Over the years NACA acquired a highly competent staff of "research engineers" and technicians at its Langley laboratory.10 Young aeronautical and mechanical engineers just leaving college were drawn to NACA by the intellectual independence characterizing the agency, by the opportunity to do important work and see their names on regularly published technical papers, and by the superior wind tunnels and other research equipment increasingly available at the Virginia site. NACA experimenters made discoveries leading to such major innovations in aircraft design as the smooth cowling for radial engines, wing fillets to cut down on wing-fuselage interference, engine nacelles mounted in the wings of multi-engine craft, and retractable landing gear. This and other research led to the continual reduction of aerodynamic drag on aircraft shapes and consequent increases in speed and overall performance.11
The steady improvement of aircraft design and performance benefited commercial as well as military aviation. Airlines for passenger, mail, and freight transport, established in the previous decade both in the United States and Europe, expanded rapidly in the depression years of the thirties. In the year 1937 more than a million passengers flew on airlines in the United States alone.12 At the same time, advances in speed, altitude, and distance, together with numerous innovations in flight engineering and instrumentation, presaged the arrival of the airplane as a decisive military weapon.13
Yet NACA remained small and inconspicuous; as late as the summer of 1939 its total complement was 523 people, of whom only 278 were engaged in research activities. Its budget for that fiscal year was $4,600,000.14 The prevailing mood of the American public throughout the thirties was reflected in the neutrality legislation passed in the last half of the decade, in niggardly defense appropriations, and in the preoccupation of the Roosevelt administration with the domestic aspects of the Great Depression. Without greatly increased appropriations from Congress, the military was held back in its efforts to acquire more and better aerial weapons. Without a military market for its products, the American aircraft industry proceeded cautiously and slowly in the design and manufacture of airframes and powerplants. And in the face of the restricted needs of industry and the armed services and severly limited appropriations, NACA kept its efforts focused where it could acquire the greatest quantity of knowledge for the smallest expenditure of funds and manpower—in aerodynamics.
As Europe moved nearer to war, however, the Roosevelt administration, Congress, and the public at large showed more interest in an expanded military establishment, including military aviation. Leading figures like Lindbergh and Vannevar Bush, president of the Carnegie Institution and chairman of the Main Committee, warned of the remarkable gains in aviation being made in other countries, especially in Nazi Germany.15 While the United States may have retained its aerodynamics research lead, the Germans, drawing, in part from the published findings of NACA, by 1939 had temporarily outstripped this country in aeronautical development.
