Cobra C-2217/7 Motor Propeller Data
Magnets Motor Wind Motor Kv No-Load Current Motor Resistance I Max P Max (4S)
14-Pole 7-Turn Delta 2500 RPM/Volt Io = 2.73 Amps @ 10v Rm = 0.020 Ohms 50 Amps 740 W
 
Stator Outside Diameter Body Length Total Shaft Length Shaft Diameter Motor Weight
12-Slot 27.8 mm,  1.094 in. 32.0 mm,  1.259 in. 47.0 mm,  1.850 in. 3.17 mm,  0.125 in. 74.0 gm,   2.61 oz
 
Test Data From Input 6.0 V 8.0 V 10.0V 12.0V Measured Kv value Measured Rm Value
Sample Motor Io Value 1.956 A 2.252 A 2.726 A 2.862 A 2563 RPM/Volt @ 10v 0.0198 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 4.75x4.25 3 11.1 24.12 267.8 25,359 102.1 566 19.96 2.11
APC 4.75x4.75 3 11.1 26.98 299.5 25,022 112.6 562 19.82 1.88
APC 4.75x5.5-E 3 11.1 29.93 332.2 24,635 128.3 526 18.55 1.58
APC 5x4.3-MR 3 11.1 34.19 379.5 24,170 98.4 983 34.67 2.59
APC 5x4.5-MR 3 11.1 34.97 388.1 24,021 102.4 967 34.11 2.49
APC 5x4.6-MR 3 11.1 35.46 393.6 23,969 104.4 1031 36.37 2.62
APC 5x5-E 3 11.1 30.89 342.9 24,461 115.8 599 21.13 1.75
APC 5.25x4.75-E 3 11.1 35.01 388.6 23,918 107.6 804 28.36 2.07
APC 5.5x4.5-E 3 11.1 35.59 395.1 23,820 101.5 856 30.19 2.17
APC 6x4-E 3 11.1 40.33 447.6 23,344 88.4 1134 40.00 2.53
APC 6x4.3-MR 3 11.1 50.15 556.7 21,685 88.3 1499 52.87 2.69
APC 6x4.5-MR 3 11.1 47.96 532.3 21,991 93.7 1504 53.05 2.83
APC 6x5.5-E 3 11.1 48.38 537.0 21,903 114.1 1067 37.64 1.99
HQ 4x4.5-BN 3 11.1 20.89 231.9 25,822 110.0 614 21.66 2.65
HQ 5x4 3 11.1 20.29 225.3 25,925 98.2 768 27.09 3.41
HQ 5x4.5 3 11.1 21.61 239.8 25,714 109.6 773 27.27 3.22
HQ 5x4.5-BN 3 11.1 34.18 379.4 24,167 103.0 1053 37.14 2.78
HQ 6x3 3 11.1 20.68 229.6 25,900 73.6 869 30.65 3.78
HQ 6x4.5 3 11.1 41.04 455.5 23,313 99.3 1410 49.74 3.10
HQ 6x4.5-BN 3 11.1 52.69 584.8 21,377 91.1 1536 54.18 2.63
 
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 4x4.5-MR 4 14.8 31.21 461.9 32,783 139.7 850 29.98 1.84
APC 4.1x4.1-E 4 14.8 24.16 357.5 33,728 131.0 623 21.98 1.74
APC 4.5x4.1-E 4 14.8 31.25 462.5 32,705 127.0 866 30.55 1.87
APC 4.75x4.25 4 14.8 37.91 561.1 31,882 128.3 897 31.64 1.60
APC 4.75x4.75 4 14.8 42.14 623.7 31,320 140.9 886 31.25 1.42
APC 4.75x5.5-E 4 14.8 45.68 676.0 30,850 160.7 823 29.03 1.22
APC 5x4.3-MR 4 14.8 54.18 801.9 29,818 121.4 1505 53.09 1.88
APC 5x5-E 4 14.8 47.66 705.4 30,538 144.6 917 32.35 1.30
APC 5.25x4.75-E 4 14.8 55.34 819.1 29,571 133.0 1233 43.49 1.51
HQ 4x4.5-BN 4 14.8 31.13 460.7 32,817 139.8 989 34.89 2.15
HQ 5x4 4 14.8 31.11 460.5 32,850 124.4 1250 44.09 2.71
HQ 5x4.5  4 14.8 33.76 499.6 32,447 138.3 1230 43.39 2.46
HQ 5x4.5-BN 4 14.8 51.38 760.5 30,212 128.7 1640 57.85 2.16
HQ 6x3 4 14.8 32.99 488.3 32,624 92.7 1449 51.11 2.97
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
584 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.