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Groups > sci.electronics.design > #489427
| From | Sylvia Else <sylvia@not.at.this.address> |
|---|---|
| Newsgroups | sci.electronics.design |
| Subject | Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. |
| Date | 2017-12-28 12:38 +1100 |
| Message-ID | <faj09fFsqq6U2@mid.individual.net> (permalink) |
| References | (3 earlier) <61H0C.24094$uY5.14366@fx21.iad> <XnsA8581666945CAidtokenpost@69.16.179.22> <p20io8$bsp$1@dont-email.me> <5fdda9b3-30ff-42e4-ab86-cd9f9bea8501@googlegroups.com> <p20p2r$48g$1@dont-email.me> |
On 28/12/2017 5:34 AM, amdx wrote: > On 12/27/2017 11:01 AM, tabbypurr@gmail.com wrote: >> On Wednesday, 27 December 2017 16:46:09 UTC, amdx wrote: >>> On 12/27/2017 1:12 AM, Steve Wilson wrote: >>>> FMurtz <haggisz@hotmail.com> wrote: >>>>> Steve Wilson wrote: >>>>>> John Larkin <jjlarkin@highlandtechnology.com> wrote: >>>>>>> On Tue, 26 Dec 2017 17:54:51 +1100, Sylvia Else >>>>>>> <sylvia@not.at.this.address> wrote: >>>>>>>> For reasons I need not go into, I wanted to make a cheap >>>>>>>> pedestal fan >>>>>>>> blow backwards, by putting the fan on backwards, and running the >>>>>>>> motor in reverse. >>>>>>> Wouldn't those two things cancel? >>>>>> Many turbine propeller aircraft can reduce their landing roll by >>>>>> placing the propellers in reverse pitch. The blades are still turning >>>>>> in the same direction, but the thrust vector is reversed. They are >>>>>> not >>>>>> very efficient in this mode, but are still able to slow the aircraft. >>>>>> To visualize what would happen in a pedestal fan, imagine turning it >>>>>> around 180 degrees. The motor is still spinning the propeller in the >>>>>> same direction, but the thrust vector is reversed in relation to the >>>>>> floor. >>>>>> In order to reverse the thrust vector, either the propeller pitch has >>>>>> to be reversed, or the motor has to be reversed. >>>>>> John is right. Doing both would cancel. >>>>> Wrong,reversing motor would reverse air flow, reversing the propeller >>>>> would be same air direction but would put the leading edge in the >>>>> right >>>>> position for efficiency. >>>> >>>> Wrong. Think about it. Reversing the propeller pitch reverses the >>>> thrust >>>> vector. This is how turbine aircraft shorten their landing roll. >>>> >>>> >>> OK I took the cover off a 3 blade fan that turns clockwise. I removed >>> the blade put it on backwards. The fan still blows air in the same >>> direction. It doesn't blow very much air though. >>> Certainly is some design consideration in the way the blade is >>> curved. >>> Mikek >> >> so if you then also change the motor direction, you get reverse flow >> with good efficiency. It's ain't rocket science, it's fan science. >> >> >> NT >> > Obviously we have a bunch of Rocket Scientists here because the fan > science was under dispute. I didn't know so I got the fan out and > checked it. Sylia knew, it's not intuitive or it would not have been > disputed. > > After a failure of a ceiling fan, I replaced it with a new one. > It has just a tad less air where our bed is, I'd like to increase the > angle just a few degrees or put a horizontal tip on the the end of each > blade to push air away from the center. Ceiling fan blades tend not to be anything like the right shape. The ones I have are just flat with a bent edge. Properly aerodynamic ones are available but are expensive, and, in truth, look a bit odd. Sylvia.
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OT: Running a pedestal fan in reverse - failed - a rant of sorts. Sylvia Else <sylvia@not.at.this.address> - 2017-12-26 17:54 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Rheilly Phoull <froggins@iinet.net.au> - 2017-12-26 19:29 +0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. mpm <mpmillard@aol.com> - 2017-12-26 04:49 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Sylvia Else <sylvia@not.at.this.address> - 2017-12-27 09:52 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. tabbypurr@gmail.com - 2017-12-26 06:07 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Sylvia Else <sylvia@not.at.this.address> - 2017-12-27 09:58 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. mpm <mpmillard@aol.com> - 2017-12-26 18:52 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Sylvia Else <sylvia@not.at.this.address> - 2017-12-27 14:57 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-26 10:21 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-12-26 11:48 -0700
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. rickman <gnuarm@gmail.com> - 2017-12-26 14:03 -0500
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. John S <Sophi.2@invalid.org> - 2017-12-26 14:31 -0600
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-12-26 15:44 -0500
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. John S <Sophi.2@invalid.org> - 2017-12-26 15:06 -0600
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. John S <Sophi.2@invalid.org> - 2017-12-26 16:16 -0600
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-26 17:26 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Sylvia Else <sylvia@not.at.this.address> - 2017-12-27 14:42 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. not@telling.you.invalid (Computer Nerd Kev) - 2017-12-26 21:00 +0000
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. rickman <gnuarm@gmail.com> - 2017-12-26 18:37 -0500
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. "David Eather" <eather@tpg.com.au> - 2017-12-27 09:48 +1000
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. FMurtz <haggisz@hotmail.com> - 2017-12-27 15:57 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Sylvia Else <sylvia@not.at.this.address> - 2017-12-27 09:50 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. whit3rd <whit3rd@gmail.com> - 2017-12-26 18:55 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Steve Wilson <no@spam.com> - 2017-12-27 05:40 +0000
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. FMurtz <haggisz@hotmail.com> - 2017-12-27 17:24 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Steve Wilson <no@spam.com> - 2017-12-27 07:12 +0000
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. FMurtz <haggisz@hotmail.com> - 2017-12-27 18:40 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Steve Wilson <no@spam.com> - 2017-12-27 12:34 +0000
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. FMurtz <haggisz@hotmail.com> - 2017-12-28 00:36 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. rickman <gnuarm@gmail.com> - 2017-12-27 17:59 -0500
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. krw@notreal.com - 2017-12-27 09:39 -0500
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. amdx <nojunk@knology.net> - 2017-12-27 10:45 -0600
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. tabbypurr@gmail.com - 2017-12-27 09:01 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. amdx <nojunk@knology.net> - 2017-12-27 12:34 -0600
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. rickman <gnuarm@gmail.com> - 2017-12-27 18:03 -0500
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. tabbypurr@gmail.com - 2017-12-27 15:18 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. amdx <nojunk@knology.net> - 2017-12-28 09:18 -0600
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Sylvia Else <sylvia@not.at.this.address> - 2017-12-28 12:38 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. M Philbrook <jamie_ka1lpa@charter.net> - 2017-12-30 09:41 -0500
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. makolber@yahoo.com - 2018-01-03 13:48 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. DemonicTubes <tlackie@gmail.com> - 2018-01-03 14:08 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-01-04 15:18 +0200
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Sylvia Else <sylvia@not.at.this.address> - 2017-12-28 12:36 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Jasen Betts <jasen@xnet.co.nz> - 2017-12-28 06:36 +0000
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Phil Allison <pallison49@gmail.com> - 2017-12-28 00:16 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Phil Allison <pallison49@gmail.com> - 2017-12-26 22:38 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. krw@notreal.com - 2017-12-27 09:40 -0500
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Sylvia Else <sylvia@not.at.this.address> - 2017-12-27 15:02 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Sylvia Else <sylvia@not.at.this.address> - 2017-12-27 18:11 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. FMurtz <haggisz@hotmail.com> - 2017-12-27 18:42 +1100
Re: Running a pedestal fan in reverse - failed - a rant of sorts. "P E Schoen" <paul@pstech-inc.com> - 2017-12-27 03:17 -0500
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. tabbypurr@gmail.com - 2017-12-27 01:59 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Sylvia Else <sylvia@not.at.this.address> - 2017-12-27 21:29 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-12-27 14:24 +0200
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. krw@notreal.com - 2017-12-27 09:43 -0500
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-27 11:25 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. tabbypurr@gmail.com - 2017-12-27 11:32 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Jasen Betts <jasen@xnet.co.nz> - 2017-12-28 06:20 +0000
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. amdx <nojunk@knology.net> - 2017-12-27 10:50 -0600
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. FMurtz <haggisz@hotmail.com> - 2017-12-28 14:49 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. FMurtz <haggisz@hotmail.com> - 2017-12-29 11:34 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. bloggs.fredbloggs.fred@gmail.com - 2017-12-27 10:22 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. Sylvia Else <sylvia@not.at.this.address> - 2017-12-28 09:41 +1100
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. bloggs.fredbloggs.fred@gmail.com - 2017-12-27 15:29 -0800
Re: OT: Running a pedestal fan in reverse - failed - a rant of sorts. rickman <gnuarm@gmail.com> - 2017-12-27 18:40 -0500
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