Can A Drone Push A Bike?

It sounds like a rhetorical question that a Midwestern engineer might ask, something on the order of ‘can you fix this bad PCB spin?’ [Tom Stanton] sets out to answer the title question and ends up building a working e-bike with a drone motor.

You might be thinking, a motor is a motor; what’s the big deal? But a drone motor and a regular e-bike motor are made for very different purposes. Drone motors spin at 30,000 RPM, and an e-bike hub motor typically does around 200-300 RPM while being much larger. Additionally, a drone motor goes in short spurts with a large fan blowing right on it, and an e-bike motor can run almost continuously.

The first step was to use gears and pulleys to reduce the RPM on the motor to provide more torque. A little bit of CAD and 3D printing later, [Tom] had a setup ready to try. However, the motor quickly burned out. With a slightly bigger motor and more gear reduction, version 2 performed remarkably well. After the race between a proper e-bike and the drone bike, the coils were almost melted.

If you’re thinking about making your bike electric, we have some advice. We’ll throw in a second piece of advice for free: use a larger motor than the drone motor, even though it technically works. Video after the break.

20 thoughts on “Can A Drone Push A Bike?

  1. I’d say that power ratings for hobby-level BLDC motors are about as trustworthy as that of sound systems.
    I also find it a bit sad they destroyed a motor in the process. Measuring the temperature on the outside of the magnets with your fingers is not an accurate method, while it would have been quite easy to add some temperature sensor directly to one of the motor coils, and if you want to push it to the limits, then cooling is also mandatory.

    Also, when doing such things, details matter if you want to do it properly, and though I have not done the math, nor looked it up in tables, the first timing belt looks much too thick for the application, and timing belts loose some efficiency at high rpm and “bend frequency”.

    I think an average human can pedal some 200 to 300Watts, and a fully trained human can maybe double that (for some decent period of time) They claim a top speed of 20 miles an hour @ 08:12 which is comparable to what an untrained human can do, which is still quite impressive for such a small motor.

    1. Why not just get a a40/p80 3000w motor? It has 42g of pushing power. It’s basically building a geared hub motor or am I wrong? I’m building a go kart with 4 hub motors and was trying to figure out how to convert pushing power to torque to figure out gear ratio if I connected to single gear gearbox independent CV axles it could give good speed but maybe 2 connected together on the gearbox?

  2. the word that’s missing from this entire article is torque. or leverage.

    “Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.”

    it doesn’t matter how fast the motor spins, it’s about the designed torque strength, and how it imparts that onto the device.

    in this case, it needed to be geared way down to create a mechanical advantage that the motors design didn’t provide.

    1. As I understand it, one problem with a small diameter drive is that it places a large load on the bearing, especially if that bearing was not designed for side loads. A large diameter drive increases speed, reduces torque. Yes you will still have to do the reduction later, but at least it can be done, where the bearings are expecting some side load. Alternately some kind of coupling to a secondary shaft to reduce the motor load to rotational, could be implemented.

    1. I also expect about half of artsandcraftsaday articles to be written by twits promoting youtube channels.

      Propeller driven wheeled ground vehicles are blitheringly stupid.
      At least when the frogs tried it, it was 1930, so just dumb. Besides French cars suck BWDB (big wet donkey balls) anyhow, putting a prop on the front doesn’t make them _much_ worse.

  3. I’m a big supporter of Tom’s projects. He often explains the computation and physics of his projects very well, often with realtime graphics and overlays. He also does well accepting failure and often does follow-up videos with iterations and improvements. Big ups. Totally agree with above comments about ‘stated output’ and torque tho, but the ‘is it possible’ is the aim of many of his projects.

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