标签: wright

I always get irritated when I read or hear someone say “the airplane was invented by the Wright brothers, bicycle mechanics from Dayton, Ohio.” While this simplistic statement is factually correct, of course, it also somewhat misleading, as makes it sound like they were a couple of clever tinkerers who “stumbled” across the secret of fully controlled, heavier-than-air flight almost by accident, in a random walk to success.   The reality is very different. The brothers were skilled mechanics, but they were also methodical and thorough engineers and scientists, and skilled projects managers as well. In the just-published book The Wright Brothers , historian and Pulitzer-prize winning writer David McCullough captures the multiple dimensions of their story—a story which has been told before but is worth refreshing. (One of his earlier books, The Path Between the Seas , details the building of the Panama Canal, an engineering feat with audacity, scope, and depth that is almost unimaginable to those who work with circuits, ICs, and software.)   A pair of diagrams from Wilbur Wright's paper title "Some Aeronautical Experiments" shows they brothers were much more than lucky experimenters (Source: From the Journal of the Western Society of Engineers, Volume VI, No. 6, December 1901.)   For example, the Wright brothers tested small and man-carrying gliders to verify their theories, assess lift factors, evaluate control techniques, and even learn how to fly (obviously, there were no instructors yet). They carefully measured the lift and drag versus airspeed of these gliders built with different wing airfoil profiles ( ratio of chord to camber ) and found their results were far less than what they had expected based on their analysis using the lift tables published by various reputable aeronautic sources and experts. They went through all the possible causes, including that the published tables were in error.   To test their conjecture on the reasons for the difference, they did what any conscientious engineer does when in test and debug: they decided to check assumptions and source data for themselves. The built a sophisticated wind tunnel with a clever parallelogram scheme to allow the wing airfoil under test to rise without tilting, powered it with a small gasoline engine (they did not have electricity in their shop), then tested different airfoils. In many case, they found that the “official” numbers were optimistic by a factor of two.   They also realized that the propeller design was not a simple "airscrew" and its design would be a critical part of the aircraft's achieved thrust; instead, it was a lifting wing that happened to rotate. As a result, they grasped that the airfoil of the propeller could not be simple. Instead, this profile had to be carefully varied from hub to tip to match the airspeed at each distance, to achieve optimum performance.   Even before they triumphed in 1903, Wilbur delivered an invited paper at meeting of the prestigious Western Society of Engineers in Chicago in 1901. This paper, with the deceptively simple title "Some Aeronautical Experiments," not only recounted their experiments, test setup, logistics, and challenges, but it included scientific analysis of the parameters of flight as they saw them, along with their test results. After some deep-diving searches on the web, I found the paper scanned in full from a copy at the Harvard Science Center Library; you can see it here.     Their expertise went beyond aeronautics. When they could not find a gasoline engine meeting their size, power, and weight constraints, they did what a truly dedicated engineer does: they designed and built their own (with their highly skilled shop mechanic, Charlie Taylor). This engine, with four cylinders, four-inch bore, and four-inch stroke, has a design goal of eight horsepower output and maximum weight of 200 pounds. They far exceed those goals: by using an aluminum block – very rare at the time – the engine came in at 152 pounds yet it delivered 12 horsepower.   Finally, their skills as project managers cannot be ignored. They kept detailed records of each idea, problem, test, and result, along with full notes about what went well, what didn’t, why results didn’t meet expectations, and what the next steps might be. They were their own purchasing agents, administrative assistants, and accountants (they paid for their RD, trips to Kitty Hawk, and more entirely out of their own modest funds, without any grants, investors, or loans). We all know how the story of the Wright brothers ends. Like good engineers, they did not get discouraged, even when their tests went badly, their gliders crashed and were ruined, and they were informed that “it won’t work”. They discarded their own ideas when they led to dead ends, and did not listen to the experts, such as one that McCullough cites: Simon Newcomb, a distinguished professor of astronomy at Johns Hopkins University, wrote, “The first successful flyer will be the handiwork of a watchmaker, and will carry nothing heavier than an insect.” Here’s my thought-provoking question for discussion and debate. We often quotes along the lines of “we went from the Wright Brothers in 1903 to a moon landing just 66 years later in 1969”, which is factually true, of course. But even if the brothers had not succeeded, would that have affected rocket-powered flight? After all, heavier-than-air flight in an atmosphere is very different than rocket launches, space flight, and related technologies.     Would space-flight development been different in the absence of powered flight? Feel free to argue both sides of this conjecture with your fellow engineers at the next off-site “team-building” day, or at an informal “after work” situation.