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Old Oct 30, 2012, 08:53 PM
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United States, IN, Bloomington
Joined Sep 2012
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Looking at motors, want your opinion

http://www.hobbyking.com/hobbyking/s...dProduct=26823
http://www.rctimer.com/index.php?gOo...8&productname=

Friend gave me a beat up old cub with a 40 inch wingspan ~775g motorless.

Looking at these two motors for it. With a 10x4 E Prop.

Ecalc says it will pull just under 13 amp. with a 1.08:1 power to weight ratio.

Does this look ok? and which motor will be of higher quality? Or maybe you know of a better option?
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Old Oct 30, 2012, 10:33 PM
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Dr Kiwi's Avatar
Chattanooga, Tennessee, United States
Joined May 2003
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Personally I'd go with RC Timer.. generally better quality and better customer service.
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Old Oct 30, 2012, 10:53 PM
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scirocco's Avatar
Australia, ACT, Kambah
Joined Feb 2001
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Is that 775g motorless with or wthout battery? Anything else missing, eg ESC servos?

With motor, you're up near as darn it to 900g or 2lb minimum

IMO the motors look like very good choices, but the 10x4 is too low in pitch. 10x5 minimum and 10x7 preferable is likely to do better, as the pitch speed on the 10x4 is too close to stall speed. Also the 10x7 will give you a decent increase in thrust for about 60W extra power at full throttle.

Say 2lb and about 150W with the 10x5, efficient setup, reasonable size prop relative to wingspan, nice low wing loading - 75W/lb will be ample. Even if you have to add 200g for a 3S 2200, 60W/lb will be enough, but the 10x7 at 190W would definitley be a better choice.
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Old Oct 30, 2012, 10:58 PM
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Quote:
Originally Posted by scirocco View Post
Is that 775g motorless with or wthout battery? Anything else missing, eg ESC servos?

With motor, you're up near as darn it to 900g or 2lb minimum

IMO the motors look like very good choices, but the 10x4 is too low in pitch. 10x5 minimum and 10x7 preferable is likely to do better, as the pitch speed on the 10x4 is too close to stall speed. Also the 10x7 will give you a decent increase in thrust for about 60W extra power at full throttle.

Say 2lb and about 150W with the 10x5, efficient setup, reasonable size prop relative to wingspan, nice low wing loading - 75W/lb will be ample. Even if you have to add 200g for a 3S 2200, 60W/lb will be enough, but the 10x7 at 190W would definitley be a better choice.
Ok cool. Yeah that 775g without battery. So I think I'll take your advice and go for the 10x7.
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Old Oct 30, 2012, 11:36 PM
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The nice thing about the motor Kv and weight you've chosen is that they will work OK with 10" for the Cub, but should happily handle even a 12x8 prop, for nearer 300W - not that your Cub would need anywhere near that. But if an 11x8 fits, it would be a fun future experiment
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