Death Roll

Today I performed some initial LOS test flights with my recently built Tyro129 7inch Quad. Power wise I was using a 3000mAh 4s.

In a hover everything initially appeared fine. Hover was maintained at less than 1/4 throttle. It also appeared very stable and precise on all axis. However after a short period of time the front left motor appeared to spool down resulting in the quad rolling and pitching downward and hitting the ground. On inspection nothing appeared to be hot, all four motors were cold to the touch. Without removing the battery I spooled it back up and put it into a hover again and after about 30 seconds the front left motor spooled down and again the quad hit the ground.

If I arm the quad and leave it on the ground with the motors running at idle speed I can hear a slight change in motor speed every so often. Unfortunately I didn’t have a SD card inserted for the Blackbox.

Back on the bench and with the props removed I connected up to Betaflight and when to the motors tab. I advanced the Master tab to the point all four motors were spinning slow but smoothly. I noticed that motor 4 would occasionally reverse direction for a few revolutions then switch to the correct direction. To rule flight controller issues out of the equation I changed the motor assignments but motor 4 still exhibited the same problem. I have calibrated the 4in1 ESC multiple times and switched between the oneshot and dshot options but still the same results.

In Blheli Configurator I have rolled back and forth between firmware versions (M-H-50) with no change to the symptoms. Altering the amount of demagnetisation has no effect either.

In the past I have experienced and rectified desync issues at max throttle values but this is the first time I’ve seen desync regardless of the throttle value.

If anyone has any thoughts on the matter I’m eager to hear them.

Nidge.

Are you sure it’s not a poor / bad connection on one of the motor poles? That’s disconnecting when vibrating or warm? Did it properly reverse smoothly? Only saying because I had one only 2 days ago.

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A good suggestion, Karl. I’ve turned the iron off for the day but I intend to swap motor 4 with motor 1 in the next day or so, that way it will show if the motor is at fault or the ESC.

I looked on BG to order another motor and 4in1 ESC but they only stock spares in their China Warehouse and I’m impatient so I ordered another complete kit from the UK warehouse as it’ll work out cheaper in the long run, and they’ve got it on a flash sale. But when I went to checkout a Tyro79 had also made it into my basket somehow :face_with_hand_over_mouth:

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:laughing:

HeHe :laughing:

Good call @notveryprettyboy on dodgy connection, for which I raise my hand and say it was my fault.

Originally I had to extend the wires for the motors, which I did by cutting the original wires back by 50% and adding extra lengths. I noticed when I stripped the insulation of the original wires that the wire was actually varnished and so I burnt the varnish off before soldering on the extensions. However I must have forgotten to do one of the twelve wires so when I inspected it the solder joint was crap. I redid the solder after burning the varnish off and “Voila” !!! No more abnormal behaviour.

Why I didn’t spot that the solder was not taking when I originally added the extensions I can’t answer, other than “don’t do drugs, kids. especially when handling dangerous machinery” For me there is a very finite window between pain and total intoxication… Your Honour.

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Glad you got it sorted
Well Done @notveryprettyboy :+1:

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Hate it when they do that.

Don’t know if any of you use contact grease, I have been using this for years and it definitely makes a difference, and also stops any oxidation issues.

https://uk.farnell.com/electrolube/sgb35sl/grease-contact-35ml-syringe/dp/317664