Why I want an autopilot in my racing drone

About a year ago Hobbyking was having one of their “Flash Sale” events. During a few days, they dropped prices on a few hundred items. An online shopaholic in me couldn’t miss it. I meticulously studied the offerings until I found something worthy of my attention and money. That was a Jumper 218 Pro racing quadcopter, almost ready to run. A bargain at a just a bit over $100! I just needed to add an RC receiver.

Jumper 218 Pro Quadcopter

Jumper 218 Pro Quadcopter | Source: hobbyking.com

I received it a few days later and, as it often happens, put it on a shelf for a few months. From time to time I would take it off the shelf, hold it in my hands, make a few plans for it, and then put it back. At the time I was still concentrating on building my Alien 560 quadcopter, and the smaller drone was a distraction. The “project Alien” appeared to be never-ending. Every time I flew it, I saw a way to improve it. I would disassemble the copter and work on it for a week or two. Then put it back together, fly it, and then dismantle again. Only when I crashed the Alien, I decided to take a break from it and turned my attention to the Jumper.

Despite it being declared “almost ready to run” by the manufacturer, it took me a while to put it together and set it up. As far as quadcopters go, the Jumper couldn’t be further away from the Alien. The Alien was large - 560mm wheelbase (the distance between the opposing motors). The Jumper was less than half of that size - 218mm. The Alien had lots of space in its frame for electronic components. The factory-assembled Jumper had none, and I still had to squeeze an RC receiver. It took me some time to consider mounting options and hook it up in a way that it wouldn’t break at the first crash. Then I faced a new challenge.

The Alien was based on Pixhawk autopilot with Ardupilot software. The Jumper had Naze32, a racing flight controller, with Cleanflight. The setup procedures for those two were entirely different. That meant that the knowledge I gained from months of reading the Ardupilot documentation was useless in the Cleanflight world. I had to start with a clean slate.

Finally, all the challenges have been overcome. The Jumper was fully assembled, tuned, and ready to fly.

Assembled Jumper 218 Pro

I charged the batteries and took it to a nearby park for a test. And a few minutes later I found out that I wasn’t a very good pilot.

You see, the Alien had a full set of sensors: a GPS, barometer, compass. If I released the controls, it would stay exactly where I left it despite the wind. I could flip a single switch, and it would fly back to the take-off spot and land itself. If I was flying it via FPV (First Person View), I could see information about altitude, speed, direction and distance to “home” overlaid over the camera feed.

The Jumper, on the other hand, had no sensors. Well, except for a gyro. But drones can’t fly without a gyro. In short, the Alien was smart, it could pilot itself, and that took a lot of pressure off its operator. The Jumper was a typical racing drone - as simple and as dumb as they get. Unfortunately, that meant that I was fully responsible for piloting it.

I would put on my FPV goggles, take off, and then in a few seconds, I was lost. Looking through the drone’s camera, all the trees around appeared the same. Without a GPS and a compass, I couldn’t tell where I was and which direction I was flying towards. Any wind made matters worse by blowing the drone off-course. Inevitably in a few moments, I would crash. Then the drone would detect a loss of signal from the radio controller and start beeping morse SOS furiously. I had to locate it by the sound, sometimes hundreds of meters away buried under leaves, or stuck in a bush. And then repeat it all over again.

It wasn’t long until the drone was stuck in a tree 20 meters from the ground. The motors wouldn’t start because the copter wasn’t level, which is a safety feature. I made a few attempts to shake the quadcopter out of the tree. But it was properly stuck. I left and was prepared to give up and cut the losses. But when I returned a few days later I found my copter laying safely on the ground under the tree. The previous night’s storm must have shaken it down.

The quadcopter is out of the tree

It’s finally out of the tree

The adventure had a happy ending, but it has got me thinking. I enjoyed the thrill of flying a racing drone and wanted to do more of it. However, I also wanted the safety of an autopilot. I wanted to see an arrow pointing to “home” on my OSD (On-Screen Display). And an ability to flip a switch and watch the drone to return to the landing point itself. Therefore, I decided on my next project. It wouldn’t be a purely racing drone. Instead, it would be a reasonably agile smart drone but with an autopilot and a full set of sensors. That was how the new quadcopter project started.