Wookong-M Failure... Whats new?

[sixshooterstang]

Had this same incident happen twice on one copter. Once on another. And once on a third.
All three are Aericam X6 RTF copters that a company I am plugged in with (for training their guys and R&D).
All four incidents included all motors stopping, and directly afterwards a loud beeeeep occurred as the 40lb copters crashed to earth.
The copters are running WOOKONG-M 5.16.
At the most recent crash I was actually present to watch.
The pilot put the copter into attitude mode, took off and slowly rose to 15 feet before the copter just stopped and fell. Once on the ground the motors started up again momentarily and the pilot shut them down quickly. I noticed on the way up that the copter seemed to jitter or jump a tiny bit as it rose up.
I found zero bad connections and all batteries were at 24.6v. radio switches were correct (only options are GPS or atti). Copter was only 20 feet away. All props still tight (though some broken) so the only thing left to fail was WOOKONG-M.

All four incidents were exactly the same. This is getting costly.
My theory is the WOOKONG BEC is failing somehow (high amp draw from other things?) or that the wookong is just deciding to reboot mid flight.
What do you folks think?

 

[PeterLester]

But how are your ESCs programmed? They can be configured for slow down cutoff or hard cutoff..... There is also a brake configuration to be made with the ESCs. The WooKong cannot override these ESC configurations.

Had this same incident happen twice on one copter. Once on another. And once on a third.
All three are Aericam X6 RTF copters that a company I am plugged in with (for training their guys and R&D).
All four incidents included all motors stopping, and directly afterwards a loud beeeeep occurred as the 40lb copters crashed to earth.
The copters are running WOOKONG-M 5.16.
At the most recent crash I was actually present to watch.
The pilot put the copter into attitude mode, took off and slowly rose to 15 feet before the copter just stopped and fell. Once on the ground the motors started up again momentarily and the pilot shut them down quickly. I noticed on the way up that the copter seemed to jitter or jump a tiny bit as it rose up.
I found zero bad connections and all batteries were at 24.6v. radio switches were correct (only options are GPS or atti). Copter was only 20 feet away. All props still tight (though some broken) so the only thing left to fail was WOOKONG-M.

All four incidents were exactly the same. This is getting costly.
My theory is the WOOKONG BEC is failing somehow (high amp draw from other things?) or that the wookong is just deciding to reboot mid flight.
What do you folks think?

 

[sixshooterstang]

they are MR escs so no brake, soft start and no cutoff. Plus if it were an ESC issue they wouldnt all die at once on a full battery then just restart.
FOund out the loud single beep was one of the voltage alarms. But at 24.6v per battery, there is no way it will just drop.
Which makes me wonder if the thing is pulled SOOOO many amps to one thing that the voltage dropped enough to cause the wookong to reboot and the voltage alarm to start to go off.

 

[PeterLester]

Seems to me that the C rating of the batteries could make quite a difference. A 65C rated battery would not fade under heavy load while a 20C battery could lead to a brownout and the results you indicate....... Unfortunately the small size of the WKM flight computer does not allow for installation of an ultracapacitor. While a 35C battery good for 70C burst might be adequate for most MRs, a 40 pound MR demands so much more!!!!

they are MR escs so no brake, soft start and no cutoff. Plus if it were an ESC issue they wouldnt all die at once on a full battery then just restart.
FOund out the loud single beep was one of the voltage alarms. But at 24.6v per battery, there is no way it will just drop.
Which makes me wonder if the thing is pulled SOOOO many amps to one thing that the voltage dropped enough to cause the wookong to reboot and the voltage alarm to start to go off.

 

[sixshooterstang]

were running two 8000mah nano techs so 25c continuous and 50c burst. Since So in other words the max amperage continuously from the batteries would be 25 X 8 = 200Amps then we have two batteries onboard so 400 amps. I am really doubting that the copter was pulling over 400 amps. The 60amp escs would blow out at 360amps total draw before the batteries would fade. We have one working copter left though so I may try giving it hard throttle on take off and see if there is any issues.
If the batteries do end up being the cause then Id say Aericam is getting a call from us because those are the supplied batteries with the RTF versions they bought.
This seems to be a serious design flaw with all of the Aericam X6s we have (and all are using the equipment supplied) if all three copters do the same thing

 

[PeterLester]

25C batteries don't seem appropriate from my perspective...... certainly not for a 40 lb MR. Motor currents can jump up to 300% above normal operating current under two conditions.
1) Motor start and 2) Attempting to overcome downward momentum of your aircraft. Since g force is an exponential curve your MR can have an effective weight that is 80 lbs when you get to 2G as an example.

were running two 8000mah nano techs so 25c continuous and 50c burst. Since So in other words the max amperage continuously from the batteries would be 25 X 8 = 200Amps then we have two batteries onboard so 400 amps. I am really doubting that the copter was pulling over 400 amps. The 60amp escs would blow out at 360amps total draw before the batteries would fade. We have one working copter left though so I may try giving it hard throttle on take off and see if there is any issues.
If the batteries do end up being the cause then Id say Aericam is getting a call from us because those are the supplied batteries with the RTF versions they bought.
This seems to be a serious design flaw with all of the Aericam X6s we have (and all are using the equipment supplied) if all three copters do the same thing

 

[sixshooterstang]

According to mathematics and basic battery theory the ESCs wouldve blown as well. I think the batteries are over specd and the C rating is inaccurate. 4Going to punch some things into the xcopter calc and see what it says

 

[sixshooterstang]

NEW INFORMATION!
Found that one of the batteries on the copter that crashed twice has a voltage reading of a little over 24 volts BUT! one cell reads 0v and the rest read as over 5v!!! 5v! thats scaring me. Makes me wonder... could this be the issue? Some kind of dead cell problem? I'm starting to think so!