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Intermediate build

How to build Flix

4-DoF quadcopter · Intermediate

Flix is an educational ESP32 quadcopter with a printed frame, 8520 brushed motors and a GY-91 IMU, flying on under 2,000 lines of Arduino code with MAVLink over Wi-Fi.

Start the buildProject files
Difficulty
Intermediate

Some soldering, calibration and Linux comfort needed.

Build time
2–4 weekends

Our estimate, part-time

Parts cost
Not published

No total is published

Degrees of freedom
4

MIT (Python tools only)

What is Flix?

Oleg Kalachev's Flix is a quadcopter built from scratch to show how flight controllers work. The firmware is under 2,000 lines of Arduino code on an ESP32.

It flies on four 8520 brushed motors switched by MOSFETs, with a GY-91 or similar IMU, and speaks MAVLink over Wi-Fi or ESP-NOW.

Gazebo simulation and a Python control library are included. Only the Python tools carry a license (MIT). The rest of the repo has none.

Flix specifications

MCU
ESP32 Mini (S3/C3 supported)
Motors
8520 3.7 V brushed
IMU
GY-91 / MPU-9265 / ICM20948
Link
MAVLink over Wi-Fi or ESP-NOW

Figures as published by the project. See Sources below.

Bill of materials

PartQtyNotes
ESP32 Mini1
IMU/barometer board1
8520 brushed motor4
55 or 65 mm propellers4
100N03A MOSFET4
5 V boost converter—Optional
Where's the full bill of materials?

The full BOM, with exact quantities and vendors, lives in the project's own files. Prices change often, so treat Not published as a ballpark. Start at the project repository.

Tools you'll need

  • FDM printer
  • Soldering iron
  • Arduino IDE

Step-by-step build overview

Electronics & wiring overview

The ESP32 PWM pins drive the MOSFET gates that switch each motor. The IMU is on SPI or I²C.

LiPo batterypower sourceLaptop / PChigh-level controlIMUsensingESP32 microcontrollerreal-time controllerESCsdrivers / busBrushless motors4 joints / motors
PowerData / commandsSensor feedbackOverview only. Follow the project's own schematic for pinouts and voltages.

Software

GazeboPython

Arduino firmware plus Python tools (MIT) and Gazebo sim.

Tips from the bench

  • ☕ Match the shaft and prop hole diameters before you order.

Flix FAQ

Is Flix good for learning?

Yes. The firmware is small enough to read in full.

Sources

Written by Bots n' Beans from the project's own documentation. Check the sources for the latest revision before you buy parts.

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