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        Discussion Smallest EDF Units Available?

#1 BigG80 Jan 30, 2008 06:58 AM

Smallest EDF Units Available?
Hi all,

I have for a long time been toying with the idea of experimenting with a scratch built EDF project and as such have been looking at various actuators and micro servos online as I think I should acquire the electronics and guts of the plane before I start to build.

I'd be grateful for your expertise if you could tell me what is the smallest EDF unit that is available on the market. Something really, really small would be ideal as I may need 6 of them in the model, yes its rather weird!

If something tiny is not available, how easy would it be to construct your own fan unit. Has anyone tried and do they have any advice they can pass on?

Also any tips on where to shop would be brilliant. I noticed Ballards who supply Round The Pole equipment sell ducted fan props but I doubt they would be effective despite the great low price.

Thanks in advance for any advice you can give.



#2 ATIS Jan 30, 2008 07:25 AM

I think GWS still makes 40mm EDF's


#3 Smokescreen38 Jan 30, 2008 08:04 AM

You could always use the ducted props off of the Airhogs Jetscream... they produce 12+g of thrust each at 3.7v...not sure how much you can push that with more voltage but they're tiny and light. 30mm?


#4 BigG80 Jan 30, 2008 08:44 AM

30 mm is good I suppose. I've just been reading about Chris T's Hawk with 15mm fan plus I saw the thread on home made impellors. Just took a bit more reading and digging about!

15mm I think would be great as I would like to fit things in scale where possible. Still very much an in my head design but today has proved extremely useful in showing that this could work.

Thanks guys.

#5 Mike Taylor Jan 30, 2008 09:16 AM

I have been testing a beta of a new 10 mm inrunner motor / 30 mm fan combo for the last couple of months. It is made by Mike Cross ('mcross' here). It weighs about 11 grams and develops mid-50 grams of thrust on under 3 amps with a 2-cell, 220 mah 12 gram pack. He has just finished a production batch, and I have ordered another one to go with the prototype unit I have. The first model I built for it weighed less than the thrust from the raw unit and would speck out vertically. Mike makes the motors and balances the fan to the motor. They are very quite and powerful. I have about 3 hours of hard run time on mine and it performs as new.

#6 BigG80 Jan 30, 2008 09:56 AM

Thanks Mike. That's brilliant to know because one of the things I am thinking about is VTOL and having dedicated EDFs for lifting, kind of like the installation on a Yak 144 with the 2 vertically mounted engines in the fuselage.

What is the minimum pipe length and intake and exhaust aperture size for the 30mm fans? That would be a useful for plotting the overall scale of the model.

#7 ATIS Jan 30, 2008 02:21 PM

caliber also carries a GWS 30mm EDF...

#8 Mike Taylor Jan 30, 2008 03:03 PM

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Originally Posted by BigG80
What is the minimum pipe length and intake and exhaust aperture size for the 30mm fans? That would be a useful for plotting the overall scale of the model.

I don't know. I measured a steady 54 grams with just the raw fan unit - no duct, no bell. SOme one has used a foam cup and seemed quite happy with the results. I then put it in a 11" long inlet/fan/outlet with >110% FSA inlet and 90% FSA outlet and got about the same measured thrust as the raw unit. I have made a stand to measure thrust easier so I can develop a decent inlet/ outlet system. Here's a picture of my first attempt... Adding a scale cross sectioned fuselage choked the flow down and a semi-scale suddenly seemed quite acceptable.

#9 BigG80 Jan 31, 2008 02:45 AM

Well if I could get 54 grams from one unit and I would probably be using 4 for downthrust that should keep it off the ground!

Thanks again Mike.

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