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Old Nov 16, 2006, 03:36 PM
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Thrust to Weight ratio?

How much thrust should I be looking for to do 3D with an AUW of around 16-20 oz?

THANKS!!
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Old Nov 16, 2006, 03:43 PM
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willhaney's Avatar
Fountain Valley, California
Joined Feb 2004
10,768 Posts
I like 2:1.
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Old Nov 16, 2006, 04:19 PM
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Just south of Cambridge, UK
Joined Oct 2003
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1.5:1 is about minimum desirable, anything over is great! 2:1 is about perfect, when you approach 3:1 it is sometimes difficult to control the power
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Old Nov 16, 2006, 04:29 PM
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So any suggestions on cheap motors in the 30-40oz thrust range... You knew that question was coming.
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Old Nov 16, 2006, 04:37 PM
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check united hobbies, xus, or grayson
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Old Nov 16, 2006, 04:42 PM
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United States, PA, Lancaster
Joined Jun 2003
24,141 Posts
Since most motors are not rated by thrust, I'd look for a motor capable of at least 20Amps with a Kv of 900-1100.
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Old Nov 16, 2006, 05:01 PM
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Hacker A20-20L
Hands down my favorite motor on models 16-21 oz.
I bought a knock off of this motor and it just wasn't as powerful imo.
You get what you pay for.
shawn
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Old Nov 16, 2006, 06:45 PM
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So what is THE best way to compare brushless motors? Watts? Amps?

I thought I understood this whole thing and now I'm starting to doubt myself.

I have seriously looked at about 50 posts and 100 different brushless motors in the last 4 days. Sorry guys, but electric flight is begining to seem like a real pain in the .

I just want to get out and fly this thing!!!!
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Old Nov 17, 2006, 12:13 AM
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United States, CO, Littleton
Joined Nov 2006
679 Posts
Quote:
Originally Posted by sbmon
Hacker A20-20L
Hands down my favorite motor on models 16-21 oz.
I bought a knock off of this motor and it just wasn't as powerful imo.
You get what you pay for.
shawn
I'd have to agree here. I had a hyperion extra 300L with the a20-20l and a 10x4.7 prop and the thing pulled vertical so fast it was too far away to see in just a few seconds. I now have that motor on my mini ultra stick that weighs in at exactl 22 oz. It has unlimited vertical, though it would be tight for 3d performance (assuming hte control surfaces were a little bigger). No, I am not into the whole 3d thing, but I am just backing up sbmon that this motor is great, very quiet, and has plenty of power. I would highly suggest it.
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Old Nov 17, 2006, 12:38 AM
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Christchurch, New Zealand
Joined Jun 2006
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Electric flight is about calculating what the motors can do. Go download motocalc and play around with it. That'll give you a much better idea; performance is a consequence of a whole bunch of factors, and it's better to do the math (or have some software do it for you) than to guess.
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Old Nov 18, 2006, 04:08 PM
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United States, AZ, Tucson
Joined May 2004
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Thrust-to-weight is usually best calculated in watts/pound. Ideally, you want a MINIMUM of 150-160 watts/pound, but ideally, 200+ is better, especially if you just want to show off your hover-pullout authority.
The A20-20L with a 10X4.7 or the EF Torque 22t-930 with an 11X4.7 (the two motors that I have the most experience with) would haul a 16-21 ounce plane quite well.
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