Wednesday, December 17, 2008

I Know You Can Get There From Here, but How Do You Do It?

What comes after this short introduction is an old blog post of mine from 2005. What reminded me to do this post was this one of Jim's over on Stonekettle Station. Jim asked why there are no good general science quizzes on the net.

There are probably a lot of factors behind the dearth of general science quizzes on the net, ranging from the fact that such a thing won't draw a lot of eyeballs or advertisers, to the fact that it would take a team of people to do it right, to the fact that that team is busy teaching or doing science already. There's also the fact that such a quiz would involve math, not everyone's favorite pastime.

Personally, I am ambivalent about such quizzes. On the positive side, they encourage scientific literacy. On the negative side, they encourage the belief that science is just a collection of facts to be memorized, rather than a systematic method to understand the physical world.

However, Jim muses that another reason is that while Americans give a lot of lip service to the value science and technology, what they really are interested in is whether Britney Spears is going to lose her kids.

Jim's right, of course. A Hungarian immigrant, a physicist, once told me that America has always imported her scientific talent, and not to worry that so few of my fellow countrymen study science. I refuse to accept that. But unfortunately he was not totally wrong. One surface manifestation of the problem is that we don't really give our kids role models and heroes who are scientists. One of the few ways in which I think the Soviet education system was superior to the American one is that every Soviet high school student could tell you who Euler, Lomonosov and Mendeleev were, while I'd bet not one American kid in ten could tell you who J. Willard Gibbs was. Ask kids who they admire most, and it's usually political figures or artists of some stripe. Of course those people are important, but there is no balance to the average American kid's pantheon of heroes.

Today we celebrate the anniversary of one of the great inventions of mankind. Elementary School kids may note this day, but I do not remember it being mentioned a single time in Middle or High School. That's a shame, because an in-depth study of the story of this anniversary holds a lot of lessons that go well beyond the fact that today you can sit in a metal tube hurtling 500 miles per hour through the sky five miles in the air. But that's pretty cool, too, and worth celebrating in its own right.

I admit I’m a geek*. When I see something like the Wright Anniversary pass by, I spend a little time marveling at the achievement of something that was previously thought impossible. Then I start to ask questions. By inclination, I’m a big picture guy, but by training, I’m a details guy. I have to remember to turn the training on, but once it’s on, it takes over. So the first thing I ask about the Wrights is: “why them, when the whole world over people were working on this problem?”. Like so many things in life, the answer is complex, and involves a little luck.

The first part of the answer can be found in this passage:

Prior to their famous 1903 flight, Orville and Wilbur had to rework the existing lift and drag tables which were found to be all wrong. New and correct tables had to developed by working with gliders and control designs to get more lift. Similarly, they had to design and build the first wind tunnel to validate their designs without jeopardizing life and limb in full-scale tests. Finally, they had to design the airplane propellers from scratch. This was because it quickly became apparent that an airplane propeller design cannot be adapted from a ship propeller design.

They were systematic thinkers, and they went through each step inventing the “enabling technologies” as we call them today, the things that you need in order to design and build an airplane: the drag tables, the wind tunnels, and the airscrews.

This is a key point that elementary school accounts gloss over. The Wright brothers created the first wind tunnel. That in and of itself is a significant achievement. It's also a great object lesson in the stepwise achievement of dreams. As Terry Pratchett put it:

"Are you listening?"
"Yes," said Tiffany.
"Good. Now ... if you trust in yourself ..."
"... and believe in your dreams ..."
"... and follow your star.. ." Miss Tick went on.
"... you'll still get beaten by people who spent their time working hard and learning things and weren't so lazy. Good-bye."

The brothers also realized that the existing knowledge of propellers was based on ship screws, and water behaves as a fluid quite differently from air:

The twisted airfoil (aerofoil) shape of modern aircraft propellers was pioneered by the Wright brothers when they found that all existing knowledge on propellers (mostly naval) was determined by trial and error and that no one knew exactly how they worked. They found that a propeller is essentially the same as a wing and so were able to use data collated from their earlier wind tunnel experiments on wings. They also found that the relative angle of attack from the forward movement of the aircraft was different for all points along the length of the blade, thus it was necessary to introduce a twist along its length. Their original propeller blades are only about 5% less efficient than the modern equivalent- some 100 years later.

The first props were only 5% less efficient than a model 100 years later! This is why the story of the Wright Brothers should be taught in depth to high school students. This is what Edison meant about 99% perspiration. The Wrights did not just dream, they paid attention to the details necessary to make that dream a reality.

Good things come to minds that think like that, when those habits of thought are combined with creativity. Unfortunately, that’s a rare combination. That’s why there are a lot more accountants than prize-winning scientists and engineers.

There was one more enabling technology that the Wrights needed, though. The engines of the day were primarily cast iron and brass - too heavy to push themselves and an airframe into the air, even with the Wright airscrew. The Wrights sent out to automotive manufacturers for bids on a lightweight (180 lbs) engine that could crank out 8 hp. The car manufacturers could not be bothered with piddling one-off custom orders at the price the brothers were willing to pay:

Immediately upon our return to Dayton, we wrote to a number of automobile and motor builders, stating the purpose for which we desired a motor, and asking whether they could furnish one that would develop eight-brake horse power, with a weight complete not exceeding 200 pounds. Most of the companies answered that they were too busy with their regular business to undertake the building of such a motor for us; but one company replied that they had motors rated at 8 h.p. according to the French system of ratings, which weighed only 135 pounds, and that if we thought this motor would develop enough power for our purpose, they would be glad to sell us one. After an examination of the particulars of this motor, from which we learned that it had but a single cylinder of 4 inch bore and 5 inch stroke, we were afraid that it was much overrated. Unless the motor would develop a full 8 brake horse power, it would be useless for our purpose.

So, the Wrights turned to the mechanic who built the engine that powered their wind tunnel, Charles Taylor:

In just six weeks from the time the design was started, we had the motor on the block testing its power. The ability to do this so quickly was largely due to the enthusiastic and efficient services of Mr. C.E. Taylor, who did all the machine work in our shop for the first as well as the succeeding experimental machines. There was no provision for lubricating either cylinders or bearings while this motor was running. For that reason it was not possible to run it more than a minute or two at a time. In these short tests the motor developed about nine horse power. We were then satisfied that, with proper lubrication and better adjustments, a little more power could be expected.

Taylor’s engine was a marvel. To borrow a line from Douglas Adams, the first thing I’d think in an aircraft powered by this engine is “please may I get out”:

What was missing from the 1903 Taylor engine is equally significant. There was neither a fuel pump, carburetor nor oil pump. Raw gasoline dripped into the cylinders from a tank mounted on the wing strut. Because it was not expected to run for long, the engine was pre-oiled.

The valves were not cooled, they ran red hot. Despite the fact that all those parts were missing, a cast iron engine would still have been too heavy. So the Wrights turned to a metal available in bulk only for about 50 years – aluminum (hell yeah, I’m Amurrican, what of it?**). But aluminum has flaws as a construction material: it melts at much too low a temperature, and it is relatively soft. By trial and error, the Wrights came up with an alloy strong enough and temperature-resistant enough to make an engine block out of. It consisted of about 8% copper, and pre-dated the systematic scientific discovery of such alloys by at least 3 years:

In 1906 Dr Alfred Wilma, a German metallurgist, discovered that aluminium alloyed with copper and heat treated correctly could be made far stronger. The alloy of aluminium with 4% copper is called Duralumin and the heat treatment process is called precipitation hardening. These alloys have typically low specific gravity (around 2.7) and high strength (450 MPa). They are limited by a maximum service temperature of about 660°C. Since then, other heat treatable aluminium alloys have been developed for aircraft use. These include a range of complex aluminium-zinc alloys which develop the highest strength of any aluminium alloy. These alloys have led to modern aircraft design where the skin of the fuselage and wings are stressed aluminium alloy members which reduces the overall weight.

Note the difference in the 1903 Wright alloy copper content and the 1906 Duralumin content. That right there is an object lesson in what David Foster was going on about here. You can’t steer a ship that isn’t moving, and Wilma was looking at Al alloys because of their aircraft applications.

As an aside, the metallurgy of these alloys is quite fascinating, and an example of nanotechnology that predates the current fad by about 90 years:

Metallurgists have long known how to make strong alloys, even without understanding their microstructure. First heat the constituents until they dissolve in one another, then allow the alloy to "age" for several days; one or more of the constituents may precipitate out of solution and form microscopic inclusions in the matrix, forming a considerably stronger alloy. Precipitation hardening has been crucial to aviation since the first powered flight- although the Wright brothers didn't know it.

The story of the engine itself is fascinating. It was wrecked in a crash not long after the first flight, Since it was a custom job and none of its parts fit other planes, it was left with the other detritus of the Wrights’ shop:

Although the airplane was repaired and flew again, the crankcase disappeared and was not found until 1985 – 80 years later. The National Park Service at Kitty Hawk, North Carolina had it squirreled away and was not aware that anyone was interested in it.

As an aside - what kind on numbnuts did we have curating the Wright collection, anyway? Well, they seem to have got their act together, now, and have a nice little page devoted to the engine.

Once found, the NIST conducted some tests on the engine, confirming the alloy composition.

The history of the mechanic, Charlie Taylor, is a sad one. He left the Wrights (big mistake), and suffered a series of failed business deals which impoverished him. When Henry Ford created a museum of American industry, he was found in a California machine shop making 37 cents an hour. He went to work for Ford until WWII demanded skills for the war effort. Orville found him penniless again after his WWII service in an aircraft factory, having suffered a heart attack. Orville set up a trust fund that was wiped out by post-WWII inflation, and Taylor died in a charity ward.

Taylor’s working method and his post-Flyer demise struck me as an object lesson in what Prof. Dutch was going on about in this screed:

It is useful, however, to distinguish between tinkering and creativity. Tinkering consists of exploring relatively minor variations on known themes, or subjecting new stimuli to an array of already known techniques. Thomas Kinkade rarely creates and mostly tinkers. Babies tinker constantly. They put every new object in their mouth. Eventually they figure out that most things are not good to eat. When they develop motor control, they throw things. Serious curiosity consists of actively seeking new kinds of stimuli. Creativity consists of juxtaposing objects and ideas in new ways, and having a sound intuition for separating the significant result from the trivial.

There are inventors and there are tinkerers. Charlie was a tinkerer. I seriously doubt he would have invented the engine of his own accord, but once the Wrights set him to the task, he accomplished it:

Given the Wrights' reputation for detail, the seemingly straightforward task of recreating the original engine has proved to be surprisingly difficult. While Orville and Wilbur kept careful records of their wind-tunnel and flight tests, engine builder Charlie E. Taylor took a more casual approach. The cranky, cussing mechanic who ran the Wright brothers' Dayton, Ohio, bicycle shop, and irritated their sister Katharine with his incessant cigar smoking, did his work on the fly. It wasn't carelessness. It was just the way Taylor preferred to work, says Howard R. DuFour, the author of Charles E. Taylor: The Wright Brothers Mechanician. "Charlie was the first aircraft mechanic in the world," DuFour tells POPULAR MECHANICS. "One of them--Orville, Wilbur or Charlie--would sketch out the part they were talking about on a piece of scrap paper. Then, Charlie 'spiked' these [scraps] on his workbench for reference in machining and assembling the engine." As the parts were completed over the next six weeks, these scraps of paper were lost, along with the details of the engine that would revolutionize transportation.

The lay public, and apparently Jared Diamond (among other sociologists of science) have a hard time distinguishing tinkerers from inventors. It is far, far better to be one of the latter than one of the former, and we rightly celebrate them (but, as I mentioned above, we don not celebrate them enough, or encourage our children to study their methods). I have a feeling that Charlie’s problems in later life were caused by his lack of systematic approach to business affairs and life in general.

A creative mind that is not systematic enough may be the polar opposite of an accountant, and exactly who you want in the machine shop, but unlike the accountant, such a mind also runs the risk of dying penniless and being memorialized posthumously. But philosophical ruminations aside, a lot of creative work is also catalyzed by the technicians and machine shop workers who build the stuff the inventors design. So stop for a moment and remember the Wrights, their work methods, and especially Charlie, the tinkering mechanic who gave us wings.

* Two little factoids stuck in my head, leading to this post. One, I saw a comment about the use of copper – aluminum alloys on a plaque attached to an early Wright engine at the WPAFB Museum. I also remember reading a Science article on the Wright Flyer crankcase by Gayle and Goodway back when I was in grad school.

** Some heathens put an extra "i" in aluminum:

The metal derives its name from alumen, the Latin name for alum. In 1761 L. B. G de Morveau proposed the name alumine for the base in alum, and in 1787 Lavoisier definitely identified it as the oxide of a still undiscovered metal. In 1807 Sir Humphrey Davy proposed the name aluminum for this metal and later agreed to change it to aluminum. Shortly thereafter, the name aluminium was adopted to conform to the "ium" ending of most elements, and this spelling is now in general use throughout the world. Aluminum was also the accepted spelling in the United States until 1925 when the American Chemical Society officially reverted to aluminum.


Anonymous said...

I haven't found the link, but another part of the Wright Brothers story is that they discovered and solved the problem of control in flight and actually learned to fly with their gliders. It was not a coincidence that they were bicycle mechanics before they were pilots.

Jim Wright said...

Great post, John. I enjoyed it.

Jim Wright/no relation

Mr. Bingley said...

Happy New Year John!

(wing warping is still for the birds...)