stunthanger.com
Electric Stunt => Gettin all AMP'ed up! => Topic started by: Chris_Burgess on January 29, 2012, 08:37:34 PM
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Ok, so I keep seeing motors labeled as "Easy Match" 15/25/32 or Power 15/25/32 and I assumed (you know what they say!) that these would be a reasonable match for that size motor; now after reading a few of these comments, I've come to the understanding that either control line is out of it's mind or RC guys are out of their mind, because there is no way that I would ever conceive using an O.S. .25 on a Legacy but in "Popular Motor Sizes and setups" http://stunthanger.com/smf/index.php?topic=24527.0 that is exactly what is happening (however, it is the so called electric equivalent)... Did I just completely miss something?
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Chris
In short, yes. You missed Marketing. To impress glow fliers electric motor builders have done this to attract in new folks to electric who do not yet understand the ways of measuring a motor's power. Then they label the motor with a much smaller glow equivalent than the motor actually is. The result is a guy puts it together and goes and flies and it knocks the socks off what they say the equivalent glow powered plane would be. Yes, you are seeing setups that are labeled as .25 flow equivalents fly legacys. There is the proof. That size motors as you will see in the setup thread will fly any size glow plane we fly if used in the right kv version and with the right batteries and props. I fly an SV-11 with an Axi 2826/12 on 4S. At a contest last year in big wind one I overheard one of the judges discussing my flight with another pilot. The judge also flies an SV with a piped PA.65. He was telling the other flier he was just "in awe" of the power I had with the electric. The tone of his voice was total shock.
bob branch
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Thank you, that explanation makes total sense to me, I guess it was screwing with me because I want to try to optimize and not way over power... so I appreciate the explanation!
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What I am finding is that if an electric motor will swing the same size prop at the same or more RPMs as a slimer it is equivlent. Assuming the prop is the correct size and I am running the correct voltage and amps for a given motor.
Next winter's project will be to rebuild my 80" Eindecker (control-line scale). While I am at it I will convert it to an electric. Originally I had planned to install a Saito 150 4C. The Saito will turn a 16 x 8 prop at 9000 rpm. So I am looking for an electric that will do the same. The Trungy RotoMax 1.2 will swing a 19 x 10 at 8000 rpm. I am guessing it will do the job. Should have plenty of power for high flight and cruze comfortably at 1/2 throttle.
http://www.hobbyking.com/hobbycity/store/__17984___Turnigy_RotoMax_1_20_Brushless_Outrunner_Motor.html
Also remember not all slimers are the same. A good OS .25 puts out the same or more as a Fox .35
D>K H^^
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What I am finding is that if an electric motor will swing the same size prop at the same or more RPMs as a slimer it is equivlent. Assuming the prop is the correct size and I am running the correct voltage and amps for a given motor.
Next winter's project will be to rebuild my 80" Eindecker (control-line scale). While I am at it I will convert it to an electric. Originally I had planned to install a Saito 150 4C. The Saito will turn a 16 x 8 prop at 9000 rpm. So I am looking for an electric that will do the same. The Trungy RotoMax 1.2 will swing a 19 x 10 at 8000 rpm. I am guessing it will do the job. Should have plenty of power for high flight and cruze comfortably at 1/2 throttle.
http://www.hobbyking.com/hobbycity/store/__17984___Turnigy_RotoMax_1_20_Brushless_Outrunner_Motor.html
Also remember not all slimers are the same. A good OS .25 puts out the same or more as a Fox .35
D>K H^^
Several good points there John:
I think motor selection should start with the prop size. Chris, this will be the best way for you to select your motor too. I tend to go a little bit oversize but not a lot, unless the bird is tail heavy then a big motor does not hurt a bit! Neat thing about electric is that an oversize motor will not tend to go oversped on a given prop.
John, just speculating here but what is the scale prop diameter for the Eindecker? YOu might be in range to achieve that for a nice visual touch. Also, the bigger motor will help you balance it.
Hmmm, I wonder if you could fit the outrunner with dummy engine sylinders that will spin up like the Eindecker's rotary engine would have???
(forget I said that...)
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Chris
In short, yes. You missed Marketing. To impress glow fliers electric motor builders have done this to attract in new folks to electric who do not yet understand the ways of measuring a motor's power.
I'm not sure if it's deceptive marketing or CYA: I always figured that if the motor says "25" on it then it matches the wildest super-duper ducted fan racing run-on-50%-nitro 25 that you could ever make -- so that when "joe racer" converts to electric, he's not disappointed.
For most glow flyers, if they convert to electric and end up underpowered then they're going to be discouraged and they're not going to want to try again. So the motor manufacturers are trying hard to make sure that they end up with a combination that can be put together with inexpert hands and still perform at least as well as slime power.
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Hmmm, I wonder if you could fit the outrunner with dummy engine sylinders that will spin up like the Eindecker's rotary engine would have???
(forget I said that...)
Don't really want to spin a dummy engine at 8K - But I have been thinking about it. I'm thinking you could mount the dummy engine on some kind of a ball bearing system and let air flow drive it like a pin wheel. Or you could lock it to the motor for display and let it free wheel for flight.
#^
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At one point during WW1 some of the rotary engines had quality problems resulting in cylinders departing from the engine in flight -- perhaps if the engine flings pieces, you could pass it off as a scale maneuver?
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I love rabbit trails! thank you all for the words of "Wisdom" I've already been playing with electric, but I haven't gotten to fly enough to really make a dent in the amount that I have to learn, I have a Cardinal ARC that has been flying the a turnigy motor for the whole summer and it performs well, and has lots of power overhead and pulls like a bear, but the motor has been getting really hot, and I don't like that... I may be spinning an unnecessarily high RPM or the 11x6 may be more prop than I need for the flight. This summer I plan on picking up a bunch of props, different pitches and tractor/pusher, and eAPC, as well has standards to see if I can make it fly just as well, but with less motor damaging heat...