Timeline for Could a Dyson fan scale up to be used as a bladeless aircraft engine?
Current License: CC BY-SA 4.0
12 events
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| S Jul 25, 2018 at 20:29 | history | suggested | ZeroOne | CC BY-SA 4.0 |
opened "TWR"
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| Jul 25, 2018 at 19:45 | review | Suggested edits | |||
| S Jul 25, 2018 at 20:29 | |||||
| Jul 25, 2018 at 11:36 | comment | added | Therac | @JollyJoker Another comparison point could be helicopters. The de Bothezat had to deliver at least 120 N/kW, more than the Dyson's fan. Everything newer is closer to 80 N/kW - but at much higher thrust speeds, even toys start at 6 m/s. So, at static thrust, Dyson's fan is not better than helicopters; it only turns out efficient when compared to cheap desk fans. | |
| Jul 25, 2018 at 10:58 | history | edited | Therac | CC BY-SA 4.0 |
added 427 characters in body
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| Jul 25, 2018 at 10:44 | comment | added | Therac | @JollyJoker You can, multiply volume by velocity by density. Dyson's setting 10 comes out to 1.83 N of thrust for 19 W, or ~96 N/kW. But this thrust is only usable when below 2.78 m/s (flow velocity). N/kW generally scales inversely with velocity, and scaling it to 278 m/s would give 0.1 N/kW. A TSFC=0.6 at 278 m/s, 46% thermal efficiency jet engine is equivalent to 3.1 N/kW. | |
| Jul 25, 2018 at 8:35 | comment | added | JollyJoker | This review shows the Dyson fan peaking at 120 CFM per watt. It would be interesting to see the same figures for a jet engine. Can you convert pounds of thrust to CFM or how does that work? | |
| Jul 25, 2018 at 1:31 | comment | added | John K | I found some data on a Dyson fan vs regular fans for CFM per watt, and the Dyson is considerably more efficient than a regular fan, but this is at gentle breeze fan speeds. The efficiency advantage drops off as you increase the velocity. This suggests that an "annular ejector thruster" device that could move enough air to be of use to propel an airplane would be a lot less efficient than driving the air directly. I would guess that the static thrust of such a device would be not so bad but would drop off a lot as speed increases, pretty much the opposite of a regular jet. | |
| Jul 24, 2018 at 19:26 | comment | added | Geoff | So, in general - a "dyson engine" would weigh much more and be a much more inefficient means of thrust. Both are good reasons NOT to make one. If only "looking totally awesome" were a more meaningful design parameter :D Thanks for the insight @Therac | |
| Jul 24, 2018 at 19:20 | vote | accept | Geoff | ||
| Jul 24, 2018 at 19:11 | comment | added | Mark | I recall reading about someone using this technique to make a flying saucer. Maneuverability was impressive, but as you note, efficiency was abysmal. | |
| Jul 24, 2018 at 17:31 | comment | added | Mat | +1 for a very well done and comprehensive answer! | |
| Jul 24, 2018 at 16:12 | history | answered | Therac | CC BY-SA 4.0 |