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motor size ??

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Old 08-24-2003, 04:22 PM
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Snowball1952
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Default motor size ??

ok you say s615 or s625 or 15G -25G . I keep seeing size like 400-480-280-600 so what is the difference? which would be a good engine without going broke?
Thanks again
Kevin
P.S. I am getting there
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Old 08-24-2003, 11:30 PM
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Default motor size ??

in teh case of 400, 480, 280, and 600, it's motor can length.

IE. a 400 motor's can nis 40mm long.
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Old 08-24-2003, 11:56 PM
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Snowball1952
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Default ok then what is 15G or 25G

ok thenwhat are the 615G 625G 15G 25G

I havea 3.25 lbs plane I want to make it electric. How many cells what size and what is a fair motor at a fair price.

Porfeild Collegiate Wing span 69.5"
Wing area 675.2

I was told use a AF 615G or 625G geared or 15 G geared or 25G geared.

All I am finding is 280- 600- 480 nothing like what I have mentioned.
Thanks
Kevin

What size glow would this take??? Maybe better.
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Old 08-25-2003, 05:07 AM
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Default motor size ??

Glow... depends. high wing or low wing?? Proably a .32-.40 if it's low and a .25 to .32 high.

Those other motor sizes you mentioned sound like varieties of Brushless motors to me. In that case, each brand is different in their nomenclature.
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Old 08-25-2003, 10:44 AM
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Matt Kirsch
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Default motor size ??

The numbers in front of the motors are essentially meaningless. They are simply model names/numbers, like a car: Graupner Speed 400 == Toyota Corolla.

You can't tell anything about a car, let alone compare different brands of cars by just looking at the model name. You need to compare the specifications of the car to see if one compares to another. If you're looking for a midsize sedan, do you want a Chevy Silverado or a Dodge Caravan? Once you look at the specifications for the two vehicles, you'll realize that one's a pickup truck and the other's a minivan. Neither is the midsize sedan you're looking for.

The same is true for motors. You can't just look at a motor's model name and decide if it's suitable for a particular airplane or not. Even if the 280, 400, 600, etc. numbers indicate the length of the armature (THEY DON'T, just measure the armatures and you'll see), that says nothing about the capapicity of the motor, how much power it can efficiently transfer from the battery to the propeller.

To effectively choose a motor, you need to have an idea of the power requirements for your plane (cell count and a current), then it's a simple matter of picking from a catalog. Things become a lot easier if you develop a brand loyalty. Most brushless motors are very good at what they do, so choosing one brand and sticking with it is simpler than you might think.
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Old 08-25-2003, 11:44 PM
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Default 615G etc

Seems no one answered your original question - i.e. what the hell is a 615 or 625G? I would suggest that these numbers refer to Astro Cobalt Sport Scale motors as listed by www.newcreations-rc.com. Basically, the larger the number the more powerful the motor. This number seems to be related, indirectly, to glow equivalents and is used to designate certain FAI competition classes. The range includes 603 (otherwise referred to as an 035 motor), 605 (= an 05 motor), 615 (=15 motor), 625 (=25 motor) ..............

The suffix G simply means geared, S is a special gear ratio, and P means planetary.

The ones you refer directly to are as follows:

615 :Wt 7.25oz, prop 8x5, prop rpm 12770. 12 cells, amp draw 28A, Cost $125.95

615G: Wt 8.5oz, geared 2.38:1, prop 12x8, prop rpm 6740, 12 cells, amp draw 25A, Cost $147.95

625: Wt 11.75oz, prop 9x5, prop rpm 12930, 16 cells, amp draw 30A, Cost $120.95

625G: Wt 13.25oz, geared 1.63:1, prop11x7, prop rpm 8690, 16 cells, amp draw 30A, cost $161.95.


Hope this helps you out, Cheers, Phil
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Old 08-25-2003, 11:58 PM
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Default thank you Dr. Phil

thanks
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Old 08-26-2003, 01:04 AM
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Jim Finn
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Default motor size ??

to help with learning which motor /gear/prop/cell count etc to try you should get Electracalc or motocalc. These are $40 computer programs with all the answers. Not super accurate but they will show you how changing the variables mentioned will effect performance.
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