Cobra C-4120-20 480Kv Motor Propeller Data
Magnets Motor Wind Motor Kv No-Load Current Motor Resistance I Max P Max (8S)
14-Pole 20-Turn Delta 480 RPM/Volt Io = 2.50 Amps @ 20v Rm = 0.036 Ohms 48 Amps 1420 W
 
Stator Outside Diameter Body Length Total Shaft Length Shaft Diameter Motor Weight
12-Slot 49.8 mm, 1.96 in. 50.3 mm, 1.98 in. 74.2 mm, 2.92 in. 6.00 mm, 0.236 in. 290 grams, 10.23 oz.
 
Test Data From Input 16.0 V 20.0 V 24.0V 28.0V Measured Kv value Measured Rm Value
Sample Motor Io Value 1.452 A 1.662 A 1.891 A 2.094 A 449 RPM/Volt @ 20V 0.0362 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 11x10-E 5 18.5 20.11 372.1 7,538 71.4 1,386 48.89 3.72
APC 12x8-E 5 18.5 19.75 365.4 7,555 57.2 1,704 60.11 4.66
APC 12x10-E 5 18.5 24.80 458.7 7,367 69.8 1,817 64.09 3.96
APC 12x12-E 5 18.5 29.04 537.2 7,225 82.1 1,702 60.04 3.17
APC 13x6.5-E 5 18.5 21.10 390.3 7,364 45.3 2,203 77.71 5.64
APC 13x8-E 5 18.5 23.43 433.4 7,265 55.0 2,235 78.84 5.16
APC 13x10-E 5 18.5 31.39 580.7 6,991 66.2 2,167 76.44 3.73
APC 14x7-E 5 18.5 28.04 518.6 7,257 48.1 2,729 96.26 5.26
APC 14x8.5-E 5 18.5 29.04 537.3 7,087 57.0 2,725 96.12 5.07
APC 14x10-E 5 18.5 30.31 560.6 7,188 68.1 2,774 97.85 4.95
APC 14x12-E 5 18.5 44.91 830.8 6,712 76.3 2,429 85.68 2.92
APC 15x4-E 5 18.5 21.94 405.9 7,481 28.3 2,609 92.03 6.43
APC 15x6-E 5 18.5 29.71 549.6 7,213 41.0 3,111 109.74 5.66
APC 15x8-E 5 18.5 32.72 605.3 7,108 53.8 3,121 110.09 5.16
APC 15x10-E 5 18.5 46.06 852.1 6,670 63.2 3,363 118.63 3.95
APC 16x8-E 5 18.5 46.31 856.8 6,506 49.3 3,845 135.63 4.49
APC 16x10-E 5 18.5 53.58 991.2 6,395 60.6 3,951 139.37 3.99
APC 17x8-E 5 18.5 52.43 969.9 6,407 48.5 4,320 152.38 4.45
MAS 12x8x3 5 18.5 25.42 470.3 7,356 55.7 2,433 85.82 5.17
MAS 13x8x3 5 18.5 27.27 504.5 7,138 54.1 2,638 93.05 5.23
MAS 14x7x3 5 18.5 33.68 623.2 7,074 46.9 3,233 114.04 5.19
MAS 14x9x3 5 18.5 40.52 749.6 6,846 58.3 3,624 127.83 4.83
MAS 15x7x3 5 18.5 41.91 775.4 6,797 45.1 3,836 135.31 4.95
MAS 16x8x3 5 18.5 46.85 866.7 6,473 49.0 4,223 148.96 4.87
 
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 11x7-E 6 22.2 19.51 433.1 9,107 60.4 2,046 72.17 4.72
APC 11x8-E 6 22.2 21.98 488.0 8,995 68.1 1,954 68.92 4.00
APC 11x8.5-E 6 22.2 24.01 533.0 8,914 71.8 2,059 72.63 3.86
APC 11x10-E 6 22.2 27.70 614.9 8,782 83.2 1,932 68.15 3.14
APC 12x6-E 6 22.2 20.67 458.9 8,883 50.5 2,377 83.85 5.18
APC 12x8-E 6 22.2 27.47 609.9 8,787 66.6 2,362 83.32 3.87
APC 12x10-E 6 22.2 34.40 763.7 8,523 80.7 2,466 86.98 3.23
APC 12x12-E 6 22.2 37.06 822.8 8,226 93.5 2,229 78.62 2.71
APC 13x4-E 6 22.2 18.58 412.5 9,136 34.6 2,421 85.40 5.87
APC 13x6.5-E 6 22.2 30.79 683.5 8,656 53.3 3,117 109.95 4.56
APC 13x8-E 6 22.2 34.40 763.6 8,542 64.7 3,147 111.01 4.12
APC 13x10-E 6 22.2 46.13 1024.0 8,146 77.1 2,965 104.59 2.90
APC 14x7-E 6 22.2 39.57 878.4 8,358 55.4 3,723 131.32 4.24
APC 14x8.5-E 6 22.2 42.08 934.1 8,274 66.6 3,758 132.56 4.02
APC 14x10-E 6 22.2 42.32 939.6 8,265 78.3 3,667 129.35 3.90
APC 15x4-E 6 22.2 30.70 681.6 8,649 32.8 3,657 129.00 5.37
APC 15x6-E 6 22.2 41.84 928.9 8,290 47.1 4,251 149.95 4.58
APC 15x8-E 6 22.2 45.26 1004.7 8,156 61.8 4,196 148.01 4.18
MAS 11x8x3 6 22.2 22.33 495.7 8,820 66.8 2,230 78.66 4.50
MAS 12x6x3 6 22.2 23.84 529.3 8,929 50.7 2,608 91.99 4.93
MAS 12x8x3 6 22.2 34.09 756.8 8,546 64.7 3,337 117.71 4.41
MAS 13x8x3 6 22.2 37.99 843.4 8,416 63.8 3,726 131.43 4.42
MAS 14x7x3 6 22.2 44.84 995.4 8,179 54.2 4,385 154.67 4.41
MAS 14x9x3 6 22.2 53.85 1195.5 7,878 67.1 4,846 170.94 4.05
MAS 15x7x3 6 22.2 53.26 1182.4 7,702 51.1 4,952 174.67 4.19
 
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 11x5.5-E 7 25.9 19.98 517.4 10,403 54.2 2,379 83.92 4.60
APC 11x7-E 7 25.9 26.00 673.5 10,361 68.7 2,684 94.67 3.99
APC 11x8-E 7 25.9 29.41 761.6 10,223 77.4 2,556 90.16 3.36
APC 11x8.5-E 7 25.9 31.99 828.6 10,136 81.6 2,665 94.00 3.22
APC 11x10-E 7 25.9 36.09 934.8 9,958 94.3 2,466 86.98 2.64
APC 12x6-E 7 25.9 29.24 757.2 10,230 58.1 3,265 115.17 4.31
APC 12x8-E 7 25.9 36.97 957.6 9,938 75.3 3,084 108.78 3.22
APC 12x10-E 7 25.9 43.17 1118.2 9,521 90.2 3,033 106.98 2.71
APC 12x12-E 7 25.9 49.59 1284.4 9,468 107.6 2,935 103.53 2.29
APC 13x4-E 7 25.9 24.58 636.5 10,418 39.5 3,212 113.30 5.05
APC 13x6.5-E 7 25.9 39.95 1034.7 9,638 59.3 3,898 137.50 3.77
APC 13x8-E 7 25.9 45.70 1183.7 9,615 72.8 4,014 141.59 3.39
APC 14x7-E 7 25.9 53.76 1392.5 9,316 61.8 4,671 164.76 3.35
APC 15x4-E 7 25.9 39.44 1021.6 9,633 36.5 4,690 165.43 4.59
MAS 11x7x3 7 25.9 25.84 669.2 10,155 67.3 2,843 100.28 4.25
MAS 11x8x3 7 25.9 29.80 771.7 10,202 77.3 2,983 105.22 3.87
MAS 12x6x3 7 25.9 29.22 756.9 10,024 57.0 3,292 116.12 4.35
MAS 12x8x3 7 25.9 43.57 1128.5 9,689 73.4 4,316 152.24 3.82
MAS 13x8x3 7 25.9 48.53 1256.9 9,489 71.9 4,761 167.94 3.79
 
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 11x5.5-E 8 29.6 27.82 823.4 11,841 61.7 3,192 112.59 3.88
APC 11x7-E 8 29.6 34.31 1015.5 11,547 76.5 3,346 118.03 3.29
APC 11x8-E 8 29.6 38.23 1131.6 11,404 86.4 3,193 112.63 2.82
APC 11x8.5-E 8 29.6 41.23 1220.4 11,265 90.7 3,302 116.47 2.71
APC 11x10-E 8 29.6 46.29 1370.1 11,043 104.6 3,064 108.08 2.24
APC 12x6-E 8 29.6 38.86 1150.2 11,375 64.6 4,113 145.08 3.58
APC 12x8-E 8 29.6 47.34 1401.3 11,029 83.6 3,808 134.32 2.72
APC 13x4-E 8 29.6 31.87 943.4 11,661 44.2 4,146 146.24 4.39
APC 13x6.5-E 8 29.6 53.56 1585.3 10,572 65.1 4,714 166.28 2.97
MAS 11x7x3 8 29.6 33.80 1000.5 11,582 76.8 3,692 130.23 3.69
MAS 11x8x3 8 29.6 35.74 1058.0 11,252 85.2 3,632 128.11 3.43
MAS 12x6x3 8 29.6 38.43 1137.6 11,398 64.8 4,299 151.64 3.78
2017 Innov8tive Designs, Inc.
This chart, and the data contained within it, are the property of Innov8tive Designs, Inc., and may not be reproduced without permission from the author.
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.