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Old 04-14-2007, 06:07 PM
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redroar
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I think I have a relatively good idea of what I'm doing, but I'm one of those people who has to know EVERYTHING about anything their getting into.

Here are my questions, to be certain of things. All of these questions are for outrunner brushless motors.

1) If a motor is 1000Kv and 75% efficient, it will run at ~7500 RPM with a 3s lipo, right?

2) The RPMs stay approximately the same between props, with the exception of 5-10% changes in efficiency, only the current draw changes, right?

3) How crucial is a wattmeter to ensuring that I squeeze the most power? Never mind. They are very important. Is the Watt's Up good?

4) How good are the GP electrifly Rimfire motors and electrifly Balanced lipo packs. They look good on paper, and the prices seem good, but I haven't seen much in the way of reviews on them.

Any answers are greatly appreciated. I'm starting to get really attracted by these nice little electric planes. I don't have enough storage space for 60" glow planes anymore.
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Old 04-15-2007, 03:21 AM
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jooNorway
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Some answers, which of course are my opinions only:

1: The kV-number is the RPM your motor will rev at unloaded (no propell). In practice the RPM might be 30% lower, and this number is just from the measurings I think I remember Might be wrong!
The efficiency is an other number which don`t relay to the kV. This number tells you how much Watt reach the propell compared to the amount of Watt your setup consume from the battery. Ideal is 100%, but impossible. Extremely good setups might reach 92% of efficiency, but I have a feeling 84-88 is pretty good.

2: The RPM stays approximately the same, but of course vary some houndred RPMs. As long as you stay within the proper range for the motor.

3: You have answered this yourself. Don`t know the Watt`s Up, but is sure works. I use the Hyperion E-Meter myself. You might fly a lot without a Wattmeter, as long as you find good testresults to relay on for the motors you use. But I know you will find a Wattmeter indispensable as soon as you start to measure your gadgets and compare to practice and what you want from the setup Not to mention you always are sure you don`t destroy your gadgets!

4: No idea. I have my favourites and don`t buy other motors/ESC/LiPo longer except for some testing and reviewing now and then. After some years I prefer Actro (expensive!) and AXI (cheap) motors, buy nothing but Jeti ESC and only FlightPower batteries.
Have of course dozens of other brands, both from reviews and bought just to try. They all have this in common: almost everything works quite good! I am able to measure slight differences, but for 95% of the pilots they won`t notice the difference. But I like the high-end stuff, because they seldom fail, runs cooler, are extra nice crafted and give a feeling of high quality. It costs, but I am so addicted to this so I enjoy spending the extra money... As I say, I am addicted!

Just my 2C... I have 3-4 glowplanes left, but they are all for sale.
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Old 04-15-2007, 10:15 AM
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redroar
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Well, as far as favorite stuff goes, I love Castle Creations. I have a few of their receivers and if the ESCs are the same quality, then I'm all good.

I think that for inexpensive motors, the Rimfires are decent, I haven't heard anything actively negative about them. Though usually whenever someone says something good about them it's preceded by "For the price..." I'd probably be better off spending the extra $20 on an AXI though.

On the other hand, I know for a fact that the Electrifly non-balanced packs are junk, and I'm getting the impression that their balanced packs are acceptable, but nowhere near great. I probably oughta just get some Thunder Power and spend an extra $20 on a good battery.

So I guess that leaves me with increasing my budget by $40.

Oh yeah, and is it just me or does it seem like E-flite is taking advantage of people with their batteries? They are barely less expensive than Thunder Power, and have a discharge rating of only 6c continuous.
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