this weekSomething in the Air

December 13, 2004

Personal Flying Machines

George Jetson, Buck Rogers, and you

SkyCar Diagram

My favorite magazine as a child was Popular Science. I vividly remember reading articles 25 years ago about all the advances in technology that were waiting just around the corner. Soon everyone would carry a small, wireless telephone to make calls while walking down the street. We would also, in just a few years, speak commands to ever-attentive computers to control the lights and climate in our homes, dictate letters, and give our personal robots instructions. And, of course, we would commute to work in flying cars or wear jet packs, prototypes of which had already been developed. I drooled over the pictures of all these gadgets and the predictions of their rapid development and distribution. The future was going to be exciting.

It took a couple of decades longer than expected, but cell phones have finally lived up to the predictions. Speech recognition has come a long way too and is nearly usable, though far from ubiquitous. As for smart homes, there is no technological barrier to a fully automated house; all it requires is time, money, and the willingness to endure the ridicule of your neighbors, who still don’t see what’s so difficult about flipping a light switch. Even household robots are increasingly common—though mostly in the form of vacuum cleaners or electronic pets, not general-purpose rechargeable servants. But still, the personal flying machine seems as elusive as ever, though year after year they continue to appear in science fiction films set in the relatively near future. Is there still hope that the idea will get off the ground?

Your Own Flying Saucer
In the late 1970s, I saw a picture of a prototype personal aircraft designed by inventor Paul Moller. It looked like a tiny flying saucer, with a passenger compartment in the middle and eight rotary engines around the outside. The idea was simple enough: force lots of air downward, the craft goes up; change the angle of the airflow, and the craft moves in the opposite direction. In other words, it works on pretty much the same principle as a helicopter, except that in place of a single large rotor, you have eight small, enclosed rotors.

Moller has worked on improving his design for over three decades, and its current incarnation, which is called the SkyCar and looks like a wingless private jet, has successfully gotten off the ground in test flights. Four rotating nacelles, each holding two engines, provide thrust; inside, there’s room for four passengers plus luggage. The SkyCar should be able to travel 350 miles per hour (about 560kph) at an altitude of up to 30,000 feet (about 9,100m)—and achieve gas mileage similar to that of an automobile. Parachutes, rather than airbags, will be standard equipment. In 2003, Moller’s Web site predicted that the SkyCar would be ready to go into full-scale production before the end of 2005; as of early 2006, the site said FAA approval is “more than four years away.” But the company maintains it’s only a matter of time—in fact, you can put a deposit down on one right now, as at least 100 people have done so far.

But before you reach for your checkbook, brace yourself for sticker shock. Early adopters will shell out US$1,000,000 for this sporty four-person coupe, though prices may one day drop to as little as $60,000—expensive for a car, but pretty reasonable for a small aircraft. Even if money is no object, though, you’ll need a specialized pilot’s license to fly it. (Moller hopes eventually to make a computer-controlled, pilot-free SkyCar…but that’s “eventually.”) There’s one more catch, too—current regulations stipulate that vehicles like the SkyCar can take off and land only at airports and heliports. Unless you live near one airport and work near another, there goes your quick commute. And, of course, there are any number of things that could still delay approval and manufacture of the SkyCar. Even under the best circumstances, it could be another two or three decades before the SkyCar does for transportation what cell phones did for communication.

Where the Rubber Leaves the Road
If a hovering SkyCar is too risky and complex, what about a solution based on dependable, proven, and simple technology—the wing? Over the years, inventors have made a number of noteworthy attempts to create a car that could be converted into an airplane. The idea is that you use the car on the road for short trips around town, but then attach wings and a propeller—perhaps towed behind the car in a trailer when not in use—for longer trips. The same passenger compartment and engine can be used for both modes, and when you get to your destination you can simply drive away. This is one of those ideas that sounds sort of interesting on paper, but when you start to work out the details, you can’t help asking, “But why?” Indeed, the aspect of this idea I find most interesting is its inexplicable longevity.

The best-known car/plane combo was invented by Moulton Taylor in 1956. He created a wing, tail, and propeller assembly that could be attached to a specially adapted small car in three minutes. The Aerocar, as he called it, flew nicely—not particularly fast, high, or far, but it flew. For decades Taylor tried unsuccessfully to make the Aerocar a commercial success. Manufacturers didn’t want to take the risk, and consumers didn’t like the cost—or the need for a pilot’s license. The idea was novel, but not compelling enough to make it fly in the marketplace.

Ed Sweeney, one of Taylor’s students, is trying to rekindle interest in the Aerocar. His new design, based on the Lotus Elise sports car, is nothing if not sleek. It lacks the trailer-mountable compactness of Taylor’s original, but makes up for it in simplicity and elegance. The prototype has not flown yet, and since his company Aerocar, L.L.C. consists only of himself, Sweeney doesn’t expect to achieve overnight success. In a few years, however, he hopes to sell a kit that will enable enterprising hobbyists to perform their own car-to-airplane conversion. Assembly time for the kit is estimated to be six months. And the projected cost? A mere $100,000—car included!

Look Ma, No Wires!
But perhaps your transportation needs are more modest. You don’t need to take the family on a vacation or haul groceries across town, you simply need to get from place to place yourself. Wouldn’t it be great if you could just strap on a jet pack and zip away? Surprisingly enough, the personal jet pack (or rocket belt) has been in use successfully for over 40 years. It’s outstandingly cool, but of course, there’s a catch or two.

The idea behind a jet pack is just like that of the SkyCar: simply direct a lot of thrust straight down. Since the only payload is a human being, you don’t need much thrust, so conceivably a device like this could be made small enough to wear. Military contractors worked on the idea in the late 1950s and early 1960s, using a hydrogen peroxide-based rocket engine for power. In just a few years, stable, dependable units were making demonstration flights across the country, to the delight of the press. They were also featured in a number of films and TV shows—when you saw someone flying one in Lost in Space, Thunderball, or Ark II, that was the real thing.

There were two serious problems, though, which prevented both commercial and military acceptance of the jet pack. First and foremost, the device could only carry enough fuel for a 20- to 30-second trip. That severely restricts its practical uses (and requires quite a few consecutive shots for some of those extended TV scenes). In addition, it’s extremely loud, dashing any hopes the military had of stealthy applications. A few jet packs still exist, and rumor has it that one or two companies are developing longer-range, more practical versions.

Meanwhile, a company called Trek Aerospace has been developing a “backpack aircraft” called the Springtail EFV-4—essentially a souped-up jet pack that uses internal combustion engines, rather than rocket power, to turn two large fan blades suspended above the rider. The apparatus is too heavy to be carried, however, and development appears to be proceeding quite slowly. Several other companies are going in a different direction by developing ultralight single-person helicopters. Already there are at least two different designs you can purchase in kit form for under $30,000—assuming you have the time, space, expertise, and nerve to assemble and fly them.

Maybe I’ll Just Get a Cape
Owning a personal flying machine—of whatever type—sounds like the ultimate in freedom and mobility. But decades of unfulfilled promises make me rather circumspect when I hear an inventor say the next big thing is “just around the corner.” In the meantime, the next best thing to being there is staying in touch by cell phone. I’ll have my robot call your robot. —Joe Kissell

More Information about Personal Flying Machines…

This article was featured in Carnival of Cars on Friday, June 23, 2006.

For information about the SkyCar, visit the Moller Web site. You can see video footage of test flights, check out specifications and technology—and yes, even put down a deposit.

Popular Science reprised its coverage of personal flying machines in its August, 2002 issue. The article was The Dream of Personal Flight by Seth Shulman.

Ed Sweeney’s new and improved Aerocar project (including a tribute to Taylor) is described on the Aerocar.com Web site.

A company called Terrafugia is designing a car with fold-up wings that can extend to turn it into an airplane. The first prototype may leave the ground in 2008.

Another company, PAL-V, is working on a vehicle that converts from a tiny, three-wheeled car into a gyrocopter. They hope to begin selling them in 2009.

Quite a few Web sites chronicle the history of the rocket belt, with lots of photos and diagrams. Examples are Canosoarus.com, a page on the Smithsonian’s National Air and Space Museum site (which, bafflingly, has numerous spelling and grammar errors), this page by Jim Noetzel, and this fascinating story of the Rocket Belt Scandal. Yet another rocket belt site (based in the Netherlands but in English) is Peter Gijsberts’s rocketbelt.nl.

An article on TechTV discusses the SoloTrek (later renamed to the Springtail EFV-4), jet packs, and other personal flying machines such as the Hiller Flying Platform. The article’s information about Thunderbolt Aerosystems, and their new model jet pack with a 175-minute flight time, seems rather suspicious to me, and I was unable to verify it. Further information on the Springtail EFV-4 is at TrekAero.com.

Among the single-person ultralight helicopters you can purchase (now or “real soon now”) are the Mosquito from Innovator Technologies, the Gen H-4 from Engineering System Co., Ltd. in Japan, and the AirScooter II from AirScooter Corporation.

Ark II was an extremely short-lived (15-episode) Saturday morning children’s show that aired on CBS in 1976 and 1977.