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E conversion help

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Old 02-08-2007, 12:05 PM
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rcmaster-RCU
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Default E conversion help

I am building a 40 sized dazzeler for electric and I want to run one of great planes's rim fire out runner motors. The two I am looking at are the 42-60-480 and the 42-60-600. Which one would you reccommend as well as the battery and prop combo to generate the most thrust. According to the motor's website the 480 will swing a bigger prop but is recommended for a 5.5lb 3d plane. The 600 swings smaller props but will fly a 6.9lb 3d plane. I think there is some trick in understanding RPM/V ratings in accordance with prop size in order to get the best performance too right?

Appreciate the advice,
Alex.
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Old 02-08-2007, 04:59 PM
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salnsp
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ORIGINAL: rcmaster-RCU

I am building a 40 sized dazzeler for electric and I want to run one of great planes's rim fire out runner motors. The two I am looking at are the 42-60-480 and the 42-60-600. Which one would you reccommend as well as the battery and prop combo to generate the most thrust. According to the motor's website the 480 will swing a bigger prop but is recommended for a 5.5lb 3d plane. The 600 swings smaller props but will fly a 6.9lb 3d plane. I think there is some trick in understanding RPM/V ratings in accordance with prop size in order to get the best performance too right?

Appreciate the advice,
Alex.
Its fairly hard to reply to this with any scientific exactness. In order to determine a motor's performance, you need three things. Kv, Idle Amps and Resistance (Io). The motors as shown on the website do not give a resistance number. My guess is that the rimfires are typical mass produced Chinese motors which are on the mid spectrum of performance compared to other outrunners. Still, I am sure they would work.

The next question would be what battery you are going to use? Actually that is the most important question because the battery limits the maximum current and voltage you have to work with. this sets the maximum watts or power you can supply to the motor. (Voltage times Amps equals Watts) Once I know that I can give you a better answer. I will need the battery capacity, the cell count, the c rating and the manufacturer.
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Old 02-09-2007, 07:07 AM
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Default RE: E conversion help

I am thinking a Thunder Power Extreme 5 cell single pack 4500mah with a 20C rating. You say the Rimfires are on the mid spectrum of performance. What type or brand of outrunners are on the high end of performance? I have two rimfires and really like them so I was just sticking with what I know. Can a better outrunner deliver more efficient power and still be the same weight and size as other motors?

Thanks for the reply,
Alex.
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Old 02-09-2007, 01:21 PM
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ORIGINAL: rcmaster-RCU

I am thinking a Thunder Power Extreme 5 cell single pack 4500mah with a 20C rating. You say the Rimfires are on the mid spectrum of performance. What type or brand of outrunners are on the high end of performance? I have two rimfires and really like them so I was just sticking with what I know. Can a better outrunner deliver more efficient power and still be the same weight and size as other motors?

Thanks for the reply,
Alex.
First to answer your question about motors. Although most motors sold today work reasonably well, some are better than others. A better motor has better magnets (both more powerful and able to withstand higher heat), More attention to the tolerances, btter design, lighter weight. Tolerances are most important in winding, and the gap between the magnet and the windings. The smaller the gap the better the power andd efficiency. Today, most outrunner motors are made in China. The Chinese make motors that are primarily price based. This means that they will make a motor as cheap as the vendor allows. Some of the branded motors cost a little more but have been designed better. Looking at the better outrunners, I would name Hacker, AXI, Himaxx as ones that will give you better output, power handling, and higher efficiency. The Steve Neu ORK's while not outrunners are wide bodies low KV high torque motors that are designed to compete with the outrunners.

Now to answer your questions about motors. Since you are going with a 5 cell battery and we will assume 20c. I like to stay reasonably conservative so we will work with 15C. For this we will work at 45-55 amps. This gives you 18.5 volts at 45-55 amps which is 832-1017 watts. Assume 95% gets to the motor or 800 to 1000 watts give or take. Since the dazzler is a 3D aircraft, I would go with the lower Kv motor so you can run with a bigger prop and get more thrust at a lower speed. Since I would want to go withthe motor that has the lower Kv. For 5 cells I would want a 450-500 Kv.
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