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03232011, 02:54 AM  #1  
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Prop Selection
How do you tell if a prop is to small or to big in regards to burning up the ESC with out using the Motocalc ? Motocalc seams confusing to me. I see Heads up's prop sizing for the motor and the prop but it doesn't really explain how you come up with the AMP/Prop rating? Any help would be great. The search function explained allot but it didn't explain how you come up with it?? Thanks again everyone Richard 


03232011, 03:16 AM  #2  
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A watt meter is a "must have" tool for electric flight in my opinion. With a quick 10 second run up you would know for certain exactly how many amps/watts you are pulling for a given prop/motor combo.





03232011, 03:20 AM  #3  
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Two Words............Watt Meter....get one. I just got mine two wks ago, when you start upgrading, you are flying in the dark without one.
have a good one cr 


03232011, 03:21 AM  #4  
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lol tony you are a faster typist than I am......ez answer though
ltr cr top this.....lol(copy/paste is tha best) 271212 Specifications: Weight (motor only) = 0.9 ounces (25 grams) Diameter = 1.1 inch (28mm) Total Length = 1.7 inch (43mm) Shaft Length = 0.4 inch (10mm) Shaft Diameter = 3mm Voltage = 7 to 13 KV = 1300 Current = 10 amp max. Propeller data for 3 cell Lipo batteries: TheGWS EP 1060 produces about 18 ounces of thrust at 10 amps with a pitch speed of 34 mph. Avoid wide open throttle. TheGWS EP 9047 produces about 16 ounces of thrust at 9.5 amps with a pitch speed of 29 mph. The GWS EP 9050 produces about 17 ounces of thrust at 9 amps with a pitch speed of 34 mph. Excellent choice for power and speed. The APC 9x6E produces about 17 ounces of thrust at 10 amps with a pitch speed of 36 mph. Avoid wide open throttle. The APC 9x3.8SF produces about 18 ounces of thrust at 9.5 amps with a pitch speed of 25 mph. The APC 8x3.8SF produces about 15 ounces of thrust at 8 amps with a pitch speed of 29 mph. TheGWS EP 8040 produces about 15 ounces of thrust at 6 amps with a pitch speed of 35 mph. TheGWS EP 8043 produces about 14.5 ounces of thrust at 6.5 amps with a pitch speed of 32 mph. TheGWS EP 8060 produces about 14 ounces of thrust at 8.5 amps with a pitch speed of 40 mph. TheGWS HD 8060 produces about 14 ounces of thrust at 8.5 amps with a pitch speed of 44 mph. TheTP 8x6 produces about 13 ounces of thrust at 8.5 amps with a pitch speed of 40 mph. TheMaster Airscrew 8x6 3blade produces about 13 ounces of thrust at 9 amps with a pitch speed of 40 mph. TheGWS EP 7035 produces about 9 ounces of thrust at 3.5 amps with a pitch speed of 37 mph. TheMaster Airscrew 7x4 3blade produces about 10 ounces of thrust at 7.5 amps with a pitch speed of 36 mph. TheGWS EP 7060 produces about 12 ounces of thrust at 7 amps with a pitch speed of 45 mph. TheTP 7x6 produces about 12 ounces of thrust at 6 amps with a pitch speed of 51 mph. Propeller data for 2 cell Lipo batteries: TheGWS EP 1147 produces about 12.5 ounces of thrust at 8 amps with a pitch speed of 18 mph. TheGWS EP 1047 produces about 12 ounces of thrust at 7.5 amps with a pitch speed of 20 mph. The GWS EP1060 produces about 12 ounces of thrust at 6.5 amps with a pitch speed of 28 mph. TheGWS EP 9047 produces about 11 ounces of thrust at 5.5 amps with a pitch speed of 24 mph. TheGWS EP 9050 produces about 10.5 ounces of thrust at 5 amps with a pitch speed of 28 mph. The TP 9x6E produces about 11 ounces of thrust at 6 amps with a pitch speed of 29 mph. TheGWS EP 9070 produces about 9.5 ounces of thrust at 7 amps with a pitch speed of 30 mph. TheGWS EP 8040 produces about 8 ounces of thrust at 3.5 amps with a pitch speed of 26 mph. TheGWS EP 8043 produces about 9 ounces of thrust at 4.5 amps with a pitch speed of 26 mph. TheGWS EP 8060 produces about 8.5 ounces of thrust at 5.5 amps with a pitch speed of 32 mph. TheGWS HD 8060 produces about 8.5 ounces of thrust at 5 amps with a pitch speed of 35 mph. TheGWS EP 7060 produces about 7.5 ounces of thrust at 4.5 amps with a pitch speed of 36 mph. The above data is a result of our own testing using fully charged Lipo batteries. 


03232011, 03:22 AM  #5  
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If Jeff recommended the setup you will not have a problem. He tests his motors with different props for a safe combo with the recommend ESC he sells.
One vendor you can trust to post true facts and not inflated ones. Here is the setup that he psoted for that motor. The GWS EP 9050 produces about 17 ounces of thrust at 9 amps with a pitch speed of 34 mph. Excellent choice for power and speed 


03232011, 04:12 AM  #6  
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Hose Man I have the very same setup in MY mini cub and I use the GWS 8040 prop. Trust me, it's more than enough. You get the same performance that the 9050 gives you (only 2oz difference BUT less amp draw) AND longer flight time per battery pack because of that.
The mini cub only weighs around 7 to 8 ounces, so the difference between 15 and 17 ounces of thrust doesn't really make much difference in it's overall performance. The pitch speed is pretty much the same and you're drawing 3 less amps from your battery. Just my $0.02 on that. 


03232011, 02:25 PM  #7  
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Thank you everyone, I guess a wattmeter is in my future. I see that Jeff has one at Heads Up anybody used that one before??
BombDropper What are your flight times with the similar set up? What prop sizes have you tried? Thanks Richard 


03232011, 02:57 PM  #8  
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Originally Posted by Hose Man
I haven't tried Jeff's watt meter, but I have the WattsUp Meter that is sold by many places. It's saved my butt more times than I would like to admit lol.
As for my flight times and prop choices, I used Jeff's web page as my bible. I've use the GWS 9050, 8040, 8060 and 7060 props, on various setups from the mini cub, to small profile 3D foamies. But sticking to the mini cubs needs, with the 9050 and a 640mAh lipo pack, I got about 7 to 8 minutes.. and with the 8040 on the same battery pack, my flight times increased to about 12 to 14 minutes. And the performance was almost identical because the plane is so light (at 78oz AUW). I've used 1300mAh lipo packs with the same 8040 prop and flown my small profile 3D Yak for over 25 minutes using this motor. 



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