RC Helicopter Motors | How to Decide?
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:
- Brushed vs. brushless
- Inrunner vs. outrunner
- How to determine the motor’s size
- How to determine the motor’s speed
- 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:
| INRUNNERS | OUTRUNNERS |
|---|---|
| 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:
- Lower KV: Spins slower but provides more torque
- 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
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
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
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
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
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
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
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
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
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
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 |
Contents
- What You Will Learn About RC Heli Motors
- #1 Brushed Vs. Brushless
- #2 Inrunner Vs. Outrunner (Brushless)
- #3 How to Determine Motor Size
- #4 How to Determine Motor Speed
- #5 How to Determine Motor Power
- About My ‘RC Helicopter Motors’ Guide
- 1. WLtoys V913 Brushless RC Helicopter Tail Motor
- 2. ESKY 3900KV Brushless Motor for 300 RC Heli
- 3. EFLITE Brushless Radio Control Helicopter Motor
- 4. DYS 1300KV Brushless Motor for RC Helis
- 5. Racerstar KV4000 Outrunner Brushless Motor
- 6. GARTT 3700KV Brushless Motor 450 RC Heli
- 7. XK K130 RC Heli 9200KV Main Motor Brushless
- 8. WLtoys V912 RC Helicopter KV450 Brushless Motor
- 9. GARTT 1220KV 2100W Brushless Motor
- 10. ALZRC Devil 380 RC Helicopter Brushless Motor