Basic settings for ASSIST receivers.
Receiver Preparation
- Using a USB adapter, PC, and the JETI Studio software, verify that your receiver is running the latest firmware version.
- If the receiver has been previously used in another model, perform a format via the transmitter in the menu Menu/Applications/Jetibox while the paired receiver is powered on.
- Bind the receiver to the transmitter.
- Set up the model functions as you would with a standard receiver.
- Install the receiver in the model on a flexible mounting pad to secure it against movement (ideally, use the supplied double-sided foam tape). Position the receiver as close as possible to the model's center of gravity, aligned with the longitudinal, lateral, and vertical axes of the model.
Transmitter Preparation
- Connect the transmitter to your PC using a USB cable and verify that it is running the latest firmware version using the JETI Studio software. The minimum required version is v4.24.
- In the transmitter menu Menu/Model/Function Assignment, create a new function that will be used to switch stabilization flight modes (e.g., Mode), and another function to control its sensitivity (e.g., Gain). Assign controls to these functions — a three-position switch is recommended for the Mode function, and a rotary knob for Sensitivity (Gain).
- In the transmitter menu Menu/Model/Servo Assignment, assign these new functions to unused channels that are not required for other controls.
Basic Assist Setup
Perform the basic setup using the setup wizard launched from the transmitter in the receiver menu:
Menu/Model/Device Explorer/Receiver Type/Configuration/Quick Wizard. Carefully follow the steps one by one.
- When selecting “All servos digital”, the output period for all servo outputs will be set to 7.5 ms. Otherwise, it will be 17.5 ms. Make sure that all devices connected to the receiver support the selected output period.
- Perform the calibration of the controls very carefully and according to the instructions in the “Primary Channel Assignment” menu.
- For the “Flight Mode Channel”, assign the flight mode switch that was configured in the “Transmitter Preparation” section (the Mode switch).
Gain Control Setup (Stabilization Sensitivity)
To the “Gain Tuning Channels” option in the receiver menu under Configuration > Channel Assignment > Assign additional channels, assign the control (Sensitivity / „Gain“) set up earlier in the “Transmitter Preparation” section.
You can assign a single control for adjusting the gain of ailerons, elevator, and rudder together, or use separate controls for each surface.
Note: The percentage value shown in the “Gain Tuning Channels” menu reflects how much higher or lower the final gain is compared to the base gain value configured in the receiver menu Configuration > Airplane Settings.
Stabilization Mode Setup
The Assist system offers six predefined stabilization modes, out of which you can select three to switch between during flight. Mode switching is controlled by the switch assigned earlier in the “Transmitter Setup” section. Each selected mode can be fine-tuned via the “Edit” option in the menu.
Description of Available Modes:
- Manual (Assist Off) – Stabilization is disabled.
- Training – Dampens wind gusts and limits maximum bank angles on all axes. The angle limits are adjustable. Ideal for learning to fly; aerobatics are not possible in this mode.
- Horizon – Automatically returns the model to level flight from any attitude. Recommended for temporary use in emergencies. Each time the control stick returns to neutral, the model is actively leveled.
- Normal (Damping) – Basic stabilization mode. Smooths out flight and reduces effects of wind and turbulence without restricting control sensitivity or aerobatics.
- Heading Hold (Lock) – Stabilization actively holds the model’s current position. Ideal for hovering, low passes, and knife-edge flight. Not recommended for takeoff or landing.
- 2D Mode – Similar to “Trainer” but adds active altitude stabilization. If the elevator control is not touched, the model maintains altitude within 1–2 meters.
First Flight with Assist
- After trimming and fine-tuning your model, perform Assist stick calibration.
- In Horizon mode, with high gain set, verify the direction of stabilization responses—control surfaces should move opposite to the direction you tilt the model.
- Before takeoff, set the stabilization gain control to minimum and switch to Manual mode (stabilization off).
- Once in steady level flight, switch to Normal mode. Fly calmly with gentle bank angles. Gradually increase stabilization gain until the model starts to feel twitchy or overreactive (over-stabilized). Slightly reduce the gain to ensure the model remains stable, even at higher speeds.
- For fine-tuning, you can adjust gain sensitivity per control surface (see section “Stabilization Gain Control Setup”).
For Proper Operation of the Stabilization System, Please Follow These Recommendations
- Regularly update the transmitter and receiver firmware.
- After each model trimming, recalibrate the Assist system (see chapter “Basic Assist Setup”).
- Recalibrate Assist every time you replace a servo in the model.
- Upon powering on, keep the model still and level until the system announces it's ready for flight.
- Assign Manual mode to the first position of the flight mode switch to allow quick deactivation of stabilization at any time.
- Ensure the onboard power supply is sufficiently dimensioned—models with active stabilization have increased power consumption.
- If in doubt, contact JETI model technical support or your local dealer for assistance.
Examples of Selected REX Assist Receiver Configurations
a) Configuration with a REX10 Assist receiver and an Rsat900NG satellite receiver for the 900 MHz band.
- E1 serves as the EX Bus input/backup.
b) Configuration with a Central Box, REX9 Slim Assist receiver, and Rsat900NG satellite for the 900 MHz band.
- Even in the event of a 2.4 GHz signal loss and switch to 900 MHz, the stabilization remains fully functional.
- Fail-Safe is disabled on both receivers (including “intelligent” mode), but enabled in the Central Box.
c) Similar setup using two 2.4 GHz receivers.
- In the transmitter menu under Advanced Properties → Wireless Modes/Trainer, set the mode to Double Path.
- Fail-Safe is disabled on all receivers (including “intelligent” mode), and enabled in the Central Box.
