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Old Feb 29, 2012, 08:28 PM
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need advice. prop for large scale electric warbird.


I just ordered the new ESM Texan II from Troybuiltmodels.com
80" wingspan, in the range of 18-21 lbs AUW.

Another RCG member electrified the ESM Hurricane, which is roughly the same size and weight with an E-Flite Power 160 on 12s 5000.

Since I have a handful of 12S 5000 packs, Im going 12S as well, and my motor choice was the Monster Power 160. My esc is undetermined yet.

However, I want to run a 4-blade prop. SInce this is setup for gas, they recommend an 18x10 4-blade.
Im not sure:
a.) what size prop to go with
b.) what ESC (leaning towards a CC 120HV)

Thanks in advance for any advice.
Matt

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Last edited by Matt Gunn; Mar 07, 2012 at 09:34 PM.
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Old Mar 07, 2012, 09:33 PM
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No replies... HMM, maybe I can narrow it down


I bought the Eflite Power 160 and it will be on 12S 5000. ESC is the CC ICE2 120HV.

Should I go with the 17.3x8 4-blade, or 18x10 4-blade?
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Old Mar 08, 2012, 03:22 AM
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As long as you're not over Amping things, go with the 18x10 for moar speed!
Old Mar 11, 2012, 10:56 AM
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Hi webdr

Due to motor spec. of the eflight power 160 the max continous current is 60 A. With a 17.3x8 4-blade, or 18x10 4-blade the motor current
is too high. I would try an apc 16x10 or 16x12 2-blade prop. The prop efficiency of a 2-blade is also much higher compared to a 4-blade prop.

Maybe you can find a 15x10 or 15x12 3-blade prop.


Best regards
Micha
Old Mar 11, 2012, 02:34 PM
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Yep. I ended up going with a 16x8 4blade. Thanks
Matt
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Old Mar 12, 2012, 02:30 PM
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Hi webdr

The pitch speed with a 16x8 4blade is maybe too low for your Texan II. I have calculated a speed of
22 m/s of your Texan II, horizontal flight. If the 16x8 4blade is to slow use e.g a 15x10 4blade prop.

Motor and speed calc see:

http://snoopy-schulz.square7.ch/

Best regards
Micha
Old Mar 12, 2012, 03:08 PM
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Im getting a little higher numbers from ecalc...around 64mph pitch speed.
However, Im taking your advice into consideration... a 15x10 does produce some sweet numbers.

74amps
89mph
400oz torque

On 12S.
I can drop it down to 10S and still pull 300oz of torque and 74mph


Menz makes a 15x10 4 blade. I'll try it out.
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Old Mar 12, 2012, 03:56 PM
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Hi webdr

My drive calculation as well as others is a point of start. Due to variation of prop, lipo and motor data it is
only a means to start. I would also use a watt meter to check the current/power.
Next point is than to see the performance during flight.

In the attachment i have a rough way to calculate the power needed to lift a model.

Best regards
Micha


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