Thread: Discussion 3DHS 47" Osiris
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Old Apr 10, 2012, 10:45 PM
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scotia ,NY
Joined Jul 2008
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Originally Posted by Jim Lee View Post
dbgood, A motor calc is only an approximation, You really need a Watt Meter to get a good Idea of whats going on with your Motor, ESC and Battery.The Omega is rated for 50A max or 700 Watts in. You wouldn't get 700 Watts at the prop because none of the current crop of outrunners are 100% efficient. Most are about 80 to 85%

I figure about a thirty percent loss, But.that may be a little high. On my set-up I'm getting 630 Watts in so I subtract 30% to get the approximate watts to the prop. 630 - 30% = 441 Watts more or less. Thats still over 200 Watts per pound. That's in 3D range and the 47" Osiris with the throws set to the Max will 3D.

The 11x8.5e APC prop may be a bit too much, If you hook up a watt meter and you're drawing over 50A, Then you need to prop down in pitch.. Props that I have used on my Omega are the APC 11x7e, 11x8e and a Xoar 12x6. I settled on the 11x8e as it flew the Osiris the way I wanted it to fly.

Some talk about the speed being too fast and that's what the throttle is for, I very seldom use full throttle and I fly the AMA Advanced and the Masters Pattern Sequences. About the only time I use full poweer is in knife edge pulling the bottom of the figure M.

The Set-up in my 47" Osiris is
130g Omega 870Kv Motor
4s 30c 2650mAh Lipo
Cobra 60A ESC w/6.0v SBEC
11x8e APC Prop
Hyperion Atlas DS-11 AMB Digital Servos
I'm pulling 45A on the 11x8e prop 45x14= 630 Watts.

Im not gonna beat up the motor that much with the 11x8.5Apc E prop,if it does pull more then 50 amps and 700 watts,
like you said thats what the throttle is for off,and on..
I do love speed though and i think the Osiris is gonna be a fast plane with my setup,i have a ICE 75,and a 4s,3300 mah ,but i'll get it to balance just fine.
I cant wait to build it its coming from Espirit models this thursday,plus i start my vacation that day...Cant wait to fly her!!
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