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Flying Cars: how close are we?

Previous in series: VTOL

So, how close are we to flying cars? For specificity, let’s pick a technological bar to hurdle that answers most of the objections to the concept we’ve seen as comments on the previous posts:

  • It should be relatively high-powered compared to current light craft.
  • It should be STOVL for safety and convenience.
  • It should be quiet enough to operate in residential neighborhoods.
  • It should fly itself, without piloting from the passengers.
  • It should be self-maintaining.
  • It should be inexpensive enough for widespread ownership.

Now I claim that current technology is, more or less, up to the first 4 of these. But the corner of the technological envelope that we are pushed into in order to satisfy them makes the last 2 that much harder.

Flying cars are a really good example of the sort of Jetson’s futuristic world that nanotech and AI together could enable, but would be essentially impossible without both. They are something that’s right on the edge of what’s possible with current technology, but current technology falls short in three crucial areas:

Power

Although Maxim arguably built a steam-powered flying machine in the 1890′s, practical powered flight had to wait for the gasoline internal-combustion engine. By WWII, piston engines had been pushed to the limit, and the second half of the 20th century saw serious flight powered by gas turbines. In optimal regimes (e.g. at high altitudes where the air is really cold) and at high compression ratios, the Brayton cycle can get up to 50% thermodynamic efficiency. This is quite good for a heat engine on Earth but with a eutactic molecular mill that didn’t thermalize the potential energy we could get close to 100%. (Fuel cells fall somewhere in between.)

I won’t speculate on specifics, but there are enough alternatives being explored that it seems likely that we may be able to replace not only heat engines but chemical fuels sometime in the coming century. (OK, I’ll mention a couple: stimulated alpha emission from long-lived radioisotopes, or proton-boron to triple-alpha fusion/fission. These produce energetic charged particles which convert directly to electricity without needing a heat engine.) Advances like this could be of as much benefit in the twenty-first century as the IC engine was in the twentieth.

Intelligence

Most of the actual advances of AI you hear about these days is about laboriously constructed programs that get better and better at various tasks, slowly approaching human performance (e.g. at driving cars). Most of the futurist hype you hear is about superintelligence erupting and taking over the world. As you can readily imagine, the reality of future AI will be somewhere in between.

The major difference between AIs today and those of ten years from now will be that the future ones will be able to learn skills on their own that must be added now by extensive, and expensive, programming. That means that the ability to fly a car — and to maintain one — will be learned as a human would, so it’s robust in the face of unexpected situations. Flying-car AIs, like all AIs, will exchange experiences and techniques. Each one will be as expert as any one. In the medium term, this will be the major impact of AI: that expertise equivalent to the world’s best will be available cheaply to all practitioners.

Manufacturing

Futurists such as H. G. Wells managed to forsee everything about the automobile except the single, but crucial, fact that everybody would be able to have one. But that is the fact that made all the difference. In the twentieth century it was Henry Ford and mass production that was the enabler; in the twenty-first it will probably be nanotech and autogenous manufacturing. This is easiest to understand in economic terms: the price of things depends on productivity, which in turn depends on capital replication rates. That doesn’t necessarily mean the time it takes a factory to make another physical factory, so much as for a factory to make stuff worth what it cost to build the factory.

This is why nanotech scaling laws are so important. Operation frequencies scale with the inverse of size, so bacteria reproduce in hours while humans take decades. Harnessing this productivity accelerator into the industrial loop means that costs of physical goods — particularly high-complexity high-tech goods — can begin to fall along the Moore’s Law curve we already see for electronics.

Bottom line: A flying car with the flight envelope I talk about could be built today but it’d cost a million bucks. One with all the capabilities you’d want will be available in 10 years, but you’ll still have to be rich to get one. Flying cars for the masses will be technically and economically possible in 20 years, if the political will is there to let it happen.

22 Responses to “Flying Cars: how close are we?”

  1. DC Says:

    And as we all know, whenever we depend on political will, there is usually never a way.

  2. Ron Fischer Says:

    VTOL craft need to accelerate more than their mass in weight of air downward. Helicopters manage this by doing it over a large area defined by the overhead blades. Doing it through the area of a car applies destructive force at the takeoff point. Even Moller has come to agree that flying cars would roll to a neighborhood takeoff pad, rather than lifting from a driveway where you’re likely to tear off the roof of your home with the downwash. This ultimately argues for ultralight structure, which mitigates multiple problems.

  3. Instapundit » Blog Archive » FLYING CARS: How Close Are We? Says:

    [...] FLYING CARS: How Close Are We? [...]

  4. T. O'Connor Says:

    Flying cars would lead to a welcome decrease in roadkill.

  5. Keith West Says:

    Due to weight considerations, small aircraft are flimsy compared to cars. The cheapest subcompact you can think of feels more robust than most any plane with a single engine.

    Then there are other car considerations such as crash worthiness, lighting requirements, and durability necessary for a car that, when applied to an aircraft, would make it difficult to get off the ground.

    Even if you could get it off the ground and approved by regulators, it’s performance will likely prove disappointing- not much more than 100 MPH with something like 10 MPG.

    I don’t think we’ll see a practical flying car within our lifetimes.

  6. Lugnut Says:

    While you discussion of the vehicle is interesting, to a point, you fail to take into consideration the operator of the vehicle. Look around. Most drivers are mentally overwhelmed by the concept of situational awareness in 2 physical dimensions. Adding a third greatly increases the difficulty, and as the fourth, time, comes in to play much more critically, the mental gymnastics increases exponentially. Your claim that it “should fly itself” as a way around this fact displays a real lack of knowledge about aviation. Pilots aren’t along for the times when everything is OK; but rather, their role comes into play when the world turns brown and smelly. A few cars raining down on the world because infallible technology suddenly failed will illustrate this law of aviation.

  7. Rich K Says:

    Any chance of magnetic assistance for VTOL? At least for the take off part. I guess it would still be an issue to land. Hmm.

    [Landing is easier -- you can land with a parachute but not take off. So mag assist would actually be very helpful. Good idea. -jsh]

  8. Bill Says:

    What about the practical aspects of flying cars. Traffic patterns? Do they just match physical roads (20 feet above them)? How do I merge into my garage at home and work? Where does one get fuel? I don’t think we can have completely automated systems. And what happens when there’s a problem with the aircraft? Certainly computers can monitor systems and force landings depending on circumstances. But what about sudden emergencies (computer crashes)? Is there really any chance of air cars plummeting from the skies?

  9. Sammy Says:

    > “It should fly itself, without piloting from the passengers.”

    Absolutely not! Your car today doesn’t drive itself, so why would you want a flying car that piloted itself. Take away control and I will lose all interest in the subject. Having an optional autopilot that can be switched on as desired is fine, but the driver must have absolute control over vehicle operation.

  10. Zach Foreman Says:

    You missed two more requirements, understandable since they are political instead of technological. But they still are major obstacles.
    1. Must be as energy-efficient as current cars, even for short commutes.
    2. Must have all safety features of current cars, including air bags, etc. This is especially true if the flying car can also be driven like a regular car.

    Of course, adding the weight required by 2 would make the first requirement virtually impossible to do.

  11. Ten Says:

    Flying cars would lead to a welcome decrease in roadkill.

    And a proportional increase in airkill, not to mention an entire new dimension — the third — added to the equation…for a nation already crying to its governments for cellphone regulation so it doesn’t kill itself driving, and to MADD for a federal nanny who forces it to blow competency before turning the key.

    Add to that the problem of lifting three thousand pounds aloft and keeping it there when today you can just roll that weight around.

    If I said flying cars were a bad idea I’d be labeled a flat-earther. Flying cars are a bad idea.

  12. John C. Randolph Says:

    the driver must have absolute control over vehicle operation.

    as long as you insist on that, we won’t have flying cars. They can have controls that let the human think they’re flying the vehicle, but until the flying car is safe for a child or a drunk to use, it will remain an experimental hobby.

  13. Sammy Says:

    but until the flying car is safe for a child or a drunk to use, it will remain an experimental hobby.

    Oh poppycock. You may as well say “until the automobile is safe for a child or a drunk to use, it will remain an experimental hobby.

  14. Lancair Says:

    Flying cars and airplanes would be cheap if they were manufactured in large volumes. Except for requirements for “self piloting” they would actually be simpler and less expensive than your average SUV. The SUV would probably cost more than light aircraft today if they were made in the same numbers and under the same rules as aircraft.

    In the end flying anything will never be practical for people who are only casually motivated, at least until they get the government out of the way.

  15. DaveinPhoenix Says:

    The five or six people a day who I see cutting across 5 lanes of traffic to hit their exit ramp on the I-10 at rush hour at 65 miles an hour should do real well with the new ability to fly.

    How will we manage the carnage on the ground below them ?

  16. Matt Says:

    Regarding energy efficiency, I’ve often wondered: while an aircraft has to spend more energy to lift whereas a car just has to roll, how much extra energy is required to clear, pave, and maintain roads and highways? To produce the asphalt, scrape and resurface them every few years? If we could eliminate that cost (except for paving short runways) could an aviation-based system rival a road-based one in terms of efficiency?

  17. John Campbell Says:

    The question of affordability is key and depended upon the only REAL innovation Henry Ford made… pay rates. You may– or may not– have noticed that most major corporations are trying to undo this one enabling innovation in order to chop out as many customers as possible.

  18. J. Storrs Hall Says:

    You can estimate road costs by gas taxes, which are about a quarter of what you pay at the pump. Half the pump price is crude price, the other quarter covers all the operations from refining to cleaning the restrooms at the service station. I.e. you spend half as much on road construction as on crude oil.
    Since car engines waste 3/4 of the energy in the fuel they burn in the first place, nanotech flying cars with efficient engines could use 6 times the power (counting not needing roads) as current cars and break even on total oil usage.
    On the other hand, we really need better energy sources — but that’s another story.

  19. Richard Karpinski Says:

    As long as it harvests its own sunlight, it need not be all that efficient. Sunlight is free.

    I think we are about to see autopilots for airplanes, and later for cars, that just take over when needed. One of the major failure modes of civilian and military aircraft is CFIT, controlled flight into terrain, which will be greatly reduced by that means.

    It’s even more of a problem on the ground because of so many things to run into in two seconds of inattention, as when texting or even just grabbing the coffee. Some cars already park themselves. Safety features to prevent accidents when drivers fall asleep or are drunk or distracted will be demanded, when feasible, by MADD and many others, like trial lawyers. Just like labels on ladders.

  20. geokser Says:

    There is another factor to consider in the car vs flying car comparison- capacity limit.
    Cars are raod based and confined to 2-dimension road space whreas flying cars are not- one could stack tiers them one on top of each separated only by safetyu distances like the airplanes. If one is not restricted to take and land only at airports and could do so at any neighbourhood take-off pads, there is really almost no capacity limit.
    However, when a certain traffic density is reached I guess we would need to develop some form of collision avoidance system but that would probably be the next problem to tackle in the distant future.

  21. geokser Says:

    To carry on the concept of an earth-bound vehicle to a flying car may not be feasible given all the limitations mentioned above and the drastically different operating environment.

    Imagine if the flying car is a human-size bubble that levitates by say, magnetic means and once airborne, propel forward by many tiny motors…

  22. USMC Says:

    Yeah we’re still fighting a war on terrorism here. Let’s not forget what happened the last time terrorists got a hold of a flying object. But I guess the rest of the U.S. feels safe and has forgotten about that. Anyway case and point it’s a bad idea.

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