First VTOL Design, Build and Flight Success

It flies like a plane and hovers like a... big hummingbird

I’ve built and flown my own VTOL, designed from scratch!

Three months ago, I had zero experience in building anything that flies, no aerospace engineering degree, and really no business even trying to design and build a VTOL.

What can I say, I like a challenge.

I made a video walkthrough of my build. It’s much easier to show than tell with hardware.

If 30 minutes of a camera pointed at my VTOL build, my voice narrating and fingers point is not your thing, let’s walk through the build here.

For the first few weeks, I modeled, mathing, sketching, sourcing and assembling a foam VTOL.

I also learned how to 3D print parts, none of which have broken (so far).

Here’s most of my build process in 30 seconds.

Followed by dissembling, reassembling, iterating on software parameters and repairing. The first version of the build was complete.

Time for the maiden hover flight.

Many fixes followed to get a stable hover and enough control authority. This is essential before attempting a transition to fixed wing flight, like a plane. Remember that VTOLs (vertical takeoff and landing) transition from hover to fixed wing flight in midair.

When the transition to wingborne flight starts, the pusher motor on my VTOL spins up, which destabilizes the frame and the motor rpms that were working in hover. That’s why a stable hover is needed before attempting a transition, unless I wanted to rebuild the whole VTOL again.

I flew into trees, fixed compass interference issues, tilted motors for better yaw authority and upgraded some structural joins to 3D printed PETG parts.

After the iterative process to fix and tune the software and hardware, it was holding a solid hover, even in winds.

The foamie (foam VTOL) was ready for its first transition flight. There was an outside chance it would gain enough airspeed, becoming wingborne and turning off the vertical motors. Alas, that did not happen.

The VTOL basically did not produce enough thrust for its weight, or so I thought at the time. I did not want to have to rewire everything and upgrade the pusher motor and thrust. So it was going on a diet.

I had been flying with the battery on the left, weighing almost 740g or 1.6 lbs. That had to go, and I swapped it out for the one in the middle, weighing about half that, 370g or 0.8 lbs.

That was the pack I had used in my quadcopter build. It did not work out well, leading to voltage sag. The VTOL could not draw enough instant current to keep hovering and was falling a few feet while hovering. Not good.

So I ordered the pack on the right, which was almost as light, but much better at handling higher current draw.

It worked, kind of. I had thought thrust to weight ratio was the problem. Just fix that and open blue skies of VTOL flying to come! Not quite.

The lighter battery made me realize the root cause. I had mounted the pusher motor too low on the fuselage. Ideally, the thrust line of planes, ie the direction of the vector propelling the plane forward, should be *in line with the vertical center of gravity (Cg)*.

Mine was too low, causing a pitch up moment. In other words, the pusher motor was using a (too) large fraction of its thrust to pitch up during the transition. You can see it in the video.

At this point I thought maybe the problem was not fixable without building a new fuselage and remounting everything inside it - the avionics, the wiring, the ESCs, etc.

I gave myself one more test run to try to minimize the amount of pitching up it would do during transitions. Ardupilot parameter tweaks, tilting down the pusher motor, and manually pitching down on my radio transmitter during the transition. Turns out that did enough.

It transitioned into fixed wing flight and flew!

My VTOL accelerated and hit 44 mph or 71 kph, before banking a full 45 degrees! I managed to keep it in the air for almost two laps of my local airfield.

A sole person building a VTOL is a recent phenomena. Two decades ago, the motors were not power dense enough, the flight controllers not small enough or cheap enough, there were few open source communities and forums, and no YouTube to learn quickly from others. The control systems for multirotor drones required algorithms and enough compute that simply could not fit onto the memory and processor of microcontrollers at the time.

Since then, we’ve had miniaturization breakthroughs in controllers and sensors thanks to the iPhone and later Arduino, and more power dense motors thanks to drones.

There may only be single digit thousands of people who have built a VTOL from scratch by themselves. Ever. O1 and Claude think less than a 1000 people have done it.

That does not include the software, firmware for the control and other systems which Ardupilot handles like a dream, albeit with steep learning curves.

Still, wild to think so few people have done this!

Next Build — 3D printed long range VTOL

I have already started specs and design for the next build, v0.2. The foamie was v0.1.

My CAD skills are basic, but surprisingly good enough to actually design the entire airframe. See the lighter 3D printed foaming PLA nose in the pic, currently on the VTOL, vs the older foamboard one.

Printing the airframe will be the way. I’m learning fast how to make a lighter airframe that my robot employee, I mean 3D printer, can make for me day and night. That should accelerate my iteration speed on this build and future builds.

I want to push it to fly as far as possible, and I think four hours is achievable. One of the most important aspects of full scale eVTOLs will be range. You and I will be able to fly them next decade, and maybe, just maybe, these VTOL experiments will help me build those eVTOLs of the future.