Greetings everyone!


Not sure how much of newbie this question is, but hopefully it's something simple...

I have assembled 7" quad on Mark4 frame on SpeedyBee f405v3 stack. Running INAV 7, and Bluejay as ESC firmware.

After 1 or 2 minutes of flight (happens both in Acro and Angle) the drone starts rotating / flipping over in air without me touching the sticks. After disarm, it's not hot.

Why could this be happening? What is the direction I should look in to?

Attaching the Backbox log graphs view here

Are the motors hot? if so start with a multimeter.. check ALL motor screws to EVERY motor wire on the esc for continuity. there should be none, doesnt mean there still is not a short. I had a gremlin similar to this, the screws wouldnt "short" until they warmed up..expanding, then cause a 'death roll'..
Do a visual on the screws...mine had 'hidden' mounts and you couldnt see, ive also seen some motors where the wires enter the windings just above a screw mount...

You should post your actual blackbox log, it would be much easier to read. From you screenshot looks like you do NOT have airmode on, you were running your throttle at 0% and all motors were at 0, then you gave full roll command and eventually added a tiny bit of throttle.
Without airmode, your drone will have no authority at zero throttle (it is simply free falling), and adding throttle will take time for motors to ramp up from 0, and the setup may not be able to execute commands such as a full roll immediately and without enough throttle.
I would suggest you look into airmode and enabling that for your flight if you plan to do zero throttle maneouvers. In that case you would still be able to do flips and rolls at zero throttle and your quad would also hold its attitude.

Thank you for the replies. I have put the actual log file in Dropbox, too large to attach here: https://www.dropbox.com/scl/fi/s0ggyaiy0...75vsm&dl=0

The motors are NOT hot, the screws are not out of the holes. The ends of wires are touching the motor stands, but I was assured that is not any kind of problem

I will try with the air mode on, but I don't feel like I did put throttle at the zero level (even though the logs do seem to say so?). 

I have my ESCs flashed for 96 kHz, would using lower PWM help? I'm not up to extreme maneuvers, prefer smooth flying, just want to do basic stuff like turning around, going up and down.

does it fall out of the sky over the same motor or is it various?
if yes switch the particular motor with anotherone and see if the issue stays or wanders with the motor.

96khz is too high, you want 48khz or 24khz for something that big.

https://oscarliang.com/bluejay-blheli-s/

@Pathfinder075 - thank you for advice. Somehow I thought it's the opposite. Flashed by 48, will do a test flight tomorrow. Any advice on the best value for "RPM Power Protection" setting?

@mstc - I turned on air mode, and in air mode it seems to perform fine. I'd still love to make things just work without air mode, because that makes landing more difficult (always needs to remember to turn it off). Thank you for that advice.

Maybe you are flying a larger drone? In the old days, pilots would set an "idle up" switch on the radio, basically that limits the minimum throttle to a fixed amount (say 10% if that is what is needed to maintain some authority on your drone). You would flip, the idle up switch after you take off, and still need to turn it off when you land, if that is what you want, but that could just be similar to air mode on a switch.
But you don't want any control of your drone at zero/low throttle?!

As Pathfinder mentioned 96khz pwm on the ESC is too high, especially for larger motors and will potentially have startup and desync issues. Going down to 24 will help, but still shutting off your motors to 0 in flight and restarting them in the air is just asking for trouble IMO and I don't see any case where you would want to fly your drown in that manner. Do you have MOTOR_STOP enabled? You may consider getting used to flying with that feature DISABLED.

If you are doing mid air disarm/rearm drills, flick angle mode when you do them, or it will be a bit of a nightmare. At least in angle the drone will self level. I have tried them in the past a couple of times, but totally unwise.

If you want to fly without airmode, you will have to learn it. You have to keep some throttle on at all times. no throttle equals no props spinning, means it falls out of the sky. That's just how it is. If you were flying in a helicopter and the props stopped turning what do you think would happen? Besides crashing and probably dying. Same thing applies to quads. if you don't like that behaviour maybe try planes instead. You can kill the prop on those and they still glide. but a quad is basically 4 fans and a lot of nothing. They don't glide, they just become a floating house brick if you stop the props spinning and like any good house brick they promptly follow the route of gravity to the ground.

Hello again!

I'm not turning off the motors in the air, the props keep spinning (but maybe not giving enough thrust?)

I tried 48 and 24 pwm, I like those better, however I still had the drone suddently flip over in the air when not using air mode. What I did notice is that I tend to keep my throttle very low (flying in my backyard so want to keep it slow and don't fly too far away). I have my "motor idle power" set to 15% (suggested by INAV for 7" drone) and my throttle is often below that - should I try lowering that down? Also, am I at the point where I should start looking into PIDs & Rates?

I am attaching some screens on my ESC and motors configuration - do you spot anything that should be different there? (using the defaults)

Thanks for all your help!

You might try increasing the rpm filtering a little.

I am not familiar with iNav, but based on the log you posted, you can see clearly throttle RC command goes to 0 and more importantly your motor commands ALL go to 0 as well. At 0 the ESCs will no longer be powering the motors. It is normal to see the props continue to spin however if no braking was applied by the ESC.

You do not mention what motors you are using, but with 15% motor idle and looks like you do have MOTOR STOP disabled, I would imagine there should be enough power to hold the drones attitude (not altitude) unless your CG is way off. But yes if your PIDS are too low, it is also very possible that at low throttle it will not be able to hold your drone stable. If you post a log from your latest flight where you do not go to zero throttle, it might be possible to verify that.

I second mstc and ask for a full spec of the drone, like all the different parts. Motors, props, etc.

The other thing is SpeedyBee v3 had a lot of reports of glitchiness, not that i'm saying yours is suffering from that, but it has to considered. Is there good airflow to the FC? Is something overheating?

I looked through the thread and can't see if you tried messing with the motor min startup power, demag compensation and other features in esc config. They might be worth a try if it is desyncing, just crank the setting up a bit for minimum startup power and lift demag compensation. I think default is 1025, try 1050 and increase in incremements of 25 to the point the motors start, but you don't achieve lift. It may make it a bit of pig to land, it did on one of mine when i played with them. Then try flying again and see if it falls out of the sky.

If you haven't played with ESC-Configurator before, then read these two pages. They are your basics on what everything does. Hug tends to have the best insights into that side of thing, so he might have some ideas on tweaks you can try. This assumes of course the issue is the ESC/Motor side and not the FC side.

https://oscarliang.com/bluejay-blheli-s/
https://oscarliang.com/best-blheli-32-settings/

The specs are the following:

7" Mark4 frame
SpeedyBee f405v4 stack
Ysido 2807 1300KV Motors
7x4x3 props (I also have a set of 7.5x3.7x3 that I can try)
6s1p LiIon battery
Reaper Extreme VTX
RunCam camera
TX ELRS 900

The airflow is good

I played with ESC configurator, but I only flashed, did not change any settings. I posted the screen of settings above

If I change "minimum startup power" do I also need to adjust other settings? Also I see "Hover throttle" in "Advanced Tuning" in INAV which is set to 1300 uS, is that relevant?

I did not try changing any configuration setting yet, except for apllying the defaults suggested by Inav.

I'm not finding equivalent for in Inav, can you give some hints where to look?

Unfortunately I'm not an expert (or even a beginner) with INav. It has it's place, but I will have to let someone else talk tuning.

As far as on here goes the number of INav users is quite low, RCG may have more. You may want to also link this topic into the INav sub forum and also Reddit.

One question. Does this happen with Betaflight as well as INav? If it does, it's hardware. if it doesn't, it's software. The question came to me after reading this random thread on INav's github.

https://github.com/iNavFlight/inav/issues/8884