When the United States entered World War I, it had no military air arm capable of fighting an enemy. It did have, however, an untapped pool of men and materials to which England and France, bled almost dry after years of war, looked hopefully. France proposed that an American "flying corps" of 4,500 planes, 5,000 pilots and 50,000 mechanics be readied for the Front in 1918. In response, the United States enthusiastically established an unrealistic goal of 22,625 airplanes, spare parts for another 17,600 airplanes, and 44,000 engines. Although Congress appropriated $640 million for aeronautics and production of training airplanes was accelerated, the United States eventually had to purchase from England and France most of its combat aircraft for use on the Front.
To meet its overwhelming expansion schedule for the Aviation Section, the United States was forced to take drastic action to acquire raw materials. For example, more than 27,000 officers and men were assigned to the Spruce Division (working in forests and lumber mills) to supply sufficient wood for building planes. Since castor oil was needed for lubricating airplane engines, 100,000 acres of land in the southern United States had to be planted in castor beans. Also, to acquire material for lining flying clothing, 450,000 Nuchwang dog skins were purchased from China.
America's greatest technological contribution to the war effort was the development and mass production of the 12-cylinder Liberty engine. During a five-day period beginning May 29, 1917, Mr. J.G. Vincent of Packard Motors and Mr. E.J. Hall of Hall-Scott Motors redesigned an experimental 8-cylinder engine previously built and tested by Packard. Weighing only 710 pounds but delivering 410 hp, the Liberty far surpassed all other aviation engines in the world. Production lines were set up by various automobile manufacturers and by the end of 1918, they had built 17,935 Liberties, 5,827 of which had been sent to Europe. The engine was destined to be a mainstay in the U.S. Air Service for 10 years following WWI.