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Old Jan 13, 2013, 06:09 PM
Lee Liddle
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Carrollton, Tx
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Quote:
Originally Posted by nighthawk0077 View Post
Wow very interesting as usual Lee, would love to see what you can do with an all metal 80 or 90mm fan. It might actually sound better than a real turbine..
If someone wants to sponser me with one, or even just loan it for testing, I`ll pump 4.5kw or more thru it and see what it will do. Performance and sound. I have a nice airframe for testing a strong 70/80mm that can easily hold 14s 5000.
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Old Jan 13, 2013, 06:10 PM
Lee Liddle
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Carrollton, Tx
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I have a couple of CS 90mm rotors. I plan to cut one down to 70mm and see what it will do.
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Old Jan 13, 2013, 07:50 PM
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United States, CA, San Diego
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Originally Posted by Knife Liddle View Post
An inrunner could work if the shaft was long enough. It takes a long shaft or a custom adapter to mount the motor behind the fan,
This is really asking for trouble--long shafts lead to vibration and spectacular failures if not done very carefully. Better to have the motor close coupled to the fan and avoid the issues all together.

Steve Neu
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Old Jan 13, 2013, 08:06 PM
Lee Liddle
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Carrollton, Tx
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The way it`s done Steve is to add a third bearing at the spot where the motor would normally mount in the fan. Then the long shaft extends thru the front bearing. It works great and there are no vibration or safety issues.
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Old Jan 13, 2013, 08:10 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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Video of the motor on 8s at 51k RPM

I just did a quick video of the motor running at 50k on 8s. The tach reads 25k because I just have one mark on the bell, so it reads at 1/2 of the rpm.

12t-4p 36mm outrunner @50k rpm (0 min 29 sec)
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Old Jan 13, 2013, 08:47 PM
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DeKalb,IL
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Wow that is impressive! That is wild now long the outrunner take to spool down from 50K. I guess once you load the motor things can change and the head scratching starts.

Awesome keep the motors turning!
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Old Jan 13, 2013, 09:01 PM
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United States, CA, Santa Clarita
Joined Aug 2009
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Originally Posted by nighthawk0077 View Post
Wow very interesting as usual Lee, would love to see what you can do with an all metal 80 or 90mm fan. It might actually sound better than a real turbine..
This would most likey be the EDF for the job. I must say that with it's heat sinking and forced fed motor cooling, it's better suited to inrunners, with thier short shafts, high quality bearings available, and higher rpm capabilies.

Lee has a great project here, and would probably do well with a larger, cut down (higher pitched) rotor spinning at lower rpms.
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Old Jan 13, 2013, 09:06 PM
Ginger or MaryAnn ??
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The Don runs his outrunners with a long standoff and it also has a 3rd bearing right by the hub, I have ran those very hard and never had a problem, and they have quite a long shaft overall.
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Old Jan 13, 2013, 09:12 PM
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Hey Joe,
Someone once inquired about putting the JS 1400 into the Mach 70. It can be done, but at nearly 4000KV it's to high for this EDF for high power setups.
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Old Jan 13, 2013, 09:20 PM
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United States, CA, San Diego
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Originally Posted by Knife Liddle View Post
The way it`s done Steve is to add a third bearing at the spot where the motor would normally mount in the fan. Then the long shaft extends thru the front bearing. It works great and there are no vibration or safety issues.

Just because "thats the way it is done" does not make it good engineering practice.

While we are discussing engineering--you don't have nearly thick enough iron behind the magnets--you can get away with less iron when you have high pole counts and small gaps between the poles but when the pole count goes down the steel needs to get thicker to close the magnetic path. I am guessing that your outer ring will have a lot of flux leakage. I would guess that you need at least double the steel and maybe more. Yes it will run---but you are not making the best use of the magnet strength.

Steve
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Old Jan 13, 2013, 09:30 PM
Ginger or MaryAnn ??
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Well, I all ready ran 4kw through that fan Gary, I have a new Mega with 5mm shaft that should do even more, just got to figure what fan to use, gonna have to cutdown a rotor so I can use a 90mm adapter thats 5mm but can also put up with well over 60k rpms
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Old Jan 13, 2013, 09:41 PM
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Me too. I have them here (fans and motors) with 4 and 5mm shaft's and versions with 100K bearings in transist.
Too many motors ....too little time.
I just finished my 6s, Habu2
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Old Jan 13, 2013, 10:01 PM
Ginger or MaryAnn ??
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You have mach 70mm with 5mm adapters?? My mega 16/45D needs a home....
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Old Jan 13, 2013, 10:16 PM
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United States, CA, Santa Clarita
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Originally Posted by fh64_lucky View Post
You have mach 70mm with 5mm adapters?? My mega 16/50 needs a home....
Dont' mean to hog up Lee's thread but.... yes (in stock).
My motors are the 16-45-1.
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Old Jan 13, 2013, 10:27 PM
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United States, PA, Doylestown
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5mm adapters.

This is good to know. Happy to hear that there is indeed a way to do it.
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