FrSky S8R.  In this FrSky S8R review we will be checking the FrSky S8R, which is an autonomous receiver with built in 3-axis stabilization, that supports stabilization, automatic level, hover and Knife-edge flight modes. These features can be edited via the S8R configuration or by S8R LUA. It features 8 PWM outputs and up to 16 channels in SBUS. It has an acceptable size and weight for any aircraft (Dimensions: 46×26×14 mm (L×W×H) & Weight: 14g).

Apart from including the FrSky S8R receiver the package also comes with double sided tape, a jumper set and a detailed manual with the operation of the receiver.

In addition to this, the FrSky S8R is compatible with ACCST protocol in D16 mode, so it can be bound with any RC transmitter and transmitter module that supports D16 (Mostly any ACCESS transmitter will be also compatible with ACCST receivers) amongst other features that we will see later in this FrSky S8R review.

S8R Features

Channels and Compatibility: The FrSky S8R is a 8 PWM channels receiver as we talked before in this FrSky S8R review, and it has similar features to its twin model, the ones of the X8R, but in addition the S8R includes 3-axis stabilization, including a 3-axis gyroscope with a definition of ±2000dps and a 3-axis accelerometer that can measure up to ±4g.

For this reason, the FrSky RX8R is the most convenient receiver for conventional Fixed Wing, Gliders, Delta Wings, V-tail models and more. The channels outputs are shown in the following diagram:


We can also choose to use it in 16-channel mode with built-in RSSI PWM output. The binding of the FrSky S8R has to be done in ACCST D16 mode, and with the LBT or FCC firmware (depending on your transmitter version) That means that it is compatible with a Taranis radio, an Horus radio or with an external XJT module as we already talked in this FrSky S8R review.

But if you have a radio system that uses the ACCESS protocol, instead than the ACCST radios already shown in this FrSky S8R review, and is compatible with ACCST protocol receivers, you can also bind it in D16 mode to that radio system without needing an ACCESS firmware to be installed in the receiver.

Other Characteristics: 

  • Built-in RSSI PWM output (0-3.3V).
  • Built-in battery voltage detection.
  • Smart Port enabled.
  • Firmware Upgradeable.
  • Operating Range: Full Range.
  • Operating Voltage: 4-10V.
  • Operating Current: 120mA when it is powered to 5V.


Flight Modes

As we talked before in this FrSky S8R review, the receiver includes also five different flight modes, some of them are only available for conventional models, and they are the followings.

  • Flight Mode - Off: When the flight mode is set to Off mode, the FrSky S8R will output the direct signal produced by the transmitter to the model, without changes.

  • Stabilization: When the stabilization mode is activated, the FrSky S8R will compensate the movement of the aircraft on pitch, roll, and roll axis, against external forces such as wind, until it receives additional signal from the radio system. Trough CH9, the gyro gain can be adjusted by increasing or decreasing the sensitivity of the internal gyroscope.

  • Automatic Level: When the automatic level mode is activated, the FrSky S8R will modify the aileron and elevator behavior according to its internal three-axis accelerometer and gyroscope readings to make the aircraft to return to level orientation once the sticks have been released to neutral position. Under this mode, rudder channel will be working only in stabilized mode.

  • Hover: When the hover mode is activated, the FrSky S8R will take effect over the rudder and elevator channels, making the model to be straight up, also changing accordingly to the gyroscope an accelerometer readings, it is important to highlight that elevator and ruder won’t be required as they will take effect by themselves.

In this mode, throttle is used to adjust the altitude of the airplane and the aileron will only work in stabilization mode as it controls the rotation of the aircraft.

  • Knife-edge: When the Knife-edge mode is activated, the FrSky S8R will roll the plane with the rudder and aileron channels so that a wing points up. Once again, it changes the signals accordingly to the gyroscope an accelerometer readings, so the aileron inputs won’t be required. This way, the elevator is used for steering, meanwhile, throttle, ruder and elevator will be used to maintain the altitude and they will only work in stabilized mode.

The different flight modes can be changed by the CH10 and CH11 trough a three-position switch for each channel, although if you don’t pretend to use it in a conventional model you will only need the channel 10 as there are less modes supported, as you will see later in this FrSky S8R review.

When non-conventional aircraft mode is selected, the signal emitted mustn’t have active mixes on the aileron and elevator inputs as the receiver will mix them automatically with a fixed percentage.

In order to set up the flight modes by channels, when the factory settings are selected, you have to take in account which position takes every switch according to the next diagram of the FrSky S8R review, these values apply when the factory settings are selected.


M: Neutral signal period (1500μs).

H: Time of required signal change to activate the mode (50μs).


To conclude with the FrSky S8R review, we can say that its advantages compared to other receivers are the possibility of choosing between several types of flight modes for almost any model aircraft with its built in 3-axis stabilization system, and what is more, the configuration can be changed easily by several ways. The FrSky S8R also includes battery voltage detection, smart port and RSSI signal compatibility.