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Jul 29, 2008, 05:44 PM
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EDF CFM ratings?


Ok, I have been out of R/C since I was about 10, but never lost interest in aircraft.

So I have decided to take on a new project. That is making a "jet" style PC case, I have yet to decided if I will go for a full on jet aircraft look (will be hard because of video cards and heatsinks) or just go with a custom made "aerodynamic" case and use pod's on the outside housing the EDF's.

So my question: Are their any charts (or anyone know off hand) what the CFM rating is for some EDF's, or rule of thumb for guesstamation? I am looking for something on the cheap side as these do not need to propel anything with thrust, but I would like them to work for cooling, though at a MUCH reduced speed for noise reasons, that brings to mind, anyone know what the dB is as well? Looking for something no less than 60mm in size, would be great to use 90mm+ for more visual impact.

I have tried modding some case fans to get the look and nothing really hits the spot, so I thought why not get the real thing?

Anyone have any info? Hell, I will even take guesses!

Thanks...
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Jul 29, 2008, 06:10 PM
Classic jets rule
AIR SALLY's Avatar
hell a 90 mm fan just turning a few hundred rpm would cool 3 PC's .can you show us a pic of what you are doing?.
Jul 29, 2008, 06:57 PM
Thread OP
Sorry, no pic's. I am getting everything sorted plan wise as this is going to be a job, and I want to get all the functional parts together and tested before I get to work on the case it self. Being swamped at work does not help.

From the ideas I had (shape wise) it will probably be made from fiberglass/acrylic/aluminum.

The EDF's will not supply the main cooling, as I am guessing they would be to loud for that, however I want them to be functional, unless I am really underestimating their CFM at a bearable dBA. Depending on what I do with the case and it's final shape the PC might be watercooled, as cooling for this PC will be extreme (heavily overclocked).
Jul 29, 2008, 07:01 PM
Just spin the EDF with a PC type cooling fan motor from the next larger dia fan. You'll get MORE airflow with the EDF than you were getting with the fan.

The PC cooling fans turn at low rpm mainly to keep the noise down.

Thats the simplest solution.
Jul 29, 2008, 07:28 PM
Thread OP
Quote:
Originally Posted by fhhuber506771
Just spin the EDF with a PC type cooling fan motor from the next larger dia fan. You'll get MORE airflow with the EDF than you were getting with the fan.

The PC cooling fans turn at low rpm mainly to keep the noise down.

Thats the simplest solution.
I had thought about something along those lines but I am not sure how mounting would go as PC case fans are one piece, the motor does not come out, I would have to hack something together depending on how the EDF works (never so much as held one in my hand). Why do you think running a standard EDF motor to be a bad idea?

I agree I should get more flow with the EDF as it is going to have better blade designs, however it will be run at low rpm with a fan controller. To give you an idea I am running 5 120mm fans each pushing 78 CFM (2000 RPM) at 21 dBA.
Jul 29, 2008, 07:34 PM
Carbon fiber is our friend
Steve C's Avatar
It looks like you're here under two different names. Why?

Steve C
Jul 29, 2008, 07:38 PM
Thread OP
Quote:
Originally Posted by Steve C
It looks like you're here under two different names. Why?

Steve C
Sorry...Not sure what your talking about...This is my first time on these boards and this is my only account.
Jul 29, 2008, 07:58 PM
The standard EDF motor... well you could get a low KV brushed motor and dircet power it from the 5 volt buss of the computer. Spin the EDF rotor that way and you'll keep the noise down.

Computer fan motors are "single phase" brushless with a built-in controller. They went that route (more expensive than just a brushed motor) to prevent creating the carbon dust from the brushes.

In order to use a "3 phase" brushless motor as we typically use in R models you'd need a different controller that is locked at one setting. (or some complex controller card that senses when the fan needs to provide more cooling)

I have dismembered a couple of computer fans hoping to swipe the fans for low speed EDF models... (It worked... sort of... definitely low speed)
You CAN open up the computer fan and get the motor out to mount it in an EDF.
Jul 29, 2008, 10:00 PM
Thread OP
Quote:
Originally Posted by fhhuber506771
The standard EDF motor... well you could get a low KV brushed motor and dircet power it from the 5 volt buss of the computer. Spin the EDF rotor that way and you'll keep the noise down.

Computer fan motors are "single phase" brushless with a built-in controller. They went that route (more expensive than just a brushed motor) to prevent creating the carbon dust from the brushes.

In order to use a "3 phase" brushless motor as we typically use in R models you'd need a different controller that is locked at one setting. (or some complex controller card that senses when the fan needs to provide more cooling)

I have dismembered a couple of computer fans hoping to swipe the fans for low speed EDF models... (It worked... sort of... definitely low speed)
You CAN open up the computer fan and get the motor out to mount it in an EDF.
I did not plan on using a brushed motor in this set up (EMI). Also, the fans I have taken apart could not be removed from the fan blade or backing, as the magnets are attached to the fan it self and the stator to the backing/PCB, though it could be hacked apart. Also, all the PC fans I have seen are 2 phase, most 4 pole. I also have no problem with running an r/c brushless motor.

What EDF would lend it self best to adapting a PC fan motor to?
Jul 29, 2008, 10:25 PM
GWS EDF fans would adapt well... There's a fair assortment of sizes. and they are relatively inexpensive.
Jul 29, 2008, 11:43 PM
Carbon fiber is our friend
Steve C's Avatar
Quote:
Originally Posted by BlueFireIce
Sorry...Not sure what your talking about...This is my first time on these boards and this is my only account.
Another account was started at the same time as you- Also asking about ducted fans for the purpose of some mystery other than airplanes. And you didn't sign your name like I do


Steve C
Jul 29, 2008, 11:59 PM
Thread OP
Thanks...Heh, just looked them up, they are cheap, cheaper than most case fans!

Also, the brushless controllers, there an easy way for setting up some kind of manual control on them?
Jul 30, 2008, 12:02 AM
Thread OP
Quote:
Originally Posted by Steve C
Another account was started at the same time as you- Also asking about ducted fans for the purpose of some mystery other than airplanes. And you didn't sign your name like I do


Steve C
Don't know anything about it, and I'm not the very mysterious type...
Jul 30, 2008, 12:20 AM
It wasn't me...
DanSavage's Avatar
Quote:
Originally Posted by BlueFireIce
So I have decided to take on a new project. That is making a "jet" style PC case, I have yet to decided if I will go for a full on jet aircraft look (will be hard because of video cards and heatsinks) or just go with a custom made "aerodynamic" case and use pod's on the outside housing the EDF's.

So my question: Are their any charts (or anyone know off hand) what the CFM rating is for some EDF's, or rule of thumb for guesstamation? I am looking for something on the cheap side as these do not need to propel anything with thrust, but I would like them to work for cooling, though at a MUCH reduced speed for noise reasons, that brings to mind, anyone know what the dB is as well? Looking for something no less than 60mm in size, would be great to use 90mm+ for more visual impact.

I have tried modding some case fans to get the look and nothing really hits the spot, so I thought why not get the real thing?

Anyone have any info? Hell, I will even take guesses!

Thanks...
HP's already blazed this trail.

See: Cooling Computers with Tiny Jet Engines

This paragraph is pretty funny.

Most propeller-driven model airplanes carry small gasoline engines (which produce that familiar high-pitched whine). But gas engines aren't ideal for model jets. These $4,000 toys can buzz about at more than 200 kilometers per hour, requiring lightning reflexes; if a pilot loses control, the plane's fuel tank can turn into a flying bomb. So in the mid-1980s, hobbyists started developing high-speed, battery-powered electric motors that could be placed in the fuselage or under the wings of a model plane.

FWIW, EDF modelers typically don't care about CFM ratings. We care about efflux, static thrust, volts, amps and watts.
Last edited by DanSavage; Jul 30, 2008 at 12:32 AM.
Jul 30, 2008, 12:35 AM
Thread OP
Quote:
Originally Posted by DanSavage
HP's already blazed this trail.
Maybe so, but I am betting mine will be allot cheaper and cooler looking.

Quote:
FWIW, EDF modelers typically don't care about CFM ratings. We care about efflux, static thrust, amps, watts and volts.
That I know, I was just hopping someone knew or could give a good guess.

In any case, they don't have to be used for cooling at all, just so long as they work, or give the appearance of a turbine.


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