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View Full Version : How to know what size of prop?


nova801428
03-04-2006, 08:48 AM
I just bought a Formosa and a Himax brushless outrunner HC2808-0980 from allerc.com and I have no clue on what size of prop I will need. What will work? and what would draw too many amps? How do you find this stuff out?

rocket_jim
03-04-2006, 01:42 PM
I just bought a Formosa and a Himax brushless outrunner HC2808-0980 from allerc.com and I have no clue on what size of prop I will need. What will work? and what would draw too many amps? How do you find this stuff out?
My Himax came with an instruction sheet that showed several props and what current they would draw with what input voltage. Perhaps you got such and it's still in the little box, all folded up??

nova801428
03-04-2006, 05:45 PM
Thanks, I have not yet recieved my Himax or plane yet it's still in the mail

rcers
03-04-2006, 05:49 PM
Prop depends on how many cells you are using.

The best way to figure this stuff out is to get a watt meter and measure your actual current. Motor manufactures give specs on how much amperage to too much (as do battery pack manufacturers).

Asking here helps too, but the Watt Meter is the way to go. O yea and lots of props to test....

Mike

nova801428
03-04-2006, 07:57 PM
I'm using a Thunder Power 3s 1320mah pack. As soon as I recieve my Himax outrunner then I will look at the data sheet then conclude on my prop size.
Thanks

rcers
03-04-2006, 08:11 PM
Well that appears to be an 8-12amp motor so I would start with a 9x5 GWS HD prop and go from there...

Mike

Masterpiece
03-22-2006, 12:26 AM
Prop depends on how many cells you are using.

The best way to figure this stuff out is to get a watt meter and measure your actual current. Motor manufactures give specs on how much amperage to too much (as do battery pack manufacturers).

Asking here helps too, but the Watt Meter is the way to go. O yea and lots of props to test....

Mike

IMHO this is the best way to do it. I couldn't agree more. I like the way you think Mike ;) . I suggest downloading a free trail version of "Motocalc" and use this as a "close to the ballpark estimate". THEN take note of what it suggests (as motocalc isn't exact BUT helpful) and buy a couple of props "around" the suggested size (if you are going to use GWS slowfly props they are cheap cheap cheap so get a couple. I suggest APC slowfly props rather, as they a stiffer and just as light. GWS props are fine for indoor and very light parkfliers, the formosa needs a sturdy prop).

The "REAL" results as mike states (and it is very true) are from a wattmeter and at the field. I use a "Emeter" by Hyperion. VERY VERY handy. A gem of a tool. Tells you everything you need to know about what is happening with the motor and battery.

Cheers
Glen