While not a dramatic scientific breakthrough, drag cleanup and reduction conducted at NACA Langley and Ames – the painstaking work to minimize airplane resistance to airflow – led to significant speed increases in our military aircraft. Beginning in 1938, Langley researchers using the famous “Cave of the Winds” Full-Scale Wind Tunnel developed a new method to measure the drag produced by every part of an airplane and make recommendations to the manufacturer about reducing drag. The military, which had before the war assumed responsibility for drag reduction work, basically turned it over to the NACA, and allowed its researchers to test virtually every new prototype both in wind tunnels and in flight. An example of the efficacy of drag cleanup was the predicted increase in the top flying speed of the Bell P-39 Airacobra from 340 mph to 392. The NACA scientists recommended a series of detail changes that could greatly increase the aircraft’s speed without a costly redesign, but the 392 mph figure depended upon the aircraft’s original turbosupercharged power plant, and an aircraft that weighed in the neighborhood of 5,500 pounds. “Figuring out a way to build a 400 mph fighter at level flight and to get to that kind of speed was a big deal,” noted Launius. Bell and the Army were quite pleased with the results of the NACA’s drag reduction work, and ultimately Bell made enough of the recommended changes to increase the Airacobra’s speed by 16 percent. Unfortunately, the replacement in the production model of the aircraft’s turbosupercharged engine with a less powerful one incorporating a geared supercharger, and the addition of armor and armament, and for that matter, olive drab paint, reduced the Airacobra’s speed again, and production P-39s never exceeded 386 mph.

North American Aviation’s legendary P-51 Mustang was altogether more successful, and could attribute much of its performance to NACA research, as Michael H. Gorn describes in Expanding the Envelope. When the XP-51 took to the air, it was borne on a laminar flow wing that derived from the research of NACA aerodynamicist Eastman Jacobs and his team. The production Mustang was among the fastest propeller-driven fighters of the war in level flight, and surpassed most of the others in dive performance. NACA flying qualities research, including some very hazardous test flying, also led to refinements in the Mustang’s ailerons that would give it the highest roll rate of any frontline fighter in the world, a vital capability in a dogfight.

Nor was NACA research limited to developing American aircraft. In a highly classified instance, a captured Japanese Mitsubishi Zero that had ditched near Dutch Harbor, Alaska, had its flight characteristics tested at Langley as well as in flight by the Navy. Chambers wrote that “some of the historians believe that the capture of the Zero (and the subsequent analysis of its flight characteristics) was as devastating to the Japanese war effort as the U.S. victory during the battle for Midway Island.” ⁵

The problem of airplane icing, which existed from the beginning of powered flight, plagued the commercial aviation industry in the 1930s, causing numerous crashes and giving passengers a genuine reason to eschew this form of transportation. During the war, icing posed a real problem to military pilots operating in the North Atlantic and out of Alaska. Into the fray went NACA’s Lewis A. Rodert, leader of NACA icing research from 1936 to 1945, who appropriately studied engineering in the cool climes at the University of Minnesota. To attack the problem, he constantly tinkered with various mechanical, chemical, and thermal deicing systems on a small Lockheed 12A and a Curtiss C-46 that became his research laboratories. After much trial and error, Rodert’s team created a heat exchanging system that piped air heated by hot engine exhaust along the leading edge of an airplane’s wing. In 1947, President Harry Truman presented Rodert and his team the prestigious 1946 Collier Trophy, aviation’s highest award, for their deicing work.