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Old Aug 13, 2002, 07:14 PM
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Mike Palko's Avatar
Telford Pa
Joined Aug 2002
278 Posts
Help me pick a brushless motor or point me in the right direction.

I would like any help or suggestions on picking a motor. I want maximum flight time and performance so i have decided to go brushless. The only problem is i have no idea how to pick a brushless motor. I am hopeing that if i tell you guys what i am looking for you could help me out.

I want a brushless motor and contoller that will give me about 45oz of thrust minimum 50oz would be better 55ozwould be great ect... I want to run 10-12 cells preferably 10cells. I would like to use a 10-11 inch prop between 4 and 6 pitch so the rpm may have to be pretty high to get the thrust i need. I want to pull 35amps or less 30 is better 25 is great ect...and this has to be able to do this continuously. I don't care if the motor is geared but to run a low pitch it might not be able to run a gear box. I also want the weight of the motor and controller to be 8.5oz or less.

This is a lot of requirements but this motor does not need to meet all of them. I think the more info i give you the better/easier it is for you to help me. I think the hardest variable i mentioned to meet is the prop pitch vrs. thrust. The prop does not have to be those sizes if it's not possible. Any help that can be given would be very appreciated!!! Thanks Mike
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Old Aug 13, 2002, 07:37 PM
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South US, by Cracky!
Joined Jul 2002
135 Posts
B/L Motor

I would suggest you read the "Throw away your S400 can motors" thread (I assume you're young enough to finish it).
It has a lot of info & testing results on the small Mega motors. Then read other posts about the larger Mega models & it will give you a good reference point. After that, you can check out the competition. Bottom line, from what I've read here, you will love the brushless motors.
Good luck,
BD


In my next life, I will be known as Dun Dat!
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Old Aug 13, 2002, 08:09 PM
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kmashima's Avatar
San Jose, California, United States
Joined Feb 2002
2,136 Posts
You need to provide information about the plane you are planning to use this motor in. It will have a big impact on your flight time and overall performance for the motor setup you are talking about. Need wingspan, wing area, weight without motor and batteries (but with everything else), thickness of wing relative to chord, style of plane (high wing trainer, low wing aerobatic, etc.).

Also, it helps to learn to use one of the computer programs -- motocalc or ecalc. You can download motocalc for 30days free at www.motocalc.com.
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Old Aug 13, 2002, 08:10 PM
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San Jose, California, United States
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forgot one item -- type of airfoil -- symmetric, flat bottom, etc.
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Old Aug 13, 2002, 09:08 PM
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Mike Palko's Avatar
Telford Pa
Joined Aug 2002
278 Posts
Here are some of the specs of the approximate airplane. Wingspan 48-52", wing area 480-520sq in, weight w/o motor and batteries 10-14oz, hopefully auw will be between 40-45oz, symetric airfoil, mid wing aerobatic plane. Hope some of this helps.
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Old Aug 14, 2002, 01:06 AM
BEC
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Auburn, Washington USA
Joined Jan 2001
12,940 Posts
Model Motors AXI 2820/10. 10 cells, 12X6 APC-E at 7700 RPM - calculated 59 ounces of thrust. Flies a much bigger plane well for me.... say 5 1/4 lbs., 810 square inches.

Sounds like you're thinking of a competition "fun-fly" type of plane and a prop you'd use on a O.S. .32.

With the right electric motor you can swing a much larger prop.....
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Old Aug 14, 2002, 07:42 AM
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Czech Republic, Plzeň Region, Město Touškov
Joined Feb 2002
535 Posts
I'd have to agree with BEC. My AXI 2820/10 runs 8 cells on a 12x6 APC'E' and takes my 56oz Pilot 'Seduction' off the floor into a near vertical climb. Not continuous climb on 8 cells, but with 10 cells I think it would be.
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Old Aug 14, 2002, 02:11 PM
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Apex, NC
Joined Jan 2002
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I recently installed the AXI 2820/10 with the Jeti 40 3P on a PT Electric trainer with an all up weight of about 50 oz (56" span, 500 square in).

The airplane goes vertical on 10x1700SCR NiCad with an 11x7 prop. It went from praying you could make it off the ground (Mag Mayhem / MAS 2.5 gearbox with 8 cells on same prop) to very insane.

I entered a 10 min duration with one minute climb last weekend. The airplane out climbed an F5B type machine. I shut the power off after 50 sec because the PT was a tiny dot in the sky. After I came in second (with a trainer) I took off and flew around for another 10 minutes on the same pack.

I measured the input at 39 amps and 407 watts.

Simple to install.

Victor
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Old Aug 14, 2002, 05:56 PM
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Telford Pa
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That helps alot!!! Where can i find info/pricing about the AXI 2820/10? What gearbox and ratio are you using? I have been doing some searching but the best way is to see what others are actually using and how it works for them. Any other setup's out there you want to mention would be appreciated. The more the better. Thanks again Mike
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Old Aug 15, 2002, 03:00 PM
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Apex, NC
Joined Jan 2002
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AXI is direct drive. Very simple and very powerful.

Hobby Lobby has the best price. Maybe if you push them a little they will cut you a deal.

Victor
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Old Aug 15, 2002, 05:37 PM
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Mike Palko's Avatar
Telford Pa
Joined Aug 2002
278 Posts
Thanks for all the replies. The motor that you guys talked most about AXI 2820/10 sounds like a very powerful motor. How does it compare to aveox or mega or astro?

One more question. How can this motor make so much power w/o a gearbox? How is it that the amp draw doesn't go way up? Thanks again Mike Palko
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Old Aug 15, 2002, 05:52 PM
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Atlanta Hartsfield, Georgia, United States
Joined Apr 2002
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I swing a graupner 10x6 folder on an electrostreak arf with a jeti 30/3 brushless and 40-3p esc. It's difficult to measure static thrust, since no landing gear, but I had the same motor/esc in a previous glider/trainer plane (folded the wings in a high speed dive/pullout) with landing gear. Attaching to a 10-lb scale, an 11x4 master airscrew pulled 42 oz static thrust. I didn't have my whattmeter then, but I think it was in the 35-40 amp range.

In my current setup, the aerobatic e-streak goes nearly vertical from level flight with the 10x6 (20-25 amps). I have an 11x7 but don't have the guts to push myself or the new plane outside the envelope (yet).

All-up weight of the electrostreak (before I extended the wings) was 54 oz (8 cells, 3000 NiMH).

Hope this helps as a comparison.

-- John
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Old Aug 15, 2002, 06:16 PM
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Apex, NC
Joined Jan 2002
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The AXI is a rotating a can (outside rotates with the neo magnets). So, the magnets are further away from the shaft center than when they are mounted on the armature (larger moment arm) and therefore have greater leverage over the propeller.

Victor
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Old Aug 15, 2002, 06:45 PM
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Mike Palko's Avatar
Telford Pa
Joined Aug 2002
278 Posts
I just looked on hobby lobby's site. I read the review and it was very helpful to me. Will this motor AXI 2820/10 turn higher and higher rpm if you put a smaller diam or pitch prop on it? If i am right the rpm's don't change drastically on my astro geared motor whether you put a 9" prop or 12" prop. Is that due to the gearbox?
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Old Aug 15, 2002, 07:05 PM
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Ryan Nau's Avatar
Elizabethville,PA USA
Joined Jul 2000
2,198 Posts
To get off the topic a little bit,
Mike, Didn't you use to fly control line at the Philly Fliers? I remember you and your name from up at the Brodak Flyins. And you flying a Brodak Accentor. Thats what I'm finishing up is the accentor, almost have it ready to put the silk span on. I'm looking foward to doing the finish on it this winter.
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