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Correct propeller pitch

Old 04-12-2016, 04:51 AM
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Default Correct propeller pitch

I am new to this hobby and have managed to totally confuse myself regarding a correct prop pitch. The motor is a Emax CF2805, 1300kv motor.
The manufacturer's suggested prop length (5" to 6") is printed on the motor. I have researched prop information and have not been able to understand what pitch would be best. I am planning on using a 12 amp ESC. I think a 6X4 prop would be correct, but I am not sure. Any help will be greatly appreciated.
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Old 04-12-2016, 06:04 AM
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Here is a prop chart from HeadsupRC. What plane you will be flying and its anticipated weight would be helpful, others here can advise on prop and ESC choices.

Propeller Test Data for the Emax CF2805 1300kv:

Battery Size Propeller Size Thrust (oz.) Amps Additional Notes
3-Cell 11.1v APC 9 x 3.8SF 20 oz. 12 amps
3-Cell 11.1v GWS 9047 19 oz. 12 amps
3-Cell 11.1v GWS 9050 19 oz. 11 amps
3-Cell 11.1v APC 8 x 3.8SF 18 oz. 11 amps
3-Cell 11.1v GWS 8040 16 oz. 8 amps
3-Cell 11.1v GWS 8043 16 oz. 9 amps 32mph pitch speed
3-Cell 11.1v GWS HD8060 16 oz. 11 amps 44mph pitch speed
3-Cell 11.1v APC 8 x 6SF 16 oz. 12 amps
3-Cell 11.1v APC 7 x 3.8WSF 16 oz. 9 amps
3-Cell 11.1v APC 7 x 4E 15 oz. 8 amps
3-Cell 11.1v APC 7 x 6E 13 oz. 9 amps
2-Cell 7.4v APC 10 x 4.7SF 13 oz. 9 anps
2-Cell 7.4v GWS 1060 13 oz. 8 amps
2-Cell 7.4v APC 9 x 3.8SF 12 oz. 7 amps
2-Cell 7.4v GWS 9050 12 oz. 7 amps
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Old 04-20-2016, 09:23 PM
Rockin Robbins
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Heads Up RC not only gives you that information, but they don't just relay manufacturer claims. The numbers you get from them are the result of actual testing done by Heads Up. That's going the extra mile to ensure that customers buy what they need!
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Old 04-20-2016, 09:47 PM
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Note the pitch speeds..

That is important information.

You want to select a pitch speed appropriate for the model.

High pitch speed on a draggy slow floater and all you are doing is trying to beat the air into submission, wasting a lot of power.
Low pitch speed on a high speed design aircraft and you may never even get the speed required to take off.

So to recommend a specific prop, we need to know what aircraft.
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Old 04-21-2016, 02:51 AM
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( I am planning on using a 12 amp ESC. )

use a 20 amp esc, its best to use a esc thats bigger than whats needed, it will stay cooler and last longer, it wont be working at its max amperage and chances are it wont burn out on you, and you wont see the Magic Smoke
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Old 04-21-2016, 07:35 AM
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As a rule of thumb based on p/d ratio (pitch divided by diameter):
  • 'General all round', sports planes, scale and trainers : around 0.7
  • 3D planes and slow flyers: around 0.5
  • Racers and speed models: around 1.0
All figures are 'give or take'

Your suggested prop at 6x4 has a p/d ratio of 0.66 so that looks just right for a trainer type model or an all rounder..
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