Cobra CM-4006/36 500Kv Motor Propeller Data
Magnets Motor Wind Motor Kv No-Load Current Motor Resistance I Max P Max (6S)
22-Pole 36-Turn Wye 500 RPM/Volt Io = 0.82 Amps @ 21v Rm = 0.113 Ohms 19 Amps 420 W
 
Stator Outside Diameter Body Length Total Shaft Length Shaft Diameter Motor Weight
24-Slot 45.5 mm,  1.791 in. 22.0 mm,  0.866 in. 29.2 mm,  1.150 in. 4.00 mm,  0.157 in. 93 gm,   3.27 oz
 
Test Data From Input 12.0 V 15.0 V 18.0V 21.0V Measured Kv value Measured Rm Value
Sample Motor Io Value 0.625 A 0.713 A .744 A .815 A 537 RPM/Volt @ 21V 0.113 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 13x5.5-MR 3 11.1 8.57 95.1 4,840 25.2 865 30.51 9.09
APC 14x5.5-MR 3 11.1 10.32 114.6 4,642 24.2 1016 35.84 8.87
APC 16x5.5-MR 3 11.1 14.65 162.6 4,185 21.8 1320 46.56 8.12
GemFan 14x4.5-MR-W 3 11.1 9.04 100.3 4,780 20.4 909 32.06 9.06
GemFan 15x4.5-MR-W 3 11.1 9.60 106.6 4,721 20.1 948 33.44 8.90
GemFan 16x4.5-MR-W 3 11.1 12.76 141.6 4,368 18.6 1182 41.69 8.35
GemFan 18x5-MR-W 3 11.1 16.92 187.8 3,909 18.5 1389 49.00 7.40
RC-Timer 12x5.5-CF 3 11.1 7.72 85.7 4,928 25.7 714 25.19 8.33
RC-Timer 13x5.5-CF 3 11.1 9.89 109.8 4,685 24.4 869 30.65 7.92
RC-Timer 14x5.5-CF 3 11.1 13.27 147.3 4,335 22.6 1045 36.86 7.09
RC-Timer 15x5.5-CF 3 11.1 16.89 187.5 3,914 20.4 1196 42.19 6.38
 
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 4 14.8 7.94 117.5 6,713 35.0 895 31.57 7.62
APC 12x4.5-MR 4 14.8 10.20 151.0 6,443 33.6 1129 39.82 7.48
APC 13x5.5-MR 4 14.8 13.52 200.1 6,045 31.5 1382 48.75 6.91
APC 14x5.5-MR 4 14.8 16.18 239.5 5,725 29.8 1585 55.91 6.62
GemFan 11x4-MR-W 4 14.8 7.16 106.0 6,799 25.8 828 29.21 7.81
GemFan 12x4-MR-W 4 14.8 9.57 141.6 6,514 24.7 1054 37.18 7.44
GemFan 13x4.5-MR-W 4 14.8 11.87 175.7 6,237 26.6 1259 44.41 7.17
GemFan 14x4.5-MR-W 4 14.8 13.86 205.1 6,003 25.6 1440 50.79 7.02
GemFan 15x4.5-MR-W 4 14.8 15.06 222.9 5,855 25.0 1528 53.90 6.86
GemFan 16x4.5-MR-W 4 14.8 19.29 285.5 5,274 22.5 1752 61.80 6.14
RC-Timer 11x5.5-CF 4 14.8 8.20 121.4 6,684 34.8 849 29.95 7.00
RC-Timer 12x5.5-CF 4 14.8 12.51 185.1 6,182 32.2 1168 41.20 6.31
RC-Timer 13x5.5-CF 4 14.8 15.99 236.7 5,752 30.0 1380 48.68 5.83
RC-Timer 14x5.5-CF 4 14.8 20.61 305.0 5,118 26.7 1496 52.77 4.90
 
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 5 18.5 9.11 168.5 8,353 43.5 1064 37.53 6.31
APC 11x4.5-MR 5 18.5 11.49 212.6 8,036 41.9 1334 47.05 6.28
APC 12x4.5-MR 5 18.5 14.84 274.5 7,643 39.8 1652 58.27 6.02
APC 13x5.5-MR 5 18.5 19.22 355.6 7,008 36.5 1904 67.16 5.35
GemFan 10x4-MR-W 5 18.5 8.74 161.7 8,398 31.8 1042 36.76 6.44
GemFan 11x4-MR-W 5 18.5 10.18 188.3 8,209 31.1 1226 43.25 6.51
GemFan 12x4-MR-W 5 18.5 13.50 249.8 7,792 29.5 1528 53.90 6.12
GemFan 13x4.5-MR-W 5 18.5 16.76 310.1 7,338 31.3 1779 62.75 5.74
GemFan 14x4.5-MR-W 5 18.5 19.38 358.5 6,941 29.6 1956 69.00 5.46
RC-Timer 10x5.5-CF 5 18.5 7.87 145.6 8,506 44.3 915 32.28 6.28
RC-Timer 11x5.5-CF 5 18.5 11.91 220.3 7,980 41.6 1254 44.23 5.69
RC-Timer 12x5.5-CF 5 18.5 18.16 336.0 7,167 37.3 1629 57.46 4.85
RC-Timer 13x5.5-CF 5 18.5 23.20 429.2 6,502 33.9 1810 63.85 4.22
 
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 9x4.5-MR 6 22.2 9.27 205.8 10,103 43.1 1127 39.75 5.48
APC 10x4.5-MR 6 22.2 12.45 276.4 9,677 41.2 1473 51.96 5.33
APC 11x4.5-MR 6 22.2 15.49 343.9 9,216 39.3 1784 62.93 5.19
APC 12x4.5-MR 6 22.2 19.71 437.6 8,609 36.7 2121 74.82 4.85
GemFan 10x4-MR-W 6 22.2 11.69 259.5 9,770 37.0 1424 50.23 5.49
GemFan 11x4-MR-W 6 22.2 13.52 300.1 9,517 36.0 1656 58.41 5.52
GemFan 12x4-MR-W 6 22.2 17.74 393.8 8,911 33.8 2013 71.01 5.11
GemFan 13x4.5-MR-W 6 22.2 21.94 487.1 8,155 34.8 2215 78.13 4.55
RC-Timer 10x5.5-CF 6 22.2 10.74 238.4 9,901 51.6 1276 45.01 5.35
RC-Timer 11x5.5-CF 6 22.2 16.24 360.5 9,140 47.6 1683 59.37 4.67
RC-Timer 12x5.5-CF 6 22.2 24.46 543.0 7,906 41.2 2002 70.62 3.69
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.