CD-ROM performance database for EDFs - RC Groups
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Nov 28, 2004, 02:57 PM
From the bowels of MI

CD-ROM performance database for EDFs

I wasn't able to find a CD-ROM performance database for EDFs so I'd like to start a thread for the topic. I figure we can post our results here and perhaps they'll get incorporated into the gobrushless database in the future. I'll just finished an EDF40 powered CDROM that I'm happy with and will post the results a little later. Please include the following in your post if possible:

1) EDF type/size (brand/size)
2) Rotor info (3 blade, 5 blade, cut down, etc.)
3) # winds (8 turns double wound)
4) Termination (delta or wye)
5) Stator size (diameter / single, double, etc)
6) Magnets used and type (dimentions and strength)
7) Magnet polarities (NNSSNNSS or NSNSNS, etc.)
8) Can size (diameter)
9) Wire gage
10) Power source used (Power supply @ xVolts, 3s TP2100, etc.)
11) Thrust measured at X current draw and volts + watts (computed)
12) A photo of test (optional)
13) Photo of EDF tested (optional)
14) If the test was performed with the EDF in a model then a model description and intake/exhaust details
15) All inclusive weight of the EDF
16) Any additional info that you consider relevant.

Am I missing anything?

Last edited by Wayno-san; Dec 13, 2004 at 08:09 PM. Reason: Added parameters
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Nov 28, 2004, 07:47 PM
From the bowels of MI


So it looks like I'm starting.

1) GWS EDF40
2) Cut down 5 blade rotor from EDF50 fan
3) 8 turns
4) Wye
5) Single Go-brushless 20mm 9pole
6) N45 5x5x1
8) Gobrushless standard 20mm can
9) Radio shack 22 ga
10) 3s TP2100
11) 2 sample points: 175g @ 11A, 128g @ 6.9A
EDF weight: 28.9g

The rotor was drilled out to just short of 3mm for the shaft. Using a wheel collar on the back of the can to prevent it from sliding off (I will JB weld it on later). Obviously I zeroed the scale with the stand/edf on it prior to starting it up.

I'm happy!

Let's see some more!!!!
Last edited by Wayno-san; Dec 13, 2004 at 08:10 PM. Reason: Added weight of EDF
Nov 29, 2004, 07:59 AM
Registered User
jalves's Avatar

Attention, Update of data


1) GWS EDF40
2) 6 blade rotor for EDF40 fan
3) 8 turns
4) Wye
5) Single 20mm 9 tooth
6) N45 5x5x1
7) 6 poles NNSSNNSS
8) standard 20mm can
9) 0.6mm (22g?) wire
Battery |Thrust (g) |Tension(V)|Tension WOT(V)|Current WOT(A)|Pin(W)
3S2P 1200 |136 |12,3 |10,48 |7,97 |83,5256
3S 320 |107 |12,4 |9,33 |6,31 |58,8723
3S 720 |121 |12,3 |9,93 |6,96 |69,1128
3S 720 |130 |11,6 |10,3 |7,64 |78,7684

here we can see that the batteries has a major importance in the results the EDF40 can obtain.

Last edited by jalves; Dec 02, 2004 at 09:49 AM. Reason: UPDATE
Nov 29, 2004, 01:50 PM
Registered User
I always wonder about these thrust-measuring methods. It seems to me, for it to be accurate, you need to add in the force of the air pushing down on the scale.
Dec 02, 2004, 09:50 AM
Registered User
jalves's Avatar

The fan is pushing downwards, the flux of air is going upwards

Dec 02, 2004, 10:10 AM
From the bowels of MI
Looking at your data. Did you use different 720 packs or is it the same back at a different state of charge?

I have a 10 turn that I should be able to test and post data for by this weekend. Probably in a EDF40 also. I've obtained another meter so this time I'll be able to read the voltage reading also. I'm hoping to get a little more efficiency and to bring the current down a little. Looks like we're getting very close results with the EDF40 impeller vs. the cut down 5 blade EDF50 impeller. It's nice that we're not losing anything by using it since the EDF40 impellers are much more difficult to find (at least here in the states), so and EDF50 impeller can easily be used as a substitutue. (Not taking eflux into consideration since I have not idea what that is in either case)

Last edited by Wayno-san; Dec 02, 2004 at 10:13 AM.
Dec 02, 2004, 10:19 AM
Registered User
jalves's Avatar
yes, it's the same pack with different state of charge.
The first row of data is with a used kokam 720 3s pack, then I charged the pack and repeat the test.

Right now I only have one rotor, the other one shatered, loose one blade totally and part another blade. But this rotor was already punished by a servo wire.

What do you think about the 175g thrust you get in first run, the value is puzzling me.

Dec 02, 2004, 10:45 AM
From the bowels of MI
OK, thanks for the info.

The 175g was at 11A which isn't practical since I don't have a LiPo pack that's light enough to fit into a nano-plane and still be able to source that much current. I wish I had RPM measurements (tachometer on order) so we could compare thrust vs. RPM to see if the EDF50 impeller has a higher threashold.... this might make sense since the blades on it are thicker/more rigid than the blades on the EDF40 impleller.

Do you have a hypothesis?

Dec 02, 2004, 10:51 AM
Registered User
jalves's Avatar
I have some RPM figures related with thrust, but I 've to retest because I did a modification in my setup gig, the older one was "stealing" almost 30g thrust

I have a EDF50, but the rotor has three blade.

I'm producing another cdrom to put in the EDF40 and EDF50, then I'll measure the RPMvs thrust and actualize my data.

What do you have in mind??

Dec 04, 2004, 09:28 PM
Registered User
Sleedo's Avatar
Here's my report
stock 6 bladed rotor
20 turns of doubled 30g wire
20mm stator
custom bell/flux ring
12 5x5x1 N45H curved magnets
6 poles
TP G2 1320 3s1p
125 gram of thrust bare
6.42A 10.99V 70.7W

Dec 04, 2004, 11:26 PM
From the bowels of MI
Nice looking motor! Thanks for the info, I haven't tried a delta termination yet. I don't have any thin wire so getting that number of turns would be a real PITA for me.

I was just wondering if you had any ideas on what the differences between our results could be attributed to. It's seems like you've been making progress with your testing though and are getting some nicer numbers.

Sorry I haven't gotten my 10 turn wye info up yet. I'm having a stator shorting problem with my last phase. I've wound it twice now with the same result. I must have lost some stator insulation somewhere. Will probably pull the last wind and apply some nail polish to the stator around the edges to see if I can eliminate the short.

Dec 05, 2004, 07:36 AM
Registered User
jalves's Avatar

For similar motor setups (same #turns, same wire, same poles and magnets), the differences observed could be due to:

1. different position of the fan in the motor shaft in relation to the shroud;

2. different capacity of our batteries to sustain voltage with the current levels we use in our little motors ( here a 0,3V could do the difference);

3. different rotor blades resistence to torsion, till now had three rotors, notice very small differences between them, but again, that could be the difference.

this third point need more investigation and thinking tough.

I notice also that the shroud of my EDF 40 has marks of rubbing with rotors blades (orange in black), since when i apply rotation by hand to the rotor the blade tips don't touch the shroud, why after a run the shroud has orange marks?

1. the blades stretch (unlikely);
2. the shroud distort when WOT (interaction between thrust and shroud support holder) (more likely)
3. the shroud motor support oscillate when the can rotates (do you notice that the sroud motor support is fragile?) (more likely).

That's my ideas,

Guys, comments please

Dec 05, 2004, 02:34 PM
Registered User
Fishnut's Avatar
Looks like I picked a good time to revisit the site. Work had me gone a good while. Here is a graph of the motors I've done. I've done an EDF40 too, and its numbers were just a tad less than the 50.

The 50 motor is a single GBL 20mm stator 20T 26G Delta with 6 5X5X1 N48SH magnets on a standard GBL can. Oh no inlet on this one.

The 55 and 64 motors are a single 22.7mm stator 22T 26G Delta with 6 5X5X2 N45s.

The 75 motor is a double 22.7 stator 12T 2X26G Delta with 6 5X10X2 N45s. Inlet is a paper cup taped on.

All testing is with a 12V marine deep cycle battery, and the 55-75 motors are turned on my lathe.

All fans are six blade except for the 75, which is a four.

I just received a Medusa Power Analyzer Plus, so I can do some more accurate testing, though it agrees with my clamp-on ammeter.

Also just picked up 25G magnet wire (great stuff!) from a local motor shop, so I'll be able to fill out the stators that weren't quite full using 26G. Should help in the efficiency department.

While I'm at it, got some curved N50 magnets. Made a bell with them on the 50, and the Kv dropped, so I need to make another stator with maybe 18 winds to compensate.


Last edited by Fishnut; Dec 05, 2004 at 03:01 PM.
Dec 05, 2004, 02:59 PM
Registered User
Fishnut's Avatar
Here's the stand. It's simple: the fans exhaust upwards, pushing down on the scale. You can see behind it a plexiglass shield I use for safety--along with safety glasses.

Below that pic is one showing the ducts mounted on test rigs.
Last edited by Fishnut; Dec 05, 2004 at 03:09 PM.
Dec 05, 2004, 04:04 PM
Registered User
jalves's Avatar
Welcome back Kurt!

I read your initial thread with interest (the posts stops abruptly, now I know why)

Do you have data for the EDF40??
Do you collect data from EDF 40 and batteries (3s lipoly) ?

I think that the utilization of a auto battery improves a bit the results compared to what we can get from our lipolys, just a thought to be confirmed.


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