Logo 800 Crash

Hello guys, not sure where to start so I guess I'll start with the setup:

Logo 800 w/stock motor and esc
Silver vbar Pro w/sats-2 Dx8 radio
Edge 813 mains Edge 115 tail
3 JR 8917HV BLS256HV tail
Pulse 5000 7s 65C fairly new
system powered by 2s lipo

There is not much insight leading up to the crash, other than it lost power and went down heavily. By heavily I mean it appeared to me like I had added negative pitch but I know I did not. When all is said and done, the left stick on the TX was all the way up and I had hit TH, couldn't tell you if throttle hold was hit before or after hitting the ground.

I was making an upright pass in front of me from right to left, maybe 30-40 feet up and the same distance away from me, leisurely not pushing it at all, it happens entirely too quickly. I remember trying to auto-rotate but i did not feel any power whatsoever, went in like a brick. As mentioned looking at how quickly it went in seems like negative pitch had been added but it could be just my imagination/perception, shocked at how fast and hard a heli goes down. When I got to the crash site all batteries were disconnected, it's a total re-kit for sure!

I know it's tough to offer ideas with such little information, any help or thoughts will be appreciated. Powered up all electrics on the bench, all work as should. Vbar event log does not offer much information as to what the issue might be but I'll attach it. Thx guys, appreciate it!

Jose

Quote:

When I got to the crash site all batteries were disconnected, it's a total re-kit for sure!

Ok - ichecked the log but didn't find a Impact hint like "senor out of range". So - it may be possible they have disconnected in flight. But then the 2s Lipo must (or only this one) have been disconnected too.

Can you tell us how much and long the heli was turned on in the regarding flight and afterwards or point us to the page in the log?

regards (EN) / Gruss (DE)

Rainer Vetter

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Thank you RV, really appreciate your time! Sorry I wasn't more specific as to which batteries were disconnected, all 3 packs were disconnected. The 2 flight packs and the 2s receiver pack were disconnected. I've started to check all my wires and connectors but not done yet, I keep coming back to the receiver 2s lipo but all solder joints there look good unless somehow the ec3 connector came loose.

As far as the log if you look go down to page 19, the last entry is the msg: "8:17 Low voltage of 3.5v Rail"

I figure this is where the receiver pack came loose.

Thx again RV, appreciate it!
Jose

Yep - you may be right. It looks like a disconnected battery at this point on page 20 of the log. There are also vibration entries and antenna switch one second before - which gives us a hint that this voltage loss must have been in flight ;-(

regards (EN) / Gruss (DE)

Rainer Vetter

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Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
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Thank you RV, I finished checking the wires, solder joints and connectors, couldn't find or see anything unusual. Have a couple of questions if I may?

How likely or unlikely is the ESC liable to cause something like this? Powers up and functions normally on the bench, spins the motor but I realize it's not under load. Any way to rule out the ESC? How reliable have these YGE 160 esc's been?

How significant is the "Antenna Switched" message right before the last message of the flight? I see other "Antenna Switched" messages further up the event log and always around "Raised Vibration Level" messages, is there a significance here?

How does this Event Log compare to others? Are there any eye openers I should have caught?

Thank you,
Jose

Hi,

if the ESC would fail, it would not take out power to the whole system, as would the 2s lipo if disconnected. The YGE are very reliable, especially with the custom firmware we have for the 800, to make them work even better with large can motors like the stock 800 motor.

Antenna switched basically means there have been packet losses on one sat so the VBar switched to the other one. This is not uncommon, and unless it happens in quick succession (like entries every second, which would indicate a serious problem with packet losses on both sats) all is well.

We can only deduct that, since there are no tell tales of the actual crash (Sensors out of range), that the VBar was already powered off at the time the model hit the ground, it just stopped logging right after the one antenna switch and the low voltage entry when it finally ran out of juice. I find the log not uncommon compared to ones I've seen from other 700s/800s with Spektrum radio system.

How's the receiver pack mounted, how's the EC3 connector placed in the model? Any tension on the wires, the wires dangling freely or fixed somehow so they can not shake the connector loose?

Kind regards

Eddi

Born to fly ...
forced to work.



Edited 3 time(s). Last edit at 03/22/2016 08:38AM by Eddi E. aus G..

Thank you Eddi and thanks to Rainer! I think you two have helped me figure this one out, you two guys are invaluable! Wish we could have that warm fuzzy 100% feeling that this is exactly what happened but with the evidence it's hard to come to any other possible conclusion.

The receiver pack and the wires leading to the vbar for power (2 servo wires on a ec3 connector, see photo) were still firmly attacked to the frame so it would have been hard to be pulled apart on impact, not much was dangling. I assumed that part of the wreckage had hit the ec3 connector and caused them to come apart but the event log shows otherwise (no evidence of impact, therefore disconnected before).

Further evidence, take a close look at the photo and see the red wire on one side of the ec3 connector, the other side of the receiver pack. That's the way I found the red wire, slid out of the connector housing, again I thought part of the wreckage had hit the ec3 connector and caused it to come apart. I figure that connector was loose inside the ec3 housing and when I connected the receiver pack for flight it made just enough contact to power the system on but vibration shook it loose in flight. Hard lesson but we live and learn!

Great work guys, really grateful and appreciative for all your help! Anything I can do to give back just name it, well, within reason! lol : )

Thank you again!
Jose



Edited 1 time(s). Last edit at 03/23/2016 02:19PM by tjmarti.

Hello Rainer, Eddi,

Have another question for you guys, appreciate your time!

I think it's pretty clear to this point the receiver pack became disconnected in flight. I'm trying to determine what the state of the ESC (powered on or off) was prior to impact. Once the vbar was powered off due to no receiver pack I assume whether I hit throttle hold or not the heli should have gone in powered up, correct? Since vbar was not powered on to see throttle hold?

There is not much evidence the heli went in hot, I'll attach a couple of pics but they're not too clear, I'm afraid.

The main gear shows a hand full of teeth damaged. The main pulley has damage around where the main shaft goes through, the part that holds the pin. Very slight rub marks on the motor. Both bevel gears in the chassis gear box have a few flat teeth (both gears). Bevel gears on the tail rotor side are intact.

Thank you,
Jose

Hi,

well if power is lost, any known ESC will power down after a fraction of a second. No signal, no joy.

If the heli went in hot, you would have more damage to the gears, the pinion mills off the main gear pretty quickly then.

I guess the damage is simply collateral, if things were still spinning and then abruptly stopped.

Kind regards

Eddi

Born to fly ...
forced to work.

Hello Eddi,

Appreciate the response, Thank you Sir!

Cheers,
Jose

sorry to hear of your crash, may be a idea to run a opti guard, you will still lose power to motor. but have servo control for Auto.

Regards
Brian

Thank you gixerman, I will look into it, appreciate it!

Cheers,
Jose

Hello all,

Just to update and to add a little cheer to this otherwise bleak and expensive lesson, here's what has transpired to date.

It's been over half a year and way over 150 flights and it's been flying great! Replaced all broken/bent parts but the electronics were not changed at all, they remain the same, including to receiver pack except I resoldered the ec3 connectors! Love this bird, really like how it feels and flys!

I'd like to thank you guys for the outstanding support and advice, I am sincerely appreciative!

Cheers,
Jose