LN-motor FS2812 and FS2306 brushless motors for FPV drones

Commonly, the product name of FPV motors is formed by a group of two numbers. The first one refers to the dimensions of the motor and the second one to the speed of the motor. Brushless motors have two main parts: the rotor with permanent magnets and the stator with copper coils. After learning to decipher the numbers on FPV motors, we will analyze two motors from LN-motor in detail.

The first number has four digits (DDHH) and represents:

  • “DD” is the stator’s diameter (or width) measured in millimeters.
  • “HH” is the stator’s height in millimeters.

For example, the LN-motor FS2812 has a stator with 28mm diameter and a stator height of 12mm. Bigger motors have larger magnets that are capable of generating more thrust.

How to measuring stator diameter
How to measure stator diameter with a micrometer

The second number is “KV” and represents the number of revolutions per minute (RPM) with no load when a one-volt is applied to the motor’s terminals. Therefore, theoretically, the FS2306 2050 KV motor will run 50% faster on a 6S battery than on a 4S one. Motors with higher KV tend to be more aggressive and power-hungry, while lower KV options are more efficient.

LN-motor FS2812 and FS2306 review

Disclosure: I received these FPV motors as part of a product review collaboration with LN-Motor. Although the motors were offered for free, all opinions in this article remain my own, and the sponsor did not influence me.

Unboxing

LN-MOTOR (Shenzhen Mingshi Innovation Technology) is an innovative technology enterprise focusing on producing brushless DC motors. “LN” comes from the Chinese names of the two founders, Lin and Na. The company has four UAV motor ranges:

FPVMultirotorFixed WingEducted fan
FS3115 900KV/1150KV4214 400KVFA2826 740KV70mm 12-Blade
3060-2000KV
FS2806.5 1400KV/1750KV3115 1050KVFA2820 870KV
FS2306 2050KV2812 900KV/1150KVFA2814 510KV
FS2207 1800KVFA2216 2400KV
2806.5 1350KVFA2216 2400KV
2307 1950KV/2600KVFA2208 1100KV
2306.5 1800KV/1950KV
2307.5 1950KV
2207 1800KV/1950KV
2004 1800KV/2800KV
1406 4000KV
1303 5500KV

Last month, LN-Motor sent me their latest FPV motor catalog (available here) to choose the ones I need for review. I always wanted to build a 9-10″ long-range FPV drone, so I opted to test a set of FS2812 / 1150KV motors. As FS2306 motors are commonly used for racing drones, and I use many of them, I also opted to test a set of 2050 kV. Both motors are packed in the same type of plastic container with foam padding. In the center of the four motors is a bag that includes mounting screws and prop nuts. FS2812 is available in black, and FS2306 in green and navy blue.

FS2306 2050KV vs S2812 1150KV

While the smaller FS2306 adopts a unibell (one-piece rotor) design, the bigger FS2812’s rotor is made of two parts: a ring with the magnets and a cap with the shaft. Booth adopt 12N14P construction, where “N” represents the number of coils and “P” is the number of magnets.

LN-motor FS2812 1150KV

The LN-motor FS2812 1150KV is suitable for 8 and 9″ long-range FPV drones. Many experts say that 900KV would have been a more appropriate choice for a nine-inch. The motors weigh about 75 grams, including the 25cm 18 AWG leads.

LM-Motor FS2812 1150KV

The base has a 19x19mm mounting pattern with M3 screws. Looking down at the motor, you can see that the motor has a hollow shaft that saves some extra grams. It uses 5mm propeller nuts.

FS2812 1150KV Technical parameters

KV1150
N/P12N14P
Shaft diameter5mm
Stator diameter28mm
Stator height12mm
Mounting pattern⌀19 M3
Weight75 grams
Wires3x250mm 18AWG
Resistance64.2Ω
Voltage3-6S
Max Power1595W
Max Current66A
Efficiency (g/W)1.93-3.87
Max thrust3230grams

I plan to use these motors on an iFlight Chimera9 ECO frame with MasterAirScrew 3MR 0945 glass fiber composite propellers. According to the manufacturer specs, using GF8045-3 propellers and 6S LIPO (24.1V) at full throttle, the thrust is around 3000g. For more test data, check here.

LN-motors FS2306 2050KV

I received green+red FS2006 motors, but navy blue+pink options are also available. These motors are suitable for 5 and 5.5″ propellers. Adopting a lightweight unibell design and a hollow shaft, they weigh just 36 grams, including the 15cm 20AWG wires. They have a 16x16mm M3 mounting pattern.

LM-Motor FS2306-2050KV

When selecting motor KV for 5″ racing drones, 1500-2000KV is designed for 6S, while 2300-2800KV is appropriate for 4S. The 2050KV is the middle way, suitable for 4S and 6S batteries.

Mounting screws
Included mounting screws with threadlocker glue

What’s weird is that only three from the four motors were printed with model number and KV value -one motor was unlabelled.

According to the manufacturer’s test results, using GF51466 propellers and 6S LIPO (22V) at full throttle, the thrust is around 1865g. For more test data, check here.

FS2306 2050KV Technical parameters

KV2050
N/P12N14P
Shaft diameter5mm
Stator diameter23mm
Stator height06mm
Mounting pattern⌀16 M3
Weight36 grams
Wires3x150mm 20AWG
Resistance64Ω
Voltage3-6S
Max Power1030W
Max Current46.8A
Efficiency (g/W)1.81-3.18
Max thrust1868grams

How do you choose the right motor size for your frame?

Before choosing a motor, it’s important to have at least a rough idea of the size and requirements of the FPV drone you plan on building. Matching your frame wheelbase with the propeller size is mandatory. For example, you can’t physically install a 5″ prop on a 100mm size frame.

WheelbasePropeller sizeMotorKV
65-150mm3″ and smaller1003 – 13063000-10000KV
150-180mm4″1806, 22042600KV – 3000KV
180-220mm5″2205-2208
2305-2306
2300KV-2600KV
220-250mm6″2206-2208, 23062000KV-2300KV
250-280mm7″2506-25081200KV-1600KV
280-420mm8 and 9″26XX
28XX
1200KV and lower
420mm+10″ and larger32xx and bigger1200KV and lower

You’ll need the estimated total take-off weight (including battery and camera) to calculate the minimum thrust required for your motors. Normally, a 2:1 thrust-to-weight ratio would be enough, but for racing and freestyling FPV drones, you will need at least a 10:1 ratio.

For example, if you have a 500g racing quad, the total thrust generated by all motors should be at least 5kg. That’s more than 1 kg thrust produced by each motor.

To drive a brushless motor, you’ll need an ESC (electronic speed controller). Commonly used ESCs on FPV drones have ratings from 10 to 100A, and you need to match them with the motor’s power needs. If you drive FS2812 motors with 214-1300W power with 20A amper ESC, this will last only a second -when you push the throttle higher, it will smoke and burn out.