Hacker News Reader

Comment by po | Hacker News Reader

Every time I've ever seen an article or report about some new flying car concept, I have pretty much zero interest in it. The flying car will only be a reality after the self-driving car. The reason is that although, I would personally love to have a flying car, I would under no circumstances want all of my neighbors to have one.

You can do a lot of damage with a regular car which is why we put fences and guardrails between our streets and buildings, but just imagine how much damage you can do if you add a 3rd dimension. It would be like visiting Flatland. No way the FAA is going to allow flying cars for the masses until they are basically self-piloting.

View on HN

> although, I would personally love to have a flying car, I would under no circumstances want all of my neighbors to have one.

That sort of applies to normal cars as well of course: a wonderful technology, as long as they're only used by a few (wonderful for those few, naturally)—and a source of massive misery and damage once everybody has them.

If you're going to allow anyone without a pilots license to drive/fly one, they would need to make it impossible to manually fly it (i.e. no flight controls whatsoever). Then the problem is that people like us would hack it.

That's not a problem because it would then be illegal to hack it and it would be solved the way all illegal actions are solved.

There are two completely unrelated kinds of flying car.

First is the Jetsons version of the flying car. This is the aviating equivalent of the personal automobile. You get in, you fly it to work from your driveway, land it on the roof of your office building, and walk in.

Second is what this was: a machine that's both a road car and an airplane.

The first one is at least conceptually very neat. If it worked, it could completely eliminate traffic jams, eliminate pedestrian-vehicle accidents, and vastly improve the efficiency of local transport. There's been little attempt to build such a thing. It basically demands VTOL operation, which vastly restricts its range and increases its cost and noise. The Moller Skycar is the only real-world attempt at this one that I can think of, and it didn't get very far.

The second one is completely pointless. The "flying car" as it actually (barely) exists, as in this example, is just a car that is also an airplane. You drive it to an airport, reconfigure it to be an airplane, fly it to another airport, land, reconfigure it to be a car, and drive off.

The problem is that design tradeoffs mean that such a "flying car" is both a bad car and a bad airplane. They have inherently different needs for things like wheels, engines, drivetrains, etc. Putting both into the same machine means it's not going to do either one well.

For every "flying car" out there, you can take the same money and buy a better car, a better airplane, a second better car to keep at your most frequently used destination airport, and have enough money left over to rent cars at other airports for years and years. This is unlikely ever to change.

The Jetsons idea is interesting, but roughly nobody is working on anything at all applicable to it.

I think the closest we'll get to a personal flying vehicle would be something similar to a powered hang glider / ultralight. The way I envision it would be retractable wings using carbon fiber for the skeletal structure, and an electric motor somewhat like in a Dyson vacuum cleaner for power (along with a fuel cell so it can run off hydrocarbons, as that has a better power to weight ratio then batteries). If the mass of the entire device is less than the mass of the person it is carrying then I would think damage (to third parties / structures) would be limited.

The most workable concept at the moment is basically a powered parachute/paraglider trike beefed up to be like a dune buggy. I always felt this was cheating though, because when I hear "airplane" I think of a fixed wing design.

EDIT: ... which is exactly the design that crashed. AFAIK these don't require a pilot's license, but that doesn't mean they're easy to fly.

It does seem less awful than other concepts, but still... why? It's a worse dune buggy and a worse airplane than you could build if you took the same resources and built the two separately.

As for being hard to fly, I believe the rationale behind not requiring licenses is simply that you're unlikely to kill anyone else when you crash, so do what you will. At least in the US, licensing requirements for different kinds of aviation scale fairly directly with the number of innocent civilians you can take out if you screw up too badly. Not 100% the case, but a decent approximation.

Oh, I'm not disagreeing with you, just commenting on flying car design.

AFAIK licensing requirements scale with aircraft size and complexity -- which does correlate nicely with its danger to bystanders.

Yep, I was just elaborating a bit.

You're right that licensing requirements go up with size and complexity, but it's a bit beyond that as well. For example, carrying people in exchange for money has stricter licensing than carrying people for fun, because the idea is that 1) you'll do it more often and 2) people paying you for services are less aware of the risk they're taking.

Even self-piloting flying cars would be a disaster. They'd be limited in speed, and the traffic collision avoidance systems would eat up too much time due to the constant slowdowns and changes in direction. Not to mention that it's impossible to simply stop in the air.

I doubt flying cars will ever be a reality. What will be reality are sustainable, electric, self-driving vehicles.

Not the pipe dream of 20th-century futurists.

Where would these slowdowns be coming from? The only part I can think of would be landing zones, otherwise you have so much more space to fly in than you do with roads that it's inconceivable that there would be jams, unless you artificially limited flight paths to very narrow "roads" in the sky. And it's trivial to widen those in the case of congestion, in any case.

>> Not to mention that it's impossible to simply stop in the air.

What if they invent one that flies like helicopters? Who knows what will come in the future...

If you cut the power in a car suddenly, you can probably avoid serious damage or killing anyone on your way to a stop. Not so much in a helicopter.

Hm. I thought the post was referring the troubles of maneauviring during a slowdown, as airplanes can only go forward.

If falling of the sky is the trouble, you can still use parachutes as a safety measure. Like this one (http://en.wikipedia.org/wiki/Ballistic_Recovery_Systems).

Anyways, I don't think flying cars are impossible. We just don't have enough technology yet to make it viable.

Helicopters can be landed softly without power, via autorotation.

It's not hard to imagine an autonomous helicopter that can manage autorotations. Some drones already do. But for people-carrying operations, it would need to have an extremely fine-grained terrain database (better than we probably have today) to pick suitable landing spots and avoid low-level obstacles.

Most helicopters can autogyro - that means they can land without working engine, using air flow to speed up the rotor, and then using the rotor to slow down the fall to relatively gentle landing. More or less like the seeds of some trees fly.

Same goes for gyrocopters, which are sth in between regular plane and helicopter (they have powered propeler to gain horizontal speed, and unpowered rotor that is speed up by autogyro effect that replaces the need for wings).

Of course in dense 3d traffic you may collide with sth before you can slow down the fall, so there will be a need for some system that sygnalizes everybody below you to quickly get out of way.

Reply on news.ycombinator.com