I’ve decided to build a smaller, lighter, but still FPV-capable quadcopter. The previous quad I built is great for holding a heavy camera and getting long (>20 minutes) flight times, but because it is so heavy (>1kg) it isn’t good for fast flying and it is not very resilient to a crash. For this next build, I’m going to try to keep the quad as light as possible (under 500g) but still have decent flying time and support for FPV.
I’ve started with a Tarot TL250A frame. The 250 in this case means it has a roughly 250mm (about 10″) frame width when assembled. I chose this frame primarily because it was the right size, it is made of high-quality 2.1mm carbon fiber, and includes a power distribution board (aka PDB) that integrates a PCB into the lower frame. This PCB allows you to easily take the main battery input (that yellow connector) and distribute power to the speed controllers. This is a big deal for quads because otherwise you have to build some kind of wiring bus to get power out and it can often end up being a mess of wires or connectors and either add weight or reduce reliability. The last thing you need when flying is to lower power because one of the connectors into a 5-wire nut connector lost contact. On the other hand, this setup can complicate things because it means soldering the ESCs directly to a frame that is already challenging to assemble. This board also has some traces to run data or power for FPV systems and flight controllers, but this seems like less of a feature because those cables aren’t hard to hookup now and it feels like a lot of extra soldering.
For the flight controller I initially purchased a $10 OpenPilot CC3D clone board. The CC3D runs OpenPilot software and is quite popular. This software is something I am very familiar with as it is similar to the ArduPilor code in my previous quad. However, after studying and reading a bit more, I got concerned that the $10 clone boards might be unreliable. I started looking at alternatives and I had always wanted to try out the MultiWii – a flight controller based (historically) on components that were used in Nintendo Wii remotes. I settled on a new MultiWii controller made specifically for these smaller quads that don’t need a GPS or a barometer called the PARIS Sirius Air Hero 32. This tiny board comes in a metal case (nice protection in a crash), is super light, and is fully configurable like all other MultiWii boards. It should be perfect for flying this type of small quad.
For the electronic speed controller (ESC), I selected the highly recommended Rotorgeeks 30A. These controllers are higher-capacity than needed for my setup, but I was worried that the little 12A might be too small if I decided to go with an aggressive prop/motor combination and Rotorgeeks doesn’t sell 20A anymore as the difference in weight and price was too small to matter. These particular ESCs are already flashed with a special FW designed to work best with multirotors.
A small divergence – traditional ESCs are designed for model airplanes and as such have features that are optimal for planes and suboptimal for multirotors. For example, the default FW is designed to shut down the motor on low battery in order to allow the plain to keep power to the servos and glide to the ground as best as possible. This makes sense for an airplane, but is a disaster for a multirotor – having a motor go out is an instant crash. It was always possible (with some work) to change the traditional ESC, but there were a limited things you could change. This new special FW is called BLHeli and allows for most parameters to be easily reprogrammed from a PC connected to a special USB-based programmer running an easy to use Windows application. That’s a welcome first for ESCs and another demonstration of how a part of the RC hobby business which as been unchanged for a decade and now suddenly gets a huge productivity boost.
For the motors I selected the DYS 1806 primarily because they were very light and yet super powerful. Even though I knew they were small I was surprised to see how small they really were – they are about the width of a quarter. I sure hope they can keep up. If not, I’ll switch to something else. But others have had good luck with this DYS series so I hope it works out. They were certainly budget-priced at less than $10 each.
For my next post I will show some build progress.