Cobra CM-4515/18 435Kv Motor Propeller Data
Magnets Motor Wind Motor Kv No-Load Current Motor Resistance I Max P Max (6S)
14-Pole 18-Turn Delta 435 RPM/Volt Io = 1.11 Amps @ 21v Rm = 0.034 Ohms 54 Amps 1200 W
 
Stator Outside Diameter Body Length Total Shaft Length Shaft Diameter Motor Weight
12-Slot 54.9 mm,  2.161 in. 37.8 mm,  1.488 in. 43.3 mm,  1.705 in. 6.00 mm,  0.236 in. 273 gm,   9.63 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 0.88 A 0.95 A 1.03 A 1.11 A 428 RPM/Volt @ 15v 0.034 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 14x5.5-MR 5 18.5 20.04 370.7 6,931 36.1 2395 84.48 6.46
APC 16x5.5-MR 5 18.5 30.06 556.1 6,512 33.9 3450 121.69 6.20
APC 18x5.5-MR 5 18.5 39.48 730.4 6,154 32.1 4382 154.57 6.00
GemFan 15x4.5-MR 5 18.5 18.40 340.4 7,005 29.9 2309 81.45 6.78
GemFan 16x4.5-MR 5 18.5 24.58 454.7 6,735 28.7 2938 103.63 6.46
RC-Timer 13x5.5-CF 5 18.5 20.38 377.0 6,917 36.0 2129 75.10 5.65
RC-Timer 14x5.5-CF 5 18.5 27.87 515.6 6,600 34.4 2634 92.91 5.11
RC-Timer 15x5.5-CF 5 18.5 40.15 742.8 6,135 32.0 3290 116.05 4.43
RC-Timer 16x5.5-CF 5 18.5 44.62 825.5 5,906 30.8 3678 129.74 4.46
RC-Timer 17x5.5-CF 5 18.5 50.00 925.0 5,711 29.7 4084 144.06 4.42
RC-Timer 18x5.5-CF 5 18.5 60.37 1116.8 5,393 28.1 4742 167.27 4.25
 
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 6 22.2 22.14 491.5 8,273 43.1 2783 98.17 5.66
APC 14x5.5-MR 6 22.2 26.82 595.4 8,067 42.0 3274 115.49 5.50
APC 16x5.5-MR 6 22.2 40.37 896.2 7,469 38.9 4760 167.90 5.31
APC 18x5.5-MR 6 22.2 51.55 1144.4 7,003 36.5 5799 204.55 5.07
GemFan 15x4.5-MR 6 22.2 24.91 553.0 8,151 34.7 3206 113.09 5.80
GemFan 16x4.5-MR 6 22.2 32.58 723.3 7,804 33.3 3986 140.60 5.51
RC-Timer 12x5.5-CF 6 22.2 21.11 468.6 8,331 43.4 2324 81.98 4.96
RC-Timer 13x5.5-CF 6 22.2 28.44 631.4 7,982 41.6 2923 103.10 4.63
RC-Timer 14x5.5-CF 6 22.2 37.89 841.2 7,566 39.4 3508 123.74 4.17
RC-Timer 15x5.5-CF 6 22.2 53.52 1188.1 6,926 36.1 4241 149.60 3.57
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.