100000 RPM : DIY Experiments #7 - Ultra fast spinning!

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Little fun experiment today : we're gonna make spin this fan motor as fast as possible!

Originally, this engine was built on two balls bearing, but we've taken off one of them to reduce the friction. What we have here is a circular magnet, which has 2 north and 2 south poles. We're going to make it spin around this handmade coil, by using a square voltage. We're going to increase the magnet's speed by gradually increasing the frequency. Roughly at first, but very precisely afterwards.

At a low frequency, the coil's impedance is very low, which forces us to limit the current by adding a resistor. We're roughly at 5 amps. Once the frequency gets higher, we'll finally be able to open fire. We'll start with 80 Hertz, which equals to 20 revolutions per second. It's basically the most speed we can generate with our fingers.

Thanks to our system and according to our calculations, we could reach around 100.000 RPM. To give you an idea, it'll spin at one thounound six hundred revolutions per second, which is very impressive. First try ! We're slowly increasing the frequency with our 100k potentiometer.

To increase the rotor's kinetic energy consistently we have to increase the frequency more and more slowly. But when we move consistently the knob of the potentiometer the frequency increases faster and faster. Therefore we need to be very careful and precise while moving the knob to avoid the motor from stalling.

A few stalls, but it's possible to synchronize again at a lower frequency when the rotor is decelerating. At this speed, the standard potentiometer is not precise enough to make sure we're not to abrupt, making it harder to avoid stalls.

It's time to use the precise potentiometer (trimmer) and make a few rotations. From now, the impedance of the coil allows us to take off the resistance (no more current limitation). Now that there's no limitation anymore, we're undoing the revolutions stored in the trimmer to use its accuracy later.

Now that the power is higher (96W, 8A under 12V), we can put the 100K potentiometer on 0 ohm. It all comes down to this moment, with the precise potentiometer. Already 1000 revolutions per second, already hard to believe. As the frequency increases, the voltage is limited by the coil's impedance so motor then consumes less energy : the efficiency is increasing. The speed limit will be reached when the energy provided at every moment will just have to compensate the friction. Imagine the noise it makes, considering the camera is 5 m away from it!

Rotation speed : 1700 revs per second.
Kinetic energy : 740 Joules.
Speed at the edge of the rotor : 800 km/h (500 mph).
Stalling, the deceleration is pretty quick because the system isn't turned off. Free deceleration test from 100.000 RPM

Next step one day… : breaking the sound barrier (1200 km/h) on-the-spot !

[psvrgamer]

100.000 revolutions per minute. wow thats a lot of french history.

[Nexalian_Gamer]

6:30 When you try to run Minecraft with shaders on a 1998 Dell PC.

[Solstice]

“100, 000 rpm”

Me: *laughs in 2x speed*

[fatelvis]

With every 10000 rpm increase.. I was decreasing my headphone volume by 1 unit

[rajankushwaha]

5:27
Bug be time to leave this place not safe

[Ash-ccom]

Sounds like my old laptop fan when I tried to play minesweeper

[ForestSongUnLTD]

Amazing, when it started wobbling toward the end i fully expected it to blow to pieces. That's one well balanced rotor. :)

[pakuro]

Me at 60k RPM: _Fack, this thing is gonna fly._

The random bug at 5:25: _Whatever...._

[jace_Henderson]

I find it really hard to comprehend something spinning 1, 666 times a second.

[danw]

I can't believe that rotor didn't explode before it got to 100K rpm. The weight of the magnet must have been huge at that speed!😲

[ledogge]

6:00 the computer fans when you open up 1 chrome tab on your grandmas computer

[JonathanMartinez-xsze]

Crazy. The fastest neutron star known to man spins at 716 rotations per second. Not far off from this. So imagine something a billion times bigger, spinning just as fast. Kinda blows your mind

[TheNormndee]

What I think is most interesting is that at such an high RPM and no sign of precision balancing, this little motor didn't blow apart was impressive!

[SteBradburyDesign]

I wanted to see someone touch it when it was at max rpm. Reckon your finger would fly off, or it would just get shaven down?

[abdeljalilpr]

Do it in vacuum ..you can get more RPMs

[haydentakara]

1:27 sounds like a rotary idling very quietly

[jm]

Damn it Scotty! We need more power!

I'm giving her all she's got captain!

[AußerirdischeLebensForm]

Reminds me of the 74 years old lady that got "rescued" in Phoenix by a helicopter and started spinning around the same speed this machine does here.

[davidahiwaaynet]

Very neat! You reached in 5 minutes what a turbocharger reaches in about a half second.

[jeffmccrea]

I'm amazed that the bearing stood up to that speed for that long. It's too bad that you couldn't design a remote release and mount a well balanced propeller to the metal cup, spin it up as fast as you can then release it and see where it goes. It might be a little hard to see when it gets to the stratosphere though. :) I saw on Myth-busters one time where they took a 120 VAC, 14, 000 RPM angle grinder and connected it to 240 VAC. they put a standard CD on the shaft and spun it up with a time lapse camera recording. At first, in time lapse, it was balanced but as it got faster, the plastic CD began to deform in a wave pattern around the circumference just before it exploded.