Formation Flying Radar Setup: ELRS Radar Module Example

I. Principle

The formation flight radar feature allows multiple aircraft to display the position, direction, distance, and altitude difference of other aircraft through OSD during flight, assisting pilots with formation flying. This feature is implemented through the ELRS radar module.

Basic Principles:

• Each aircraft wirelessly broadcasts its own GPS information through the ELRS radar module while simultaneously receiving GPS data from other aircraft;
• Through a series of calculations and algorithm processing, the aircraft can display the direction, distance, and altitude difference of other aircraft on the OSD screen.

II. Equipment Preparation

2.1 Two or more complete aircraft

1. Flight Controller: Any of the following flight controllers are suitable for this tutorial: CoreWing F405 WING V2 / SpeedyBee F405 WING APP / SpeedyBee F405 WING MINI.

2. RC Transmitter: Using RadioMaster Boxer / RadioMaster TX16S as examples.

3. Receiver: Using SpeedyBee ELRS Nano 2.4G RX as examples.

4. GPS Module: Using Beizheng BZ-251GPS module as examples.

5. Motors: Using 2306 KV1950 motors, suitable for AIRWING, for reference only.

6. ESC: Using 35A~45A ESCs, suitable for AIRWING, for reference only.

7. Servo: Using 9g metal digital servos, suitable for AIRWING, for reference only.

8. Battery: Using 4S1P 4000mah batteries, suitable for AIRWING, for reference only.

9. Propellers: Using 7-inch three-blade or two-blade propellers, suitable for AIRWING, for reference only.

10. Analog VTX: Using SpeedyBee TX 1600 VTX and RunCam Phoenix2 SE V2 camera as examples.

Optional:

11. Airspeed Sensor: It is recommended to use a digital airspeed sensor.

2.2 ELRS Radar Module Manufacturing Tools

• TTL programmer, ELRS receivers (the brands have been explained above, which have been tested and can be used. There are four ELRS receivers in total, with two used for writing radar firmware and the other two used for regular receiver use).

III. Specific Operations

1. Making the Radar Module

• Prepare materials: You will need an ELRS receiver and a USB to TTL programmer. Download and install the ESP Flasher programming software.

• Download and program the software: ESP-Flasher.exe

• Download the radar firmware for ELRS. Taking the SpeedyBee Nano 2.4G ExpressLRS as an example, download this firmware: expresslrs_rx_2400_PA.bin

• Connect the receiver and programmer using the following wiring:

Programmer	Receiver
RXD	TX
TXD	RX
5V	V
GND	G

• Press the BOOT button or short the solder pads to enter BootLoader mode, then connect to the computer. The receiver indicator light should remain constantly on.
• Flash the firmware: Use ESP Flasher to begin flashing.

• Continue until a success message is received. At this point, the receiver has been flashed into an ESP32-based radar module.

2. Flight Controller Wiring and Configuration

• Flash the AP firmware that supports Formation Flight functionality. The firmware is as follows: arduplane4.4.4_merge_AP_RADAR_ENABLED_20240415.tar
• For flashing tutorials, refer to:
• Wiring and flight controller connection: Remove the ELRS radar from the programmer and desolder the solder from the BOOT pads (if present).
• Connect it to the flight controller using the following method:

ELRS Radar	Flight Controller
R	TX6
T	RX6
V	4.5V
G	GND

Important

For CoreWing F405 WING V2, use serial port 1; for SpeedyBee F405 WING APP/MINI, use serial port 6.

• Configure flight controller parameters: Enter Mission Planner, go to the full parameter list, and set the following parameters:

SpeedyBee F405 WING APP/MINI:

Parameter	Value	Description
RADAR_TYPE	1	Enable radar function
SERIAL6_BAUD	115	Set serial port 6 baud rate to 115200
SERIAL6_PROTOCOL	32	Set serial port 6 to MSP
SERIAL6_OPTIONS	0	Default

CoreWing F405 WING V2:

Parameter	Value	Description
RADAR_TYPE	1	Enable radar function
SERIAL1_BAUD	115	Set serial port 1 baud rate to 115200
SERIAL1_PROTOCOL	32	Set serial port 1 to MSP
SERIAL1_OPTIONS	0	Default

3. Radar OSD Information Configuration

Configure the OSD to display radar information.

4. ELRS Radar Function Testing

Important

1. Before flight, perform compass calibration in the field.
2. If there are other AP tuning and configuration issues, refer to the following links:

After completing hardware installation and configuration, you can perform the following tests:

1. Power Test: Power on the flight controller with the ELRS radar module installed, wait for approximately 15 seconds, and the radar module indicator light should enter a fast flashing state.

2. Wi-Fi Connection Test: In the Wi-Fi settings, connect to the radar module's Wi-Fi network. The password is inavradar.

3. Access Radar Management Page: In a web browser, visit http://192.168.4.1/#/ to view and check the radar function status.

4. Radar Function Check Items:

Important

When all radar function check items pass, the radar module is in a usable state.

a. FLIGHT CONTROLLER: Check flight controller information feedback

Important

If this item fails, please check:

1. Whether the ELRS radar is correctly connected to the flight controller;
2. Whether the flight controller is correctly configured;
3. Whether the ELRS radar has the correct radar firmware flashed.

b. GPS FIX: Confirm GPS lock status

Important

This item will only pass correctly when the GPS has properly acquired satellites.

c. PEERS: Display number of friendly aircraft (maximum 6)

When other ELRS radars are powered on, the number of friendly aircraft will be displayed here.

Important

If this item fails, please check:

1. Whether other ELRS radars are powered on and their indicator lights are flashing rapidly;
2. Whether the ELRS radars have the correct radar firmware flashed.

d. ENCRYPTION: Binding code function verification

Important

If this item fails, please check: Whether the ELRS radar has the correct radar firmware flashed.

5. Using Radar for Formation Flight

Two-Aircraft Formation Flight

1. Equipment Preparation: Two aircraft with correctly configured radar functions, confirmed GPS lock (at least 8 satellites).
2. Formation Flight: Observe the OSD information of both aircraft, which can display the friendly aircraft's ID, direction, distance, and altitude difference.

Three-Aircraft or More Formation Flight

1. Equipment Preparation: Three or more aircraft with correctly configured radar functions and good GPS lock status.
2. Formation Flight: Observe the OSD display, which alternately shows each friendly aircraft's ID, direction, distance, and altitude difference, assisting the pilot in formation flying.

6. Important Notes

1. Radar Module Firmware Version

• Ensure all radar modules participating in formation flight have the same firmware version. You can check by visiting http://192.168.4.1/#/.

2. Compass Calibration

• Failure to perform or incorrect calibration will result in inaccurate display of friendly aircraft方位, compass calibration must be completed.

3. Unified Altitude Before Takeoff

• During formation flight, try to unlock all aircraft at the same altitude to avoid large altitude differences causing inaccurate OSD information.

4. Maximum Number of Aircraft for Formation Flight

• The maximum number of supported formation aircraft is 6.

5. Firmware Selection

• It is recommended to use the SpeedyBee Nano 2.4G ExpressLRS receiver, which has been practically verified to ensure stability and functional accuracy.
• If using other receivers, try to flash the corresponding firmware for the receiver models listed on the query website. If the wrong radar firmware is flashed, the radar function will not work properly.

6. Video Transmitter and Camera Equipment Requirements

• Must use video transmitters and cameras that support full OSD display (such as DJI first-generation air-end units used with MSP-OSD).

4. Q&A

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