Just mind that this model does not fly properly yet and is considered experimental
1- First install gazebo harmonic: https://ignitionrobotics.org/docs/harmonic/install
2- Clone this repo: git clone https://github.com/bitcraze/crazyflie_simulation.git
3- Put this repo in your ~/.bashrc and source it in your terminal
export GZ_SIM_RESOURCE_PATH="{PATH ON YOUR COMPUTER}/crazyflie-simulation/simulator_files/gazebo/"
Note that indeed this is still IGN_GAZEBO_RESOURCE_PATH, eventhough gazebo dropped the name IGN so this should be updated at one point
4- Try out the crazyflie world with: gz sim worlds/crazyflie_world.sdf
5- Spin motors
gz topic -t /crazyflie/gazebo/command/motor_speed --msgtype ignition.msgs.Actuators -p 'velocity:[250,250,250,250]'