From Airships to Jetpacks – Five Ways to Fly.
Humans have wanted to fly for as long as birds have teased them, and over time — especially the last century or so — we’ve come up with a lot of interesting proposals for how best to approach the problem. Some were successful; others contained the kernels of success; and some died ignobly at once, usually taking their so-called innovators with them.
MEN WITH WINGS
The story of human flight parallels very closely the story of mechanical power (and industrial advancement in general). This is no accident — even the most brilliant aircraft design can’t be built, tested, or duplicated if there don’t exist sufficiently powerful motors, or sufficiently strong and lightweight materials, to make the physics work.
Naturally, one of the first ways humans attempted to fly was by copying birds, usually by attaching wings to their arms and flapping really hard. Sometimes the men — these foolhardy beings were invariably men — would bypass the “testing” phase and skip right to leaping from a tall cliff or tower, flapping all the way down, only occasionally surviving.
As far back as 1678, a French locksmith named Besnier attempted to use flapping oars (left) to conquer the air, and while I don’t think it actually worked, his skill at PR certainly did: later reports indicate he was able to “raise himself by short stages from one height to another, or skim lightly over a field or river.” Suuuure he was.
But humans are just too heavy and too weak to flap hard enough to fly. In order to be borne aloft by wings like those of birds, the wings would need to be dozens of feet long, pumped far harder than human muscles could manage.
In the 1890s, German Otto Lilienthal (right) made great progress with gliders. He constructed a tower at the top of a hill, and managed to make numerous controlled descents, working out the princples of airfoil (flat-wing) aerodynamics. He was killed in a crash (as these types tended to be) in 1896, but left a legacy that led directly to the development of controlled, powered flight.
Lilienthal had some good ideas — and over the years, even as powered aircraft became common, single-person hang gliders remain a popular way to fly. But true, “flapping” flight did become real until 2010, when an ornithopter named “Snowbird” actually took to the air by flapping its wings:
Good job, guys! Lightweight materials have made this somewhat dumb dream into a reality. For my money, though, the more exciting somewhat-birdlike flight technique is one made possible by modern compact jet engines, fiberglass composite materials, and the indomitable adventurer-aeronaut spirit of Yves Rossy:
This guy is amazing. I will take one of these wing things, please! Just drop it off right here and I will fly around in it, I promise.
Otto Lilienthal’s dreams of soaring and gliding had their antecedents in a technology well-known for centuries: that of the kite. A flat plane of sufficient surface area, with air moving across it at a sufficient speed, will stay aloft. A kite large enough could surely support a man, and if there were some way of powering the kite, so that it wouldn’t have to rely on the caprice of the wind, a self-propelled flying machine seemed downright simple to build.
But again, the problems encountered were practical. Hiram Maxim, made famous by his earllier invention of the machine gun, turned his attention to the construction of a flying machine, and after a series of careful and precise experiments, in 1894 he tested a massive steam-powered contraption that ran on a length of railway track.
The best material available to him at the time was steel, as the much lighter aluminum was prohibitively expensive; and the best motor available was steam, as gasoline engines were still some time away from being able to match them in horsepower per pound. So Maxim had hard minimums on how light his machine could be, and that was “not very light at all.” His solution was simply to make the thing massive.
And he might have done it, too — on its first (and last) flight, the machine broke free of a system of restraints Maxim had constructed to prevent its going too high, and in the ensuing crash it was destroyed. Although this was far from a total failure, he was unable to raise the money to continue his experiments.
This is, of course, the other limiting factor on innovation — finding the money to actually build prototypes. This becomes even more difficult when every incremental step results in the total loss of an extremely expensive flying machine (and occasionally the life of the person whose idea it was in the first place).
The Wright brothers found success in 1903, but kept their achievements secret. Their most revolutionary discovery was a manner of controlling aircraft that we still use today — before them, experimenters had attempted to steer their aircraft like a ship, using rudders but keeping the craft fundamentally level. The Wrights’ wing-warping controls changed the shape of each wing, causing the airplane to bank into turns. They patented this configuration before showing it to the world, and for a good part of the 1910s embroiled themselves in a legal battle with many other pioneers of early flight, demanding royalties from other inventors whose control systems resembled theirs.
But in 1917 the patent expired, and this method of controlled flight became free to the inventors of the world. And although airplanes today are common and reliable, new discoveries are still being made. Famed designer Burt Rutan and his company, Scaled Composites, are responsible for some of the most efficient and innovative aircraft ever built. (Below: Rutan’s ‘Proteus’ observation plane.)
And just as the Wright brothers were able to use the newest gasoline engines to achieve performance that Hiram Maxim never could, innovators today are still looking to new technologies to make flight even easier. Most light aircraft today are still powered by reliable gasoline (or occasionally diesel) engines, but a Chinese company called Yuneec has created an all-electric airplane (below), featuring a motor with only two moving parts. Lighter, cheaper, more powerful: the ingredients for continued innovation — even today, at a time when it seems like we’ve got this flying thing pretty well figured out.
LIGHTER THAN AIR
In 1782, the French Montgolfier brothers were the first to realize that rising hot air could be used to fill a balloon, which could be used to carry passengers. They built giant balloons out of paper, and to keep the hot air coming, they carried aloft a fuel supply of straw and wool. Owing to the tendency of the balloons to burn up upon landing, this was not a popular design, and was quickly superceded by a diffferent model, that of a giant bag filled with hydrogen.
But even with the question of lift answered — by the 1780s, the lifting power of hydrogen was well understood, and balloons were being constructed made of silk, coated with rubber varnish to be made impermeable — the question was how to use this technology. Balloons were used in minor ways in all wars of the 19th century, mainly for observation, but they were uncontrollable and fragile, subject to weather and wind.
The first impulse of balloon engineers to solve the controllability problem was to take a clue from ships, and affix sails:
The noble sail-powered airship is a familiar image to fans of steampunk fiction, but unfortunately, it doesn’t work. In a ship, the water provides resistance, giving the wind something to push against; it fills the sails and pushes the ship through the water. In the air, there’s nothing to push against — the sails never fill, because the whole craft just gets blown whichever way the wind is blowing. So there’s no way to tack, and thus no way to steer.
That’s a problem with round, unpropelled balloons even today: they’re unsteerable. Hot air balloons have only one control: up and down. Experienced balloonists can read air currents, and travel up or down to reach a wind that’s going the direction they want, but that’s it.
Enter the dirigible. As its name implies, dirigibles are rigid, built in a specific shape to provide greater or lesser resistance to the wind in different directions. The cigar shape that we’re familiar with was designed to have an easier, more aerodynamic time going the direction the whole thing is pointing.
The first attempts at propelling dirigibles through the air involved the use of oars and paddle-wheels. Propellers and rudders were added in the mid-1800s, and here again the problem became one of power: the most powerful motors available were steam, which were also extremely heavy. But by the turn of the 20th century, dirigibles were becoming more and more common.
We all know what happened next.
In 1937, the Hindenburg caught fire and crashed in Lakehurst, New Jersey after a transatlantic flight. This destroyed public confidence in the airship as a means of transportation, and coincided with the development of bigger, faster and more powerful airplanes, which took over virtually all commercial aviation.
But less well-known is that the U.S. Navy built and flew several dirigibles of its own in the 1920s. The first, the USS Shenandoah, was the first ever to be inflated with helium rather than hydrogen. Hydrogen was easily obtainable — early balloonists immersed pieces of iron in barrels of sulfuric acid, and captured the hydrogen produced as a result of the chemical reaction — but helium was so rare that the Shenandoah contained most of the world’s supply, and had to share with a later ship, the Los Angeles.
All four of the Navy’s airships, however, ultimately crashed, three in storms and one due to structural failure while aloft. However, modern entrepreneurs still rhapsodize about the luxurious, leisurely flight provided to airship passengers. The Aeroscraft (above right) combines the large volume and buoyancy advantage of an airship with power provided by modern electrical engines. Unfortunately, while a prototype was slated to be built by 2010, the same old problem is back again: money. Good idea or no, the Aeroscraft currently doesn’t exist.
Like screws pushing a ship through the water, it was understood that a rotating blade of some sort could — theoretically at least — pull an aircraft through the air. Leonardo da Vinci made some models of spiral-winged devices, and he is credited with inspiring the word ‘helicopter’ — a portmanteau of the Greek words helix and pteron, meaning spiral wing.
The 1800s saw a number of ill-conceived concepts reach the prototype/immediate crash phase of development, and even Thomas Edison applied significant effort to the problem. The French ‘Gyroplane Laboratoire’ of 1933 was the first controllable helicopter, but it wasn’t until the 1940s that Igor Sikorsky landed on the first reliable helicopter design — the main rotor/tail rotor configuration that has become the standard. (Below: Sikorsky’s VS-300 of 1941.)
But one of the more successful pre-Sikorsky experiments birthed a type of flying all its own. Spanish inventor Juan de la Cierva tackled the rotorcraft question in the 1910s and ’20s, and came up, once again, against the problem of engine power. Engines at the time just weren’t powerful or light enough to power rotor blades — if they were one, they weren’t the other.
De la Cierva’s “Eureka” moment was the realization that a rotor didn’t have to turn under its own power to provide lift. If he could get a craft moving fast enough in a forward direction, the wind would spin the rotor for him. And in that case, if the aircraft had only as much lift as its speed could sustain, then it would self-regulate — descending automatically as it slowed down, rather than slowing down and stalling at a high altitude, as airplanes were prone to do. The device de la Cierva invented was the autogyro.
The autogyro was an instant success. It could take off and land in a shorter space than any airplane of the time, and so was immediately recommended for ship-based service. It was also fast, maneuverable, and relatively safe. For a few decades in the mid-century before helicopters became capable of doing its tasks better, the autogyro enjoyed a period of wide service.
Recreational autogyros are still quite popular even today. Aerodynamically they’re some of the simplest aircraft, and many hobbyist homebuilt kits exist. They’re extremely maneuverable as well:
Similarly, as engine technology has improved and helicopter flight physics have become more greatly understood, it’s become possible to build a personal helicopter in your own garage. This is probably one of the greatest things I’ve ever seen:
If I didn’t think it’d give me the world’s worst headache, I’d be out building one right now.
After WW2, private avation experienced a huge boom. Veterans trained to fly in the military were coming home with the desire to continue flying. Aircraft manufacturers such as Cessna and Beechcraft struggled to satisfy a burgeoning market for small aircraft. And with constant improvements in technology, it seemed obvious that everyone would soon want an airplane in their very own garage. Or a flying car! The best of both worlds!
Most of the first flying cars took for granted that you’d need to attach wings to your car in order to fly, but then you’d need to take them off in order to drive. One of the early attempts was the Taylor Aerocar (below), built in 1949. The wings and tail were detachable, and designed to be towed behind the car when in road configuration.
Unfortunately, the orders just didn’t materialize, and the project folded. (Aerocars still exist, however, and at least one is still in flying condition.)
Another common technique was to simply bolt airplane parts to your existing car. Below, the 1947 ConvAirCar prototype:
During a test flight of the ConvAirCar, the pilot looked at the automobile fuel gauge (which read full), and happily took to the air. Unfortunately, the aviation fuel tank (which was separate) was not so full. The pilot survived the crash, but the project was abandoned soon after.
Along the same vein was the ‘Flying Pinto’, the AVE Mizar — an honest-to-God Ford Pinto bolted to the back half of a Cessna Skymaster airplane:
It almost worked, except for the part where it came apart in the air because it was bolted together with sheet metal screws. The resulting crash killed the developer.
The reason that flying cars have never really caught on — well, one of the reasons — is that as cool as they are, flying cars are a fundamentally bad idea. Everyone likes the idea of being able to pull a helicopter from the garage (something like the 1965 Wagner Aerocar, below) and zip off to work…
But air is a three-dimensional space. Imagine all the jerks out there on the road today — but now in the air. And if something goes wrong, you don’t get to pull over to the side of the highway — you die. Airspace is extremely complex, and piloting through a busy airspace system requires a lot of training, attention, and skill. Not something best left to everyone who drives a car.
That’s why one of the best flying car concepts around isn’t a flying car at all — it’s a ‘roadable aircraft.’
The Terrafugia Transition (above) is marketed specifically to pilots, and designed to solve the problem that while flying is a great way to cross long distances, you’re limited by the fac that you can only go to airports. But what if your destination isn’t an airport, or isn’t even close to an airport? Rather than renting a car or taking a cab, the Transition pilot simply folds up the wings and drives away. In addition, in the case of inclement weather, the Transition can land and continue a journey on the road. And on the return home, the Transition can be stored in your home garage.
It’s a very clever idea and a solid pitch to pilots. But the huge flying-car problem remains: by virtue of the compromises required, most flying cars are usually both not very good airplanes and not very good cars. The Transition must meet both FAA aircraft safety standards and NTSB automobile safety standards — and strong highway-quality road bumpers, for example, add to the vehicle’s weight, decreasing airplane performance. It’s neither fish nor fowl, and I’m not sure how inescapable that compromise is.
So I was very excited to learn about an entirely different approach to the flying car concept: the Parajet SkyCar.
It’s super-simple. It’s a dune buggy, and it drives as well as a dune buggy does. Off-road, wherever you want. Go nuts.
Then, when you want to fly, unfurl the huge parachute (or, more properly, parafoil), turn on the propeller, and hit the gas. The faster you go, the more wind catches the parafoil, and the whole thing is pulled upwards. Want to descend? Just slow the propeller, and the parafoil carries you down. It’s beautifully simple and, because it’s designed primarily as an off-road vehicle, not terribly concerned with the problems of airplanes and airports.
I want one real bad. I don’t know where I’d go with it, but I’d figure it out.
Let’s talk about jet packs. Everybody who’s ever seen The Rocketeer wants a jet pack.
The question, again, is one of power. Different engineers throughout the latter half of the 20th century approached the question of propulsion in different ways. Hitler commissioned a true jet-powered device that allowed soldiers to make brief “hops” over, say, minefields. A 1958 “jump belt” used jets of high-pressure compressed nitrogen, forced out of vertical nozzles. 1960s’s “rocket packs” harnessed a chemical reaction — pure hydrogen peroxide, when mixed with a catalyst such as silver, decompresses powerfully into superheated steam and oxygen. This type of hydrogen peroxide reaction is what fueled the classic “jet pack”, the Bell Rocket Belt (left).
This method certainly worked, but the amount a fuel that could be carried along was limited. The Rocket Belt could only be flown for about 20 seconds. Not exactly enough time to fly around an entire obstacle course, Pilotwings for the Super Nintendo notwithstanding.
This chemical rocket system proved much more simple and reliable than heavy and complex jet or turbine engines, so there have been very few actual “jet packs” in the combustion-powered, jet-airplane sense of the word “jet.” The Bell Jet Belt (right), which had a much greater range than the Rocket Belt, was one such experiment, but the inherent danger of strapping a working jet engine onto the pilot’s back was too much to overcome.
However, one modern invention overcomes the limitations of the rocket belt — namely, propellant and power. The JetLev water jet system (below) is designed for use over open water. Like a jet ski, it draws water in (using a long suction hose that hangs down to the surface) and forces it back out. Because water, unlike air, does not compress, the force of the “stacked” water provides a lifting effect, and the wearer “flies” over the water.
Obviously it’s tactically limited, but it looks like a great way to have fun at the lake.
The concept also works when applied to a footboard instead of a back harness:
I want one of each, please!
Flying is awesome. Although it seems like we’ve got airplanes and helicopters pretty well figured out, as powerplants become stronger and materials become lighter and stronger, we’re likely to see more and more amazing developments. As they are invented, please send one of each to my P.O. box and I will be happy to keep track of all of them for you. Please now cover your ears as I jet-helicopter-wing-flap my way out of your fancy conference room.
David Malki ! is the author of the comic strip “Wondermark”, a gag strip created entirely from 19th-century woodcuts and engravings. He’s also co-editor of the bestselling Machine of Death series of fiction anthologies. His most recent book is Dispatches from Wondermark Manor, a parody Victorian novel that features all kinds of flying machines that wouldn’t actually work.
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