rc united

Does anyone have a chart that shows the power comparisons of various brands of motors [ie. hacker, e-flite, axi, etc.]? I know that manufacturers label their motors with meaningless numbers and letters to keep us from buying another brand. However, I think that airplane sales are hurt by this if they recommend one brand and the customer prefers another or already owns one that would work. If no chart is available, maybe someone could tell me how to compare motors by looking at the specs for each.

Fliprob17

I do not know of a chart that does this. What you can do is look at the amp and voltage ratings, amps x volts = watts, which is power for an electric airplane. The kv rating is important too, that is how many rpm's per volt you are going to get.

Example:
total watts = amp draw of motor x voltage of battery, take that number and divide it by the weight of your aircraft and you get watts per pound. This example uses a 3 cell LiPo such as the Thunder Power Pro-Lite 2100mah, and the manufacturer's supplied amp ratings and various points during flight. Full charge, mid. charge, and min. charge. And a plane weighing 1.69lbs.

E-Flite Park 480 1020 kv
Max. Voltage Supplied (4.2v per cell) = 12.6v x 22amp Continuous = 277watts / 1.69lbs = 164watts per pound
Max. Voltage Supplied (4.2v per cell) = 12.6v x 28amp Burst = 352watts / 1.69lbs = 208watts per pound

Mid. Voltage Supplied = 11.25v x 22amp Continuous = 248watts / 1.69lbs = 147watts per pound
Mid. Voltage Supplied = 11.25v x 28amp Burst = 315watts / 1.69lbs = 186watts per pound

Min. Voltage Supplied (3.3v per cell) = 9.9v x 22amp Continuous = 218watts / 1.69lbs = 129watts per pound
Min. Voltage Supplied (3.3v per cell) = 9.9v x 28amp Burst = 277watts / 1.69lbs = 164watts per pound

If you use this formula to compare motors, it will help you get an idea of how much actual power each motor is providing.

Greg Covey

A simple chart exists at the end of my [link=http://www.gregcovey.com/Glow_Conversions_Made_Easy.htm]Glow Conversions Made Easy[/link] article. Once you read the article, you will be able to calculate your own comparisons.

Good luck!

aerofart

rc united has posed a good question, and one that has been asked (and answered) quite often on RCU. I'd like to add to that question by asking if there are motor mfrs (or independent sources) out there that provide more complete specs for motors. I find this would be especially useful when adding a custom motor to Realflight's G3.5 simulator, for example.

In G3.5, the four (4) parameters required to set up a new, simulated motor are KV, IO (Amps), Motor Resistance (Ohms) and Weight (Ounces).

Now, from my limited experience, it seems that KV and Weight are pretty common specs provided by the mfr, but what about IO (which is "the amount of Amps it takes just to get the motor spinning"') and Motor Resistance? These last two parameters are nowhere to be found for the specs on my XTRA 2829/16, for example.

My next question is, are these specs sufficient to provide realistic power output for any given motor? Would this information give me real-world results, or just a pretty darn close approximation? Is motor output so linear/is it really that simple to describe? My guess would be no . . .

Comments appreciated.

Dr Kiwi

If these four parameters were, indeed, provided by manufacturers and distributors there are several very good calculator programs out there which one can use to estimate real world performance. http://www.peakeff.com/ , http://www.badcock.net/ The problem is, how many manufacturers and distributors provide ACCURATE figures?

70+rcFLYER

MotoCalc (RC Software Co), has all tha data you will ever need, on motors, esc,s etc. go to their link at:

http://www.motocalc.com and go to the Data/Motor section.

Hope you find what you need. Also it's free.

Dr Kiwi

As long as one realizes that Motocalc can provide a ballpark figure, but one needs to test one's own system to see exactly what is going on.

JLIN26

Check this out!!! Great Planes has really done something here with their Electrifly line.
http://www.electrifly.com/index.html

If you click on the motor configuration you can convert your glow airplane to a brushless electric or brushed to brushless conversion.
The printable brushless power system brochure has helped me learn more about brushless power. Seriously guys, you have to check this out. Print off the brochure & keep it in your workshop. It is a handy tool.

coupar

rc_united, you hit the nail on the head. It's very frustrating.

I've been flying glow planes for years. I've bought a couple of simple electrics with 400 motors - great. The kit said it needed a 350 or 400 so I had a simple choice of a dozen motors. I'd dearly like to get into more electrics but trying to match plane to brushless motor!!!!

If a glow plane maufacturer says it needs a .30 -.40, I know what to buy. I can even figure that if a .46 has the same dimensions it will also work. I've been looking at Advantage Hobby's web site. They list some of their Electric offerings as needing a Park 400 or 450 brushless motor. The have many brushless motors available but NONE of them (that I could find) say they are Park 400s or 450s. You'd think they would want to sell product!

A couple of sites I've looked at list a single matching motor for a kit but I cant figure out why they picked that motor (other than that's the one they sell). The motor specs are so inconsistent across manufacturers as well! It's very difficult to compare apples to apples.

The info here I'm sure will help (thanks all), but how do you know if the motor will fit the plane? or if the mount will work?

I've saving this thread - thanks again all.