You mean you still haven't flown your own UAV? Systems engineer Dave Shevett, who has flown remote-controlled gliders and aeroplanes, and built his own racing car, decided to make his own remotely-operated quadcopter after seeing an incredible first-person-view (FPV) quadcopter-racing video on YouTube. Here's how to do it. Be sure to check the Civil Aviation Authority's drone code, though, to keep you out of trouble...
- GATHER THE DRONE PARTSYou'll need a frame. Shevett decided to go with a 250mm model, the diagonal distance between motor centres. You'll also need four motors and propellers, a flight controller (FC; he used a CC3D from OpenPilot) and four electronic speed controllers (ESCs). These can be purchased as a kit or separately. Also, you'll need a lithium polymer (LiPo) battery, a power-distribution board and, depending on the requirements, a 5V regulated power supply for your FPV camera and other things. A common battery size is 1300mAh; too large and it will be too heavy to take off. Finally, you'll need straps and zip ties to keep it all in place.
- ASSEMBLE THE CONTROLLERTo control the quadcopter, you'll need a handheld transmitter (TX) and a radio signal receiver unit (RX) attached inside the drone. Shevett uses a FlySky FS-T6 transmitter and FS-R6 receiver. The RX is wired to the FC unit, which commands the motors via the ESCs. FPV hardware is fairly simple, comprising a camera and video transmitter on the drone and a receiver and display on the ground. He uses a Fatshark 600TVL camera with a 5.8GHz 250mw transmitter, powered by the 5V power supply. He uses 5.8GHz radio frequency Fatshark goggles to receive and display the signal.
- BUILD THE FRAMEShevett's kit consisted of two layers of carbon fibre that were attached together with Allen screws and standoffs. It's a basic kit assembly, so you have a frame in your hands that looks like a drone, but without the wiring or motors. "It only takes about two hours," he says. "Adding motors, wiring, radios, however, can take weeks." Motors are generally attached with Allen screws as well. Install propellers on each motor (to be removed before testing); two will need to use clockwise propellers (front-left and back-right), and the other two anti-clockwise propellers.
- WIRE THE MOTORSStarting with your LiPo, hook up each of your ESCs so that the red wire goes to the positive battery wire, and the black to the negative. Each is powered in parallel, so the red and black from the battery can be connected to four separate wires to power each ESC. This can be done by soldering, but connectors are available to make this easier. The other end of each ESC will have three connections that are hooked to the three wires of each motor. Unlike the connections from the battery, accurate wiring is not critical - it simply determines which way the motor spins. If one or more motors spins backwards, flip any two wires.
- CONFIGURE THE CONTROLSConnect each of the ESCs to the flight control board using a three-wire connector, then plug the connectors from the FC into the RX. Attach your camera where you'd like to view when flying. Wire this, as well as your transmitter, up to the proper voltage supply; in Shevett's case, this is a 5V, drawing power off of the main battery. Use zip ties to keep errant wiring in place, and shorten wires to fit the frame. Before testing, remove the blades until you're ready to fly. Turn the unit on, and if everything's connected, you should hear the ESCs beep. The motors may also twitch.
- CALIBRATE AND TESTWith the propellers still removed and power supplied, plug a USB cable into the FC, and into your computer. Boot up your ground-station software, then calibrate the maxim um and minimum throttle positions for your ESCs. You should be able to spin up and stop your motors with the computer. Disconnect the USB cable and bind your TX to the quadcopter RX. Assign the correct channels to each quadcopter action and test the function on a bench. Once you're confident the drone is working, it's time to reinstall the rotors and take it to a clear outdoor area to fly.
- TAKE A TEST FLIGHTAt first, you'll be flying the quadcopter without using FPV equipment. According to Shevett, if you've never flown a radio-controlled craft, "usually the next step is a brief flight and a crash". He recommends that new fliers lift their craft cleanly up a metre or two "before trying any manoeuvres" so you're at least clear of the ground as an obstacle. Once you're confident with your "line of sight" flying, you can then try out the FPV gear. "Flying FPV is really hard. So make sure you learn how your quad works before putting on the goggles," says Shevett.
This article was originally published by WIRED UK
