Division placed the design and development of the airplane within a parcel of projects which were designated "High-Speed Flight Investigations," classified "Confidential" and as-signed the project number MX-524.

Following the conference, General Carroll reported to the Air Staff that, while at Langley, Kotcher had taken the opportunity to look into the status of NACA research studies on supersonic flight. Based on his conversations with various laboratory personnel, he had decided that "sufficient engineering information was now available from which to conclude that a supersonic airplane appear-ed to be a feasible project." Furthermore, Kotcher had "encouraged" the NACA "to integrate the existing knowledge on the various components of a supersonic airplane and submit a report to the Army Air Forces on a design proposal." When Stack finally submitted the NACA design study to the Engineering Division on July 10, however, it still incorporated the turbojet engines and it was optimized to fly in the speed range between Mach 0.8 and 1.0 with a typical high-speed dash velocity of Mach 0.85 (approximately 650 mph). Stack had held firm. He wanted an airplane that would collect transonic data, not one that would fly at supersonic speeds.

In early November, General Carroll once again reported to the Air Staff on the status of "the purely experimental supersonic research airplane which the AAF is planning to procure for the NACA." After outlining the studies submitted by Kotcher’s Wright Field team and the NACA’s turbojet proposal, he certainly did not overstate the circumstances when he reported that "thus far none of the designs has engendered spontaneous approval." He also noted that Kotcher’s team would be holding another conference with the NACA in the near future in order to come to some agreement concerning the most suitable configuration for the airplane but that, even if some consensus could be achieved, "it will be a problem to find a competent airplane manufacturer to undertake its fabrication."

Kotcher had, indeed, run into problems in his search for a suitable manufacturer. Douglas had never followed up on his request for a preliminary design proposal and, while both North American and Republic Aviation had expressed some interest in taking on such a project, they were both too busy with wartime production work to dedicate the engineering personnel that would be required for such an effort. By late November, however, both Bell and the McDonnell Aircraft Company had agreed to submit some very preliminary design proposals for review at the upcoming AAF-NACA conference.

That conference was held at Langley on December 13 and 14. After Kotcher reiterated his preference for rocket propulsion and, once again, reminded the conferees that the primary objective of the project was to "attain a Mach number slightly greater than 1," the AAF contingent quickly dismissed the NACA’s turbojet proposal as too conservative to achieve that goal. Then they turned to the preliminary proposals from the two contractors. McDonnell’s approach was immediately rejected because it required both a vertical dive technique and the use of a mothership to air-launch the test airplane. The NACA was adamantly opposed to the latter. John Stack was not well impressed with Bell’s initial design effort, either. Among other things, it incorporated the use of rocket engines mounted beneath the wings. Kotcher, who was predisposed in favor of Bell because of the innovative resourcefulness of its design staff and its substantial experience with highly unconventional projects, reminded him that the proposal was far from a final configuration. For all intents and purposes, the issue was settled. Bell had effectively been given the job.

As the conference was coming to a close, Kotcher raised a couple of points which would ultimately become major issues as the program evolved. He suggested, for the first time, that ideal conditions and the facilities required to test a highly unconventional, rocket-powered airplane already existed on southern California’s high desert at Muroc Army Air Field. Moreover, if NACA pilots were reluctant to fly it, he indicated that the AAF might be willing to hire a civilian pilot for the program. He believed that veteran test pilot Harry Crosby, who had recently completed tests on Northrop’s rocket-powered MX-324 at Muroc, might be willing to undertake the job "for suitable compensation."

This was probably not welcome news to his NACA auditors, for it was the first mention of the possibility that the airplane might be tested at some location other than at Langley and by someone other than an NACA test pilot. Moreover, it fit into a disturbing trend which they had seen unfolding over the preceding months. It centered on the issue of control over the research program and, although they were perhaps not fully conscious of its long-range implications, it reflected a much larger development which was then evolving in AAF research policy. In the prewar era, the NACA had ruled supreme as the arbiter of fundamental aero-nautical research in this country and, for a variety of reasons, the U.S. Army Air Corps had been quite willing to defer to its wisdom and expertise. The wartime experience, however, had severely tarnish-ed the NACA’s image. British and, especially, German development of turbojet technology had taken the U.S. by surprise and forced the AAF into a "catch-up" mode in which it had been forced to depend upon the British. Throughout the war, it became increasingly apparent that the German research establishment had come up with a host of other new systems and concepts--rocket engines, guided missiles, the application of swept wings for high-speed flight, to name a few--which were well in advance of the state of the art in this country. Although the fault certainly did not rest entirely with the NACA (the prewar Army Air Corps was at least equally culpable), there was a perception among senior AAF leadership that the NACA had failed to remain on the cutting edge of aeronautical science. This, coupled with the realization that science and warfare had become inextricably inter-twined and advanced technology would be the key to success in future conflicts, set the AAF on a course to establish a comprehensive postwar re-search and development capability which would be second to none--one which, while still including the NACA, would also encompass industry, the universities and, for the first time, a major in-house capability, as well. As it developed this in-house expertise, the AAF would no longer automatically defer to the NACA’s judgments and, increasingly, it would vest management control over major research efforts in the hands of its own technical experts. All of this would come into much sharper focus in the postwar era but the trend was certainly evident much earlier on when, for example, the AAF chose to exclude the NACA and team up with industry to develop turbojet technology. It was also certainly evident in the effort to develop a transonic research airplane.

Ezra Kotcher could well have served as the archetype for the kind of technology manager that the AAF would attempt to develop in the future. In addition to his solid technical credentials across a wide spectrum of disciplines, his wartime assignments had given him extensive hands-on experience with an impressive array of radical new cutting-edge technologies. He had played key roles in the development of the top secret XP-59A and XP-80 turbojets, the semi-tailless, rocket-powered MX-324, and the pulsejet powered JB-2 cruise missile (a U.S. copy of the German V-1 "buzz bomb"). Thus he had more than a passing acquaintance with the latest developments in high-speed aerodynamics and reaction propulsion systems and he was not inclined to presume NACA omniscience on either of those subjects. In addition to confidence in his own technical judgments, of course, Kotcher--and Stack--also knew that he held the ultimate trump card; since the AAF was procuring the airplane, the NACA had little choice but to acquiesce and begin preparations for its support of the program. And, though the partner-ship between the AAF and the NACA was not without discord and Stack and several of his colleagues were not optimistic about the outcome of the project, the NACA’s support would prove to be critical to the success of the program.

Disappointed and feeling more than a little skepticism concerning the prospects for any airplane employing rocket propulsion, Stack had persisted in his efforts to convince the Navy to build the type of research airplane favored by the NACA. Confiding to officials in the Bureau of Aeronautics that the AAF's airplane probably would not survive many flights, he pushed for a turbojet configuration which would meet the NACA's specifications. Since the Navy was already inclined in that direction and because, compared to the AAF, it had conducted very little of its own research, Navy officials agreed to proceed with construction of an airplane that was very close to the NACA's more conservative design concept. The NACA-Navy collaboration would ultimately result in the development of the Douglas D-558 Skystreak. This, recalled one of Stack’s close associates, "was the research airplane the NACA wanted" and "we extended ourselves in every way to assist in its development." The Skystreak was designed to meet both research and military requirements so that the data acquired from its flight test program could be directly applied to a future tactical aircraft. Its maximum speed was not to exceed Mach 1. In hindsight, its development was unnecessary. It was essentially a 650 mph airplane. New tactical fighters that were soon to enter the inventory would exceed its performance and, at substantially less cost, could have been employed to collect transonic data. Nevertheless, three airplanes were built and, for many years, they were used by the NACA for extensive flight research at high subsonic speeds.

The Army’s transonic airplane represented an entirely new kind of research program and, with it, the AAF and the NACA had entered into a new kind of relationship. Because there were no precedents to guide them, they proceeded without any well-established ground rules and thus each side was still feeling its way. They had entered into the program with roughly similar assumptions; the AAF would procure an airplane and the NACA would oversee the technical aspects of its development and then complete the research program. That assumption had been based on long-standing custom. Yet, in part, because the AAF and the NACA personnel who came together in this effort were the progeny of two very different organizational cultures, they entered into the relationship with differing objectives and, therefore, widely disparate views on the best way to approach and solve the problem. Although their labors had certainly resulted in a wide variety of very practical and palpable applications, John Stack and his Langley colleagues were laboratory scientists long accustomed to seeking after truths that were, in some sense, quite abstract. They were accustomed to studying a problem in painstaking depth and detail, pondering over it, and then rendering an unimpeachable verdict. Because they were scientists and seeking "truth," they had always tended, by nature, to be very methodical, very thorough, and very cautious. All of this took time. By contrast, in their recent experience, Ezra Kotcher and his AAF peers had been project officers driven by the exigencies of war to find prompt and pragmatic solutions to immediate problems and this often involved accepting elements of risk. In order to exploit the potential advantages offered by radical new technologies, they had to be able to quickly translate them into practical, fieldable combat systems. This meant they could seldom afford to pursue perfection; their circumstances dictated that they find the most expedient way to get a job done and then press ahead. They were problem solvers, not seekers after truth.

Moreover, though it was not perhaps immediately apparent to any of the participants in this episode, their respective organizations were each undergoing a metamorphosis. During the war, the NACA had largely been relegated to the unfamiliar role performing "clean-up work" in support of the military. As a result of developments during the war, the AAF was in the process of assuming a much more active role in the management of research activities. In hindsight, it would have been to everyone’s advantage if, at this juncture, someone could have stepped forward and clearly defined just who was going to actually be in charge. This, apparently, did not happen. Thus, although they knew full well that the AAF held the purse strings, the NACA contingent had entered into the partnership assuming that this would be their program and, for the longest time, no one would explicitly disabuse them of this assumption. This was no doubt due, in part, to the fact that the AAF participants were breaking new ground and really did not know where the process was heading. In essence, they were playing it by ear. And thus, as the two sides attempted to work their way through this new partnership, they did so with increasingly divergent assumptions and they would have to find their way, more or less, through trial and error. There was, after all, no blueprint for what they were about to attempt.

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