Cobra Brushless Multirotor Motors offer performance and value for Your RC Models. They are built from high quality components, and are designed to give years of top-level performance. All Cobra Motors are shipped in a custom designed package that features protective foam on all sides, with separate compartments to protect the motor and accessory pack.
The Cobra CM-3520 series motors have a 5.00mm motor shaft for extra strength, as well as oversize ball bearings to support the shaft and provide a long life. The stators are made with 0.20mm laminations for maximum efficiency and minimum Eddy Current losses. Since these motors are typically soldered directly to the speed controller for reliability, and often need to be cut to length for the specific installation, the CM-3520 motors come without bullet connectors and feature extended pre-tinned motor leads that are 17 inches (430mm) long. These motors also have 3mm threaded holes in a 25x25mm pattern on the back plate for easy installation on your model.
The CM-3520 series motors include a bolt-on style prop adapter has an M6x1.0mm thread for holding traditional multirotor props that have a 6mm center hole. The included prop washer and nylon insert prop nut provides a solid attachment for your propellers that will not loosen up and slip during use.
Included with every Cobra CM-3520 Series Motor is a complete accessory package which contains the following items:
● Four M3x4mm Socket Head Screws
● Four M3x6mm Phillips Head Screws
● Two M3x8mm Socket Head Screws
● Machined Aluminum Top Plate for Carbon Fiber Props
● Machined Aluminum Prop Adapter
● Machined Aluminum Prop Washer
● Locking Prop Nut with Nylon Insert
Click here for the Cobra CM-3520/20 Propeller Data Chart
Motor Performance Graphs
|Cobra CM-3520/20 Motor Specifications|
| Stator Diameter|| 35.0 mm (1.378 in)|
| Stator Thickness|| 20.0 mm (0.787 in)|
| Number of Stator Slots|| 12|
| Number of Magnet Poles|| 14|
| Motor Wind|| 20 Turn Delta|
| Motor Kv Value|| 480 RPM per Volt|
| No Load Current (Io)|| 0.68 Amps @ 15 Volts|
| Motor Resistance (Rm) per Phase|| 0.104 Ohms|
| Motor Resistance (Rm) Phase to Phase|| 0.069 Ohms|
| Maximum Continuous Current|| 32 Amps|
| Max Continuous Power (4-cell Li-Po)|| 470 Watts|
| Max Continuous Power (5-cell Li-Po)|| 590 Watts|
| Max Continuous Power (6-cell Li-Po)|| 710 Watts|
| Motor Weight|| 234 grams (8.25 oz.)|
| Outside Diameter|| 43.0 mm (1.693 in.)|
| Motor Shaft Diameter|| 5.00 mm (0.197 in.)|
| Prop Shaft Diameter|| 6.00 mm (0.197 in.)|
| Motor Body Length|| 52.0 mm (2.047 in.)|
| Overall Shaft Length|| 55.6 mm (2.189 in.)|
| Motor Timing|| 5-10 degrees|
| PWM Frequency|| 8 KHz|
The following downloadable PDF files show the performance data curves of the Cobra CM-3520/20 motor, over its entire throttle range, with a variety of propellers. These graphs can be downloaded and printed to use as a reference for calculating power requirements at specific thrust levels, and enable the user to calculate flight times, current draw and other motor parameters.
4-Cell Li-Po Power
Cobra CM-3520/20 Performance Data with APC 18x5.5-MR prop on 4S Li-Po
Cobra CM-3520/20 Performance Data with RC-Timer 16x5.5-CF prop on 4S Li-Po
5-Cell Li-Po Power
Cobra CM-3520/20 Performance Data with APC 16x5.5-MR prop on 5S Li-Po
Cobra CM-3520/20 Performance Data with GemFan 16x4.5-MRW prop on 5S Li-Po
Cobra CM-3520/20 Performance Data with RC-Timer 14x5.5-CF prop on 5S Li-Po
6-Cell Li-Po Power
Cobra CM-3520/20 Performance Data with APC 14x5.5-MR prop on 6S Li-Po
Cobra 3520/20 Performance Data with GemFan 15x4.5-MRW prop on 6S Li-Po
Cobra CM-3520/20 Performance Data with RC-Timer 13x5.5-CF prop on 6S Li-Po
Performance Graph Instructions
This downloadable PDF file shows the step by step process to use for interpreting the data shown in the Motor Performance Graphs. By following this procedure, you can determine how to select a proper motor for a Multirotor aircraft, as well as calculate required power levels, determine overall prop efficiency and calculate expected flight times based on the battery size that is used. This document can be printed out and saved as a valuable reference tool to keep in your workshop for future use as well.
Motor Performance Graph Instructions
Items Included in Hardware Package
NOTE: Cross Mounts are NOT included with any multirotor motors.
For more information about this product and the rest of the Cobra Motors product line, please check out the Cobra Brushless Motors web site.