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Scorpion HKIII-4020-1100kv Motor (5mm) - Goblin 500 / GAUI X4 II / OXY 5

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Product Description

Scorpion HKIII-4020-1100kv Motor - 5mm shaft
  • Use for: Goblin 500 / 500 Sport / GAUI X4II / OXY5 (or similar size helicopters with 430mm to 550mm blades, check your manual for proper motor size and KV suggestions)


The Scorpion HKIII-4020 Series Motor is designed for use on 430mm up to 550mm bladed models running on 6S to 8S LiPo power. This motor represents the most technologically advanced power source ever offered for this class electric helicopter.

There are several key differences between the earlier HKII (HK2) series motors and the new HKIII (HK3) series motors from Scorpion. Here’s the break-down:

  • 1. The new HKIII motors use a different alloy in the stator laminations. This material has a higher efficiency and lower hysteresis for less internal losses and less internal heating of the motor.
  • 2. The shape of the stator has changed to concentrate more of the magnetic flux fields towards the magnet faces for greater efficiency and higher torque.
  • 3. The rotor can of the new HKIII motors is made of a new alloy that retains more of the magnetic fields and also helps to increase the motor efficiency.
  • 4. The rotor can features a new spiral cut cooling fin pattern that not only increases the flux pattern for the magnetic fields in the motor, it also increases the surface area and acts as a built-in heatsink for better cooling. Unlike other motors, that use a series of circular cuts in the rotor can, the HKIII motor use a continuous cut from one end of the motor to the other. This actually pulls air down the sides of the motor for increased cooling and lower operating temperatures. This new cooling technique has been patented in several countries worldwide.
  • 5. All of the changes to increase the efficiency in the motor naturally cause the motor to have a lower Kv value. In order to get the Kv value back up where it originally was, the motors are wound with fewer turns of wire. Since fewer turns are needed, the wire used to wind the motors can be larger. This allows for lower internal resistance (Rm) in the motors, and also increases their current handling capability.

All of these changes work together to make the new Scorpion HKIII 40mm motors the highest power and most efficient helicopter motors every created.

The Scorpion HKIII-4020 motors follow in the footsteps of the larger HKIII-4035 models which have re-wrote the book on power for helicopter models. The HKIII-4020 motor features a new patented rotor can that provides several benefits. First, it is thicker for more stability at higher speeds, and this also helps to retain more of the magnetic field for higher efficiency. Second, the outer surface of the rotor can features a new spiral rib pattern that increases surface area and helps to move air around the motor for increased cooling and lower operating temperatures.

In addition to the mechanical changes to these motors, changes in metallurgy in the stator assembly and rotor can have increased the overall efficiency. This allows the motor to handle higher currents while developing more torque and more power that will allow your helicopter to perform like never before.

Scorpion HKIII Series Brushless Motors are built from the best materials available, and are designed to provide both quality and performance at an affordable price. Scorpion starts with high quality aluminum alloy parts that are produced on the latest CNC milling machines. These parts are then gold Electro-plated to provide a beautiful, long-lasting finish. The stators are made with 0.2mm laminations to give maximum efficiency, and minimum Eddy current losses. The stators are epoxy coated to prevent shorts, and are wound with wire that is rated at 180 degrees C (356 F). The magnets used in Scorpion Motors are the highest temperature rating available, making a motor that is virtually impossible to burn up in normal use.

All Scorpion HKIII-4020 series motors come with 4mm male Bullet style connectors already attached, and include a hardware package that contains 3 matching female Bullet connectors for your speed controller with matching heat shink tubing. For maximum strength, the Scorpion HKIII-4020 series motors feature an 8mm motor shaft that is ground down to a 5mm diameter at the output end to fit standard size pinion gears. Since the HKIII Series motors are primarily designed for Helicopter use, they do not include a prop adapter. If you intend on running a prop on this motor, you will need to purchase a prop adapter for a 5mm shaft.

Scorpion Motors are built to last, and are backed with a 2-Year warranty against defects in materials or workmanship. However, due to the high RPM of these motors, and the fact that we cannot control the installation and setup, the bearings are not covered by the 2-Year warranty, nor is any subsequent damage caused to the motor by a bearing failure. Bearings are a normal wear item, and as such, need to be maintained and changed periodically. For maximum life, make sure that a sufficient gap is left between the pinion and main gear during motor installation to avoid binding, and put a small drop of oil on each bearing every 5-6 flights. It is the responsibility of the pilot to ensure that the bearings are maintained properly.

The Scorpion Motor Bearing Lubrication Kit is now available for maintaining the bearings in your helicopter motor. To view this product, please check out the Bearing Lubrication Kit.

For the best overall combination of quality, performance, and value, use Scorpion Motors in your helicopter!


Stator Diameter 40 mm(1.57 in)
Stator Thickness 20 mm(0.79 in)
No. of Stator Arms 12
Magnet Poles 10
Motor Wind 3T/4T Delta
Motor Wire 24-Strand 0.29mm
Motor Kv 1100KV RPM/Volt
No-Load Current (IO/10v) 3.15 Amps
Motor Resistance (RM) 0.008 Ohms
Max Continuous Current 78 Amps
Max Continuous Power 1640 Watts
Weight 302 Grams (10.65 oz)
Outside Diameter 49.98 mm (1.97 in)
Shaft Diameter 4.98 mm (0.20 in) (for 5mm pinion)
Body Length 46.8 mm (1.84 in)
Overall Shaft Length 78.7 mm (3.10 in)
Max Lipo Cell 6S - 8S
Peak Current 90 Amps (5 seconds)
Peak Continuous Power 1890 Watts (5 seconds)
Motor Timing 5deg
Drive Frequency 8kHz

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