A rail gun would be a great science fair project. The only problem is calling it a gun
Also, the flying car has been on the market for over a year now, although technically it’s a plane you can drive, not a car you can fly.
Exo skeloton is here:
All “flying cars” are really planes you can drive. It’s something I point out every time we have a flying car thread. You can have your flying car, except the engineering compromises to make your airplane drivable means you’ll have an expensive but crappy airplane, and an expensive but crappy car. You could buy an airplane and a car and combined they cost a lot less and perform a lot better than if you tried to combine them into one machine.
Regardless of quality, I think it’s fair to say “flying car” is no longer fictional or hyperbole. 
Flying cars have been around at least since the late 50s, and probably longer.
Flying substitutes-for-cars are what we don’t have, and probably never will.
Don’t call it a gun. Call it a linear motor. That’s what it is, after all; a distinctive application of the linear motor.
So when people complain about not having flying cars, you explain that flying cars do exist, they’re just not really cars but drivable planes and totally impractical.
Maybe, just maybe, that’s not what people mean when they complain about not having flying cars? I’m thinking most people imagine something that uses an anti-gravity technology, like the cars in Back to the Future Part II.
Yes, anti-gravity technology doesn’t exist yet. But that’s exactly what people are complaining about! They don’t want a car that requires a runway to get airborne and has long wings to provide lift. They want anti-grav vehicles fully maneuverable in three dimensions.
Powers &8^]
There’s also the issue that car/plane thingies that could successfully take off, fly, land, and drive on the ground have been in existence for, oh, 75 years. (My all-time favorite.) They’ve been invented time and time again.
You never had one, and your parents never had one, and your grandparents never had one, though.
It’s not the flying car, it’s the ubiquitous flying car.
I see on re-reading that I’m repeating JWK. But they really do go back before the 50’s. Many, many of them.
I want a flying car like the ones they have in Blade Runner. What is taking so long?
I want an android that looks like Daryl Hannah, too.
Well put. I was about to say the same thing in many more words.
Out of interest, why do you suppose it probably won’t happen? Because of how energetically inefficient it is? Safety concerns?
Or by never do you mean “not in the near future”?
(genuine question, not trying to attack your POV)
Actually, it’s not for sale as of yet. At this point, you merely pay $10,000 for a chance to pay almost $200,000 in the sometime distant future for a chance for one of these things.
The problem with a plane/car is that as a car, it needs the aerodynamics to stay on the ground while as a plane, it needs aerodynamics to stay in the air. Thus, a car uses the wind to help push it downward to help the tires grip the road while a plane uses the wind to pull it upward.
At least those old German boat/cars didn’t have mutually exclusive design goals.
That’s not a flying car. That’s merely an airplane that you can drive on the street. A flying car is something that’s sitting in your driveway you hop into and fly off hovering a few feet over the roadway.
This is a flying car. Of course, it has been almost ready for years. The longest test flight was about five minutes of hovering tethered to a crane.
All of the above and about 10,000 other reasons. We won’t see flying cars until and unless we get a technology that is essentially magic to us.
Same with jet/rocket packs.
Back in the nineties, I worked for a small company that sold medical sensors and software. We received the DARPA ‘projects we want’ catalog. There was some boring stuff. There was also the mention that DARPA had been trying to develop leg amplification exoskeletons for years but having problems with the controls. I asked my boss if I could keep the catalog. He never got around to giving it to me, so I sadly have no cite.
ETA- Sadly, I’m on dial up and can’t watch the video.
The energy budget, the insanely difficult traffic-control situation, unless they’re all remotely piloted, and the parking problems. (Anti-gravity might solve the last, by reducing the physical footprint à la The Jetsons, but there are serious problems with anti-gravity even in scientific theory, let along theoretical engineering.)
Most of the “secret” DARPA projects are openly “hidden” at scientific conventions. Fundamentally, so was the A-Bomb. Everyone in science knew it could be done at the time, and that people were doing it.
And yes, there are often some pretty spy looking foreign people secretly snapping photos at the bigger conventions (like ACS). Of course, they could just be grad students, but its the sort of behavior that will quickly get you kicked out. You are specifically warned not to take pictures or record lectures. If it’s something you really want, you could probably just ask the presenter for a copy of the slides.
By that definition, hovercrafts have been around as long as vacuum cleaners.
And preferably in “Arrest Me Red”, or “Yank My License Yellow”!
In the latest Technological Review in the Economist, two Darpa projects are cited. One is about robots/vehicles that can forage for fuel and the other is a blob-like robot that can change its shape to squeeze through small gaps.
Many other interesting articles in there as well - no flying cars, but electric aeroplanes sound (or, in fact, don’t sound at all) quite interesting.