Ultimate 250-size mini-quad build (2 years of work)

In this post I will summarize all of my 250mm quad copter builds, and share what I have learned in the process. I have been meaning to publish this for quite some time, but, due to the long nature of the post, never got around to properly finishing it. Rather than letting it sit in my drafts indefinitely, I thought I would post what I have (mostly images) with the hope that I will find time to update it in the future. As such, this post is under development, with many details still missing. Feel free to contact me directly if you have a question that isn’t answered here.

I built my first mini quad after seeing my friend, Adam Polak’s, 250mm mini quad. He started with 3D printed 250mm frames and had just finished developing a cast polyurethane resin version. He had several prototype frames that he gave me to test. The first build in this post is using one of his prototype frames.

Polyurethane frame parts list:

1 x Frame
4 x SunnySky 2300KV motors
4 x Afro 12A ESCs
1 x ImmersionRC Video Transmitter
1 x SpiroNET antenna
1 x 600tvl sony camera
1 x D4R-II receiver
1 x MinimOSD
1 x Naze32 (original board)
1 x 1800mAh 3S Lipo
1 x FrSky DR4-II receiver (for use with my Taranis)
1 x HQ 6″ props
1 x Scorpion battery strap
1 x GPS

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Later with T-Motors. They were worse than the SunnySkys.20140711_174647

After struggling to get the previous quad to fly well (there was a disaster with the SunnySky motors. My entire batch had magnets that fell out), I decided to go for a more standard bus-configuration quad frame. I preordered the Nemesis frame because I liked the idea of having a clean plate (which later turned out to be terrible).

 

My next build was based on the Nemesis carbon fiber frame, which I preordered. The main reason I was interested in the frame was the fact that it had “dirty” and “clean” plates, separated by rubber dampers. The ideas is that you mount your vibration sensitive components (camera and flight controller) on the “clean” plate, while the motors are attached to the “dirty” plate. It sounds great in theory, but turned out to be terrible. First, the rubber dampers were apt to break in a crash. As they are quite expensive, this alone was enough for me to stop using the frame. Second, I started to get pretty serious “wobble” on the upper plate as the rubber dampers wore out and became more compliant. I would occasionally hit some sort of resonant frequency coming out of maneuvers which would cause the wobble to become quite severe until I changed the speed of the motors. In any case, I eventually moved on to a better (and significantly less expensive) frame. The parts I used for the Nemesis build were recycled from the previous quad.

Nemesis carbon fiber frame parts list:

1 x Nemesis carbon fiber frame
4 x SunnySky 2300KV motors
4 x Afro 12A ESCs
1 x ImmersionRC Video Transmitter
1 x SpiroNET antenna
1 x 600tvl sony camera
1 x D4R-II receiver
1 x MinimOSD
1 x Naze32 (original board)
1 x 1800mAh 3S Lipo
1 x FrSky DR4-II receiver (for use with my Taranis)
1 x HQ 6″ props
1 x Scorpion battery strap
1 x GPS

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Finally, after my first two 250mm builds turning out pretty badly, I switched the a ZMR250 frame with a separate, power distribution board, which managed most of the power and signal connections for the quad. I also switched from 12A ESCs to my trusty old 20A ESCs, as I had had a lot of problems with the 12A afros burning out. Besides these two modifications, the rest of the parts were again recycled from the previous build (however, I started using different props and experimented with various cameras).

Nucleus PDB frame parts list:

4 x SunnySky 2300KV motors
4 x Afro 12A ESCs
1 x ImmersionRC Video Transmitter
1 x SpiroNET antenna
1 x 600tvl sony camera
1 x D4R-II receiver
1 x MinimOSD
1 x Naze32 (original board)
1 x 1800mAh 3S Lipo
1 x FrSky DR4-II receiver (for use with my Taranis)
1 x HQ 6″ props
1 x Scorpion battery strap
1 x GPS

This build turned out to be excellent. The ZMR250 frame was simple, and extremely durable. I had several crashes where I thought that the entire quad would be totaled, only to find that it was completely unharmed (I just flipped it over and took off). The only thing I had to replace frequently were the props. The power distribution board (PDB) was excellent, and made the build super clean. No wires hanging around to get caught in propellors, and an integrated power supply and beeper, which were great. The PDB also had white LEDs in the front and red LEDs in the back, which were very bright, and really nice at night. The only negative thing I will say about the frame is that the vibration-isolated camera mount is useless. Not only does it pop off (with your camera) in even the most minor crashes, but it introduces horrible wobble to the upper plate/camera. However, I found that strapping the camera (Mobius) directly to the top of the quad worked pretty well, with only minor jello from motor vibrations at certain throttle levels. I flew this quad for quite some time before selling all of my equipment.

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Almost no wires!IMG_0535 IMG_0536 IMG_0537 IMG_0539

Routing the antenna using zip-ties and shrink-wrap.IMG_0556 I took the DR4-II receiver and removed the cardboard package. Then I coated the board in liquid electrical tape. Then, just to be extra safe, I put shrink wrap around the board (mostly to make sure the antenna didn’t disconnect from the board. IMG_0557