My first quad: HMB-235 Buildlog – Building part 2

Buildlog, Multirotor, RC

Ok, the new ESC’s and the VTX have arrived, so time to get building again! With some luck it will see it’s first airtime today.

The first order of business was to get that 4th ESC back in place and check to see if all the motors spin in the right direction. And of course hope that the reason that the other ESC blew up was not because of a broken motor. Luckily this time the ESC managed to keep it’s magic smoke inside and I even guessed correctly that I had to swap 2 motor wires to reverse the motor direction. I know it’s possible to reverse motor direction in BLHeliSuite or via a custom motor mix in cleanflight, but I would like to keep the settings on all my ESC’s identical for ease of configuring them.

While benchtesting the motors I noticed 1 of the motors started to stutter and jitter a lot at about 3/4 throttle and up. All the other motors were fine tho, so it was probably not a timing issue. After re-soldering the motor connetions the motor was still acting up. I also noticed it was a lot hotter then the others and it even started to smell weird, probably because of the heat. I also noticed it did not ran as smooth as I tried to rotate it by hand. Time to disassemble it and check out if there were any visible problems. Unfortunately I couldn’t find any problems, but I cleaned it as well as I could and reassembled it. Luckily that seemed to have solved the problem, as the problem seemed to have gone away. Perhaps some threadlock from the motor mount screws made it’s way into the motor and caused it to run differently. I’m glad the problem has gone away, but I will be keeping a close eye on that motor over the next weeks to see if it was just a 1 off fluke.

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Next up was all the smaller stuff, power to the VTX. Connect up the LED strip, buzzer and receiver. By the time everything was connected the back of the quad started to look like a big mess of wires, but luckily everything fits.

The hardest part to place was the receiver. I want to get Telemetry from my quad to my transmitter, but the only RX I have that supports telemetry is a Futaba R7008SB, which is quite bulky. My initial plan was to place it in the back under the VTX, but since that spot is filled with cables going everywhere, theres no room there. The frame does have a little tray in the back that sticks out, but that would leave it quite exposed and prone to getting damaged in a crash. Eventually I settled on mounting it upside down above the PDB/FC with a tie-wrap and a small piece of velcro to stop it from sliding around. I would have prefered to mount it completely with velcro, but that wouldn’t fit because there’s no space for an extra layer of velcro. I will have to see how well it holds, but so far it seems to be pretty solid.

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I have yet to find a good mounting solution for the LED strip/buzzer combo. Doublesided tape to the back doesn’t seem to hold very well, so I simply tie-wrapped it to the back supports. The downside is that they aren’t visible from the back as soon as the quad reaches a tilt of about 25-30 degrees. Ideally I want to mount it further in the back.

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Everything is connected up and working, except the FPV camera, that one is still stuck in transit somewhere between Hong Kong and me. Unfortunately it’s too dark outside for a test flight, so that will have to wait until tomorrow. Since the FPV cam is still missing it will be a simple LOS test flight to see if everything is working.

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