Building an FPV Racing Quadcopter, Part 4

By Terry Dunn

It's time to put the Strider in the air. Today, I discuss my initial test flights, some configuration changes I made, and my thoughts on flying a quad racer.

The previous three articles of this series were all about getting the Strider Mini Quad assembled into an aerial racing machine. With all of those steps complete, it is now time to put the Strider in the air. I will cover my initial test flights, some configuration changes I made, and my thoughts on flying a quad racer.

Test Flights

I planned for my initial test flight of the Strider to be a quick, knee-high hover in my backyard, lasting only long enough to confirm that the controls operated correctly. Things started off well and all of the controls worked perfectly. Things worked so well in fact, that I spent more time hovering than I anticipated.

A few minutes into the flight, the Strider unexpectedly tumbled into the grass and I heard something bounce off of the fence. In my excitement to get the quad in the air, I had neglected to adequately tighten the prop nuts…a rudimentary task that I really should not have missed. Remember when I mentioned that I was much too astute and diligent to need CCW-version motors? I guess I asked for it.

There was zero damage to the Strider, and I quickly found the flyaway prop. The offending prop nut is another story. It is definitely somewhere in my back yard, but I gave up looking for it. Lawn mowers are great at finding (and hurling) such things, so it’s only a matter of time before we are reunited. Luckily, I had a pair of replacement prop nuts that, while not the same color, fit the threads on the prop shaft.

WHETHER THE STRIDER IS DOCILE OR AGGRESSIVE DEPENDS ENTIRELY ON YOUR RADIO CONFIGURATION AND FLIGHT CONTROLLER SETTINGS. TAKE THE TIME TO EXPERIMENT AND SEE WHAT EFFECTS PROGRAMMING CHANGES CAN MAKE.

Subsequent flights took place at my RC flying field, where I have plenty of room to let the Strider run free. I began with a few line-of-sight flights in Attitude Mode so that I could get a feel for the quad’s speed and handling. I don’t know how my Strider compares to other racing quads, but it’s fast! Because of the quad’s small size, I had to be very careful to keep it in relatively close, or it would quickly morph into a tiny black blob in the sky.

I soon became comfortable flying the Strider in Attitude Mode, so I switched to Rate Mode. The stock Rate Mode settings in the CC3D felt pretty aggressive to me. So, I toned down the rotation rates and added about 30% exponential (using Open Pilot GCS) for subsequent flights. Even though that helped tame the quad, I decided that I still wanted an easier transition to Rate Mode. The solution was using Rattitude Mode.

Rattitude provides all the secure warm fuzzies of Attitude Mode, but still permits aggressive maneuvering and aerobatics when you input large control movements.

Rattitude provides all the secure warm fuzzies of Attitude Mode, but still permits aggressive maneuvering and aerobatics when you input large control movements. It immediately became my go-to flight mode. I actually ended up increasing the rotation rate values in Rattitude Mode to make it more aggressive.

My goal is to become comfortable with pure Rate Mode. Mastering that will be the key to unlocking the precise flying that I aim to achieve with the Strider. I’m sure that seasoned RC helicopter pilots could make the jump quite easily. Although I have flown a number of helicopters, the bulk of my flying experience is with airplanes. Confidently flying a racing quad in Rate Mode requires a slightly different skill set than I currently have. I will continue to bump up my Rattitude settings and take more frequent interludes in Rate Mode. I’ll get there.

In addition to selecting and tuning your flight modes, dual-rates are an effective tool for fine-tuning the quad’s flight performance. With low rates for pitch and roll set to 60%, flying the Strider in Attitude mode is as easy as flying my DJI Phantom (only without GPS features) or one of my mini quads. The power is there when you want to unleash it, but the quad is easily tamed with the flick of a switch or two.

THE STRIDER IS PROVING TO BE A TOUGH BIRD. I FLEW IT INTO A CHAIN LINK FENCE (HARD) JUST BEFORE THIS PHOTO WAS TAKEN. REPLACING THE PROPS WAS THE ONLY NECESSARY REPAIR.

Fast FPV

One of the primary hurdles of flying fast FPV is sound. The aural data coming into my brain didn’t mesh at all with what my eyes were seeing in the goggles.

The Strider is not my first FPV ship. I’ve been using the same goggles and VTX on my Phantom for over a year. In my opinion, FPV with a racing quad is a much different experience. The added speed and maneuverability of the Strider introduced some challenges that I wasn’t expecting. I mentioned these topics briefly in my look at starter FPV quads.

One of the primary hurdles was sound. The Strider is pretty loud. So when no other aircraft are flying, it’s easy to approximate its location just by the buzz of the props. My issue was that the aural data coming into my brain didn’t mesh at all with what my eyes were seeing in the goggles. It was a bit unnerving at first, because I never felt like I never knew exactly where the quad was. The faster I flew, the more pronounced the effect.

After a few flights, I began teaching myself to tune out the sounds and rely primarily on the FPV view to keep my bearings. I’d say it’s a non-issue for me at this point.

FAST FPV FLYING IS A VERY UNIQUE EXPERIENCE. THE PERSPECTIVE IT PROVIDES AND THE SKILLS IT REQUIRES ARE LIKE NOTHING ELSE I’VE EVER DONE BEFORE WITH RC.

Another thing that I had to adapt to was low-altitude flying via FPV. Half the fun of flying racing quads is hugging the earth and narrowly missing (or not) obstacles. For me, it can be tough to accurately sense altitude through the wide view of the FPV camera. I’d often think I was skimming the ground only to have my spotter tell me I was flying four feet high. It’s just a matter of calibrating myself to the camera’s viewpoint and expanding my comfort zone.

My flight times have been averaging about 5 minutes with 1300mAh batteries. I also use a 3S-1800mAh ElectriFly lipo on occasion and get a couple extra flying minutes with it. I’m finding the OSD to be very useful--when I pay attention to it. When the Amp-hours-used value hits about 1000mAh, I know it’s time to start heading back. Sometimes I get so focused on the video image, that I look right past the OSD data. I really should stop doing that.

Crashes are not a matter of “if”, but “when, and how harsh”.

Despite (or perhaps because of) the new challenges, I have really been enjoying my FPV flights with the Strider. It’s a new kind of flying for me. It’s fast-paced and has a moderate element of risk to bump the excitement up a notch or two. Crashes are not a matter of “if”, but “when, and how harsh”. So far, my crashes have resulted in a few broken props…and I managed to fold one of the quad’s arms back slightly (that’s an energy-absorption feature – it pops back into place). I’m sure that more severe damage is coming, but I’m very impressed with how resilient this setup is.

Looking Ahead

Although I don’t see any need to change anything about the setup of my Strider, personalizing and experimenting is half the fun. All of the electronic components that I chose, and the PDB integrated into the Strider, are capable of handling 4S battery packs. I don’t necessarily need any more speed at the moment, but I’m sure that my curiosity will coerce me before long. I think it’s safe to say that some 4S flights are in my future. I will have to do some experimenting to see if smaller props are needed when using 4S to prevent pulling too much current through the motors and ESCs.

The Strider frame has six built-in LEDS, three green in the front, three red in the back. I’m considering adding more, just for visual flair. I can easily tap into the 12v source on the PDB to power a few light strips. Red Rotor offers 3D printed skids that are also LED mounts, so that may be the easiest option.

More than anything, I look forward to logging a lot of flight time on the Strider to get more comfortable with it, and maybe catch some interesting video. I’m always on the lookout for interesting and safe flying locations to try out. Perhaps I’ll even find a few other quad racer pilots in West Texas and we can have an actual race.

I hope that you have found this series of articles helpful. I know that many of you are already flying quad racers of your own. I encourage you to share your own tips, strategies, opinions and experiences in the comments section below.

Terry spent 15 years as an engineer at the Johnson Space Center. He is now a freelance writer living in Lubbock, Texas. Follow Terry on Twitter: @weirdflight