Cobra C2217/20 Motor Propeller Data
Motor Wind Motor Kv No-Load Current Motor Resistance I Max P Max (3S)
20-Turn Delta 960 RPM/Volt Io = 0.55 Amps @ 8v Rm = 0.110 Ohms 20 Amps 220 W 
 
Outside Diameter Body Length Total Shaft Length Shaft Diameter Motor Weight
27.7 mm,  1.09 in. 33.0 mm,  1.30 in. 47.0 mm,  1.85 in. 3.17 mm,  0.125 in. 72.0 gm,   2.54 oz
 
Prop Prop Input Motor Watts Prop Pitch Thrust  Thrust Thrust Eff.
Manf. Size Voltage Amps Input RPM Speed Grams Ounces Grams/W
APC 9x6-SF 7.4 8.37 61.9 5,326 30.3 459 16.19 7.41
APC 9x7.5-SF 7.4 9.66 71.5 5,110 36.3 453 15.98 6.34
APC 10x3.8-SF 7.4 7.61 56.3 5,450 19.6 494 17.43 8.77
APC 10x4.7-SF 7.4 8.45 62.5 5,320 23.7 534 18.84 8.54
APC 10x7-SF 7.4 11.04 81.7 4,900 32.5 572 20.18 7.00
APC 11x3.8-SF 7.4 8.45 62.5 5,300 19.1 556 19.61 8.89
APC 11x4.7-SF 7.4 10.35 76.6 5,000 22.3 634 22.36 8.28
APC 11x7-SF 7.4 13.44 99.5 4,520 30.0 690 24.34 6.94
APC 12x3.8-SF 7.4 11.71 86.7 4,780 17.2 697 24.59 8.04
APC 12x6-E 7.4 10.62 78.6 4,970 28.2 672 23.70 8.55
APC 12x6-SF 7.4 14.77 109.3 4,270 24.3 775 27.34 7.09
APC 12x8-E 7.4 13.05 96.6 4,590 34.8 606 21.38 6.28
APC 12x8-SF 7.4 16.45 121.7 3,950 29.9 753 26.56 6.19
APC 13x4.7-SF 7.4 14.45 106.9 4,310 19.2 791 27.90 7.40
APC 13x6.5-E 7.4 13.40 99.2 4,520 27.8 771 27.20 7.78
APC 13x8-E 7.4 14.47 107.1 4,340 32.9 762 26.88 7.12
APC 14x7-E 7.4 15.28 113.1 4,210 27.9 841 29.67 7.44
 
Prop Prop Input Motor Watts Prop Pitch Thrust  Thrust Thrust Eff.
Manf. Size Voltage Amps Input RPM Speed Grams Ounces Grams/W
APC 9x3.8-SF 11.1 9.88 109.7 8,160 29.4 737 26.00 6.72
APC 9x4.7-SF 11.1 9.93 110.2 8,140 36.2 743 26.21 6.74
APC 9x6-SF 11.1 15.80 175.4 7,020 39.9 835 29.45 4.76
APC 9x7.5-E 11.1 17.59 195.2 6,680 47.4 786 27.73 4.03
APC 10x3.8-SF 11.1 14.63 162.4 7,250 26.1 978 34.50 6.02
APC 10x4.7-SF 11.1 15.60 173.2 7,060 31.4 997 35.17 5.76
APC 10x5-E 11.1 12.13 134.6 7,720 36.6 871 30.72 6.47
APC 10x6-E 11.1 13.17 146.2 7,550 42.9 906 31.96 6.20
APC 10x7-E 11.1 14.75 163.7 7,240 48.0 916 32.31 5.59
APC 11x3.8-SF 11.1 15.79 175.3 6,990 25.2 1060 37.39 6.05
APC 11x4.7-SF 11.1 18.31 203.2 6,500 28.9 1142 40.28 5.62
APC 11x5.5-E 11.1 15.56 172.7 7,090 36.9 1052 37.11 6.09
APC 11x7-E 11.1 17.51 194.4 6,690 44.3 1056 37.25 5.43
APC 11x8-E 11.1 18.46 204.9 6,480 49.1 1040 36.68 5.08
APC 11x8.5-E 11.1 19.25 213.7 6,260 47.4 994 35.06 4.65
APC 12x3.8-SF 11.1 20.36 226.0 6,000 21.6 1207 42.58 5.34
APC 12x6-E 11.1 18.46 204.9 6,450 36.6 1189 41.94 5.80
APC 13x4-E 11.1 16.95 188.1 6,790 25.7 1223 43.14 6.50
GWS 9x5x3-DD 11.1 10.97 121.8 7,940 37.6 778 27.44 6.39
GWS 10x6-DD 11.1 11.71 130.0 7,830 44.5 845 29.81 6.50
GWS 10x6x3-DD 11.1 14.57 161.7 7,234 41.1 969 34.18 5.99
GWS 10x8-HD 11.1 17.29 191.9 6,724 38.2 818 28.85 4.26
GWS 11x7-DD 11.1 16.39 181.9 6,910 45.8 1077 37.99 5.92
 
Prop Prop Input Motor Watts Prop Pitch Thrust  Thrust Thrust Eff.
Manf. Size Voltage Amps Input RPM Speed Grams Ounces Grams/W
APC 7x5-E 14.8 8.80 130.2 11,460 54.3 602 21.23 4.62
APC 7x6-E 14.8 9.29 137.5 11,360 64.5 658 23.21 4.79
APC 8x4-E 14.8 10.30 152.4 11,150 42.2 819 28.89 5.37
APC 8x6-E 14.8 14.64 216.7 10,240 58.2 920 32.45 4.25
APC 8x8-E 14.8 18.43 272.8 9,470 71.7 795 28.04 2.91
APC 9x4.5-E 14.8 14.22 210.5 10,310 43.9 1112 39.22 5.28
APC 9x6-E 14.8 16.25 240.5 9,900 56.3 1158 40.85 4.81
APC 9x7.5-E 14.8 20.64 305.5 8,860 62.9 1135 40.04 3.72
APC 10x5-E 14.8 18.13 268.3 9,370 44.4 1303 45.96 4.86
                   
Propeller Chart Color Code Explanation
   The prop is to small to get good performance from the motor. (Less than 50% power)
   The prop is sized right to get good power from the motor. (50 to 80% power)
   The prop can be used, but full throttle should be kept to short bursts. (80 to 100% power)
   The prop is too big for the motor and should not be used. (Over 100% power)
PLEASE NOTE: 
The data contained in this prop chart is based on actual measurements taken in a controlled test 
environment.  The test voltages used are based on a properly sized Li-Po battery for the current
draw of the motor being tested.  If you are using a larger than normal capacity battery, or a very
high C-Rated battery, your actual voltages will be higher than those shown in this chart, and this
will result in higer current draw for each prop used.  You should always test your power system
with a watt meter whenever a prop is used to ensure that you are not exceeding the recommended
rating of the motor being used.  The prop recommendations in this chart are based on the motor
receiving adequate cooling throughout its operation.  If your motor is being used inside a cowl, you
must provide adequate cooling to the motor and make sure that the motor is not getting too hot
during operation.