Originally published at: https://boingboing.net/2020/05/07/what-does-a-fan-do-in-a-vacuum.html
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Here’s a less intuitive one: what happens with a lawn sprinkler if you suck instead of blow?
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Complains about a female lead in Star Wars?
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Q: What does a fan do in a vacuum chamber
A: It doesn’t work. Unless you’re not really in a vacuum. Then you just have to turn up the fan really high.
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That doesn’t require a vacuum.
But their echo chamber is quite leaky so not particularly sound.
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“Now if we turn the voltage up again, so that the fan blades are spinning at about 0.99c, we start to see frame-dragging effects take over…”
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Anyone else think of the Mars helicopter?
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It would have been good if he had measured the fan speed with a hall-effect sensor as the pressure dropped. As the pressure dropped, the fan speed should increase since there is less air to push against (less resistance).
Also, as the air pressure dropped the fan would get hotter since there is no way to efficiently dissipate heat from the motor. Cooling motors in space is a fun engineering problem. The lunar rovers used paraffin wax.
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Below is my favorite vacuum chamber video. I had no idea such a giant vacuum chamber was even possible. Knowing the physics of what Galileo’s Leaning Tower of Pisa experiment would do in a vacuum is one thing, seeing it in this video was another.
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Now try it with an Alabama fan.
What does a fan do in a vacuum chamber?
There are definitely some Star Wars fans I’d like to test this with.
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“I saw a on video where, and I’m not a medical doctor, just a person with a tremendous brain, but in this video the scientist had virus particles that moved very, very fast, and then he used a vacuum and they stopped moving, just slowed until in a very short time the movement was close to zero so I asked Jared and some of the other experts, our tremendous team of very very smart experts, some of whom are doctors and I’m not a doctor just a person with a fantastic brain if perhaps because when the virus gets in and it does a number on the lungs, just tremendous damage, so we use a very tiny vacuum and we insert it, either through the skin or some other way, and then the virus particles stop moving and then in just a very short time, their movement is down to zero but nobody of course in the media, the fake news media I like to say, has reported on this but it looks very promising.”
–Donald Trump, probably
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You are a little too good at that 
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Why? Mars has an atmosphere. It’s just not a very good one.
A: Nothing, it just waved.
I’ll bet that everything we see in the video was bought from McMaster-Carr.
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… and it was in that vacuum, that Mr. B. Ball and Miss Felicity Feather finally got to know each other, fell in love, and stayed together 'til the end.
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Yeah, I was thinking that the answer was: overheat. Higher speed lead to more heat generated and thin air means less cooling. A friend was working with computers South America (Ecuador?) and getting hardware that was certified to work at high altitudes was difficult.
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From 1:30 to 2:08 (while the power supply’s red Volt / Amp readouts are visible), you can see the motor pulling less current (Amps, the lower readout) as its air resistance drops, going from .24 to .13 before being obscured by a camera shift.
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