possible motors for Open B

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BenJammin
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possible motors for Open B

Post by BenJammin »

I've been doing a little research on motors that would possibly work in Open B. I like the "Electrocutioners" idea of a pusher config where the motor should be fairly protected in the event of a dirtnap and most midairs. I've been looking for motors that will spin a 9" or smaller prop at 30 amps or less. I thought I would throw these links out and see if anyone has any knowledge of these motors.

Gunther "Black Gold":
http://www.rc-dymond.com/index.php?productID=1196

Tornado 450-T-950:
http://www.rc-dymond.com/index.php?productID=1195

Gunther Outrunner 040:
http://www.rc-dymond.com/index.php?productID=1198

BP or Tower Pro 2915-5D:
http://www.bphobbies.com/view.asp?id=V4 ... id=W392031

Any opinions would be appreciated.
Lee Liddle
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Post by Lee Liddle »

I have one of the TP2915-5D motors ordered, and it may come in tomorrow. I`ll be doing some testing, but my thinking is that it will make an SSC motor.

Here are a couple of limiting factors.

To turn an 8/3MA prop at 17.5k static, it takes a little over 300watts. Watts = Volts x Amps. The motors that you are looking at seem to be in that power range, but the ones at rc-dymond aren`t even listing kv rating or max watts limits.

To turn a enough prop fast enough to create Open B performance, you need about 700watts. 750w is equal to 1 horse power. That`s about what the 25`s on moosecans are developing. So you are going to need more motor.

Also, large outrunners generaly have low KV ratings 600 to 800 or even less. This means that you have to run higher voltage (more cells) to get the RPM`s that you need for either SSC or B. I`ll have to run the 2915 on 5 or 6 cells to get the voltage to turn 17.5k.

Running batteries in a series is pretty easy. You can turn two 3s packs into one 6s pack by just hooking the - of one to the + of the other. I run 3.5 bullet connectors on all of my batteries. Male on the - side and female on the + side. I "shroud the male conector with a piece of 3/16" sugerical tubing to keep the two ends from accidently touching. With this setup I can easily "build" higher voltage packs for hipo use, then take them back appart to run more tame applications.

I also have one of the 700w TP motors comming to see what it will do. I think that it will develop Open B power with the right battery/prop combo.

I`ll let you know how testing goes asap.
slam
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Post by slam »

the motor that we are using for 3696 are very capable of spinning a 8x3 prop at 19k at 24a, or 17.5 at about 23a on 4cells. this motor will not work for open b, but at 4s, will work well for ssc.

i would really like a motor that would work for both. i know it is out there, just have to find it.

slam
BenJammin
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Post by BenJammin »

It would be nice to get the same thrust and speed as the 25 FX on a pipe but I doubt it's going to happen on my budget. I would at least like to get close to the same speed and then adjust my flying style to be able to keep up. I have a bad habit of getting into turning battles. That not only bleeds off speed but is a good way to get in a midair.

I emailed rc-dymond.com today to see if I could get some KV ratings. If I hear anything I will post the specs.
BenJammin
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Post by BenJammin »

I got a reply today. I asked about the motors listed and told him what I was looking for. Here's his reply:

Ben
The GB outrunner has 1200 KUV, the 450 T 950 KUV
Max 600 is not powerful enough for your ap.
May I recommend"
Gunther 30/3 Inrunner 1350 KUV swings a 9x6 to 10x5.5 at around 35 A
Enjoyable power with almost 3lbs thrust. 500 Watt at 45 A draw.
So chose a 3 S 2P battery 12 V 4200 mah. Light weight and capable of
handling the Amp draw.
Best regards
Helmut

The Max 600 is a brushed motor he has listed.
slam
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Post by slam »

thanks for the info ben

looks promising.
here's a link to that motor

http://www.rc-dymond.com/index.php?productID=292

slam
BenJammin
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Post by BenJammin »

So what's your guess Slam, would the 30/3 work on 4S Emoly with a 9x4?
drewjet
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Post by drewjet »

Ben,

I think that may work, however, probably not on a 9X4. You have to use the advantage of an electric motor and swing a prop at a more efficient place, instead of trying to match what an IC engine does. I would try something like an 8X6 instead and build light.

It might be too many amps for the emoli though, you need to be around 30 amps in order to get the 5 minute flight time. Plus anything more than bursts above 30 amps and the emolis sag pretty bad.
BenJammin
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Post by BenJammin »

Thanks Drew,

I sure would like to use Emolis.

Up here where I live we have this thing called winter. It appears that it's coming early this year so I won't be doing much flying till July when spring gets here. [:o)] I think I'll hold off, maybe something better will come along before next season. [8D]
drewjet
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Post by drewjet »

Winter, That's my flying season! Plus its a lot nicer to build when the temps drop down to the 60s.

I am still experimenting with the emolis and the Mega 16/15/4 and the 22/20/3 as those are 2 motors I already have.
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