Potential Thrust loss with Cube Orange

rcdevil · August 11, 2020, 3:59pm

Hello everybody,

I made my first flights yesterday with the Cube Orange System and had to find out again and again that during the flight the message Potential Thrust loss suddenly comes up and the copter suddenly reduces the speed of the rotors and goes down by itself.
I have also noticed that the flight voltage is displayed too low after a few minutes of flight, even though it was measured with an external measuring device and is higher.
At the start of the flight, the voltage is displayed correctly in volts.
Does the whole thing have a connection?
That´s my last log file:
http://www.sonotonia.com/binfiles/2020-08-10%2020-14-59.bin

dkemxr · August 11, 2020, 5:01pm

No way to know without posting a link to the .bin log file.

amilcarlucas · August 11, 2020, 7:23pm

Try googling for “battery internal resistance”. If your battery is damaged or not correctly dimensioned, the voltage WILL drop during flights.

rcdevil · August 11, 2020, 8:44pm

Hi Dave,
here is my last flown, log-file, i hope that you can see the reason.
http://www.sonotonia.com/binfiles/2020-08-10%2020-14-59.bin
thank you

rcdevil · August 11, 2020, 8:48pm

i had tested it with new batteries.
And it was the same battery type in my drone, flown with DJI Wookong flight controller, without any problems.
5S with 10.000 mAh.

dkemxr · August 11, 2020, 9:03pm

Nothing really to see in that log it doesn’t look like any of those attempts got off the ground and I don’t see a Thrust Loss error. Do you have a log of it actually flying?

rcdevil · August 11, 2020, 9:27pm

strange, i will download other logs and i will make new flight test and i will post the bin file again
Is that normal that the downloads from the copter is during so long?
For one file aprox. at least 30 minutes?

xfacta · August 11, 2020, 10:36pm

You can eject the SD card and copy the logs straight off it if you need to.
That last log has nothing useful in it, as Dave said.
I’m guessing an Octaquad with Cube orange is not destined to be a small racing quad, so please post more details about the craft, especially prop size, motors, ESCs, frame size and construction, anything else that might be relevant.

Making a few guesses, and if you’re staying with 5S LiPo, set these:
ATC_INPUT_TC,0.22
BATT_FS_CRT_ACT,1
BATT_FS_LOW_ACT,2
BATT_ARM_VOLT,18.4
BATT_CRT_VOLT,17.5
BATT_LOW_VOLT,18
MOT_BAT_VOLT_MAX,21
MOT_BAT_VOLT_MIN,16.5
ACRO_YAW_P,2.7
ATC_ACCEL_P_MAX,60000
ATC_ACCEL_R_MAX,60000
ATC_ACCEL_Y_MAX,30000
ATC_RAT_PIT_FLTD,17
ATC_RAT_PIT_FLTT,17
ATC_RAT_RLL_FLTD,17
ATC_RAT_RLL_FLTT,17
ATC_RAT_YAW_FLTE,2
ATC_RAT_YAW_FLTT,17
ATC_THR_MIX_MAN,0.1
INS_ACCEL_FILTER,20
INS_GYRO_FILTER,20
MOT_THST_EXPO,0.69
MOT_THST_HOVER,0.2
ATC_RAT_RLL_P,0.15
ATC_RAT_RLL_I,0.15
ATC_RAT_RLL_D,0.007
ATC_RAT_PIT_P,0.15
ATC_RAT_PIT_I,0.15
ATC_RAT_PIT_D,0.007

And then see if you can get it up off the ground and hover for a while in ALTHOLD mode, and just some gentle stick movements. Let’s see that .bin log file.

These are the resources to start with:
https://ardupilot.org/copter/docs/tuning-process-instructions.html

rcdevil · August 12, 2020, 10:03am

thank you Dave,

here are all bin files from this test day and every flight i get the error message “potential thrust loss” message and the copter sunks automatically down.
www.sonotonia.com/binfiles/octoxbinfiles.zip

rcdevil · August 12, 2020, 10:04am

thank you very much for this tipps,

My copter is an octa X with coaxial props and 15" props.
Total weight:

5.4kg
here are all bin files from this test day and every flight i get the error message “potential thrust loss” message and the copter sunks automatically down.
I will compare all this parameters with my own prams…
www.sonotonia.com/binfiles/octoxbinfiles.zip

dkemxr · August 12, 2020, 1:00pm

This craft is under powered/over weight. At a Hover condition with no forward speed some of your motors are being commanded to max and the average PWM output is too high for stable flight.

What motors and props? 5S battery power?

rcdevil · August 12, 2020, 1:10pm

The motors are Tiger Motors 3510-25 KV 360

Props: 15X5,2 folded props
Battery: 5S, 10AH
ESC: Hobbywing Slim 40A
Octo Quad X, in the past flown very well with DJI Wookong Flight controller

dkemxr · August 12, 2020, 1:20pm

Why are you running 5S power?

rcdevil · August 12, 2020, 1:23pm

that as the batteries that i flown in the past.
I think about to change it to 6S 8000mAh
What do you mean, maybe better?
They will have more thrust with 6S, when i calculate it with the table from T-Motors.

dkemxr · August 12, 2020, 1:28pm

Yes, it should be on 6S power. On 5S at that weight predicted throttle at hover is ~68% and a thrust-Weight ration of 1.6:1. This is close to what the log is showing. If you do go with 6S some of the parameters that Xfacta supplied will change. But if you read the Tuning Instructions you will know that.

rcdevil · August 12, 2020, 1:33pm

i will try this and i will report.
Question, how can i read the graph that you have analyzed here?
Thank you very much.

dkemxr · August 12, 2020, 1:46pm

The graph is from APM Planner 2. The log file I used is 2020-08-10 20-07-04. Plot the RCOUT values. You really want the average value to be ~1500us at hover. To accomplish that on 5S you would have to reduce the weight significantly

rcdevil · August 12, 2020, 2:19pm

actually i fly it with an 5S 10.000 mAh, weight: 1132g
the new LiPo will have 6S, 8000 mAh weight: 1054g

dkemxr · August 12, 2020, 2:29pm

I think that would put you over 2:1 so it should be good. You probably know that a coaxial is a bit less efficient than a flat design so that has to be taken into account also when looking at manufactures thrust charts.

rcdevil · August 12, 2020, 2:52pm

that is my analysing graph from Mission Planner.
Seems to be the same and good to see, the potential thrust loss message.