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Lancifer
09-07-2009, 07:57 PM
Im trying to figure out what i should be getting on my eflite power meter when i have my Power 32 engine at full throttle!!! Also what should the eflite Power 25 be putting as well and also the Parkzone Corsair and Trojan motors as i just got my power meter so i need to check theses things out as my motors arent working to par:blah:????!! Thanks peeps!!:cool:

Sky Sharkster
09-07-2009, 08:20 PM
Hello Lancifer,
In reply to your question, I can't answer without more info. Mainly it depends on the input voltage (number of cells) and prop size.
So, I took a guess and ran it through the free online calc; http://brantuas.com/ezcalc/dma1.asp
But first I checked E-Flite's specs for the Power 32. This is a 770 Kv motor that uses a voltage range of 12 to 16.8 volts, prop sizes recommended 11" x 7" thru 14" x 10" and a 60 amp speed controller.
http://www.e-fliterc.com/Products/TechnicalSpecs.aspx?ProdID=EFLM4032A
So, I ran a 12" x 8" APC prop, 4 cell 3200mAH LiPo and came up with ;
Motor amps; 55.185
Watts in; 750.65
Watts out; 657.1
Efficiency; 87.5% out of a max possible efficiency of 88.4
Prop RPM; 9624
Prop Pitchspeed; 72.9 MPH
Static Thrust; 125.4 Ounces
Full-Throttle duration; 3:29 minutes
They also list the Power 25 on the calc, you can give it a try.
Good Luck!
Ron

Lancifer
09-07-2009, 11:09 PM
Hello Lancifer,
In reply to your question, I can't answer without more info. Mainly it depends on the input voltage (number of cells) and prop size.
So, I took a guess and ran it through the free online calc; http://brantuas.com/ezcalc/dma1.asp
But first I checked E-Flite's specs for the Power 32. This is a 770 Kv motor that uses a voltage range of 12 to 16.8 volts, prop sizes recommended 11" x 7" thru 14" x 10" and a 60 amp speed controller.
http://www.e-fliterc.com/Products/TechnicalSpecs.aspx?ProdID=EFLM4032A
So, I ran a 12" x 8" APC prop, 4 cell 3200mAH LiPo and came up with ;
Motor amps; 55.185
Watts in; 750.65
Watts out; 657.1
Efficiency; 87.5% out of a max possible efficiency of 88.4
Prop RPM; 9624
Prop Pitchspeed; 72.9 MPH
Static Thrust; 125.4 Ounces
Full-Throttle duration; 3:29 minutes
They also list the Power 25 on the calc, you can give it a try.
Good Luck!
Ron
Thanks, wow i guess i should have stayed in math..lol!! Thats a usefull site, i just have to learn how to use it!! Thanks:ws:
Im just trying to figure out how to use this eflite power meter as well!! Thanks Ron!!

Sky Sharkster
09-07-2009, 11:37 PM
Thanks, Lancifer, glad I could help.
The "Calcs" aren't the final word, it's theory based on manufacturers' specs, which aren't always accurate. The Wattmeter will be the best answer, but the calc can get you close.
It's pretty easy to use, just scroll to the motor you want, click it on (dark blue). For some reason this automatically calculates a reply, even though you haven't entered a prop or anything else. Don't worry about it.
Now, try entering a certain size prop diameter and pitch, change prop type to "APC" and change the battery to the closest mAH they have compared to what you intend to use. Change cell count unless it's "3" LiPO's, that's the default number. Change the speed controller to a 60 amp.
Hit "recalculate"
I like to print out the best results, it's hard to remember all the specs.
Next, change ONE factor, like prop diameter, a little at a time. Stick to props you know you can get.
Hit "recalculate"
Compare the numbers, especially Amps, Watts in and Out, efficiency and thrust.
It's fun!
Ron

slipstick
09-08-2009, 10:08 AM
As for using the power meter just plug it, go to full throttle, then read off Volts, Amps and Watts. Of those the current (amps) is probably the most important. That's the one you really don't want to be more than the motor specification allows.

Just don't run the plane on full power on the bench for very long...it needs the moving air of flight to keep it cool.

Steve