I have been using the Holybro Durandal Flight Controller for over a month and I’m really impressed. My plan with this Durandal / Bixler build was to build a reliable and dependable fixed wing UAV that I could use as a tool to learn ArduPlane functionality and practice autonomous missions. If you don’t have time to read the rest of this blog post, the short version is that based on my experience of using it for this task, I completely recommend it.
Full disclosure; Holybro kindly sent me the unit to test and I’m a member of CanberraUAV.
I’ve been flying ArduCopter enabled Quads since 2013, but I’ve only moved across to flying fixed wing aircraft and ArduPlane this year. This is the third flight controller type that I have tried. The first was one of the cheap single IMU boards; it had a complete failure during my maiden; that led to the Dev team developing the Independent Watch Dog to prevent anyone else from having that problem. Next I tried one of the early Pixhawk clones; I found that temperamental and I didn’t really trust it.
The Durandal on the other hand feels like a high quality piece of equipment compared to the others. It arrives smartly packaged and I was immediately impressed. What was even more pleasing was that it came complete with HolyBro telemetry radios and a power module. As someone that doesn’t yet have a near infinite supply and variety of leads and cables, I find it a huge bonus to get everything that I need from one supplier, so I know that it will all fit together and work. The only other thing that I needed was an RC receiver, so I added one of those.
The Durandal is a snug fit inside the Bixler 2 airframe. I shaved approximately 1mm of foam from both sides of the rib inside the fuselage behind the cockpit. This allowed me to slide the Durandal in easily, and it now fits flat behind the cross-beam on the floor at the rear of the cockpit. As you can see, the fit is quite tight.
One of my bug bares with these flight controller kits is the really short wires for key parts of the system such as radios and GPS. These are often fine for small quads, but they can be difficult for fixed wing applications. I like to keep RF emitters and receivers as far apart as possible, but the length of the included wires forced me to keep them quite tightly packed around the cockpit. If I was a supplier of these flight controllers and ancillaries I would probably add a number of cable length options in my shop. Based on this constraint I mounted the telemetry radio laterally across the cockpit, with the antenna mounted through a hole in the side of the fuselage under the cockpit. I was worried about potential RF interference, but I haven’t had any issues with this set-up.
As you can see below, I mounted the GPS unit in the cockpit cover. That allows me easy access to the safety switch that is built into the GPS unit.
I have now flown about 30 take-offs and landings with this set-up, most of them fully autonomous. The video below gives you an idea how reliable I am finding it. I don’t have an airspeed sensor fitted, but I am finding that the accuracy of the auto land is really impressive!