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Old Aug 19, 2014, 01:27 PM
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30 mm Fan Test Results

Hi, I thought I'd post my early test results in a new thread. My first thread was about designing and printing out a test stand and custom fans. I've always been fascinated by EDF and micro's in particular so when I saw Meerkat's Hunter thread and his high tech approach I thought I have got to give this a try. I'm a retired Senior Designer from Ford and have years of experience in various CAD programs.
Based on what I've read the HyperFlow fan looked like a good design to start with. My goal is to equal or exceed its performance.

This is my first 'go around' at this this so every step is a new experience.

This is my setup :

SMC 2s 4600mah 70c 'shorty' battery
Neu 7300Kv and 4000Kv motor
Ammo 11500Kv
CC Talon 25 amp ESC

Blades............. A.............. V.............W............... T ...................G/W
___3________4.83 _____7.95____37.8______70__________1.85********* HyperFlow Fan........... ?P/D.........Ammo 11500Kv............2S

___3________2.12______8.11____17.1______42________ __2.45*********HyperFlow Fan............?P/D............7300Kv........2S

___3 _______ 3.27______7.88____25.8______60__________2.32****** *** Version 1 Fan..............1.5 P/D........7300Kv......2S
___5________ 3.68______7.80____28.3______64_________ 2.26
___7________3.84______7.75____ 29.6______62_________ 2.09

___3________ 4.74______7.82_____33.2 _____69________2.07 ********** Version 2 Fan..............2.5 P/D.........7300Kv......2s
___5________5.34 ______7.74_____ 41.6_____ 78_______1.87
___7________5.65_______7.70_____43.2_____80_______ 1.85

___7________3.05_______11.75_____35.4____72_______ _2.03***********Version 2 Fan..............2.5 P/D...........4000Kv.....3S


My next step was to design a version 3. I sent out 7 new designs to print and hopefully I should have them by the end of the week.
Fingers crossed ....
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Last edited by jumo004; Aug 19, 2014 at 02:25 PM.
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Old Aug 19, 2014, 02:28 PM
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This is the link to my test stand thread :

http://www.rcgroups.com/forums/showthread.php?t=2174076
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Old Aug 20, 2014, 03:21 AM
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Nice Barry

Did you take any pics and how did the rotors hold up?
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Old Aug 20, 2014, 09:10 AM
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I'll take some pics of the fans (sorry I only have a camera phone).

The fans held up really well to my surprise, maybe because I'm only running them on 2S ? They require very little clean up and seem to require very little balancing.
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Old Aug 20, 2014, 11:55 AM
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Here's some pics and some CAD screen shots which show the fans in comparison.

The 2.5P/D had better numbers and it's obvious why ...

Still not happy with the performance, got some more stuff to try ...

Thanks.
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Old Aug 21, 2014, 11:58 AM
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Those rotors look great!

I really like how you have overlayed your CAD models to show the difference in P/D. Looking forward to seeing how the new rotors perform.
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Old Aug 21, 2014, 10:42 PM
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I am looking forward to seeing your results! Don't forget the stators, different pitches on the stators can greatly affect the overall fans efficiency.
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Old Aug 22, 2014, 08:17 AM
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I like the coarse pitch....good for speed
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Old Aug 22, 2014, 10:05 AM
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Quote:
Originally Posted by danj31 View Post
I am looking forward to seeing your results! Don't forget the stators, different pitches on the stators can greatly affect the overall fans efficiency.
yea the stators .... another whole new world to explore ... LOL. I have some pipe dreams .... but for now I going to stick with something simple.
These ducted fans are so complicated and involved with math, theory and black art that for me leaves my brain spinning faster then any EDF I've ever seen ... lol.

I'm using the 'shot gun' approach. Throw everything I got at it and see what hits.
It's not very scientific but it allows some fun to be part of the work ..... anyway .... this is what I'm using at the moment ...

btw, any comments or suggestions would be welcome.

Thanks.
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Old Aug 25, 2014, 01:01 PM
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Wanted to try a longer inlet and outlet along with some new design fans.
Everything came in good except the inlet ................

Thanks UPS ...
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Old Sep 01, 2014, 08:36 PM
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It's been slow going with the new fan designs. I submitted 10 new fans (my third batch) last Thursday for printing. It takes about 7 to 10 days to get them back but I forgot about the holiday and that will stretch it out even more ... so ... I managed to get the first batch test results into an efficiency calculating spread sheet (thanks Steve!) so that I can compare the different fans and try and make sense of what I'm doing.
I also had tested some new (what I call hybrid) blades (my second batch) and have posted some screen shots and the spread sheet of the results for those. A few of the hybrids show better efficiency then the P/D ratio fans. Based on those results I redesigned the hybrids by basically shorting the chord from 10mm to 7mm which are the fans I'm waiting on now (third batch). I also included a screen shot of the 7mm chord blades with an outline of the 10mm shown for comparison.
I also went up on blade count to 9.
I also ordered a 8300Kv motor.

I don't know where all this is going but it sure is FUN !!
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Old Sep 01, 2014, 08:44 PM
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This is the 10mm hybrid results (second batch):

The green fan is part no. 1515Tv1
The blue fan is part no. 0515Tv1
The red fan is part no. 1530Tv1
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Old Sep 01, 2014, 08:49 PM
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These are the 7mm chord fans (third batch) that I'm waiting on ...
You can see the 10mm airfoil outlines for comparison.
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Old Sep 02, 2014, 05:14 AM
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Nice work Barry!

There's lots of good info for me to pickup on when I get back to testing.

It's interesting to see the thrust increasing with pitch. I would have expected it to drop with a static test.

I recon you could increase the pitch until it tops off and then increase it a fraction more. That way when its flying and in a dynamic condition (air speed) the rotor becomes efficient again. Then again I'm a complete noobs at all this .

It would be great to build a small wind tunnel to dynamically test them. I remember a guy on one of the other EDF forums building something using a larger EDF... I will have to try and find the thread.

I would be really interested in Nitros or pdawg's thoughts.

You are right about all the testing being a load of fun.... the wife thinks I've gone barmy getting all excited about little bits of plastic
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Old Sep 02, 2014, 09:27 AM
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Thanks Steve, I may have got off the P/D ratio fans too early. I may have to try a 2.75 and 3.0 P/D to find where they drop off in performance. One thing with the P/D fans is that it takes a lot of calculations to set up the fan blade to model. The good thing is that they are easy calculations .... but just a lot of them. I may try a spread sheet type of approach to cut down the work load ..... now that sounds interesting ... lol.
I switched to the hybrid blade because it was easier to model and showed an improvement in efficiency. The hybrid starts out with a P/D ratio but ends with a 'twist'. It difficult to explain but even more difficult to keep track of when you have 6 fans in your hand and you can't tell them apart!
My current train of thought is to try a fan with a smaller chord blade, more blades (9 or more) and spin it faster..... too many thoughts going through my brain ... lol.

I like the wind tunnel idea .... maybe take everything outside and fire up the leaf blower and aim it at the fan ... wondering what the neighbors would say...
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