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12S packs for pattern

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Old 06-27-2007, 10:32 AM
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mups53
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Default 12S packs for pattern

OK I need opinions. Has anyone attempted to use a 12S setup for 2 meter pattern? According to the rules this is legal in AMA up to Masters but not for FAI. If one was to do this would it work better than a 10S setup? What mil packs would you need? TIA for your thoughts. Mike Mueller
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Old 06-27-2007, 04:38 PM
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Default RE: 12S packs for pattern

Going to higher voltage, your amps are gonna go way up also. You'd need to go to a smaller prop or a lower kv motor. You might be able to go to a smaller mah pack but the extra cells would prob be a wash as far as weight. Just guessing though.
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Old 06-27-2007, 06:17 PM
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Default RE: 12S packs for pattern


ORIGINAL: rm

Going to higher voltage, your amps are gonna go way up also. You'd need to go to a smaller prop or a lower kv motor. You might be able to go to a smaller mah pack but the extra cells would prob be a wash as far as weight. Just guessing though.
The 12s would require a different Kv to yield the same power (same prop at same rpm). You would draw LESS current and therefore have better efficiency. The capacity in Watt-hours would be the same but in Amp -hours could be less due to the higher voltage.

You'd need to select from the stuff available to see how you'd come out on weight.

The big problem is the charging stuff. The TP charger/balancer for 10s is the greatest and I guess you'd have to charge the 12s, as two 6s packs.

Jim O
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Old 06-27-2007, 06:38 PM
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Default RE: 12S packs for pattern

Jim any ideas about what would work? What KV rating? Thanks again, Mike
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Old 06-27-2007, 07:03 PM
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Default RE: 12S packs for pattern

I am flying a 4 cell A123 setup in a Diamante -and a small Extra 300 3.4 lbs
at end of 8 minutes I can accelerate vertically a long way with these packs
so far so good

the setup works and the models are 500 squares.
the motor calc guys may give you a thumbs down - been there -
The actual performance of the packs does NOT fit into same parameters as the LiPos (and I have plenty of those )
If you are a "buy n fly guy "- forget it tho -
some actual work is needed to get everything sorted out.
I am going for bigger model with more power (my own design-more like the indoor pattern models than the current outdoor stuff.)
The really big plus is that with everything sized right -the cells work--- and the total cell cost is far less than LiPo and you won't cook em unles you really don't think things through.
I suspect --that the ready to fly airframe bare has to hit 48 ounces - I did close to this with my EMC design years backat 1100squares so it is doable. I DID do it on my homely petro Petrel l
battery pack is 30ounces for 10 cells -36 volts . a simple charger is 3-wheelchair batts in series -36v
no need to watch for fires etc. charge in the model also.
This is not a follow the leader setup but should make a good performer
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Old 06-27-2007, 08:32 PM
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Default RE: 12S packs for pattern

The Schulze chargers would be your answer to 12s, however they are double the price of the TP's.

12s on current motors might be the key to a very high RPM glow-ish setup at reasonable current levels. Prop sizes would probably need to drop to 18"

Give her a go Mike and let us know Not that we can change in FAI!
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Old 06-28-2007, 01:09 AM
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Default RE: 12S packs for pattern

It's in the works. Not by me, but by a person I know..

Chris
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Old 06-28-2007, 06:17 AM
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Default RE: 12S packs for pattern

Mike you didn't say what you were hoping to accomplish. If your goal is just more available power, then you'd want to stick with the same motor, prop, then you'd have more available watts as voltage and amps would be increased, increased power. Your entire system would have to be able to handle it though. If you want greater efficiency then you'd need a lower kv motor, that would swing about the same size prop at a higher voltage with reduced amps, with available watts in the ball park as your present system if you'd want the same power. If you want more speed, then you'd use the same motor, but a smaller prop to bring the amps back into line, but at a higher voltage which would translate into a higher rpm. Battery selection to keep the weight in line would have to be trial and error, as no one would be able to predict accurately. R & D. The whole problem I see with 12s, is the weight constraints in pattern and the cost associated with finding the right battery combo. That was pretty much done for us with the 10s setup.

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Old 06-28-2007, 07:31 AM
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Default RE: 12S packs for pattern

Hry Robert I'm just kicking the idea around. The feedback that I'm getting is very interesting. The reason is to see if there is a better way to skin the cat. I'm not thrilled with what I'm doing now but I'll chalk it up to the learning curve. Thanks, Mike
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Old 07-02-2007, 11:37 AM
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Default RE: 12S packs for pattern

ORIGINAL: mups53

Hry Robert I'm just kicking the idea around. The feedback that I'm getting is very interesting. The reason is to see if there is a better way to skin the cat. I'm not thrilled with what I'm doing now but I'll chalk it up to the learning curve. Thanks, Mike
I can't speak as to the pattern specific question but I do run 12S in the new H9 Sundowner (Axi 5330/F3A, Jeti Spin 99, 2 x EVO 5000 6S2P. Mejzlik 20 x 12E) with an AUW of 13 lbs and the performance is staggering. The whattmeter shows 3,650 watts @ 81 amps @ 7,110 RPM, a bit high for my taste but obviously a side-effect of beating all that air on the ground with the 20 x 12 prop, in the air it's much more efficient. The plane accelerates in a vertical climb and hovers at 2 ticks shy of half throttle.

Before anyone wonders why 12S, it's mainly because I already own 10 EVO 5000 6S2P packs from my Fliton Inspire, I was trying to figure out a way to get the most use from these without buying another couple grand in LiPo's and it seems running 12S over 10S is fine if it allows me to make use of what I have, kind of a modular design to battery buying. Besides, I can always limit the throttle endpoint to 80% if it's too much power and make it seem like a 10S (granted, the extra weight is a hit but I can live with that over spending several grand)...

JFetter (Jack)
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