Half a croissant, on a plate, with a sign in front of it saying '50c'
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2 Approaches To The Hoverboard From Back To The Future

Very lightweight, multi fan powered affair or solid rocket powered.
  [vote for,

1- A drone with wheels. Wouldn't be able to hold you up once you jumped on it, but you could recreate the scene where he throws the board down and it hovers along for a moment before he begins riding it.

2- The one I favor - remotely ignited rockets that hold it in initial hover stage for a few seconds until you jump on it at which time the main solid rocket motors are triggered by switches under the feet to ignite and provide enough thrust to support the rider.

It would by necessity be pretty thick but it's doable.

I much, much, much prefer the rocket powered model. Yes, you could have it powered just enough to keep you off the ground but you could also have it shoot you into the sky where presumably you would open a parachute that would lower you to the ground in the unlikely event that you survived.

The advantage of the second one (screw the first one) is that you could fly off cliffs.

doctorremulac3, Jan 08 2019

Hoverboard scene. https://www.youtube...watch?v=TkyLnWm1iCs
[doctorremulac3, Jan 08 2019]

Done with turbojets. https://www.youtube...watch?v=DeFFrHQxQVc
Easily redoable with solid motors. [doctorremulac3, Jan 08 2019]


       If it's that light (and therefore flimsy) it will be an expensive single-use device.   

       Basically, you'll be jumping on a drone.   

       We forsee huge sales.
8th of 7, Jan 08 2019

       Hmm. Got an idea.
doctorremulac3, Jan 08 2019

       How would you modulate power output from the solid rocket motors? Without an extremely tight control loop, the thing will quickly end up upside down.
mitxela, Jan 08 2019

       Shhhh. Don't tell him, just wait for him to test the prototype.   

8th of 7, Jan 08 2019

       //How would you modulate power output from the solid rocket motors?//   

       Not only possible naysayers...   

       basically baked. (link) The only difference is the turbojets can be throttled to turn up the thrust while the rider adjusts. Easily doable with variable thrust solid rocket motors that start with lower thrust and ramp up as more powerful propellant further up the rocket starts burning to allow the rider to adjust. Something that doesn't exist because there's no call for them, but something that's of course quite easily done.   

       Those who said this can't be done, please refrain from engineering, designing or evaluating new systems and technologies in the future.   

       Thank you.
doctorremulac3, Jan 08 2019

       Hypergolic bi-propellants will get you reliable, controllable thrust. I’d go with dinitrogen tetroxide and aerozine. Just don’t drop a socket wrench on the thing...
Whistlebritches, Jan 09 2019

       // Something that doesn't exist because there's no call for them //   

       And you know this how, exactly ?   

       // something that's of course quite easily done. //   

       Let's get this right, before we pour the oil over the pile of faggots* ...   

       On the basis of a user between 60 and 70 kg, whose mass can vary by +/- 500g in a matter of hours depending on food and fluid intake balanced by waste elimination, you're going to manufacture solid propellant motors that can reliably - after a variable interval in storage, even in controlled humidity and temperature - ignite simultaneously within a few milliseconds, and produce an absolutely identical thrust (typically 220N) per device (working on the basis of three devices for inherent stability) which rises at an identical rate over time to another identical thrust value of 240N, causing the user to accelerate gently upwards ?   

       Have you ever personally designed, made and tested any form of solid-fuel rocket motor, using solventless nitrocellulose sticks, extruded double-base propellants, or even black powder ? Because we have, and know how difficult it is to make such a device operate with the precision this requires.   

       // Those who said this can't be done, please refrain from engineering, designing or evaluating new systems and technologies in the future. //   

       We consider ourselves rebuked ...   

       *By "faggots", we refer to thin lengths of dry wood used as kindling, rather than a dish of meatballs in rich gravy, or a slang term for a gay male.
8th of 7, Jan 09 2019

       I assumed, but thank you for the clarification.   

       Hey, forget about pyrotechnic reaction mass, get a bunch of compressed air cylinders. How long does this thing need to fly?   

       Then you've got control and it's easy to refill. So you just shoot across the field for a few seconds, that works for me. It would be more of a surfboard than a skateboard but it might work.   

       Enough thrust to weight ratio juice in compressed air tanks to lift somebody for a few seconds and shoot them across the parking lot at 40 MPH or so?
doctorremulac3, Jan 09 2019

       // I assumed //   

       What did you assume, exactly ?   

       // forget about pyrotechnic reaction mass, //   

       Oh, taking the easy way out, now ...   

       // get a bunch of compressed air cylinders. //   

       Carbon-fibre wrapped pressure vessels would be light enough, but the problem with air is that the output pressure will drop continuously as soon as the valve is opened - unless there's a restrictive regulator.   

       A dense, volatile gas in equilibrium with its liquid would be ideal; even better, eject the liquid with the pressure from the vaporizing gas.   

       Yet another method would be a container of water capable of sustaining high internal pressures, pressurized on demand by a slow-burn pyrotechnic gas generator, distributing the outflow through a manifold to ensure even thrust.   

       Then again, water is cheap, plentiful and relatively safe, so it's not the best solution; hydrocarbons would be much more spectacular.
8th of 7, Jan 09 2019

       //unless there's a restrictive regulator.//   

       Well duh.
doctorremulac3, Jan 09 2019

       Would you settle for a conventional mini-hovercraft?
RayfordSteele, Jan 10 2019


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