How to Implement a 4+2 Quad-UAV and Twin-Motor USV Hybrid Vehicle? VTOL Firmware or Other Method?

ArduPlane VTOL Plane
1

Hi everyone,

I am currently working on a hybrid vehicle project and would like some guidance on the correct firmware architecture in ArduPilot.

My Vehicle Concept

  • In the air: a normal quadrotor (4 motors) for takeoff, hovering, and landing

  • On the water: a twin-motor boat (2 motors) using differential thrust for steering

  • The aircraft should land on the water, switch to boat propulsion, and then switch back to quad flight later.

My Questions

  1. Should I start from ArduPlane VTOL firmware and modify it, since VTOL already supports multiple motor groups?

  2. Or is there a more appropriate method, such as:

    • Using ArduCopter with custom mixing?

    • Using Lua scripts to switch between quad outputs and boat outputs?

    • Setting up a custom SERVOx_FUNCTION mapping and mode switching?

  4. Is there any existing project or recommended approach for a “quadcopter + USV” hybrid vehicle?

  5. Is it feasible to use VTOL framework only for motor mixing (quad + 2 rear thrusters), even though the vehicle does not include a fixed-wing component?

Goal

I want the vehicle to:

  • Fly normally as a quadcopter

  • Land on water

  • Use the two boat motors for propulsion and differential steering

  • Switch back to quad mode when needed

I would greatly appreciate any suggestions, example configurations, or references to similar builds.

Thanks!