5 ms·
IIRC submarine screws use prime-numbered blades (5, 7, 9) to cut down on harmonics. Perhaps the same would be useful here, though I don't see many prime-numbere
by mLuby 4y ago
IIRC submarine screws use prime-numbered blades (5, 7, 9) to cut down on harmonics. Perhaps the same would be useful here, though I don't see many prime-numbered turboprops, which you'd expect to benefit from similar noise reduction. Related, I highly recommend HI Sutton's youtube channel if you're into submarines. https://www.youtube.com/watch?v=ugSEIiTZ1Pg https://www.youtube.com/watch?v=ugSEIiTZ1Pg
A magnus effect drone may have a decent chance at being quiet. IANAAeroEng but I'd guess that the moving part's interaction with the fluid can be made laminar or at least non-turbulent, and also unlike some propellers, the moving part shouldn't be approaching or interacting with the sound barrier. https://youtu.be/hlmvHfIAszo?t=16 https://youtu.be/hlmvHfIAszo?t=16
However my money's on ionic propulsion drones since they have no moving parts to make noise. I wonder if the air accelerated through the grids produces an audible hiss. https://youtu.be/UGM4JXVB5FM?t=126 https://youtu.be/UGM4JXVB5FM?t=126
- gonzo41 4y agoIonic propulsion requires massive power. It's cool but you'll probably never see it in real life applications.
- mLuby 4y agoClarke's first law applies here. Maybe beamed power could help around a delivery hub.
- throw_away_8080 4y agoI love when primality is useful. Like cicadas. But 9 is not prime.
- ilyt 4y ago>IIRC submarine screws use prime-numbered blades (5, 7, 9) to cut down on harmonics. Perhaps the same would be useful here, though I don't see many prime-numbered turboprops, Might be just odd-numbered ones, not neccesarily prime. But other interesting case is how car tyres have variable feature size on the tyre so the produced sound is more spread over the spectrum and appear quieter > However my money's on ionic propulsion drones since they have no moving parts to make noise. I wonder if the air accelerated through the grids produces an audible hiss. https://youtu.be/UGM4JXVB5FM?t=126 https://youtu.be/UGM4JXVB5FM?t=126 That would be literally shocking (and changes properties heavily based on humidity) so I'd think use would be limited, it's not exactly great way to lift anything heavy
- sgtnoodle 4y agoThat ionic propulsion drone/startup you linked to is a scam. Their drone has a ducted fan in the center that's providing the thrust.