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Old Jun 07, 2001, 04:29 PM
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Gordon's Avatar
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Best Motor for Wemotec Micro-fan

Anyone any recommendations?

Is there a small brushed cobalt or brushless motor which would match this fan? Say on 7 cells and about 10-12A?

Someone mentioned a small Hacker, and I think I've heard of a small Pletti as well. Is it likely that an Astro 020 would fit and work?

OK ... I'll stop now

Cheers

Gordon
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Old Jun 07, 2001, 05:31 PM
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Steve McBride's Avatar
Agra, Oklahoma
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I have the fan and a Hacker B20-12L which is quite a bit smaller in diameter than a 300 motor, a bit longer and had a constant of 4750 rpm/V (!). No current measurements but this thing screams on 8x600AE cells. If I could get it balanced though........
I hope to make up a 7 cell pack tonight and give that a try and measure current.

Good luck!

Steve
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Old Jun 07, 2001, 08:47 PM
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orlando fl
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ok, I have the same set up, tried the hacker motor. Why do you think it needs to be balanced? If vibration is present check for runout of the spinner. I balanced mine on a magnetic balancer and still vibrated like crazy. Did you ream the hub or just press on?
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Old Jun 07, 2001, 08:59 PM
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reamed it and is a press fit except when the vibration starts and then it chatters against the duct and works itself off (this on 8 cells). On 7 and 6 it is much more civilized.

Added an intake just this evening and what a difference (by the arm-o-meter). Probably put in F-16 for first trys.

Have a good one!

Steve
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Old Jun 08, 2001, 05:26 AM
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Steve & Dave

Thanks for coming back.

Why I asked the original question is I spent yesterday pm as launcher/in-flight photographer with clubmate (stand by for name drop ... Chris Golds and his new 24in span Hawker Hunter, which weighs about 16oz, and is equipped with a Sp300. It's a real gem!!

He was having huge problems with glitching - Jeti sub-min RX and esc - which ruined 3 flights, and he finally got control by replacing the Jeti RX with an elderly JR PCM-10 rx, which looked huge in comparison but still fit the space available. The plane now beame quite nose-heavy due to the heavier PCM RX, but still displayed a good performance. However, I felt a more efficient motor than the Sp300 would have done the model justice. Besides which, a brushless motor should last for ever and not conk out after relatively few flights.

Regarding vibration, whilst I was holding the plane before releasing it on the bungee, I couldn't feel much, but the fan unit was very noisy and it did sound as if there was a lot more than just thrust happening inside that duct.

I've just had a look at the Hacker website:
www.hacker-motor.com/english/englisch.html

and noted the very small diameter and relatively long case of the motor B20L. If no-one has tried it, I wonder if supporting the rear of the motor case would damp down vibration?

Which escs and cells are you guys using?

Is the 12-wind B20 going to be optimum for this fan unit, or in retrospect would the next lower kV be more appropriate?

Looking forward to reading those current meaurements.

Cheers

Gordon
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Old Jun 08, 2001, 08:56 AM
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orlando fl
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I made a bushing out of hard plastic on a lathe that I press fit into the fan mount, then the hacker has a lite press fit into it. This supports the motor very well. I used 7 cell's of 600ae's. I think I was right at 10 amps with that setup. 8 cells might be ok (600ae's) but only if used with considerable restrait as the 600ae's would not hold up very well at higher currents. I noticed the same thing about the noise, not the same kind you hear from other fans. Also if you touch the fan unit while it is running you can feel the sever buzzing. I compared it to the pro-scale which was virtually buzz free. If you carefully examine the spinner while turning it by hand you can see if there is any run out. I think this is the cause of the noise and vibration. Even with the noise and vibration it out perfomed my pro-scale equiped with a speed 300, But then it had the hacker and pulled 10 amps as apposed the 8 amps from the speed300 proscale. test results in static thrust
wemotec with BL hacker 10amps 6.25 oz
proscale with speed 300 8amps 4.25 oz

no inlet rings were installed on either

my plan is to make a fan out of ply that fits the smaller hacker, thereby allowing more room for blades, then try to copy the blade twist, taper, and AOA of the wemotec using ply. The resuling impeller will be mounted using a convetional prop adapter (no more pushon).
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Old Jun 08, 2001, 08:57 AM
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using the schulze 18be future
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Old Jun 08, 2001, 09:47 AM
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Using Jeti 18 on Hacker B20-12L

Steve

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Old Jun 08, 2001, 12:00 PM
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UK, Greater London, Uxbridge
Joined Mar 2001
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The Microfan is bored for a 2mm shaft and the Hacker B20 has a 2.3mm shaft - just pressing the fan onto the shaft didn't work for me! However, Ulf Herder (Schulze) did show me his own Microfan and he told me that he 'just pressed the rotor on'. He also ran it on 10 cells - very impressive!
Now all we need is a nice model to suit the fan.
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Old Jun 08, 2001, 12:08 PM
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Hi Gordon

Was Ulf using a Hacker B20 - how many winds for 10 cells?

BTW, have you got 'em in stock Gordon, and if so, how much? (You haven't had time to get 'em on your website yet

Cheers

Gordon

[This message has been edited by Gordon (edited 06-09-2001).]
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Old Jun 09, 2001, 04:54 PM
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Re the aforementioned Chris Golds Hunter, I just asked today, and he's using 8 x 500AR - the green ones - on his Sp300/Wemotec setup.

Gordon
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Old Jun 10, 2001, 05:28 PM
steve neill
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I also ran mine on 10 cells and the fans vibrated very badly even with balancing.
Increase in thrust was not much. I found that 8 cells is the magic number, very
smooth. Thrust is about 4.5 oz. on a speed 300. Two of these fans in a light airframe
would be super.
Please let me know guys if your getting higher thrust on different motors
because one of my new jets I designed is grounded because of the early claims I
expected 8 oz. of thrust. The problem is now that the bore of the intakes and out
takes is to suit a 2 inch fan.
If I can't get more thrust out of them I'll have to get out
the rotor rooter and try the new Hobby Lobby mini fans, I hope.
It was real dumb of me to build two scale birds around these fans without knowing
for sure what the REAL numbers actually were. I won't do that again. I didn't get a
chance to try them out before I started building. Never do that! Always get the fan
units first and test them and then build the frame in accordance. I'm sure you all know
that but I just had to say it, it worries me to think I might have built two Hanger queens!
Steve Neill
PS The plane is the Heinkel H P. 1080. I'll post some pics as soon as I finish moving.




[This message has been edited by steve neill (edited 06-10-2001).]
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Old Jun 10, 2001, 09:08 PM
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orlando fl
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4.5 sounds like a reading without an inlet lip. I had over 6oz without a lip on a hacker BL and 7 cells.
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Old Jun 10, 2001, 09:55 PM
steve neill
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Dave I did have the lip but I don't think I made it deep enough and I'm changing it. Also a speed 300 cannot compete with the Hacker motor. Still 12 oz. ( I have twins in the plane ) will not fly my bird very well.
Dave thanks for your input! Try it on 8 cells if you can I'd be curious to see the results.
Steve
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Old Jun 10, 2001, 10:24 PM
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orlando fl
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I will but first I plan to cut off the spinner, gut the rotor of the 4 vanes that support the center of the rotor, and make a aluminum adapter that I can glue to the rotor. This will allow a prop adapter to be used. I will then make a spinner out of blue foam. My hope is to end the vibration that has been plaguing me. I have a small lathe that should do the trick. I belive the vibraion I have been experiencing is due to run out, not balance, so the adapter should cure this and the foam spinner has much less mass so any remaining run out have less effect on vibration. The hacker is a real gem, it should be nice.
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