Cobra CM-2217/26 Motor Propeller Data
Magnets Motor Wind Motor Kv No-Load Current Motor Resistance I Max P Max (4S)
14-Pole 26-Turn Delta 695 RPM/Volt Io = 0.36 Amps @ 12v Rm = 0.179 Ohms 16 Amps 235 W
 
Stator Outside Diameter Body Length Total Shaft Length Shaft Diameter Motor Weight
12-Slot 27.7 mm,  1.091 in. 33.0 mm,  1.299 in. 30.1 mm,  1.185 in. 3.17 mm,  0.125 in. 81.2 gm,   2.86 oz
 
Test Data From Input 10.0 V 12.0 V 14.0V 16.0V Measured Kv value Measured Rm Value
Sample Motor Io Value 0.33 A 0.36 A 0.39 A 0.43 A 660 RPM/Volt @ 10v 0.179 Ohms
 
Prop Prop Li-Po Input Motor Input Prop Pitch Speed Thrust  Thrust Thrust Eff.
Manf. Size Cells Voltage Amps Watts RPM in MPH Grams Ounces Grams/W
APC 11x4.5 MR 3 11.1 7.35 81.6 5,952 25.4 693 24.44 8.49
APC 12x4.5 MR 3 11.1 9.25 102.7 5,576 23.8 840 29.63 8.18
APC 14x5.5 MR 3 11.1 13.50 149.9 4,818 25.1 1097 38.70 7.32
GemFan 11x4.7 MR 3 11.1 8.99 99.8 5,639 25.1 778 27.44 7.80
GemFan 12x4.5 MR 3 11.1 10.75 119.3 5,300 22.6 819 28.89 6.86
GemFan 11x4 MR-W 3 11.1 6.81 75.6 6,038 22.9 639 22.54 8.45
GemFan 12x4 MR-W 3 11.1 8.87 98.5 5,666 21.5 782 27.58 7.94
GemFan 13x4.5 MR-W 3 11.1 10.64 118.1 5,340 22.8 909 32.06 7.70
GemFan 14x4.5 MR-W 3 11.1 12.25 136.0 5,075 21.6 1032 36.40 7.59
GemFan 15x4.5 MR-W 3 11.1 12.84 142.5 4,931 21.0 1061 37.43 7.44
GemFan 16x4.5 MR-W 3 11.1 16.02 177.8 4,324 18.4 1182 41.69 6.65
RC-Timer 11x5.5-CF 3 11.1 7.51 83.4 5,919 30.8 641 22.61 7.69
RC-Timer 12x5.5-CF 3 11.1 10.69 118.7 5,328 27.8 831 29.31 7.00
RC-Timer 13x5.5-CF 3 11.1 13.02 144.5 4,888 25.5 956 33.72 6.61
RC-Timer 14x5.5-CF 3 11.1 15.73 174.6 4,300 22.4 1025 36.16 5.87
RC-Timer 15x5.5-CF 3 11.1 18.38 204.0 3,775 19.7 1109 39.12 5.44
 
Prop Prop Li-Po Input Motor Input Prop Pitch Speed Thrust  Thrust Thrust Eff.
Manf. Size Cells Voltage Amps Watts RPM in MPH Grams Ounces Grams/W
APC 10x4.5 MR 4 14.8 9.57 141.6 7,782 33.2 937 33.05 6.62
APC 11x4.5 MR 4 14.8 11.58 171.4 7,387 31.5 1127 39.75 6.58
APC 12x4.5 MR 4 14.8 14.11 208.8 6,818 29.1 1295 45.68 6.20
GemFan 8x4.5 MR 4 14.8 6.83 101.1 8,328 35.5 660 23.28 6.53
GemFan 9x4.7 MR 4 14.8 7.79 115.3 8,127 36.2 771 27.20 6.69
GemFan 10x4.5 MR 4 14.8 11.26 166.6 7,434 31.7 1013 35.73 6.08
GemFan 11x4.7 MR 4 14.8 13.73 203.2 6,930 30.8 1216 42.89 5.98
GemFan 12x4.5 MR 4 14.8 15.85 234.6 6,423 27.4 1234 43.53 5.26
GemFan 10x4 MR-W 4 14.8 9.80 145.0 7,722 29.3 926 32.66 6.38
GemFan 11x4 MR-W 4 14.8 10.50 155.4 7,583 28.7 1034 36.47 6.65
GemFan 12x4 MR-W 4 14.8 13.22 195.7 7,005 26.5 1218 42.96 6.23
GemFan 13x4.5 MR-W 4 14.8 15.47 229.0 6,484 27.6 1365 48.15 5.96
RC-Timer 10x5.5-CF 4 14.8 8.38 124.0 8,009 41.7 821 28.96 6.62
RC-Timer 11x5.5-CF 4 14.8 11.74 173.8 7,331 38.2 1034 36.47 5.95
RC-Timer 12x5.5-CF 4 14.8 16.05 237.5 6,386 33.3 1250 44.09 5.26
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, at an altitude of
512 feet above sea level.  The test voltages used are based on the standard output of a Li-Po battery under load, which is 3.70 volts
per cell.  If you are using a battery that is larger in capacity than normal, or has a very high C-rating, then your actual voltages will
be higher than those shown in the chart, and this will result in a higher current and power value for every prop used.  You should
always test your actual power system with a watt meter before flying your model to make sure that you are not exceeding the 
recommended current and power ratings of the motor being used.  The prop recommendations in this chart assume that the motor
receives adequate cooling throughout its operation.  If your motor is being used inside a cowl or fuselage, you must ensure that
the motor receives sufficient airflow, and does not get too hot during operation.  It is always best to use a prop size that pulls no
more than 80% of the motors maximum recommended current value to ensure safe operation under all conditions.