F-35B VTOL
PROJECT TIMEFRAME
Spring 2015 - Present
PROJECT PURPOSE
To create the first flying scale model of the F-35B with a fully functional VTOL lift system and intuitive flight controls.
TECHNIQUES USED
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Conceptual and detail design
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CAD modeling
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3D printing
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Programming in Arduino & C/C++
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ArduPilot configuration and tuning
SKILLS LEARNED
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ArduPilot development
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PID control design and tuning
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SITL simulation
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Video and written documentation
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Iterative & continuous improvement
I started this project with a touch of hubris. I assumed that 3D printing would enable me to easily build the three bearing swivel module (3BSM), and that doing so would put the most complex part of the project behind me.
That eventually came true. But it took seven iterations of the 3BSM nozzle design, four versions of the nozzle controller, and three different actuator configurations to arrive at something that worked reliably. Only then could I mount everything to a hovering testbed and take on the flight controls.
After the hovering testbed, transition to wingborne flight was the next giant leap. The easiest path was to mount simple wings and tail surfaces to the testbed itself. That way, inevitable mishaps wouldn't cost too much time or effort.
The decision to use ArduPilot was pivotal here. Its formidable VTOL feature set could be extended to the F-35B configuration with few modifications. At this point I had lots of ArduPilot configuration and tuning experience as well, so the first transitions went smoothly.
Despite the cheap and simple nature of the testbed, I still preferred a non-destructive method to test new firmware and features. So I learned how to build custom models for the RealFlight simulator and to drive them using a software-in-the-loop (SITL) instance of ArduPilot.
This way, I can test changes to the firmware in a realistic simulated environment running the actual flight control code. It's a great way to speed development and reduce risk.
With the 3BSM design working reliably, I decided to commercialize it. This would help self-fund the project while allowing interested enthusiasts to build their own VTOL vehicles using my thrust vectoring design.
I packaged the actuator control electronics into a single custom PCB and source them from an assembly vendor in bulk. I created a cross-platform Electron app and published a series of video instructional guides to walk users through assembly and configuration.
This F-35B isn't the culmination of the project - only the latest step. Additional firmware and flight control improvements, larger and smaller airframe variants made from different materials, and more scale details like lift fan doors and hidden roll thrusters are all on the table for future work.
