We have spoken of the fact that in the early twenties aircraft designers were hesitant about attempting to overcome the prejudice of aviators against the internally braced monoplane design. However, there was one young man who had never been timid about the idea. He was a tall, scholarly fellow who, as a youngster, was designing and flying model planes before the Wright Brothers made their first flight. Like the Wrights he was the son of a minister. This young man, William Bushnell Stout by name, worked his way through the University of Minnesota by firing a furnace. After graduation he worked for a newspaper and edited a boys’ page, one of the first in America that gave complete directions for building model airplanes.

With the outbreak of World War I, Bill Stout became technical adviser to the Aircraft Board in Washington. His first advice to the aviation experts there was to scrap all existing designs and build a streamlined monoplane with an internally braced wing without struts or wires. They said it could not be done. Bill promptly sat down and drew workable plans for such a ship.

Eventually the Government bought Bill Stout’s design and with the money he set up his own engineering laboratory in Detroit, Michigan. He decided that wood and fabric were not suitable to stand the strain required in a modern plane. His first all-metal plane, a Navy torpedo bomber, flew successfully in test flights, but a Navy pilot wrecked it on its official trial. The Navy would not order another one, so Bill had to raise more money. He got it and built America’s first all-metal transport plane. It carried eight passengers in addition to the two-man crew. Bill knew it was a good plane and he was satisfied with it, but he did not want to be a manufacturer. He wanted instead to stay at his engineering work, so he sold his airplane company to Henry Ford, and the famous Stout-designed, Ford tri-motor, “Tin Goose” was born.

Just about the time the Ford tri-motors were proving themselves in tests an important law was passed by Congress. It was the Kelly Air Commerce Act of 1925. It authorized the Post Office Department to contract with private firms to fly the air mail routes maintained by the Department of Commerce. This law was designed to encourage private capital to enter the aviation field, with the objective of carrying not only mail but passengers. In February, 1926, officials of one of the newly formed air transport firms proudly watched their first big air transport plane take off from the Detroit airport. The big plane was a Stout-designed, all-metal Ford, the first of a series of airliners that were destined to make aviation history.

By the end of 1926, there were sixteen air transport operators holding air mail contracts. Most of the flying was still done in single-engined planes. Up to that time the weight of the big water-cooled engines in multi-engined transports left little to spare for pay loads. It was not until the development of the radial engine that commercial aviation really started.

The in-line engine required a long, heavy crankshaft with sections for each cylinder. This required that separate crankshaft bearings be used for each cylinder. The whole crankshaft assembly was heavy and cumbersome. When extra cylinders were added, the engine’s weight increased and it became longer. In the radial engine a single crankshaft hearing was used.

The radial air-cooled engine immediately showed many advantages over the in-line, water-cooled engines of that time. The use of aluminum in its construction made it lighter. It was cooled by allowing air to rush through finely spaced fins on cylinder heads and barrels. The weight of the cooling liquid (water) and the pump and mechanism to circulate it was avoided.