Cobra C2820/8 Motor Propeller Data
Motor Wind Motor Kv No-Load Current Motor Resistance I Max P Max (3S)
8-Turn Delta 1450 RPM/Volt Io = 2.50 Amps @ 10v Rm = 0.020 Ohms 55 Amps 610 W 
 
Outside Diameter Body Length Total Shaft Length Shaft Diameter Motor Weight
35.0 mm,  1.38 in. 40.0 mm,  1.57 in. 60.0 mm,  2.36 in. 5.00 mm,  0.197 in. 139 gm,   4.90 oz
 
Prop Prop Input Motor Watts Prop Pitch Thrust  Thrust Thrust Eff.
Manf. Size Voltage Amps Input RPM Speed Grams Ounces Grams/W
APC 7x5-E 11.1 26.19 290.7 14,520 68.8 965 34.04 3.32
APC 7x6-E 11.1 27.19 301.9 14,371 81.7 1047 36.93 3.47
APC 8x4-E 11.1 30.79 341.8 14,096 53.4 1315 46.38 3.85
APC 8x6-E 11.1 46.13 512.0 12,893 73.3 1477 52.10 2.88
APC 8x8-E 11.1 57.37 636.8 12,203 92.4 1306 46.07 2.05
APC 9x4.5-E 11.1 42.24 468.9 13,200 56.3 1846 65.12 3.94
APC 9x6-E 11.1 48.20 535.0 12,847 73.0 1775 62.61 3.32
APC 10x5-E 11.1 57.45 637.7 12,162 57.6 2119 74.74 3.32
 
Prop Prop Input Motor Watts Prop Pitch Thrust  Thrust Thrust Eff.
Manf. Size Voltage Amps Input RPM Speed Grams Ounces Grams/W
APC 6x4-E 14.8 19.62 290.3 20,353 77.1 913 32.20 3.14
APC 6x5.5-E 14.8 24.39 361.0 19,825 103.3 944 33.30 2.62
APC 7x4-E 14.8 35.30 522.4 18,999 72.0 1603 56.54 3.07
APC 7x5-E 14.8 43.89 649.6 18,301 86.7 1607 56.68 2.47
APC 7x6-E 14.8 45.22 669.2 18,208 103.5 1713 60.42 2.56
APC 8x4-E 14.8 52.04 770.1 17,641 66.8 2098 74.00 2.72
APC 9x4.5-E 14.8 69.03 1021.6 16,218 69.1 2942 103.77 2.88
 
Prop Prop Input Motor Watts Prop Pitch Thrust  Thrust Thrust Eff.
Manf. Size Voltage Amps Input RPM Speed Grams Ounces Grams/W
APC 6x4-E 18.5 30.50 564.2 24,675 93.5 1310 46.21 2.32
APC 6x5.5-E 18.5 36.96 683.8 24,064 125.3 1370 48.32 2.00
APC 7x4-E 18.5 55.42 1025.2 22,384 84.8 2258 79.65 2.20
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.  The test voltages used are based on a properly sized Li-Po battery for the current
draw of the motor being tested.  If you are using a larger than normal capacity battery, or a very
high C-Rated battery, your actual voltages will be higher than those shown in this chart, and this
will result in higer current draw for each prop used.  You should always test your power system
with a watt meter whenever a prop is used to ensure that you are not exceeding the recommended
rating of the motor being used.  The prop recommendations in this chart are based on the motor
receiving adequate cooling throughout its operation.  If your motor is being used inside a cowl, you
must provide adequate cooling to the motor and make sure that the motor is not getting too hot
during operation.