Technical Progress in the U. S. Army Air — Corps in the Thirties
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.
Battleships of the Air — Lead the Way to Victory
Regardless of the fact that this country was at peace and our military policy a defensive one, our farseeing Air Corps leaders continued to build American air power around the heavy, long-range bomber. As the heavy bomber was primarily an offensive weapon, many Americans believed the Army’s development of it to be contrary to our declared policy. As a result, we did not build great numbers of bombers. However, with the small number that we did have, our Army aviators made great progress in the technique of high-altitude bombing.
As in all branches of the United States Army, great stress was laid on good marksmanship. Army aviators were trained to hit the mark with their bombs just as the infantryman does with his rifle. Other countries developing heavy bombers were satisfied if their airmen dropped a great many bombs in a given target area. In this country the development of the bombsight enabled our aviators to hit a target with great accuracy from high altitudes. This is called precision bombing. It was also known as pin-pointing a target, because of the ability of our bombardiers to score direct hits on small targets. It was the B-17 Flying Fortress that gave Army airmen the greatest help in perfecting high-altitude, precision bombing. The broad wings of the Fortress furnished a steady platform from which to aim the bombs, and the great plane was able to fly smoothly in the higher altitudes. The bombardier riding in its transparent nose could carefully line up his target and drop his bombs with precision accuracy.
It was not until the outbreak of World War II that most Americans came to realize the value of the airplane in modern conflict. As the fighting grew to global proportions, Americans began in particular to appreciate the farsightedness of our Air Corps leaders in developing the long-range bomber.
By 1940 the original Boeing 299 or B-17 had grown from a sixteen-ton ship to a giant twenty-two-ton bomber. The new version, the B-17D, was powered with two 1,200-horsepower radial engines, giving it a speed of more than 300 miles per hour. Continual improvements were made on it and by the spring of 1942 a still more formidable member of the Fortress family, the B-17F, was in production.
The B-17F was the most powerful bomber yet produced. It was armed with eleven.50-caliber machine guns and manned by a crew of ten. It could carry more than three tons of bombs to targets over seven hundred miles distant. Its oxygen system permitted its crew to fly the Fortress at altitudes above 35,000 feet. With its eleven heavy machine guns in the hands of a perfectly trained crew, the Fortress was capable of defending itself with deadly effectiveness.
The first Flying Fortresses went into action with the United States Army on the day after the attack on Pearl Harbor. Although this country had then only a limited number of Fortresses, they and their successors quickly began to distinguish themselves on the battlefronts of the world.
By the summer of 1942 Flying Fortresses had begun what was to be the greatest sustained aërial invasion the world had ever known. Starting with a small group of Fortresses, the United States Army Air Forces went to work to wreck Adolf Hitler’s “Fortress Europe” and clear the path for an Allied invasion.
From small raids by a dozen Fortresses the number of bombers grew until the raids became huge aërial invasions involving hundreds of bombers and thousands of airmen. That the path for invasion was cleared and victory brought nearer was due in no small measure to our big bombers and the farsighted American airmen who had brought them into being against almost insurmountable obstacles.