Tuesday, February 24, 2009

Great Moments in Aviation, Part VII

We are coming to a point in the story where everything seems to be happening at once. That is mainly due to the fact that none of this is happening in a vacuum. For most of aviation's history to date, progress has been due to the lone work of a genius here, a tinker there, all working in isolation. This would all change in the 1890s. And in my opinion, that change is mostly due to the work of one man: Octave Chanute.

Octave Chanute was a French-born engineer who had already made a name for himself working on railroad and bridge projects all across America. He came to an interest in aviation relatively late in life. In 1890, he retired from his rail and bridge practice to study aviation full-time. He spent the next several years studying everything he could find about the subject, and in 1894, he published the first comprehensive index of aviation research to date, Progress in Flying Machines. Also, in 1893, he organized an aviation conference at the Columbian Exposition. Chanute had won enough respect for his earlier work that he could not be dismissed as a crackpot. If as eminent an engineer as Chanute thought it possible, well, there's probably a decent chance that there's something to this "flying machine" stuff after all...

One of Chanute's more important contributions was the refinement of the biplane form. He applied his bridge experience to the problem, and devised a structural bracing system that was both strong and lightweight.

But his most important contribution by far was the fact that he maintained a correspondence with everyone who was anyone in the field. He shared everything he knew freely, encouraging other experimenters to take up ideas that he'd had. Ideas began to fly thick and fast. Blind alleys were quickly identified and cut off. Gliders were built with successively better and better control methods. By the turn of the century, several projects were underway that could result in the long-sought flying machine. It was no longer a question if man would fly. The question became who and when. Three of Chanute's pen-pals were in the running. All would eventually succeed, but only one of them could be first.

Monday, February 23, 2009

Great Moments in Aviation, Part VI

(Editor's Note: I'd meant to continue this series last week, but I forgot that it was Tour of California time again. For those of you who care, Levi Leipheimer won his third straight Tour of California. It was also Lance Armstrong's first USA appearance since coming out of retirement, and Floyd Landis' first race since finishing his suspension. It's four months and change 'till the big race kicks off on July 4 in Monaco. It's the Return of the King, baby! Be there!)

When we last left our story, Sir George Cayley had just made a key realization that would ultimately pave the way to controlled, powered flight: the functions of lift, propulsion, and control must be separated in order to be made practical. The half-century separating 1853 from 1903 would see each problem attacked in turn, with varying degrees of success. Truly, we're still contending with them. We're always finding better ways of doing things, and cannot consider these things "solved" even now.

But the obvious thing to do in the latter half of the 19th Century was to study gliding flight in detail. And by far, the biggest name in gliders would have to be that of Otto Lilienthal. Lilienthal made over 2,000 flights with his gliders between 1891 and 1896. He became sufficiently skilled that he could use an updraft against a hill to hang seemingly motionless in the air, with respect to the ground.

The key differences between Lilienthal's gliders and Cayley's original design is first that Lilienthal eliminated the "basket" that Cayley's reluctant passenger rode in, and also that Lilienthal's wings were of a more advanced design. He spent a considerable amount of time studying the gliding flight of birds, especially storks, making detailed aerodynamic diagrams. Today, we call such plots lift polars and drag polars. The data he gathered drove his designs. Among other things, he was the first to build biplane gliders, which gave twice the lifting surface for the same wingspan, and also a more rigid wing structure. He also experimented with a movable elevator for improved pitch control.

His remarkable feats of gliding brought him worldwide fame. Unfortunately, they were also his downfall. On August 9, 1896, he lost control of a glider, falling more than fifty feet to the ground. He broke his spine, and died of his injuries the next day. A grievous loss, but yet not in vain. He gave everyone who followed a firm foundation on which to build. True controlled flight was scarcely more than seven years away.

Saturday, February 14, 2009

Valentine's Day

A wife of noble character who can find? She is worth far more than rubies.

Her husband has full confidence in her and lacks nothing of value. She brings him good, not harm, all the days of her life.

She selects wool and flax and works with eager hands. She is like the merchant ships, bringing her food from afar.

She gets up while it is still dark; she provides food for her family and portions for her servant girls.

She considers a field and buys it; out of her earnings she plants a vineyard. She sets about her work vigorously; her arms are strong for her tasks. She sees that her trading is profitable, and her lamp does not go out at night. In her hand she holds the distaff and grasps the spindle with her fingers.

She opens her arms to the poor and extends her hands to the needy.

When it snows, she has no fear for her household; for all of them are clothed in scarlet. She makes coverings for her bed; she is clothed in fine linen and purple.

Her husband is respected at the city gate, where he takes his seat among the elders of the land. She makes linen garments and sells them, and supplies the merchants with sashes. She is clothed with strength and dignity; she can laugh at the days to come. She speaks with wisdom, and faithful instruction is on her tongue. She watches over the affairs of her household and does not eat the bread of idleness.

Her children arise and call her blessed; her husband also, and he praises her: "Many women do noble things, but you surpass them all."

Charm is deceptive, and beauty is fleeting; but a woman who fears the LORD is to be praised. Give her the reward she has earned, and let her works bring her praise at the city gate.

(Proverbs 31:10-31, NIV)

Tuesday, February 10, 2009

Great Moments in Aviation, Part V

Meanwhile, across the English Channel, big things were also happening in England at the end of the 18th Century. The next important development in flight involves a man who is the most important figure in aviation that you've probably never heard of: Sir George Cayley.

Cayley was probably the first figure in aviation history to go about it in a scientific, systematic way. He spent a lot of time in the early 19th Century testing different wing shapes, finding out which ones worked best. He tested different configurations of wing and tail. His experiments led him to develop an efficient cambered airfoil, and he also discovered the beneficial effects of dihedral on a glider's stability. He set all of this out in his three-part treatise "On Aerial Navigation", published between 1809 and 1810. But, most importantly, in 1799 he etched this drawing onto a silver disc, preserved in the Science Museum of London:

The important thing about this image is that here, Cayley clearly separates the functions of lift, propulsion, and control. Prior flying machines attempted to do all with a flexible bird-like wing. This is the key conceptual breakthrough that eventually made powered flight feasible. Propulsion was a problem that Cayley never did solve, though. Although he experimented with gunpowder-fired internal combustion engines, they simply did not provide enough power-to-weight to make a flier work. He then turned his attention exclusively to gliders.

His diligent research paid off, though not quickly. He did not build a full-size man-carrying glider until 1853. But in 1853, man finally experienced gliding flight. It was a short flight, close to the ground, and nothing like soaring with the birds. Not yet. But a gigantic step had been taken.

Sunday, February 08, 2009

Great Moments in Aviation, Part IV

Taking up the thread again in Western Europe, the story takes an unexpected turn when Joseph-Michael and Jacques-Etienne Montgolfier start fiddling around with the odd properties of hot gases.

I say "unexpected" because, although people had been gazing at birds and wondering for as long as humanity had existed, no records exist of anyone imagining the lifting power of hot air until November of 1782, while contemplating an assault on the British-held fortress at Gibraltar.

Gibraltar: it had been ceded to Britain by the 1713 Treaty of Utrecht, and it commanded the western end of the Mediterranean Sea. Needless to say, this was a major thorn in France's side. Assault from the seaward side is simply suicide. There are no beaches. The only harbor is well-covered by artillery from above. And the only approach from the landward side is narrow, and just as easily covered. As badly as the French wanted Gibraltar, well, they could want in one hand and spit in the other. Guess which one fills up first?

Which drove Joseph to wonder: what if there was somehow a way to approach from above? Say, if you could harness the lifting power of the smoke that headed up from a fire? There was no way for artillery to fire high enough to cover that approach. What a fine thing that would be ...

This might have gone the way of most idle thoughts, if the Montgolfier family hadn't been experts in cloth, paper, and wood. Joseph had exactly the right skills and materials to build a small proof-of-concept device that, when held over a fire, promptly sailed up to the ceiling. Once he showed his brother, well, there was nothing for it but to build a full-scale version that could carry the both of them.

About a month later, on December 14th, 1782, the brothers took their first balloon aloft. They lost control, not expecting the lifting force to be so great, and sailed one and a quarter miles across the countryside before making a safe landing. Larger balloons followed, as well as public demonstrations, until in September of the next year they made a demonstration at Versailles for King Louis XVI and Queen Marie Antoinette. Their fame, and fortune, had been assured.

Hot-air ballooning would become a dead end, though, since hot-air balloons are inherently limited by the cooling of the trapped gas. Hydrogen balloons were developed in parallel, and in competition with, hot-air balloons. Hydrogen balloons would come to dominate ballooning for the next 180 years, until helium became available in quantity.

Nevertheless, hardly anyone remembers the inventor of the hydrogen balloon. The Montgolfier brothers were first past the post, and are therefore enshrined as history's first balloonists.

Saturday, February 07, 2009

Great Moments in Aviation, Part III

Lest we think that Western Civilization was having all the fun, we turn our attention to China in the 16th Century. The Chinese had invented gunpowder, and rockets. It's only natural for an inquisitive soul to imagine using rockets' power for flight. But that's a road fraught with peril, as poor Wan Hu found out the hard way.

Gunpowder rockets are, by modern standards, fairly simple devices. But they were absolutely cutting-edge state-of-the-art in the 16th Century. Heretofore, rockets had no use aside from fireworks and antipersonnel artillery, but Wan Hu saw potential in them for something more. As legend has it, he had a grand chair constructed, with forty-seven gunpowder rockets built into the base. One fine morning, he sat himself in the chair, and had his men touch off the rockets, sure he was taking a voyage into history. Well, he did, just not in the way he'd imagined.

There are challenges inherent in using rockets for propulsion. The main problem is symmetric thrust. If you want to fly straight, the axis of thrust MUST pass through the vehicle's center of gravity, or else the vehicle will begin to rotate. And once the vehicle falls even a little bit off vertical, its natural tendency will be to fall even farther off vertical, making a bad problem worse. If you've ever tried to balance a pen or pencil on end, you've seen how this works. Most of the other problems are related to maintaining symmetric thrust. All the rockets must start at the same time, and cut off at the same time, for example. They must produce uniform thrust, if you're using more than one. And they must burn in a stable, predictable fashion.

Well ... Forty-seven being a prime number, it's difficult to imagine a symmetric configuration. And with forty-seven lackeys with torches touching off fuses, it's difficult to imagine all the rockets starting simultaneously. And to top it all off, early gunpowder was notoriously finicky. Two rockets made from exactly the same batch of powder, made by exactly the same craftsman, rarely if ever flew the same.

Wan Hu's ride into history was short, but absolutely action-packed. The chair was consumed in a gigantic explosion, and Wan Hu was nowhere to be found afterwards. I suspect the searchers were looking for an intact body, not the small flaming fragments that poor Wan Hu had been blasted into.

It took hundreds of years of work to get it right, but even today riding into orbit on a controlled explosion isn't what anyone would call safe. Next time you watch a manned space launch, raise a glass in honor of the first poor brave soul to give it a try. He didn't go far, but he was the first, and that's worth something.

Great Moments in Aviation, Part II

After the legend of Icarus and Daedalus was first told by the Greeks, many years passed. They were forgotten, then re-discovered during the Renaissance. The next man to pick up the ball and run with it was Leonardo da Vinci.

Da Vinci had a lifelong fascination with, well, damn near everything. He had that remarkable combination of a fertile creative imagination coupled with an intensely analytical mind that could look at a bird in flight and not only wonder how such a thing could be, but deduce more or less how it works. There's scarcely a field of human knowledge at the time he didn't touch, but here, we're concerned with some of his most famous inventions: his flying machines. Interestingly enough, he left enough clues in his work for us to follow his thought process.

His first thought was to mimic birds mechanically.

This is a rather ingenious device that uses pedals to work the wings, which would flap like those of a bird, producing both lift and thrust. But the problem with this design is that a human simply cannot provide enough power to achieve flight this way. Which isn't the same as saying human-powered flight is impossible -- it's been done -- but it can't be done this way.

His second thought was to build a large man-powered vertical screw, with the idea that he could pump air in the same way that a screw of Archimedes pumps water, thus lifting the man airborne. The key thing here is that da Vinci realized that air is a fluid just like water, and thus obeys the same laws. This is a key revelation, one that will be put to great use later. Today, we look at this design and see the precursor of the modern helicopter. This, also, suffered seriously from the limit of man's direct mechanical power. It also suffered from da Vinci's insistence upon providing lift and thrust with the same device. It's his sole conceptual failure in both of these powered designs.

Once he'd given both of those up as bad ideas, his thoughts turned to pure gliding flight. And here, he finally hit upon something that was practical with the technology of his time. Unfortunately, history does not tell us if he actually tried a full-scale test with a human pilot.

Despite never having worked full-scale, though, the designs in his sketchbooks served as inspirations for all the great pioneers of aviation to follow. By documenting what didn't work, he prevented later generations from pursuing blind alleys and false starts. This, too, is progress.

Friday, February 06, 2009

Great Moments in Aviation, Part I

In the Western tradition, the first story about human aviation was the Greek legend of Icarus and Daedalus.

Daedalus had built the Labyrinth for King Minos of Crete. Minos, being an ungrateful and suspicious sort, imprisoned Daedalus in a high tower with his son Icarus. Daedalus got to thinking -- when you're shut up in a tower, you've nothing better to do -- and came up with a very clever plan. He figured that if he couldn't escape Crete by sea, then he'd fly out like a bird. How hard could it be?

So he got a bunch of feathers, and some wax, and made two pairs of man-sized bird's wings. One pair for Daedalus, and one pair for his son. At this point I feel compelled to mention that Daedalus had a wife and another son as well. Had they already escaped? Had he grown weary of their company, and decided to leave them behind? The legend doesn't say. It just says that just before they flew the coop, Daedalus warned Icarus not to fly too high, lest the sun melt the wax of his wings.

And so, they took to the air. The legend says that they passed Samos, Delos, and Lebyhthos -- which is a damned odd path. Those three islands don't lie in any kind of line. If you visit each in that order, then you've basically flown a victory lap around the Aegean Sea, including a pass by Crete between Delos and Lebynthos. Perhaps they flew by old Minos' palace to taunt him as they escaped. Anyway, when they were passing Lebynthos, Icarus was having so much fun that he soared up towards heaven, and exposed his wings to too much sun, and the wings came apart. This left poor Icarus to plummet towards the Aegean from a height where there's not a whole lot of difference between a splash and a splat.

Now, this was meant to be read as a morality tale, cautioning the young and hot-headed to heed the wise words of their elders. The details were never meant to be taken seriously. Nevertheless, it holds a place in my list of Great Moments in Aviation, since it was the first story where men used machines of their own making to take to the air.

A Stimulating Conversation

Generally speaking, I try not to wander too far afield from my areas of expertise. And I admit, forthrightly and without embarrassment, that economics isn't one of those areas. There's a damn good reason why I married an accountant. That said, I'm going to try to organize my thoughts about the current situation.

I think we needn't rehash the sub-prime mortgage mess. We've all heard about how the toxic paper got into the banks' portfolios, and touched off last fall's financial crisis. The TARP fund, set up last fall, was intended to staunch the wounds and allow time for more permanent fixes. And, most indicators seem to say that TARP is working more or less as intended. A system that had been heading towards total failure had, at a minimum, recovered some kind of normality. We are left with two major problems to address, near as I can tell.

Numero Uno: The banks are still holding a non-trivial amount of the aforementioned toxic paper. This issue must be addressed in some way, form, or fashion before banks really feel confident in lending again. The fundamental problem here is that no one knows what these sub-prime mortgages are actually worth. In the long run, the actual real estate is worth a good bit, though maybe not as much as was paid for it originally. In the long run the holders of those notes will turn a profit on them. If the government sets up a "bad bank" to buy some amount of these, it'll be an expensive proposition in the short run ... but remember, the RTC back in the '80s ended up turning a profit for the taxpayer. It's not unreasonable to think that might happen again. Maybe. I just don't know for sure.

Numero Two-O: This is the stickier problem. Aggregate demand has fallen off a cliff, and doesn't seem to be going anywhere. Consumers aren't buying, neither are businesses, and between them they form the bulk of the economy. The only agent left that is in a position to spend money is the government, and that's where the stimulus bill comes in. See, government does exactly two things well: it collects money, and it spends money. Government doesn't always spend it prudently, or for good reasons, but it's always spent on something. And here's where my foresight fails me. In theory, I think increased public spending is a good idea just right now, but on what? I got bupkis, man. Recapitalizing infrastructure sounds like a good idea. It'd need to be done sooner or later anyway. And I don't think tax cuts for consumers will do a whole lot. I know that if I got a one-time windfall, I'd probably pay down some bills instead of throwing down on a big-ticket purchase. Nice, but that doesn't pull us out of this ditch.

So, mostly, I'm going to pass on the stimulus discussion. A man's got to know his limits.

Tuesday, February 03, 2009

Video Del Fuego, Part XVIII

It's a blast from the past today on VDF, with video of a pair of restored, fully functional Me-262 jet fighters.

Although the regime that spawned them was among the most repulsive in human history, the Me-262 Schwalbe was a beautiful aircraft. It is nothing short of astonishing that Germany could field such fighters with the U.S 8th Air Force blasting their factories to kindling by day, and RAF Bomber Command taking over for the night shift. We got lucky, folks. Imagine how badly things might have turned out if the Nazi leadership wasn't stone barking mad. Fortunately for us, Hitler was a complete nutter, and kicked off into Russia's arse before he'd well and truly taken care of business with Britain. Then, in late '41 he declared war on us, making his mutual defense pact with Japan the only treaty he ever honored. It's no wonder Britain's SOE called off their assassination plans. Hitler might well have been replaced with someone competent...

The Me-262 was only one example of Germany's technical superiority in some areas. So great were Germany's aeronautical advances, that for decades afterwards, a functional reading literacy in German was mandatory for doctoral candidates in Aerospace Engineering. This requirement was only dropped a few years before I started grad school. I sometimes wish they hadn't dropped it, but that's neither here nor there.