first research authorization on the subject was approved. The chief of the navy's Bureau of Aeronautics wrote to Lewis just a week after the 1926 conference to ask for help with the cowling of one of the navy's fighter planes. He noted that considerable work on cowling had been done abroad but none of the results were available in the United States. Like all requests from the military, this one was assigned a research authorization and work began on the prototype mentioned in the letter.37 But this was not the work that produced the NACA cowling.

At the second conference the following year, cowling again attracted considerable attention. In fact, the vice chairman of the Aerodynamics committee judged it to be the "outstanding problem presented to the subcommittees" and recommended on behalf of his committee “a research authorization covering the investigation of cowling and streamlining an aircooled engine, both as a fundamental study and as applied to special types of commercial aircraft." The Committee saw this investigation as an ideal opportunity to serve industry directly and to pursue at the same time a line of research basic to all aviation.38

What the Aerodynamics committee failed to state was that the time was now ripe for this investigation. The industry request was tabled the previous year because the propeller-research tunnel had not yet been completed. This would be the ideal facility for conducting such an investigation. It was large enough to enclose a full-scale engine, precluding the need to correct for scale effects and thus surpassing even the variable-density wind tunnel for verisimilitude. The NACA had gone along with the military request the previous year because it always honored such suggestions, but the real breakthrough on cowling would be made under the industry authorization using the propeller-research tunnel. Shortly after the industry request received a research authorization, Lewis decided to keep the two authorizations for the same investigation entirely separate, on the curious ground that the more recent request applied to commercial planes.39

From the industry investigation came quick and dramatic results. Wind-tunnel tests began in July 1927. By the end of the year the NACA was circulating blueprints and plans for a proposed cowling to industry representatives and soliciting their comments and suggestions. Results were available and ready for publication by the summer of 1928. That November, the Committee published a Technical Note and sponsored an article in Aviation, the latter so that "there may be no question in the minds of aircraft people and the public in general as to the fact that the cowling is a N.A.C.A. development." The following year two separate technical reports made public the detailed results of the investigation.40

By then, however, the results were already well known. The 60percent reduction in drag and 14-percent increase in speed predicted by the NACA were demonstrated in February 1929 when a Lockheed Air Express equipped with the NACA cowling established a new transcontinental speed of 18 hours and 13 minutes. The company wired the NACA: "RECORD IMPOSSIBLE WITHOUT NEW COWLING ALL CREDIT DUE NA CA FOR PAINSTAKING AND ACCURATE RESEARCH AND GENEROUS POLICY." Industry representatives and other aeronautical experts on the Collier trophy committee echoed that praise later in the same year. And manufacturers around the world gave the ultimate vote of confidence by adopting the NACA cowling almost universally in the 1930s and later, making this one of the most significant aeronautical advances of the 1920s.41

The NACA began exploiting this success with the Bureau of the Budget and Congress even before its full dimensions were known, and the hyperbole was breathtaking. Describing to the director of the BoB the NACA cowling's part in the record-breaking flight of the Lockheed plane, George Lewis reported that "the Committee feels that this development is the greatest single advance that has been made in commercial aviation." Somewhat less sweeping (though no less calculated) was the Committee's claim in its Annual Report for 1928 that "never before in the committee's history or in the history of the development of aeronautics has the value of a new piece of scientific equipment been so well demonstrated." 42 The NACA got as much mileage out of the cowling in the halls of Congress as any plane ever got out of it in the air.

Like all successes, the NACA cowling had its share of criticism. Historian of technology John B. Rae has reported Lockheed's claim that the cowling on its Vega aircraft, first marketed in 1927, had been the basis of the NACA design; however, the enthusiastic telegram sent to the NACA by Lockheed after the record-breaking flight of 1929 suggests that this was not the official position of the company. More likely, some engineers at Lockheed took exception to the claims made for the NACA cowling and wanted to suggest that the Committee's work was not entirely original. Chance Vought also provided the NACA with blueprints for one of its planes and an aircraft of similar fuselage and landing gear was used in the NACA experiments. But the correspondence on this transaction contains no evidence that the manufacturer saw any duplication of the kind of cowling it had been using before the NACA experiments.43

The most serious criticism of the NACA cowling was the claim that it was preceded by (and inferior to) the Townend ring, another type of cowling for radial engines developed in England's National Physical Laboratory at about the same time. Townend published his results

before the NACA and thus claimed precedence. The NACA retorted that its investigation had begun before Townend's and proceeded independently of it and, in any event, the cowling it had developed was categorically different from Townend's; while his provided only a ring about the bank of engine cylinders, the NACA cowling enclosed practically the entire engine and incorporated special ducting to pass cooling air over the cylinders. Both cowlings had their merits and both saw wide use, thus feeding the dispute over which was more important or more original. That dispute ended in court, in a series of patent suits that dragged on into the 1930s.44

Many of the disputes over the NACA cowling arose from a misperception of what the Committee had claimed for it. The NACA had professed neither conceptual originality nor revolutionary development. In fact, it had decided against taking out a patent on the cowling, leaving that tactic to its competitors and detractors. The NACA did claim that it had done more comprehensive work-original in its waythat had improved on an existing idea. The NACA cowling, said the Committee, was admittedly an innovation of an idea as old as World War I. What was different about the NACA version was that the Committee's better facilities (i.e., the propeller-research tunnel) had yielded better results and a superior configuration.

The last two claims, better facilities and better results, went hand in hand and helped to intensify the controversy. What the NACA wanted most from the cowling was more appreciation and support in Congress. It wanted to make the case that the research facilities of the Committee had helped determine the quality of the product. As the NACA had the best tunnel, so it got the best cowling. The Committee made the latter claim not so much to blow its own horn as to make a case for more tunnels. Nonetheless, the claims sounded like bragging, especially to those informed about the background of the cowling. Furthermore, singing one's own praises-for whatever good and practical purposes-can become a habit. 45

If the Committee hardened some of its critics with the public display over the cowling, it achieved important results as well. When it had requested an unprecedented full-scale wind tunnel in 1928 at a projected cost of almost $1 million, Congress demurred. The following year, however, after the success of the NACA cowling became known, Congress authorized the building of not only the 30- by 60-foot wind tunnel but also a new maintenance building and a towing tank for testing seaplane models. These were the first construction authorizations since the propeller-research tunnel had been approved more than four years previously. The message was clear. Demonstrated results from equipment already funded could be parlayed into more new equipment, even to making the Langley Memorial Aeronautical Labora

tory the best equipped in the world. It became just that with the construction approved in 1929, if it had not been so before.

The primitiveness of early NACA research is shown in these two 1921 photographs. Above, a model helicopter rotor is tested in Langley's wind tunnel #1, an exception to the NACA pattern of ignoring helicopter research before World War II. Below, a cockpit is equipped with a new airspeed indicator (next to the empty space on the right side of the panel) to aid flight research. (LaRC)

PLEASING EVERYONE

Not all the work done with this equipment was for industry. The NACA continued to work during the late 1920s for its principal customer, the military services. All military requests for research were honored with a research authorization. The Committee on Aeronautical Inventions and Designs continued to be primarily a service for the military as its previous incarnations had been since World War I. Some NACA research applied only to military aircraft: development of accelerometers for aircraft being catapulted from a carrier, improvement of the range of pilot vision in pursuit aircraft, or analysis of stresses on pursuit aircraft in combat maneuvers.46

However, most of the NACA's research-whether requested by the military or by industry or by the NACA staff-applied to all flight, commercial or military. As early as 1922, when trying to identify research applicable to commercial aviation, George Lewis confessed an inability to draw any line between the various uses to which aircraft could be put. As he had written to the chief physicist at Langley: “I have been thinking for sometime [sic] of problems which we could properly undertake at Langley Field that would apply directly to the development of commercial aviation but so far have not been able to think of a single problem that does not apply to aviation as a whole." 47 Devoted as it was to the fundamental problems of flight, the NACA by definition directed its efforts toward problems of wide applicability. For an agency continually called upon to answer the question, "Yes, but what have you done for me lately?", this was not only good programming, it was also good politics.

The advance of civil aviation and military aviation carried about equal weight in Washington in the late 1920s, to judge by the claims made by the NACA. Describing for the director of the Bureau of the Budget in 1928 "Some Accomplishments of the National Advisory Committee for Aeronautics," George Lewis divided his comments almost equally between civil and military aviation. In the military category he cited the development of instruments to measure aerodynamic loads on aircraft and on airships and to measure controllability and maneuverability of high-performance aircraft, determination of airplane-design characteristics that would control spinning, measurement of loads and stresses on seaplane bodies and floats, and improvements in propeller design and construction. For commercial aeronautics, Lewis listed cooling and cowling of aircooled engines (overlooking the fact that this work had first been requested by the military, and was equally applicable to military aircraft), reduction of interference effects created by the junctures of wing and fuselage, and development of standard sets of wing sections and of a diesel engine for aircraft. Lewis