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Technology Review

“I’ve been lecturing on this subject for about a decade and a half,” says Dennis Bushnell, chief scientist at NASA’s Langley Research Center, “and at the end of every talk, people ask me two main questions: Where can I buy one; and where can I get a franchise to sell them?” “These things” are aircars — a.k.a. flying cars or personal VTOL (vertical-take-off-and-landing) aircraft, and many people do want them. What could be a more appealing vision of the world of tomorrow than stepping into one’s own flying machine and heading off into the wild blue yonder?

This vision could be realized sooner than you think. The technology of personal VTOL transportation is “expanding and will soon be exploding,” says Bushnell, with at least a dozen individuals and groups in the United States now competing to produce a safe, dependable aircar. The U.S. Army and Navy are developing aircar-type vehicles for military applications, and a NASA researcher has also been working on a design. Most of the action seems to be in the United States, though at least one foreign company — Urban Aeronautics in Israel — is also in the race. These aircraft, Bushnell contends, are “not only feasible but inevitable.”

The development of aircars stems from a confluence of need, desire, and enabling technology. To gauge the need, one need look no further than our automobile-choked roadways. “Building virtual ‘highways in the sky’ would be a modest technical achievement in the almost unused airspace above us,” insists Paul Moller, a California aeronautical engineer who thinks the automobile has had its day and has been working for many years to develop a flying car.

Beyond the clogged roads, there’s the problem of an increasingly dysfunctional airline industry. Airport hassles, delayed flights, fears of terrorism, and the rising threat of new infectious diseases such as SARS have made airline travel a stressful experience. Most people who fly do so out of necessity, not because they relish spending two or more hours in a cramped airplane seat with a bag of peanuts. Aircars, if they’re ever made practical, would let people zip across the city, or across the country, in their own flying machine.

Automated flights
What is making aircars a more imaginable possibility is information technology. Thanks to highly sophisticated and compact computers, GPS and other advanced navigational technologies, and aerial collision-avoidance systems, it is possible to build aircraft that, through a combination of on-board guidance systems and ground control, would fly themselves. The “operators” of an aircar would simply get into the vehicle, key in (or maybe just speak) their destination, and let the vehicle, like some futuristic flying carpet, carry them up and away. Moller contends that current airplane navigational systems could handle most of a flight, except for takeoffs and landings. Fully automated flights from beginning to end, he readily admits, would require a new system.

A system that could serve as the starting point for controlling personal VTOL aircraft is the Small Aircraft Transportation System (SATS). A joint project between NASA and the Federal Aviation Administration, SATS aims to outfit a nationwide system of more than 5,000 small airports connected by virtual — yes — “highways in the sky” for the use of a new generation of small, safe, easy-to-fly, and inexpensive airplanes. NASA and the FAA expect the system to be fully operational after about 2015.

But if limited to airplanes, this idea has a couple of obvious flaws. First of all, it’s questionable whether many people would want to buy and maintain an airplane. And even if they did, they’d still have to use an automobile to get to and from airports — hardly the ideal solution to our transportation problems.

Moller has long insisted that the answer to this dilemma is aircars that could operate completely free of airports. SATS would have to be greatly expanded to include VTOL’s departing and landing at a multiplicity of locations far removed from traditional landing strips. Will that be done? In fact, says NASA’s Bushnell, “The SATS vision has always included that as an end point.” He adds, though, that until the infrastructure for aircar guidance has been completed, we will see a transition period in which the vehicles will have to be piloted by the people flying them during the takeoff and landing portions of the flight.

Building the aircar
An infrastructure that supports aircars won’t be much use if there are no aircars to buy. But such flying vehicles could become available in the not too distant future.

One company that appears close to bringing an aircar to market is Moller’s enterprise, Moller International in Davis, CA, which has developed a VTOL vehicle called the Skycar. A four-passenger Skycar, dubbed the M400, is undergoing extensive flight testing aimed at getting FAA certification. The company says the M400 will initially cost just under $1 million, but as manufacturing volume ramps up, the price will come down to $40,000 to $60,000 — comparable to a mid-range luxury automobile. The company hopes to have the million-dollar version on the market by mid-2006.

The Skycar looks a bit like a small fighter jet with stubby wings. It is powered by eight rotary engines, similar to the ones used in some Mazda sports cars. Two of these engines, which turn fan blades to produce thrust, are mounted in each of four large pods, called nacelles, at the front and back of the fuselage. The nacelles tilt downward for takeoff and landing and turn horizontally for level flight. These engines will enable the Skycar to cruise at 480 kilometers per hour at a height of 9 kilometers (though so far it has been tested only in low-altitude flights). The Skycar is designed to keep flying if one or more engines fail, as long as they are in different nacelles. In the event of multiple engine failures — which could happen from, say, flying into a flock of birds — two ballistically ejected parachutes will carry the vehicle gently to the ground.

The Skycar does have one shortcoming that could put it in a bind: it’s mostly sky and a lot less car. Although it can taxi around, the vehicle is not meant to be driven on the ground for more than a few kilometers. Moller is counting on aircars being able to operate to and from a variety of urban spaces, such the tops of buildings, making it unnecessary for them to be driven any appreciable distance on the ground.

Auto/air hybrid?
NASA’s Bushnell, however, believes it is unlikely that the FAA or municipal governments will allow swarms of personal aircraft to be buzzing around highly built-up areas. Lots of people are therefore going to continue traveling in and out of big cities — and they’ll most likely have to do so on roads. Thus, says Bushnell, for aircars to be mass-market vehicles, they will have to operate just as efficiently on the ground as in the air.

Some people are putting their money on just this concept of an auto/aircraft hybrid. The idea has even been incorporated into the name of at least one company, Roadable Aircraft International of Camarillo, CA. Roadable, which is designing an aircar-type drone for the Navy, is developing a civilian VTOL — named, with a nod to the Wright brothers, The Flyer — that it claims will be as roadworthy as any conventional automobile.

Nicholas L. Geranio, Roadable’s vice president for product development, says The Flyer will be capable of traveling as fast as 135 kilometers per hour on the ground and 400 kilometers per hour through the air. Geranio says the company has tested two prototypes and is now working on a model for FAA certification. Once Roadable receives FAA certification — which Geranio hopes will happen by late 2006 — the company expects to sell the vehicle at an initial price of $300,000 to $400,000 Roadable has plans to market a $100,000 kit version of The Flyer, minus the engines — a jet turbine engine for flight, a piston engine for ground travel — by the end of 2004.

Critics: It's not that easy
The seductive vision of personal flight for everyone has its skeptics. Among them is R. John Hansman, director of the MIT-based International Center for Air Transportation. VTOL aircraft are difficult to design, Hansman says, because they must lift all their weight with vertical thrust before they can attain forward flight and stay in the air with lift. “Because weight is such a critical consideration, it’s hard to design a vehicle that is as crashworthy as a traditional car,” he says. He is especially doubtful about aircars of the hybrid type. “You can design a good airplane, or you can design a good car,” he says. “When you try to do both, you inevitably compromise somewhere, so you have a suboptimal car and a suboptimal airplane.”

Hansman thinks there could be greater possibilities for small aircraft that achieve lift quickly and can take off, and land, on the flat roofs of large buildings. But of course, that takes us back to the question of whether large numbers of small aircraft would ever be allowed to fly in cities.

While he’s dubious about the near-term prospect of millions of Americans flitting through the air in their own flying machines, Hansman is careful not to deny the possibility. He just thinks that if that day does arrive, it will not be for a long time, in part because it will be quite a while before people will be willing to trust their lives to fully automated aircraft. Nevertheless, Paul Moller and others in this growing sector of aeronautics agree with Dennis Bushnell that aircars are the inevitable next step in personal transportation.

David Louis Dreier is a science and technology writer based in Chicago.

Copyright © 2012 Technology Review, Inc. All Rights Reserved.

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