Although prevented from any great expansion in the years following World War I, the Army led the way in many phases of aviation. United States Army planes were the first to fly around the world. Army aviation also pioneered night flying and the use of the lighted airfield, refueling in the air, and radio communication between ground and plane. It made great advances in aërial photography. In 1929, Captain Albert W. Stevens photographed Mount Rainier from an airplane 227 miles away, establishing a record of long-distance aërial photography. The same year, Lieutenant “Jimmy” Doolittle, in a demonstration of instrument-flying, accomplished a take-off and a landing solely through the use of instruments. This was the beginning of “blind flying.” The Army Fokker Question Mark under the command of Carl Spaatz and Ira Eaker, generals commanding our heavy bomber forces in Europe in World War II, established an endurance record by staying aloft for 150 hours. Their plane was refueled in the air during the record flight. Army aviators were trained in the use of oxygen at high altitudes and in the use of instruments for “blind flying.”
In 1927 the great Matériel Division of the Air Corps was established in its new home at Wright Field, Dayton, Ohio, close by the birthplace of Orville and Wilbur Wright. The Air Corps Matériel Division was the testing laboratory for all Army aviation equipment. Here all types of new engines, planes, and instruments were developed and tested. Aircraft manufacturers co-operated closely with Army technicians in developing ideas which would help to further the advancement of military aviation. New types of planes were taken to Wright Field, where Army technicians and test pilots put them through grueling tests before releasing them for Army service. Here the Army research engineers worked with oil companies to develop fuels which would increase the performance of aircraft engines. Clothing and equipment for pilots were tested. High-speed aërial cameras were developed, and it was through the efforts of the men at Wright Field that aërial photography in general was perfected to so high a degree.
Many of the features developed for the Army at Wright Field also were applied to commercial aviation and contributed greatly to the safety of air travel. From the earliest postwar days, Army aviation leaders had been insistent that safety was the most important factor in the development of airplanes and of aviation equipment. The experts at Wright Field have contributed greatly to the high record of safety which consistently has prevailed in Army aviation.
THE ALLISON ENGINE
For several years after World War I, all Army airplanes were powered with water-cooled, in-line engines. In the majority of cases it was the Liberty engine developed during the war, but some water-cooled Wright engines also were used. As late as 1927 the Army still was experimenting with the Liberty engine and trying to increase its horsepower. James A. Allison became interested in this project and, when the job was given up as hopeless, went on to create his own engine. He died before he had completed his engine, but his assistant, Norman H. Gilman, continued its development in conjunction with General Motors. The first successful Allison engine was completed in 1932, and the following year the Navy used it to power the dirigibles Akron and Macon.
The Army became very much interested in the Allison engine. Although a number of Army fighters were equipped with radials following the early successes of that type of engine, Air Corps men believed that, due to its narrow frontal area, the in-line engine could help to streamline fighters. Finally, in 1939, after many changes, the first Allison engines were installed in Curtiss P-40 Army fighters. The first Allison engine had developed 1,090 horsepower. By 1940 its horsepower was increased to 1,150 and the Army adopted it as standard. It was installed in all P-40’s and later in Lawrence Bell’s P-39 Airacobra. In the P-39 the engine was installed in the fuselage behind the pilot. A ten-foot shaft carried the power to the propeller in the nose of the ship. This installation permitted the housing of a 37-millimeter cannon and two machine guns in the nose of the Airacobra. The Lockheed P-38 Lightning was powered with two Allison engines, making it the first fighter with more than two thousand horsepower.
