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Thread: I'm going to put a jet engine on a bicycle.

  1. #21
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    Quote Originally Posted by Dicknose View Post
    Drag numbers are hard to do without some experimentation.
    As long as you have an approx number, test it and get terminal speed and work backwards.
    Yeah. Best experiment I could think of would be a coast-down test, pedal it up to a certain speed, stop pedalling and see what the speed each second thereafter. A phone app w/ GPS might possibly be accurate enough to do this and log it. Do it in both directions and you could potentially account for gradient and wind, assuming the latter remains fairly constant. A phone app connected to a sensor counting a magnet on the wheel would be more accurate tho.

    (Since the jet is yet to be attached).

    But yeah, super-hard to work out a theoretical calc for the pictured bicycle with you on it. I guess that racing bicycles are relatively well-modelled and thus reasonably representative figures are known, but this thing is a lot different from one of those

  2. #22
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    Quote Originally Posted by Dicknose View Post
    And just to be even more confusing, that dimensionally torque and energy are the same - Force * distance. But you should never use Joules as the unit!
    Force and distance are both vectors (have a direction). Energy is when the force and distance are in the same direction (or opposite direction).
    Torque is when the distance is at right angles to the force.
    You know, that had never occurred to me. I'm totally doing my wheelnuts up to 50 kJ now!

  3. #23
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  4. #24
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    Just a little update. I was having trouble getting the little telemetry box to connect to the jet engine. The company sent me some replacement parts, and it turns out the fuel pump/electronics module was bad. So now I have the engine electronically up and running. I have not actually plumbed all the fuel lines into it and fired it up, but that will be next.

    The biggest technical hurdle in all of this was how I was going to control the throttle on the engine. Since it's designed for a radio controlled airplane, the fuel pump module is looking for a throttle signal from a radio control receiver. It's the same signal that an RC car uses for the throttle and steering servos if anyone is familiar with those. But luckily, there is a library for the Arduino that is specifically made to control servos. So I was able to use that to send the proper throttle signals to the electronics on the jet.

    I also managed to connect an e-bike throttle to the Arduino as an input. So ultimately, I'm going to have a standard twist grip throttle on my handlebars to control the jet engine, which I think is pretty cool. I have seen other people put jet engines on bikes before on YouTube, but they are all really hacked together installs with weird little knobs (servo testers) to control the jet. I didn't think it seemed very practical or safe to be fiddling around with a little knob while you're riding a jet bike. So I'm looking forward to having a nice clean install, and a twist grip throttle.

  5. #25
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    You're going to be famous/infamous.

  6. #26
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    Yes, we are witnessing the birth of Iron Little Man.

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