The next few entries will detail some add-ons I use with my Crazyflies to make them safer, easier to use, and more enjoyable.
To that end, this entry is about blade guards. For the Crazyflie 1.0*, members of the Crazyflie community created 3D printable propeller guards that worked out well for those who have ready access to 3D printers. I cannot, unfortunately (yet), count myself among those people. So, for the entirety of the last six months that I’ve been hacking on the Crazyflie 1.0, I’ve flown it “bare” so to speak. In general I haven’t had too much trouble.
There were a couple wall crashes that resulted in very tiny chips on the propellers. There were some ceiling collisions that scratched the top surface of the blades. Oh, and there was that one time it ran into my toddlers head… It didn’t draw blood but it left a little, raised, red bump that made me worry about flying with anyone but me in the room. Fortunately, there were no broken items, painful injuries, or lost eyes!
When the Crazyflie 2.0 came out I didn’t worry about flying it without guards — in fact, I’ve become quite the pilot with all my 1.0 training. When I came across this post on the Bitcraze forum though, I decided to try out the propeller guard mentioned there and see how it worked. Even though it was made for a different quad-copter, it could supposedly fit the Crazyflie 2.0.
The look of the guard is cool. I don’t dislike it. The way the guard mounts is a little annoying. It essentially just sits loosely on top of the motors with the propellers mounted directly on top of it. It essentially “floats” between the tops of the motors and the bottoms of the propellers. It works, I just don’t like the “looseness” of it. If you press the props on too tight, it prevents them from rotating freely. Conversely, if you leave them too loose, they can fly off. The latter situation actually happened once when I was first mounting the guard. It was quite the entertaining crash.
The guard actually reduces handling a bit. It makes the Crazyflie seem more stable but you’re actually giving up agility in return. It’s not that it’s actually more stable, the flight characteristics just feel more stable because it’s a bit less maneuverable. This turns out not to be an entirely bad thing though. With the guard in place, I can fly with my iPhone exceptionally well. I have no problem keeping it hovering. I can fly (easily) through my kitchen pass-through, and I can even keep yaw enabled without it being a big problem. It made iPhone flying a lot more fun!
The only other aspect I can report about is that it changes the sound of the Crazyflie. The prop noise became a little louder, a little rougher, and a little higher pitched. It’s not a problem, just different.
In all, if you’re a new flyer, want to predominantly use the iPhone client, or (especially) have kids and/or pets running around when you’re flying, it is certainly a good investment of the measly $3USD it costs. If you’re mounting first-person view (FPV) camera gear, advanced electronics, or other accoutrements, or if you’re doing some specialized experimentation you’ll likely not want it. For sport flying though, it’s not a bad investment to have around.
*Note: The guard mentioned here does not fit the Crazyflie 1.0.