RC Helicopter Motors | How to Decide?

Posted on

Choosing RC motors for helicopters or other aircraft can be daunting for the novice. That’s because the product descriptions are technical rather than descriptive. Don’t worry. You’ll have a better grasp of those numbers and abbreviations by the end of this short intro. The sections below look at the ones that matter most. You can go on to learn more once you have these basics down.

What You Will Learn About RC Heli Motors

Here are the areas covered in this introduction to RC motors:

  1. Brushed vs. brushless
  2. Inrunner vs. outrunner
  3. How to determine the motor’s size
  4. How to determine the motor’s speed
  5. How to determine the motor’s power

Let’s get started and break these things down into plain English.

#1 Brushed Vs. Brushless

The older brushed technology is inferior to brushless in many ways, but it still has a place. Brushed motors are simple in design with their two-wire control. They’re also quite reliable and cost much less than the brushless alternatives. Another advantage is that they’re highly configurable. These things combined make them an attractive choice for novice RC pilots and those who like to tinker.

Brushless motors may cost more, but they last longer because there are no brushes to wear out. They have better power efficiency as well. These motors are quieter as they don’t suffer the same electromagnetic and electrical noise. So, the advantages of brushless motors are less maintenance, fewer problems, and cost savings in the long term.

#2 Inrunner Vs. Outrunner (Brushless)

Inrunner and outrunner motors are not the same, so which is best? Let’s compare:

  • Inrunners: The shaft rotates on the inside of the motor’s hub
  • Outrunners: The entire outer hub spins around the center

The best option depends on flying styles and expectations. Here’s a side-by-side comparison:

INRUNNERSOUTRUNNERS
High Revolutions per minute (RPM), low torque
More energy-efficient
Need a gearbox to function
Wider propeller selection
Noisier than outrunners
Low RPM and higher torque
Less energy-efficient than inrunners
Don’t need a gearbox to function
Narrower propeller selection
Quieter than inrunners

Inrunner motors turn the fastest out of the two, which makes them more efficient. However, the extra internal parts also mean there’s more to go wrong. The gearbox shafts bend easily, and the gears eventually get stripped. Inrunners are often—though not always—the preferred option for RC helis.

#3 How to Determine Motor Size

A simple height/width number tells us the size of RC motors and is usually printed on the casing. The number may look something like this, 2204 or 22-04, but it’s the same reading. The first number “22” is the motor’s diameter, and the second “04” is its height. Wider motors produce the most torque.

#4 How to Determine Motor Speed

The quicker the motor, the faster the potential is for your RC heli or other aircraft. The way to identify the speed that an RC motor turns is to look at the KV number. It tells us the relationship that links volts to revolutions per minute (RPM). Let’s use KV1000 as an example. This number means the motor spins at 1000 RPM per 1 volt. There are 2 things to consider with the KV numbers:

  1. Lower KV: Spins slower but provides more torque
  2. Higher KV: Spins faster but has less strength

Point to note: RC engine manufacturers tend to be overly optimistic with KV numbers.

#5 How to Determine Motor Power

AMPS (current) x VOLTS = WATTS (the motor’s equivalent to horsepower)

The “watt” is a unit of power named after the inventor of steam engines, James Watt. The watts of an RC motor determine its power. Watt ratings are found on the motor’s spec sheet. Higher numbers mean more power. Check the motor’s amps to find the correct Electronic Speed Controller or ESC. Opt for an ESC current value that’s 20% or more than the motor’s current value.

Keep the following points in mind:

  • GOOD: ESC AMP capacity 20+ percent or higher than the motor’s draw
  • BAD: Motor AMP draw is equal to or larger than the ESC capacity
  • The flight battery must supply the burst AMPS the motor’s rated for

That’s the basics covered. The second half of this page looks at some real motors for RC helicopters of various types and sizes. The maker’s specs should now make a lot more sense.

About My ‘RC Helicopter Motors’ Guide

This straightforward guide is for novice heli fans looking for new or replacement RC motors. The products below are some of the popular choices used by enthusiasts for various models. Whether you use these or not doesn’t matter. The point is to get used to reading the product descriptions. Knowing what the specs mean is the only way to make well-informed decisions.

Where there is a dash (—) indicates missing data from the company specs sheet. The table below shows the 10 products in the order they appear on this page.

Point to note: These tiny motors use millimeters (mm) for measurements and grams (g) for weights.

1. WLtoys V913 Brushless RC Helicopter Tail Motor

WLtoys V913 Brushless RC Helicopter Tail Motor

EDITOR’S RATING: 4.9/5

RC helicopter motor compatibility: WLtoys V913 brushless 2.4G 4CH RC RTF helicopter.

This is WLtoys low energy consumption, brushless V913 RC helicopter tail motor V913-p-03. It’s a compact, durable, easy to replace tail motor made from a high-quality metal material.

MANUFACTURERS’ QUICK SPECS
Brand: WLtoys
Part Type: Heli tail motor
Item No.: V913-p-03
Material: Metal
Color: Silver
Dimensions: 36 x 12 x 10mm
IN THE BOX
1 x tail motor

2. ESKY 3900KV Brushless Motor for 300 RC Heli

ESKY 3900KV Brushless Motor for 300 RC Heli

EDITOR’S RATING: 4.6/5

RC helicopter motor compatibility: 300 RC helis, RC airplanes, and radio-controlled boats.

Full product description: ESKY 2010 brushless 3900KV RC motor.

MANUFACTURERS’ QUICK SPECS
Brand: ESKY
Product Type: 2010 brushless motor
RPM/ V: 3900 KV
Plug Type: 3.5mm banana
Battery: 3S–4S
Maximum Current: 13A (amps)
Minimum Current: 0.7A
Screw: M3
Motor Diameter: 25.6mm
Motor Height: 28mm
Install Hole: 16mm/19mm compatible
Weight: 1.58 oz. (45g)
Application: 300 RC Heli, plane, boat
IN THE BOX
1 x brushless motor

3. EFLITE Brushless Radio Control Helicopter Motor

EFLITE Brushless Radio Control Helicopter Motor

EDITOR’S RATING: 4.8/5

RC helicopter motor compatibility: 450–480 RC helicopters.

Full product description: EFLITE 2216 brushless 3900KV motor.

MANUFACTURERS’ QUICK SPECS
Brand: EFLITE
Application: 450-480 RC helicopter
Product Type: 2216 brushless motor
RPM/ V: 3800 KV
Plug: 3.5mm banana
Battery: 3S–4S
Maximum Current: 20A (amp)
Minimum Current: 1.9A
Screw: M3
Gear: 10
Diameter: 27.8mm
Height: 30mm
Output Shaft Diameter: 2.3mm
Output Device Shaft Diameter: 12.4mm
External Diameter: 5.2mm
Internal Diameter: 2.3mm
Install Hole: Compatible 16mm/19mm
Weight: Approx. 63g
IN THE BOX
1 x brushless motor

4. DYS 1300KV Brushless Motor for RC Helis

DYS 1300KV Brushless Motor for RC Helis

EDITOR’S RATING: 4.2/5

RC helicopter motor compatibility: Radio control helicopter, multicopters, and RC planes.

Full product description: DYS D2830 1300KV RC brushless motor.

MANUFACTURERS’ QUICK SPECS
Brand: DYS
Item Name: D2830
KV: 1300
Pull: 930g
Motor Size: Ф28 x 30mm
Shaft Size: Ф3.17 x 45mm
Battery: 2–4s LiPo
Weight: 52g
Max power: 210W (watts)
IN THE BOX
1 x D2830 brushless RC motor
Instructions

5. Racerstar KV4000 Outrunner Brushless Motor

Racerstar KV4000 Outrunner Brushless Motor

EDITOR’S RATING: 4.8/5

RC helicopter motor compatibility: Trex 450 RC helicopter

Full product description: Racerstar outrunner KV4000 brushless RC helicopter motor.

MANUFACTURERS’ QUICK SPECS
Brand: Racerstar
Motor: X450
Color: Green
Rotational Speed: (RPM/V) 4000Kv
Diameter: 0.26mm
Net Weight: 64g
Max Current: 45A (amp)
Voltage: 11.1V–14.8V
Shaft Diameter: 3.17mm
Shaft Length: 16mm
Length: 47mm
Diameter: 29mm
Max KV Value: (RPM/V) 3813Kv
Min KV Value: (RPM/V) 4387Kv
No-load Speed: 38130 to 43870 RPM/s
No-load Current: 3.4–4.8A
Load Voltage: 14.8V
Load Current: 24.3V
Load Power: 360W (watts)
IN THE BOX
1 x KV4000 brushless heli motor
Accessories

6. GARTT 3700KV Brushless Motor 450 RC Heli

GARTT 3700KV Brushless Motor 450 RC Heli

EDITOR’S RATING: 4.9/5

RC helicopter motor compatibility: Align Trex 450 RC helicopter.

Full product description: GARTT 3700KV 330W brushless RC Heli motor (motor gear not included).

MANUFACTURERS’ QUICK SPECS
Brand: GARTT
Type: 450 brushless motor
Model: MT-011
KV: 3700KV
Maximum Current: 32A (amps)
Maximum Power: 330W (watts)
Idle Current: 3.6A
Resistance: 0.0185Ω
Shaft: 3.175mm
Product Weight: 75g
Suggested ESC: 40A
Cell Count: 2–4S LiPo (voltage)
Bolt Holes (Spacing): 16mm
Bolt Thread: M2.5/M3
Size: 28 x 49 x 3mm
IN THE BOX
1 x 3700KV 330W RC heli motor
3 x heat shrink tubing
2 x screws

7. XK K130 RC Heli 9200KV Main Motor Brushless

XK K130 RC Heli 9200KV Main Motor Brushless

EDITOR’S RATING: 4.8/5

RC helicopter motor compatibility: XK K130 RC helicopter.

Full product description: XK K130 main brushless motor for RC helis.

MANUFACTURERS’ QUICK SPECS
Brand: XK
Product: Brushless RC heli motor
Voltage: 7.4V
KV: 9200KV
Application: XK K130 RC chopper
IN THE BOX
1 x Brushless motor

8. WLtoys V912 RC Helicopter KV450 Brushless Motor

WLtoys V912 RC Helicopter KV450 Brushless Motor

EDITOR’S RATING: 4.7/5

RC helicopter motor compatibility: WLtoys Ready to Fly (RTF) 4CH V912 Sky Dancer RC Helicopter.

Full product description: WLtoys Brushless V912 KV4500 main RC heli motor.

MANUFACTURERS’ QUICK SPECS
Brand: WLtoys
Product Type: Brushless main motor
Model: V912-p-01
Speed: 4500KV
IN THE BOX
1 x KV4500 RC heli main motor

9. GARTT 1220KV 2100W Brushless Motor

GARTT 1220KV 2100W Brushless Motor

EDITOR’S RATING: 4.8/5

RC helicopter motor compatibility: 550/600 Align Trex RC helicopter.

Full product description: GARTT 1220KV, 2100W brushless RC helicopter motor.

MANUFACTURERS’ QUICK SPECS
Brand: GARTT
KV: 1220KV
Maximum current: 95A (amps)
Maximum Power: 2100W (watts)
Idle Current: 4.0A
Resistance: 0.015Ω
Shaft: 6mm
Weight: 380g
Suggested ESC: 100A
Cell count: 3–6S LiPo (voltage)
Bolt Holes (Spacing): 25/30mm
Bolt thread: M3
Connection: Bullet-connector 4.0mm
IN THE BOX
1 x 220KV RC heli motor

10. ALZRC Devil 380 RC Helicopter Brushless Motor

ALZRC Devil 380 RC Helicopter Brushless Motor

EDITOR’S RATING: 4.9/5

RC helicopter motor compatibility: ALZRC Devil 380 fast RC helicopters

Full product description: ALZRC Devil, 380 3120-PRO, 1000KV brushless RC heli motor.

MANUFACTURERS’ QUICK SPECS
Brand: ALZRC
Stator Diameter: 30mm
Stator Thickness: 20mm
Number of Stator Arms: 12
Number of Magnet Poles: 10
Wire: Φ2.0/1.0 x 70mm
KV: 1000 Kv
No-Load Current (IO/10V): 1.9A (amps)
Motor Resistance (RM): 0.039
Maximum Continuous Current: 50A
Maximum Continuous Power: 1250W (watts)
Maximum Peak Current: 75A
Maximum Peak Power: 1700W
Product Weight: 162g
Diameter: 39mm
Length: 40.2mm
Shaft Diameter: 5mm
Shaft Length: 63mm
Maximum LiPo Cell: 6S
Motor Timing: 15
Drive Frequency: 8kHz
Plug: 4mm Banana (Gold-plated)
IN THE BOX
1 x 3120 PRO RC heli motor
0/50 ratings