RC, and how to fly, and then come back here. The board is essentially just an Arduino with some sensors connected which we will program in this article with our own software – by using it you have everything connected you’ll need to get flying – you’ll also be able to play with the excellent ArduCopter software. The ArduPilot project is sponsored by 3D Robotics – this means that they build the hardware and sell it for a small profit, and then feed some of this profit back to the community. The hardware and software is entirely open source and anyone is free to copy it. You can buy the original from them direct, or identical copies from Hobbyking (named HKPilot) and RCTimer (named ArduFlyer). In this article, I am going to assume you have the ArduPilot hardware which is essentially an Arduino with attached sensors. If you choose to ignore my advice and build your own hardware, or use the arduino board, then you’ll need to replace the lower level code (the HAL library). I’m also going to assume you have a quadcopter in X configuration – although not a lot of work is required (just different motor mixing) to switch between +/X and octa/hexacopters, they won’t be given it any substantial attention in the article. Ideally, you’ve already flown your quad with the ArduCopter code loaded and hence you should have your motors connected as follows and spinning in the direction shown.