Freestyle Drone (2019+)

The reboot of the 2015 hit classic!


After having difficulty building a drone at the beginning of high school, I chose to try again in junior year. I had tinkered with drones and planes the previous few years but never got the drone working quite right. I decided to start again from scratch. I started with a Youtube channel by Joshua Bardwell. He teaches the ins and outs of building drones, and I had been watching his videos for a few years. I started by refreshing what I knew. I re-learned the ins & outs of Betalfight (the control firmware) and caught up on recent technological advancements. Turns out, there was a lot.


The Controller

Seeing as I was starting over, I'd need a way to control the drone. I wanted something that wouldn't lock me into a specific ecosystem. I was looking at the Taranis QX7, until Bardwell released this video. It detailed a new controller, compatible with almost every radio protocol out there, that was less expensive than what I was looking at before. I was hooked. It was exactly what I needed.

Unfortunately, many issues plagued the earlier batches. I had to replace the SD card slot in mine. When I did, I also added a USB type-c port for charging. This radio has since been improved and upgraded, but mine's going strong, despite being dropped a few times.



The Quad


Powertrain:

I researched motor, ESC, and prop(eller) combos for a long time. The ESC controls the motor speed with incredible accuracy, and it's also the first part to "smoke" if it's low quality. This combo was the main thing to get right. I watched reviews for a solid few months, and eventually decided on a mid-Kv motor and basically bulletproof ESC. What's Kv? Well, it's not kV, which means kilovolts. Kv is a measure of motor rotations per 1 volt. So a 2400kv motor (standard mid-Kv) would spin at 38400rpm at full throttle with a 4s (16v) battery (2400*16). Why 4s? It's a good middle ground. The batteries are relatively cheap, lightweight and last a decent amount of time. 6s batteries (22v) are becoming more common, but they're more expensive. I'd rather damage a $22 battery than a $35 one. Depending on flight style, 4s batteries give me anywhere from 3 to 6 minutes of flight time.


The final parts:

Frame:

I just looked for a reasonably durable and light frame that I thought looked nice and had good reviews. I eventually got a Hyperlow RS+. It's a light, durable frame made by Richard Howarth. It's a small company, and I'm pretty sure Richard is one of the only employees. I contacted their support to change my order from their "CG" frame due to camera compatibility, and we had a really helpful discussion about the best frame to choose. I couldn't be happier with my choice. It fits everything I need perfectly. Or almost, anyway. I'll get to that later.


Video (FPV)

FPV stands for first-person view. This means there's a camera on the drone that transmits in near-realtime (22ms latency) exactly what it sees to a pair of goggles on my face. This one's a bit convoluted, so stick with me. I initially got used Fatshark HD3 goggles from eBay. When they arrived, they were a bit gross (the previous owner hadn't cleaned them well) and the lenses seemed damaged. I sent it back and decided to go with a new player on the scene. DJI. Da-Jiang Innovations is most well-known for its Phantom and Mavic series. If you've ever seen a consumer drone, chances are it was made by DJI. They had made consumer and professional videography drones for years and had recently released a somewhat groundbreaking new technology: HD Digital FPV. Digital video links were nothing new, but they were never low latency enough or reliable enough for use in FPV. Their main use case was in long-range R/C planes. DJI's technology was, well, revolutionary. It transmitted 720p video at 120fps with less than 25ms of latency, or 1080p60fps with ~50ms of latency, at a further distance than traditional analog video. The only issue was that the transmitter that went on the drone was quite large. It was manageable for roomier frames, but the RS+ was built to be compact. It just wouldn't fit. I decided to get the goggles only. They have an analog input, so I wired that to the external analog receiver I had used with the HD3s until something smaller was released. I wrote a mini-project about my design process for adding the analog receiver here. There had been leaks of a version called the Caddx Vista, a smaller single-antenna version of the original DJI Air Unit. It was made in collaboration with Caddx, an FPV camera company. I knew it would be released sometime in November 2019, so I bought the goggles with the intention of upgrading later. It finally was announced and I bought one as fast as I could. I'll detail that process later.


The Rest

The remaining components were an FC (flight controller), a control system, and accessories.


Flight controller

This is the brain of the drone. It receives control signals and turns them into positional movements. It filters out accelerometer and gyro noise, taking into account motor RPM, position, control link stability, and external forces (such as wind or impacts). This allows for incredibly precise positional control when coupled with an accurate ESC. In terms of the high-end, they're mostly the same, it's all about choosing one that has the right outputs. I bought one from Lumineer (Lux F7) and it died twice. I got my money back both times and then bought a TMotor F7, which has been rock-solid ever since.


Control system:

You might be thinking, didn't he buy a controller already? Well, yes. It's compatible with most radio protocols and works fine. However, to get the best & most reliable performance, TBS Crossfire (or now IIRC Ghost or TBS Tracer) is the recommended control link. It can go for miles, it's lower latency, and output is smoother, which is important for flight smoothness and filtering. At the time, Crossfire modules were out of stock everywhere. I ended up buying one from someone on Joshua Bardwell's Discord server. For a few dollars a month, you get access and can talk with other knowledgeable fans of his channel, as well as designated "know-it-alls" who you can rely on for expert advice. It's worth every penny, and the paywall helps filter out those who are just there to cause trouble. I've bought things from 3 people on that server and every time it worked out great.


Accessories:

  • Backpack: You've gotta transport this stuff somehow, right? After some basic research, I decided to buy the Lowepro BPX3. Unfortunately, it's all but discontinued. I hunted around and found someone selling their BPX2 (the previous version) on the aforementioned Discord server. The only difference is the lack of a laptop slot (I have come to regret the lack of a laptop slot, but it's not a huge deal). I chatted with him to make a deal. It was a bit touch and go at first, but he let me know there was some event outside of his control that needed dealing with first. After that was resolved, I paid and he sent it to me. Unfortunately, it smelled, as used fabric can do. Not badly, but noticeably. I had to figure out how to get rid of it. I started by putting baking soda in a Tupperware inside the bag and putting it in the hot sun. This removed about 40% of the smell. The rest I took care of with white vinegar in a spray bottle over the course of a couple of weeks. Sure, it smells vaguely vinegary now, but not in an unpleasant way. It's almost like a new-car smell in its freshness.

  • Others: I bought a portable soldering iron for field repairs and a main one for at home. This plus some tools, extra wire and heatshrink were plenty.

Batteries

This consisted mainly of a bunch of research. I watched some reviews, read some articles, and found the RDQ Series 14.8V 4S 1500mAh 100C LiPo Battery. They're reasonably light, have a good discharge curve, and are manufactured by a reputable company. I got a few, though they went out of stock and I actually ended up buying a similar battery from CNHL. They're of similar quality and often go on sale.


The charger was a bit more complicated, though. After realizing I didn't want to wait hours for 6 batteries to charge, I bought an ISDT Q8. It's a 500w 20a charger. Basically this means it's fast. It doesn't however, come with a way to plug it into the wall. I needed to find a separate hobby power supply and wire that to the charger. Thanks to Bardwell, I learned that 24v PSUs (power supplies) are preferable to 12v ones. This is because the charger hits its amp limit before its watt limit when using higher voltages. I bought a 500w PSU off Amazon and wired it to a cut-off AC computer cord. This, along with an XT60 (battery) connector attached to the output, allows me to connect it to the charger. I upgraded that setup later with a custom 3D print and a power switch. Check that build out here.


The Build


(more coming soon, lot of pictures)


The Caddx Vista: It took a bit of finagling to squeeze it into the frame, but after removing a couple of standoffs it fit perfectly. I had measured to make sure it fit, but I still couldn't believe my luck-it fit perfectly. It changed how I fly-I could fly farther, see better, and all with confidence.

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