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That Flying Car Problem

One of the regular features at The Speculist during its inauguration was Phil's "Seven Questions" interview. Phil's last question was always "Why is it that in the year 2003 I still don't have a flying car? When do you think I'll be able to get one?"

Phil was asking the question metaphorically (when I answered I wrote about how large scale tech has been trailing small tech for the last thirty years). But really. It's 2005 and we still don't have flying cars. What gives? When Phil asked Aubrey de Grey, he got a more direct answer:

You don't have [a flying car] because it's very hard to build something that fits the bill — fast, safe, affordable. "Safe" is probably the hardest.

Of course, when I think of a "flying car" I imagine something like this:


But it doesn't look like we're going to get a gravity-defying roadster anytime soon. For now, this flying car will remain a "past-futures" fantasy. But why can't we have an intermediate vehicle - a "fast, safe, and affordable" aircraft; an everyday, everyman aircraft?

Safety is a big part of this problem. A "safe" aircraft is "idiot-proof." Most adults of average intelligence can be taught to be reasonably safe behind the wheel of a car. The flying car has to be comparably safe or it will never be adopted.

In order to be safe today, a pilot must be smart, fly constantly, have an understanding of his aircraft, a respect for the weather, and be humble about his skill. Many pilots don't measure up to this, let alone the average "Joe."

The answer is a push-button aircraft. You command it to "take me to Hot Springs, Arkansas" and it would file a flight plan, communicate with air traffic control, take off, fly, and land at your destination without interference from the pilot. Obviously this would require a sophisticated computer and software.

Assuming that could be accomplished in the short run, there is another obstacle to the everyday, everyman aircraft. Present-day aircraft are often more trouble than they're worth, especially for short trips. Even people who have spent $100,000 + for a private plane often find that they don't use them enough to justify the expense. Every flight requires a trip to an out-of-the-way airport and arrangements for ground transportation at the destination. Airports are put in out of the way places because they take up so much land.

If airplanes were made simple enough so that more people flew, and the amount of land required for a runway were reduced, then there would be more airports, making it more likely that an airport would be at or near your desired destination. Heliports don't take up significant space - a good flat roof fits the bill. But helicopters are difficult to operate, and, even if a fully automated helicopter were developed, it would still require constant, expensive maintenance.

And the helicopter still wouldn't be as safe as a fixed wing aircraft. There is a certain altitude range for helicopters called the "dead man zone." If you lose your engine in this zone then there is insufficient time for the formerly powered rotor to be switched to auto-rotate mode. You drop like a rock to the ground.


Carter Aviation Technologies is developing a hybrid solution to these problems. Their "Cartercopter" allows vertical take off and landing, will fly as fast as a fixed wing aircraft (which is much faster than a helicopter), and will not be subject to the "dead man zone" problem. Why no "dead man zone?" Because as a gyroplane it is always in auto-rotate mode. If you lose power you just float down. Theoretically it would be safer than either a helicopter or an airplane in a power-off emergency landing.

There's nothing new about gyroplanes. They've been around since 1923. But this form of aircraft has been neglected since the helicopter became practical. Carter Aviation saw an opportunity to innovate.

The Cartercopter's first innovation is depleted uranium on the tips of the overhead rotor. Depleted uranium makes the tips of the rotor very heavy. While safely on the ground the overhead rotor is powered up by the engine. A gyroplane rotor is never powered in the air because it lacks a rear-stabilizing rotor like a helicopter. But once the Cartercopter's rotor is spinning, the heavy tipped blade will maintain its spin and provide significant lift before the aircraft even begins its roll forward.

Second, the aircraft has wings like what you would expect on a fast moving jet. These wings are small and thin to hold down drag, but small wings provide limited lift. Without the rotor, the aircraft would stall at about 150 knots - the rotor makes up the difference.

At cruising altitude, the CarterCopter's third innovation becomes available. Overhead rotor drag makes traditional gyroplanes very slow. The drag of the rotor is a cube function of the speed of the rotor. And the faster a traditional gyroplane flys, the faster the overhead rotor turns creating increasing drag. But the Cartercopter slows the rotor speed as airspeed increases. By slowing the overhead rotor from about 300 rpm to 100, the drag on the Cartercopter is significantly reduced which allows speeds comparable to fixed wing aircraft.

You might be wondering why they don't just stop the rotor if drag would be reduced. Stopping the rotor would reduce drag, but it would be costly to engineer a stopped rotor, and the aircraft is safer with the rotor still spinning. This slowed rotation appears to be a smart compromise.

If a flying Delorean is out of the question, a fully automated Cartercopter would be a nice consolation prize.

UPDATE: Here's a link to the video page at Discovery.com where you can see the program that inspired this post.

UPDATE II: And here's a link to a 60 minutes print story on "flying cars" that also mentions the Cartercopter.

UPDATE III: In the comments Jim Strickland points out two additional problems with "flying cars" - noise pollution and petroleum depletion. To that I would add increased fossil fuel emissions.

Hydrogen fuel cells could address all of these problems. Hydrogen fuel cell vehicles run on electricity produced by hydrogen. It would be very quiet, would not deplete petroleum reserves, and would be clean for the environment.

Honda has done some impressive work in the last few years improving power output of fuel cell vehicles (see here and here). Whether fuel cells have been developed to the point that they could power an aircraft is another question. Probably not...yet.


There are a couple other problems with flying cars.

First, most drivers behind the wheel of cars are barely competent to drive, if my experiences on the road are any measure. (Yes, I'm quite sure other drivers say the same about me, in all fairness.) They are bad enough on established roads, which are carefully delineated areas in which you can expect them. Would you really want this collection of people who can't signal for turns, back up on freeway onramps, talk on their cellphones instead of paying attention to the road, and so on flying over your house, or perhaps near that airliner you're flying in? I don't.

Second and more crippling is the problem of energy. The world of automobiles is just barely dabbling in power systems other than internal combustion of fossil fuels. Aerodynamic flight as we know it today is exclusively the domain of internal combustion engines, and the demands of flight are quite energy intensive. Flying cars would be a huge step backwards in energy consumption and pollution.

Finally, while one can certainly argue there is far more sky than road, it bears remembering that some of the major air travel corridors are quite crowded. Given that most flying car designs and all airplanes have to *move* to stay aloft, a traffic jam would be very, very bad.

Sadly, I don't think flying cars are practical. Flying taxies and limos perhaps, where the driver is a full time pro, surrounded by full time pros, but I doubt you'll see flying cars without solving the energy problem and making the car artificially intelligent.

(And then of course Microsoft will make the software, lending 'crash' a more literal meaning. ;)

There are also environmental issues with flying cars. The most immediate is this. To fly, aerodynamic vehicles move a LOT of air around. If this motion happens to be at a frequency between seventy and seventy thousand hertz, this is called noise. Lots of noise.

The objections to flying cars always come down to the two issues that Jim points out:


I think the gyroplane is a great idea. Between it and the personal submarine we're well on our way to the amazing gyrosub of Spy Smasher.

But it's still not a flying car. To get there, we're going to need some kind of anti-gravity technology. That will take care of the noise and half the safety problem. Then all we need is some really good AI software to take care of the rest of the safety problem.

So maybe I should be asking:

"Why is it that in the year 2005 I still don't have anti-gravity technology and really good artificial intelligence?"

But somehow that isn't as catchy.

You've all covered the safety issue quite thoroughly but I can't resist adding this: When you consider how clueless most drivers are about their "coordinates" on one (geometric) plane, it would be insane to expect them to pay attention to spatial orientation in all planes.

Anti-gravity technology would be nice. But transporter technology would be better. Sigh...


Fortunately people won't have to think three dimensionally.

From the 60 minutes link:

"The folks at NASA have built something called "The Highway in the Sky." It's a computer system designed to let millions of people fly whenever they please, and take off and land from wherever they please, in their very own vehicles…

Bruce Holmes is one of NASA’s chief strategists and has served in the White House, where he worked on the future of aviation. He showed Simon a flight simulator, a new computer system that can be put into any new airborne vehicle. He says it will make flying easy, and will manage all the new traffic up there.

It’s called "The Highway in the Sky," and here’s how it works: In a NASA animation, pilots focus on one main screen. It’s very much like a videogame. Keep the plane inside the box, away from other vehicles, and the plane’s computers automatically guide them towards their destination. They can even follow the highway down to the ground. "

Check out this picture:


There was some allusion to this sort of thing in Back to the Future 2 (floating roadsigns and exit markers). A virtual road overlayed over the sky is just a tad more realistic. :-)

The pushbutton aircraft would be easier than even this. Just pick your destination and you're on your way.

"transporter technology would be better."

We have a small problem with the amount of data involved - not to mention compensating Heisenberg. :-)


Flying cars, people and packages too all would be nice when fail safe controlled, but we need to get beyond the combustion age for moving fluids in trasnportation in order to do it.

Is this not a flying car?

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