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FunCub QuadPlane (Pixhawk)

The Fun Cub QuadPlane VTOL is a standard tailplane aircraft (the Multiplex FunCub) that has been retrofitted with a QuadCopter system.

Key information:

  • Frame: Multiplex FunCub
  • Flight controller: Pixhawk

Fun Cub VTOL

Unmodified, the Fun Cub is a relatively affordable plane and relatively easy to fly. After the conversion the plane is significantly heavier and less aerodynamic. It still flies quite well but needs around 75% throttle in forward flight.

Bill of Materials

The actual plane looks roughly like as shown in the image above (other similar models will work just fine - this is a Multiplex Fun Cub).

The minimal equipment required is:

  • Multiplex FunCub (or similar)
  • Pixhawk or compatible
  • Digital airspeed sensor
  • 900 kV motors (e.g. Iris propulsion set - motors and ESC)
  • 10" props for quad motors (10x45 or 10x47)
  • 10" prop for fixed-wing motor (10×7)
  • GPS module
  • 4S battery
  • Aluminum frame for mounting the quad motors (10x10mm square tube, 1mm wall thickness)
  • TOW is ~2.3kg with a 4200mAh 4S battery

Structure

The structure is made out of aluminum booms as shown below.

quad_frame Fun Cub -frame for vtol mounted

Wiring

Motor and servo wiring is nearly entirely up to you, but should match the Generic Standard VTOL configuration, as shown in the airframe reference. The geometry and output assignment can be configured in the Actuators Configuration

For example, you might wire it up like this example (orientation as if "sitting in the plane"):

Port Connection
MAIN 1 Front right motor (CCW)
MAIN 2 Back left motor (CCW)
MAIN 3 Front left motor (CW)
MAIN 4 Back right motor (CW)
AUX 1 Left aileron TODO
AUX 2 Right aileron
AUX 3 Elevator
AUX 4 Rudder
AUX 5 Throttle

For further instructions on wiring and configurations please see: Standard VTOL Wiring and Configuration.

Airframe Configuration

  1. For Airframe select the vehicle group/type as Standard VTOL and the specific vehicle as Generic Standard VTOL as shown below (do not forget to click Apply and Restart in the top).

QCG - Select Generic Standard VTOL

  1. Configure the outputs and geometry following the instructions in Actuators Configuration
  2. The default parameters are often sufficient for stable flight. For more detailed tuning information see Standard VTOL Wiring and Configuration.

After you finish calibration the VTOL is ready to fly.

Video

@youtube

Support

If you have any questions regarding your VTOL conversion or configuration please visit https://discuss.px4.io/c/px4/vtol.