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THE WRIGHT BROTHERS designed and developed the first powered heavier-than-air craft with theoretical as well as practical considerations. “The Wright Brothers—Aero Theoreticians” here at SimanaitisSays described one aspect of this, its aerodynamics. Today and tomorrow, in Parts 1 and 2, let’s examine its power.
The Wright Flyer wasn’t particularly small, a biplane of 40-ft. wingspan. I stood beside a replica at Maine’s Owls Head Transportation Museum. (In modern perspective, a high-wing Cessna’s span is 36 ft.) The brothers calculated that its engine would have to produce at least 8 hp and contribute no more than 200 lb. of the craft’s 745-lb. maximum weight at launch.
No existing engine met these criteria. So, with Charlie Taylor, their “mechanician,” the brothers designed and fabricated their own. Its inline-four design was crude in some ways, yet advanced the state of powerplant art in others. In particular, the engine met the Wrights’ design criteria: It weighed 180 lb. and produced nearly 16 hp, a steady 12 hp at 1025 rpm once warmed up.
Horizontally aligned individual cast-iron cylinders had bore and stroke of 4.0 x 4.0 in., yielding a displacement of 201 cu. in., 3.3 liters. The four pistons were also cast iron, machined down and grooved for piston rings. Mechanician Taylor was in charge of these tooling operations, the Wright shop equipped with a lathe and drill press. Its machine tools were belt-driven by a stationary gas engine, an earlier Wright design with Taylor fabrication.
In the “1903 Wright Engine” article at wrightbrothers.org, Charlie Taylor described fabrication of the engine: “We didn’t make any drawings. One of us would sketch out the part we were talking about on a piece of scratch paper, and I’d spike the sketch over my bench.”
“The crankshaft,” he said, “was made out of a block of machine steel 6 by 31 inches and 1-5/8 inch thick. I traced the outline on the slab, then drilled through with the drill press until I could knock out the surplus pieces with a hammer and chisel. Then I put it in the lathe and turned it down to size and smoothness.”
The crankcase to which the cylinder barrels were mounted was of cast aluminum alloy, the work done by Buckeye Iron and Brass Works, a nearby Dayton, Ohio, foundry.
The aluminum-alloy crankcase proved to be metallurgically innovative. According to newscientist.com, “The alloy, a mixture of aluminum and 8 per cent copper, was used to make the Flyer’s crankcase…. also the first time an aluminum alloy had been toughened by heating it.”
“The finding,” continued NewScientist, “published in the current [November 1994] issue of Science, overturns the accepted theory of technology. The first alloy of this type had been thought to be Duralumin, which was patented by the German metallurgist Alfred Wilm in 1910.”
“Frank Gayle and Martha Goodway of the National Institute of Standards and Technology and the Smithsonian Institution examined the Wright brothers’ crankcase with an electron microscope…. Gayle and Goodway found a distinctive pattern of fine copper precipitation which is now known to strengthen the alloy. However, the theory of precipitation hardening, as it is known, was not published until 1919.”
The Wright brothers were ahead of their time in many ways. Tomorrow in Part 2, we’ll learn that they could be traditionalists as well. ds
© Dennis Simanaitis, SimanaitisSays.com, 2018