/dist/images/branding/favicon

Crash, how can you protect yourself from this happening?

Discussion in 'Cinestar 8' started by Nick Adams, Aug 2, 2013.

  1. Nick Adams

    Nick Adams Member

    Joined:
    May 7, 2013
    Messages:
    182
    Likes Received:
    7
    I am absolutely gutted, I just made some gimbal upgrades, longer tilt booms, black o'rings etc. I walked down the road to test fly and this happened:




    I guess I am incredibaly lucky that it didn't happen 10' further forward in the saltwater or 2' further back on tarmac.
    Luckily I dont see any major damage (yet), just a twisted frame and gimbal. The camera still works too.
    I had a headphone in and I got a low voltage warning a split second before it dropped out of the sky.
    As I walked up I noticed the battery cable was disconnected so my immediate thought was I must have not connected it properly but as looked closer I noticed melted solder splattering all over the gimbal. The EC5 connector
    on the Power supply board cables had melted off????
    No wonder I got a low voltage warning!
    The only things that I did differently to any other flight was that I was trying a new 9000mah freefly battery.
    I had also bench tested a parallel battery setup using 2 x 9000mah batteries about 30 mins before. I ran the copter at idle for under a minute, I would guess.
    Can anybody shed any light on why this could happen?
     
  2. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Photos of the connectors, copter, etc would help. Also the GPX file. Likely some type of short unfortunately. You don't mention what you are using for flight control or power distribution board.
     
  3. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,383
    Likes Received:
    1,164
    Did you solder up the EC5 connector the power distribution board yourself, Nick?
    The fact that the solder melted means that it was a high-resistance so-called "dry joint."

    That's unfortunately all to easy to do when you are making up those connectors -- when you dunk the wire into the solder cup it momentarily shock cools the solder in the solder cup and you think you've got a good contact but you may not - you have to dunk the wire and keep the soldering iron against the side of the EC5 pin to bring the solder back to molten state with the wire in the cup -- and only then let it cool.

    Do you have a GPX file from this flight that you can post so we can see if there's anything else wrong?

    Andy.
     
  4. Nick Adams

    Nick Adams Member

    Joined:
    May 7, 2013
    Messages:
    182
    Likes Received:
    7
    Gary-I am using Mikrocopter for both.
    Andy- I must have soldered it if it didn't already come soldered in the DIY kit, although I do not remember specifically.
    Why now after so many other flights? Is there anyway you can test such a critical solder?

    I have attached the GPX files from today I believe the first one is the bench test
     

    Attached Files:

  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,383
    Likes Received:
    1,164
    Nick:
    If you start out with a dry joint, it can gradually get worse. Each time it heats up, it weakens it more (either by local melting, or oxidizing), so it goes into a positive feedback cycle until it fails.

    If you have a good volt/ohm meter, you can measure the resistance from the EC5 connector to the Power Distribution Board and get a sense of whether the connector is good. I just measured from the EC5 positive connector to the blob of solder where it attaches to the PDB and get a reading of 0.1 ohms on a Fluke volt/ohm meter, just to give you some idea of the likely reading.

    EDIT: I forgot to add that you need to test the positive connector and also the negative connector -- didn't mean to imply that you only test the positive.

    Hope that helps.
    Andy.
     
  6. Nick Adams

    Nick Adams Member

    Joined:
    May 7, 2013
    Messages:
    182
    Likes Received:
    7
    Here are some pics of the wires etc.
     

    Attached Files:

  7. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,383
    Likes Received:
    1,164
    Nick:
    Did both the red and the black wires melt out of the EC5? IMG_3259 makes it a bit hard to see, but the melted solder in IMG_3528 is somewhat irrefutable evidence of a melt-down. :)

    Andy.
     
  8. Nick Adams

    Nick Adams Member

    Joined:
    May 7, 2013
    Messages:
    182
    Likes Received:
    7
    Makes sense, I will try it.
     
  9. Nick Adams

    Nick Adams Member

    Joined:
    May 7, 2013
    Messages:
    182
    Likes Received:
    7
    Yes they did. When I walked up to the copter both the positive and negative were dangling without the EC5 connected.
     
  10. Nick Adams

    Nick Adams Member

    Joined:
    May 7, 2013
    Messages:
    182
    Likes Received:
    7
    I dont think one wire pulled out the other when it found the ground:( as the battery was still in place
     
  11. Steve Maller

    Steve Maller UAV Grief Counselor

    Joined:
    Oct 30, 2012
    Messages:
    3,981
    Likes Received:
    807
    Wow, that sucks. GULP. Off to check all my batteries!

    I completely endorse Andy's assertions, because I sent him a LiPo to test for one of his RGG series, and when he took it out of the shipping box, the EC5 came off in his hand. And presumably that was under ZERO load. Just a sloppy soldering job by me. The good news is after dozens of flights with my newly re-soldered Zippy LiPos, I've not experienced a failure.

    Man, you were lucky! And doubly so because not only did your copter survive, but I strongly suspect that you (and all of us) have learned a valuable lesson.
     
  12. Maxis Gamez

    Maxis Gamez Member

    Joined:
    Jul 1, 2013
    Messages:
    60
    Likes Received:
    2
    Wow... Unfortunate and I hope you get it back in the air very soon!
     
  13. Nick Adams

    Nick Adams Member

    Joined:
    May 7, 2013
    Messages:
    182
    Likes Received:
    7
    Seriously! I felt like something died inside of me but in hindsight I am a very lucky boy... very grateful :)
     
  14. Steve Maller

    Steve Maller UAV Grief Counselor

    Joined:
    Oct 30, 2012
    Messages:
    3,981
    Likes Received:
    807
    Yeah, I lost a little quad to Davey Jones' locker this week.
    Mystery as to exactly what happened.
    But it's gone in 50-100' of seawater. :(
    More info here: http://diydrones.com/profiles/blogs/the-end-of-my-quad
     
  15. Nick Adams

    Nick Adams Member

    Joined:
    May 7, 2013
    Messages:
    182
    Likes Received:
    7
    Just to clarify it was the copter side of the EC5 that came off not the battery side. Like it makes any difference, same end result:eek:
     
  16. Steve Maller

    Steve Maller UAV Grief Counselor

    Joined:
    Oct 30, 2012
    Messages:
    3,981
    Likes Received:
    807
    "The weakest link in the chain..."
     
  17. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Steve is that the quad that you just won last week? Have you been out to the trees yet?
     
  18. Nick Adams

    Nick Adams Member

    Joined:
    May 7, 2013
    Messages:
    182
    Likes Received:
    7
    Just checking: Should the wire coming from the power distribution board to the battery be 12 awg? I just butchered a EC5 parralel adapter
    to use the EC5 and was going to solder the 4 wires together and shrink wrap them. I noticed the Parralel adapter is made of much thicker wire.
     
  19. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,383
    Likes Received:
    1,164
    In the hopes of cheering you up a bit, Nick, and I know it sounds harsh, but my copter flight instructor**, said "Never fall in love with anything you fly by remote control. You are going to crash it. It is just a question of when."

    So kiss it goodbye now -- and the odds are it will be around for a long time!!
    But if you should "prang" it (Royal Air Force slang for "crash"), or it enables auto-self-prang mode, you'll be ready for it.
    It will happen so suddenly that you can just relax and say something like, "Oh! I say! That's rather a pity isn't it? Now where did I put my jolly old credit card? James, would you be a good chap and put those pieces that you can find in this biscuit tin. Thanks awfully."

    But, to be serious for a moment, now you know why Gary, Brad, Shaun, and I are (in common with many others on this forum) so careful about not overflying people. It only takes the sight of one uncontrolled descent (aka plummet) in to the ground to make you realize what could happen to anyone if you were flying inappropriately close to them.

    Steve Maller, on the other hand, is demonstrating a tendency to overfly goats.
    We are worried about Steve. :)
    I can see the movie: "Men who overfly goats..."

    Andy

    ** He prefers to remain anonymous after seeing how I fly after taking lessons from him, but his name is Casey. :)
     
    Nick Adams likes this.
  20. Nick Adams

    Nick Adams Member

    Joined:
    May 7, 2013
    Messages:
    182
    Likes Received:
    7
    Thanks for cheering me up Andy, that is seriously funny. I am going to take it to heart it's a great way of Looking at it:) can't beat a bit of English wit!
    There's one positive thing about what you said: I won't need to pull out my credit card after this crash, it has never been put away since I started out on this adventure several months ago:) .... I'm going to Just carry on swiping as normal my friend.
    Lesson learned about flying over people... Loud and clear ( sort of makes water less appealing too:) )
     

Share This Page