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Bouncing ball flying car

dubba dubba dubba
  [vote for,

One of the problems with making a flying car capable of VTOL and hovering is that air is pretty low density. Therefore, in order to produce a reasonable amount of lift, you have to have very powerful fans throwing the air downward. Truly immense volumes of air must be moved in this way.

This need to move large volumes of air causes problems. For example, a hovercar will inevitably be very noisy. It will also tend to blow away anything underneath it. It's all not terribly good.

Fortunately, the clever people at MaxCo. have a solution.

The MaxCo Bouncing Ball Flying Car (marketing are working on the name) has, at each of its four corners, a highly- modified tennis-ball-firing machine. Each such machine fires 3-inch silicone-rubber coated steel balls downward, at a rate of about 20-40 per second, at moderately high velocities.

These balls, on being fired, act as a dense and efficient reaction mass, providing lift.

But wait! There's more! You are probably wondering how long the MaxCo Bouncing Ball Flying Car can remain aloft, before running out of balls. Fear not. The downward trajectory of each ball is chosen so that its rebound (hence the silicone rubber coating) brings it back up into a catcher on the underside of the car, whence it is directed back to one of the four ball-throwers for reuse.

In early versions, the bounciness of the balls was adjusted so that they would rebound with just enough speed to reach the catcher. However, inadvertent use of some over- bouncy balls revealed an unexpected bonus: the balls deliver extra lift as they slam upward into the catcher.

It turns out the maximum lift is provided if the balls are as perfectly elastic as possible, providing both reaction mass as they are fired downward, and the greatest possible force when they rebound to strike the catchers on the underside of the car.

Noise-wise, the MaxCo Bouncing Ball Flying Car has proved considerably quieter than comparable vehicles using fans or rotors. The only drawbacks are the need for a reliably flat road surface, and the greater risk to anyone who is overflown by one.

MaxwellBuchanan, Jul 14 2015

Triple-Barreled, Pn...eaction Hovermobile
[xaviergisz, Jul 17 2015]


       // need for a reliably flat road surface // loses any kudos that might have come from "flying".   

       // risk to anyone who is overflown by one // no foul. Anyone loitering in the road has only themselves to blame if they happen to be mown down by a vehicle of any sort.
Tulaine, Jul 14 2015

       Horizontal motion is possible by slightly vectoring the ball-throwers; the throat of the catcher is wide enough to make this possible.
MaxwellBuchanan, Jul 14 2015

       //// need for a reliably flat road surface // loses any kudos//   

       In practice, we find that many irregular surfaces become flat after being overflown a few times.
MaxwellBuchanan, Jul 14 2015

       For // other than vertical motion // there would need to be additional catchers outside the notional 'footprint' of the vehicle, such that balls may be directed at variance from from purely vertical to provide lateral impetus. The external catchers would need to be mounted on extensible booms to adjust to compensate for varying lateral speeds.   

       If enough such vehicles were deployed, and were equipped with appropriate on-board communications and suitable protocols, a sharing system may be possible with vehicles emitting and collecting balls. Computational power required to co-ordinate this scheme is unlikely to be available for some time.
Tulaine, Jul 14 2015

       // many irregular surfaces become flat after being overflown a few times //   

       How does that happen? If the surface is irregular the balls won't return in the required trajectory and will be lost, resulting in catastrophic failure due to lack of balls. Any driver (pilot?) would surely avoid any surface which is not already sufficiently flat.   

       Perhaps there's scope for tethering the balls on elastic just in case they're deflected and fail to return to the catcher. This brings further complications though, since the firing mechanism must then support the passage of tethered balls.
Tulaine, Jul 14 2015

       // catastrophic failure due to lack of balls//   

       Being under a catastrophic failure is known to cause flattening.   

       //tethering the balls on elastic//   

       We did briefly do a trial with loops of very dense rope. Briefly.
MaxwellBuchanan, Jul 14 2015

       (+) The balls can be made to rebound vertically plumb from slightly irregular surfaces if you spin them just right. There would be a maximum kilter you wouldn't be able to fly above but there wouldn't be too many roads, other than in San Francisco, you couldn't hover above.   

       //But this only lasts for time t e.g. 0.02 of a second.//   

       Ah, but you see, there's the problem. I could e.g. a different time t and get a very different answer.
MaxwellBuchanan, Jul 16 2015

       For horizontal motion one could use boomerangs, generating thrust by hurling the reaction mass of boomerangs rearward, and extra thrust via the impact of returning boomerangs. Perhaps one large boomerang would be best to avoid fouling the outgoing with the incoming.
bungston, Jul 16 2015

       Maybe boomerang propulsion should be its own separate idea. I was going to say that a standard propeller would be much better than a boomerang, but assuming you could get it to work (the halfbaked part), theoretically you could get some of the benefits of a very large propeller without the difficulties of mounting a huge propeller.   

       I think you would need to figure out how to have many in the air at once though to get any benefit.   

       Those benefits might be tempered by the amount of mass required in the boomerangs being larger than the mass of the equivalent large propeller
scad mientist, Jul 16 2015

       I suspect that a mechanical boomerang thrower could throw in a standardized way such that the path taken of each boomerang is very like the one before and after. One could keep a stream of boomerangs in the air this way.   

       Also boomerangs could be thrown from multiple sites on board as long as the paths do not cross.
bungston, Jul 16 2015

       Don't space-hoppers give kids wonderful dreams to pursue.
wjt, Jul 17 2015

       You could cross the paths as long as the releases were suitably staggered.
pocmloc, Jul 17 2015

       "There's a ball-thrower to see you, Doctor, who's been slightly vectored, and a catcher with something in his throat. Oh, and this gentleman here has suffered some kind of catastrophic failure that he's too distressed to explain."
pertinax, Jul 17 2015

       I recommend flubber.
RayfordSteele, Jul 17 2015


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