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Old Apr 12, 2010, 04:38 PM
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Dennis Everett's Avatar
United States, CA, Ontario
Joined Mar 2002
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Question
Are there any efficient ducted fan motors ?

Hi all , like the heading says , are there any ? Im looking for motors in the 64 mm fan size range, 500 ish watt range , Neu , scoripion , Daves , little screamers ? Has the good Dr tested any with fans ?....thanks..Dennis
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Old Apr 12, 2010, 05:40 PM
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Dr Kiwi's Avatar
Chattanooga, Tennessee, United States
Joined May 2003
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I think combining "efficiency" and "EDF" in the same sentence is an oxymoron...... however I am sure there are motors out there which "work well". I have no experience with large EDFs but I believe certain ARC motors have been used successfully at the 500W+ power levels. I imagine Neu will be good, and the brand new Scorpion inrunners have GOT to be worth a look.
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Old Apr 12, 2010, 08:40 PM
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manuel v's Avatar
Mexico, BC, Mexicali
Joined Aug 2004
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I have this test.
2810.
Kv. 4300.
8T., 37pulgadas de longitud.
KV. medido 4361.
59g.

Kv posibles.
7t = 4984.
9t = 3876.
10t = 3488.
11t = 3171.
12t = 2907.
13t = 2683.

Rebobinado a 8T.
21AWG, 34” alambre
45,600 rpm, 10.66V, 1.56A, Kv=4277

Con EDF 64mm. (Starmax)
36,250 rpm, 10.30V, 29.90A., 308 Watts. Kv Ratio. 82.2%
40,700 rpm, 11.43V, 38.23A., 437 Watts. Kv Ratio. 83%
estas dos pruebas se hicieron con 2 baterias diferentes, totalmente cargadas.

Thread in spanish.
http://www.rcgroups.com/forums/showthread.php?t=1185976

Manuel V.
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Last edited by manuel v; Apr 13, 2010 at 01:02 AM.
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Old Apr 12, 2010, 09:56 PM
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vintage1's Avatar
East Anglia, UK
Joined Sep 2002
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we currently tip the Turnigy 2836 3700 KV into 64mm fans I think. About 400W on 3s, and 800W on 4s..but beware, that's not for ever. Use the throttle stick! But it will take a lightweight EDF model straight up.
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Old Apr 12, 2010, 10:20 PM
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Canada
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Quote:
Originally Posted by Dennis Everett View Post
Hi all , like the heading says , are there any ? Im looking for motors in the 64 mm fan size range, 500 ish watt range , Neu , scoripion , Daves , little screamers ? Has the good Dr tested any with fans ?....thanks..Dennis
Unfortunately 64mm is an inadequate descriptor.
There MANY fans of differing design and ..Amp Hunger.. out there.
Some are 5 blade,or 6 blade others are 7 blade.Some will only take a 24mm diameter motor others up to a a 28mm one then there are the "stand off' mount motor versions.
Big watts require a fan capable of absorbing the power and not grenading that narrows the field somewhat.
As mentioned though, the SAME motor spinning a prop will easily outperform one inserted into ANY fan unit.
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Old Apr 13, 2010, 07:45 AM
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Bruce Abbott's Avatar
Hastings, New Zealand
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Most 64mm fans have a motor tube diameter of 24mm or less. Unfortunately this eliminates the majority of better inrunners (eg. ARC, Neu) and helicopter outrunners (eg. Scorpion). Many smaller motors are available, but few can handle 500W.

I tested a Turnigy EDF 2615-3400 in a GWS EDF64 on 4S. It drew 497 Watts (14.5V, 34.3A) producing 43033rpm ('Kv ratio' 80%) and 817g static thrust when installed in a GWS ME-262 nacelle. This is pushing the motor pretty hard, with an estimated 123W loss at 75% efficiency. Note that the actual Kv of this motor is 3700rpm/V.

Quote:
Originally Posted by Bare
the SAME motor spinning a prop will easily outperform one inserted into ANY fan unit.
Only if the prop has larger diameter. To match thrust and efflux velocity of the above setup with a 2.5x1 prop, you would need a motor that draws 600W at 137000rpm!
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Old Apr 13, 2010, 08:48 AM
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Wallingford, Ct
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Does Astro have anything in that size range?
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Old Apr 13, 2010, 09:08 AM
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Donsrc.com

you'll thank me
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Old Apr 13, 2010, 11:01 AM
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United States, CA, Ontario
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Thanks all , you right about the prop , i had a phase 3 f 16 , used a hoffman mighty mite edf motor as a pusher prop , 4.1x4.1 apc , on 3 cells last weekend radared it at 120 , then i lost sight of it and "landed" at 120 , totaled of course , all electronics ok , i have a f86 , still stock , was thinking of doing a upgrade on the motor , i have the hoffmans , but was wondering if anything is more efficient , i hate the short flight times of the edf's , im guessing as the good Dr said , no such thing as a efficient edf ...
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Old Apr 13, 2010, 05:13 PM
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Dr Kiwi's Avatar
Chattanooga, Tennessee, United States
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Originally Posted by gundamnitpete View Post
Donsrc.com

you'll thank me
I know Don's smaller units are impressive, but does he have anything capable of handling 500+W?
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Old Apr 14, 2010, 07:04 AM
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Originally Posted by Dr Kiwi View Post
I know Don's smaller units are impressive, but does he have anything capable of handling 500+W?
The dons wicked plus will handle 750ish watts, but that's about the limit.

I've got lots of dons motors, they pretty much dominate the 50mm-64mm range.

Of course, I did just get a wm300 60mm, which can take 28mm motors I haven't run mine up yet, but using a arc/neu/mega, I could see +1kw with this fan.
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Old Apr 20, 2010, 05:00 AM
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In terms of efficiency, what is the efficiency of a ducted fan compared to a prop of the same diameter? 50%? 60 %?
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Old Apr 20, 2010, 06:26 AM
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Hastings, New Zealand
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Originally Posted by knlever View Post
In terms of efficiency, what is the efficiency of a ducted fan compared to a prop of the same diameter? 50%? 60 %?
Actually, a ducted fan can be more efficient than a prop of the same diameter! For example, I tested a B2040-3350Kv inrunner on 3S, with both a 4" prop and a 2.5" fan:-

GWS EP4025 (4"x2.5"); 118W, 367g, 70mph, 3.11g/W, 0.59mph/W

GWS EDF64 (2.5"x4"x6); 128W, 387g, 91mph, 3.02g/W, 0.71mph/W

Despite its much larger diameter, the prop produced only slightly higher 'thrust efficiency', while its 'speed efficiency' was significantly worse. Had I compared the EDF to a 2.5" prop, the difference would have been even more dramatic (estimating a mere 257g and 76mph for an EP2510 at 128W) but I can't do that test because I don't have a motor that can do 81000rpm!

An EDF should be more efficient because blade tip losses are reduced, and the stator vanes straighten out the airflow. However these gains may be offset by the duct's extra weight and parasitic drag.
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