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Thread: short burst of thrust for quadcopter... is electric a possibility?

  1. #1
    Associate Engineer
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    short burst of thrust for quadcopter... is electric a possibility?

    My end goal here is to have a quadcopter that will be able to dodge projectiles with incredible speed (without having to wait for the propellers to rev up). I need a thruster that wouldn't necessarily have to emit a constant thrust, but I do need a good burst. The module has to be extremely lightweight, as it will be on-board the drone, so I'm wondering if there's some method that can convert electricity into directable kinetic energy. To get the burst I'm thinking something along the lines of a capacitor? This would need to charge up, but would also emit a lot of electricity when it's released. Thoughts? (oh, and also I'm only a teenager and hardly have anything of a budget, so it'd be nice if I could get a relatively cheap option. However, even if it's expensive I'd still like to know if it exists!) Thanks in advance!

  2. #2
    Principle Engineer Cragyon's Avatar
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    The motors will probably respond to an increase in voltage and I think a capacitor won't do what you want.

    You need to investigate how the electric motors operate to increase or decrease lift.

  3. #3
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    I meant I would have the thrust mechanism on a separate circuit and activate it with a relay or something. The motors would be acting normally; according to their circuit someone could've just manually pushed the drone up from below with their hand and it would have the same effect. In fact, I could just do that and get the basic effect that I want, but I'm trying to automate the action.

  4. #4
    Project Engineer
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    An interesting problem.
    Some rambling thoughts.

    Two things come to mind.

    Cut power and let gravity help you out.
    It is always there, always constant.

    If you need to act faster than that, add CO2 cartridges pointing in the right direction.
    Control would be via a servo actuated valve.
    Light weight, fast, electronically controlled.

  5. #5
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    hmm... you might be onto something with the CO2 cartridges. I never thought to have PRESSURIZED air. What if I have and on-board, lightweight air pump to pump up an air tank, then have it remotely release it all in one direction? That way I wouldn't have to put in a new cartridge every time I use it.

  6. #6
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    You need pressure and volume to displace the load at the speed and distance you want, thats not hard to calculate really, But then find if you can get the gear you need for those numbers and if it's light enough to fit what you have and still be balanced. All that kind of thing with Solenoids, tanks and nozzles are available off the shelf and have well defined specification.

    One option I thought of was solid rocket fuel or motors. Not too dangerous and could be set off with the onboard electric you already have. In terms of available energy vs weight this is very attractive But each motor is a one shot deal and stopping it once it's started is a problem so you would want short duration and maybe a lot of pieces

  7. #7
    Associate Engineer
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    yeah, that's presicely why I'm NOT doing rocket... but yeah I'll look into the pneumatic blast

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