Potential thrust loss, previous flights were ok

I am not quite sure what the problem is, the copter weighs about 7.5Kg and is equipped with 4x T-Motor MN501 240KV with 20" propellers, controller: T-Motor F45A.
The device is mainly used in the early morning hours for fawn hunting. When the pilot flew with it in the midday heat the problems with potential thrustloss occurred…
Maybe someone can give me a second opinion?
Thank you!

No mystery here. When this error occurs graph the RC Outputs. If a motor(s) is commanded to max and it’s not meeting commanded action this error will occur.

The craft is generally underpowered/overweight. Graph an early section of the flight where it’s essentially at a Loiter hover. You average commanded motor output is ~1700us. The MOT_THST_HOVER value indicates this also.

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The F45, being a BlHeli32 unit, does thermal throttling. I once lost yaw authority on a quad. One motor had a twist, CCW were working harder, then both went into thermal throttling and the quad spun nine times in place while the ESCs cooled down.

We made a test with the same MN501 with 22“ prop running 20min the f45a was packed in a uncooled case. The esc outer temperature was 70°C after 20 mins, but the temperature throttle is activated at 145°C per default :thinking:

Can that be disabled from BLHelisuite? It still has a general lack of thrust/weight.

@webmotions depends on how you test. You need a fast moving input to generate heat. Constant throttle or slow direct RC variation won’t do.

@dkemxr I see this quads hover point, and it’s pretty high, but in hindsight this may be an advantage. I tried a similar setup a couple of years ago. Mine was built for hover ~1450 but was prone to entering oscillations and I couldn’t tune it to anything approaching stable flight. Didn’t have much time, and the test quad was soon disassembled and parts scattered to other projects, but I always wondered how it would respond if the motors were kept in higher revs.

No matter what you don’t want to peg the commanded output . There have been countless crash posts on here due to the lack of stability that can cause. RPM would be interesting to look at but those over priced ESC’s don’t have telemetry output. There is a Bdshot target for Cube Orange but not running here.

These puny BlH32 ESCs will overheat until solder melts, heatshrink melts and FETs start shifting position, if pushed. I’ve repaired a Wraith32 Mini by just soldering in a replacement to the cleanly missing transistor. And I mean plainly missing. Hot-air extraction would’ve been a bit messy because of the flux.
I tend to believe that the throttling I’ve experienced actually saved the quad, while pegging the commands. It still flies today.