ALTA death spiral and crash

Discussion in 'ALTA' started by Adam Varadi, Nov 26, 2015.

  1. Adam Varadi

    Adam Varadi Member

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    Rolf,

    Please answer me this.
    IF the air module was connected to only 1 battery (of the 2), how could it crash the whole copter?
     
  2. Rolf Ableiter

    Rolf Ableiter Active Member

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    sorry - i can't answer anything.
    But the problem comes when connecting the module. so it doesn't matter if there is another batterie connected.
    sometimes components work for a while after something happened (whatever happened).
    do you know wich batterie was connected first? the one with or the one without the module? and do you know how you did that at your last flight? do you really know?

    i wouldn't change anything at such a system - that's all i want to say. Not because it is better but because it is better for you when it comes to trouble. but freefly was really smart and changed the copter. But i don't think they will do it again with the next modified ALTA...
    freefly did what no (copter) company did before. they really tried to find out what happened and even if they think it COULD be the current sensor or the antispark they shipped you a new ALTA... this is really, really great and i am more than happy to use an ALTA after that story.
     
  3. Adam Varadi

    Adam Varadi Member

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    You might not believe me, but every time I connect the left battery first, then the right. (The right one had the air module)
    I still don't think it's possible that the air module crashed the copter. Just think about it. What could it do that killed the copter?
    I'm very curious to get back the air module. Going to put it on a test bench with a motor + herkules and will try to kill it. Connect, disconnect, etc...

    Freefly did replace my copter (sadly didn't get it yet). But! Please let me know if I'm wrong, but I never saw anything in the manual that said: "Don't change the connectors or add anything or you will loose the guarantee".
    In this logic if you add a video tx that is not the one they like that could kill the copter too? No one except them, know where are the cables go.
     
  4. Dave King

    Dave King Well-Known Member

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    Adam

    I am not quite sure how it could have caused the crash either and I have a degree in electronics and IT with 5 years experience building my own copters. However I do take Freefly for their word. They are not coming out and saying that it 100% certain caused the crash if you read correctly. I think that all Alta users have learned a lot of very important information out of this which is "don't modify the Alta". The alta seems be very sensitive to any changes PERIOD! They don't even want you using different props as it can change the way the alta flies.

    As far as your saying the manual does not say this or that to lose the warranty that's a given with everything. Once you modify anything all bets are off on the warranty. I know a guy that had his engine warranty voided on a "brand new" car because he put a K&N airflow system on it. I think you are lucky that you are getting a replacement.
     
  5. Adam Varadi

    Adam Varadi Member

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    Dear Dave,

    I'm not sure also what caused the crash. But Rolf was so defensive regarding the ALTA that I wanted to show him that no one can confirm that it caused the crash. (Not the air module and not the XT90S)

    Freefly was generous enough to replace my copter, and I'm thankful for it.

    Will see the next few months, hopefully no other ALTA will crash, and in a year we will know better.
     
  6. Rolf Ableiter

    Rolf Ableiter Active Member

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    no i wasn't , adam. read what i wrote.
    and read the manual of the air module.

    you say that you don't believe in this or that. i am not a believer - i read the manual of the air module and mix it together with what i experienced the last 5 years and say it is possible(!) that one of them or both caused the problem.

    AND i said: don't change anything. In case of emergency there is only one thing to blame: the ALTA.
     
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  7. Adam Varadi

    Adam Varadi Member

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    So you say that one of them cause the crash. No way the ALTA had some problem?

    I'm sorry for your bad experience with the air module and Herkules. I have bot of them on other copters and never had problems with them.
    Been flying rc helicopter for 13 years and drones for 5, never had a crash like this. If there was a crash, every time I knew what caused it.
     
  8. Rolf Ableiter

    Rolf Ableiter Active Member

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    o_O sorry Adam, why don't you read what i wrote?
     
  9. Adam Varadi

    Adam Varadi Member

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    You are right! Misunderstood the last comment. My bad!
     
  10. Adam Varadi

    Adam Varadi Member

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    Got the ALTA back! :)

    It's really a brand new copter, thank for it Freefly!
    They were nice enough to cut the battery cables from the ALTA and include it with the package.
    I will put the air module to the test!
     
  11. Steve Maller

    Steve Maller UAV Grief Counselor

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    No, it's some combination of the antispark and the Graupner thing that requires you to separate the connectors. That's on you.

    The stock ALTA doesn't have any of that hardware so the EC5 works perfectly (and yes, mine spark each time I connect a LiPo...).
     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Adam: Apart from the EC5 connections from the Graupner Electric Air Module (EAM), were there any other connections from the EAM to anything else on the ALTA? For example, did you have a connection from the EAM to the RC Receiver? If so, did that connection power the Receiver?

    To answer your question fully, it would be really good if you could hand draw out a wiring diagram showing how the EAM was connected into the ALTA. Might you have time to do that?

    Andy.
     
  13. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Adam:
    Firstly, let me remind you: I'm a volunteer. I don't work for Freefly. I don't speak for Freefly. My opinions are my own.
    Secondly, please "don't shoot the messenger." See https://en.wikipedia.org/wiki/Shooting_the_messenger
    While that would be interesting to know (and please post the results -- I really am interested as I'm planning to use a Graupner Electric Air Module on some fixed wing sUAV/RPAs), the possible outcomes are:
    1. It works fine.
    2. It doesn't work at all.
    3. It works intermittently.

    Unfortunately, none of those outcomes allow you to infer what might have actually happened during the flight where the ALTA crashed. Why? Because you're not starting from the same initial conditions. You're bench testing with an entirely different set up.

    As you say, "you never saw anything in the manual." Well, I'm afraid the bad news is not that it is not there, but that you did not see it: :)

    Page 5 of the ALTA Setup Guide and page 8 of the RevC ALTA manual have the Limitations of Liability -- which describes what FF will not (in some cases, cannot) be held responsible for. It includes the statement (right hand column, fourth bullet down):


    • Use of third-party products on ALTA.
    As you have described (and thank you for doing that, by the way) you used third party products on the ALTA -- these are third party products over which FF has no control of the products or how they were installed. You are the first person that I'm aware of that's installed a Graupner Electric Air Module (EAM) on an ALTA (or even a Cinestar). You did not follow the Graupner instructions to use bullet connectors to avoid damaging the EAM.

    By the way, I must confess, I was really surprised to see that the EAM requires you to use bullet connectors and connect negative, positive, and then the balance connector. As far as I know it's the only device on the market like that (but I don't know the entire market). I would have done exactly what you did and used an EC3 or XT60 on the fixed wing sUAV's!

    Nevertheless:
    1. You used a third party product.
    2. It's not even a third party product that FF has tested.
    3. You did not install it according the Graupner's (rather surprising!) instructions.

    If the video TX injects a voltage spike down the connectors to the ALTA, then yes. You are correct. I could see how it could "kill the copter" in a few milliseconds.


    That's incorrect. The Setup Guide tells you exactly where the cables are that you need to connect up the Receivers, the batteries, the FPV camera and transmitter. If you change any other cables, then you do so with the understanding that you're doing it at your own risk and FF is not responsible for any damage.

    That said, as we have seen, FF will take responsibility (as they have demonstrated both to you and others) for things that FF feels it has responsibility for. So if FF adds a third party Tx (and you can indeed order an ALTA with an FPV Tx and camera installed) then FF will take responsibility.

    Apologies if the "message" above is not what you want to hear, but, sadly, I think it is likely to be the reality.
    Andy.
     
  14. Chris Boots

    Chris Boots New Member

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    Lots of good points being thrown around. Reading this from the beginning, even I still don't have a solid opinion of what caused the failure.

    On one hand, I've had nothing by success with EAM's in the past. And Adam makes a good point about both batteries being plugged in, yet a "Brownout" occurred and a component fried on the Alta internally, and while it was in the air. Typically when things go wrong, it is on power up, but it was flying for some time before the little chip in the Alta gave up. I'm curious how the EAM testing will go.

    On the other hand, Freefly considers this a modification that could in the future void the warranty. Another good point is about aftermarket video transmitters. If one were to short circuit for whatever reason, what is the path of least resistance? Would the copter spiral and crash or is their redundancy between accessories and main power?

    Definitely an interesting case, we'll continue to follow this.

    Those XT90S's gotta go though.
     
  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Chris: Thanks for posting -- when you've used the EAM's in the past did you follow the bullet-connector negative, positive, balance lead connect protocol, or did you use negative-positive-simultaneously connectors?


    The LiPo's have so much stored energy that I think it more likely that the Video Tx would turn into a fuse -- and for a few microseconds of the fireball it could cause a spike in the power supply. When it comes to spikes and digital devices (especially with high impedance devices like MOSFETs in ESC), my experience is that all bets are off. As they say in Texas, "some days you're the dog, some days you're the bush." :)

    Andy.
     
  16. Chris Boots

    Chris Boots New Member

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    I've attached some food for thought.

    I've used both the 33611 and the 33620 EAM's. I first started using the 33611 on my fixed wings, and changed out the standard red plug for EC5's. It should be noted that it came from graupner with those red plugs installed and no mention of plugging negative in first when reading the manual. The 33620 came with bullets the first time I bought one, and assumed the same was true with this one and installed EC5's; it wasn't until I was reading the 33620 manual that I noticed it said "negative first and last". By then I had been using it for some time just plugging the battery straight in. Nowadays, if I even use one, I angle the EC5 so negative touches first.

    The aforementioned information has only been used on my own custom projects. I've never modified the ancillaries of an Alta since we found the Futaba setup to be sufficient for our needs. I have however modified a tablet with a wifi booster and SMA plug to attach a decent antenna to it and incredibly increase my connection range to the Alta's wifi to monitor everything while testing different payloads, the amp draws, temps, etc.

    Yup, hard to say what would happen in a catastrophic situation with a TX. In my experience, the TX internals have always been the weak link, then sometimes the power leads melt off the plug, but thankfully have never had one bring a copter down.
     

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  17. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Thanks, Chris. Looks like the General Air Module (GAM) does not have the dire warnings about negative then positive.
    Curious.

    Andy
     
  18. Adam Varadi

    Adam Varadi Member

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    Hy Andy,

    Fist of all thank you very much for your hard work, and the detailed previous comment.
    I hope all of you understand that I have nothing against Freefly, and I don't get mad at anyone who says something I don't like. If I disagree, I will try to make a compelling case.

    So the EAM was connected to the receiver via a standard servo cable. For my knowledge power doesn't go trough there.
    On the other comments, you are absolutely right, regarding the manual and the connector!

    I didn't have time to test the EAM jet, but will start tomorrow, since i'm very curious about it.

    Attached a picture about the EAM connection. This isn't my drawing by the way. :)

    12064300_1148571401823936_2054216817_n.jpg 12092558_10207973898654527_754600865_n.jpg
     
  19. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Adam:
    Thanks for your understanding -- as you can tell I'm hoping to use the EAM's on fixed wing aircraft so I'm disappointed that Graupner would do something so unusual.

    The concern I would have is that the servo cable from the EAM to the receiver -- if it has the center conductor as I suspect it does -- will either (a) be providing power to the receiver or (b) be receiving power FROM the receiver, or (c) (worst case) there would be 5 volts at BOTH ends of the servo cable and some current flowing depending on whether the voltages at the EAM and the receiver are identical or not -- it's a wiring "loop," if you see what I mean.

    What I would do is see, if you remove the EAM to Receiver cable entirely, whether the receiver still powers up. If it does, then I'd use a voltmeter to see if the EAM is providing 5v. If it is, then (c) is true. If it is not then (b) is true.

    To avoid voltage loops, I would remove the center conductor from the EAM to Receiver servo cable so that it only has signal and ground.

    I realize this is hypothetical for you as you don't have the replacement back and you're hoping to sell it anyway, but for others who might read this thread that's what I would suggest.

    Andy.
     
  20. Dejan Mugosa

    Dejan Mugosa Member

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    Hello,

    Well I can search for the new manual. But this will be faster.
    If you see on graupner page they are selling the same electric module with xt90 and without. HOPE I MADE MY point. BULETS; xt90, ec5 or whatever you like can be used with it.

    http://shop.graupner.de/webuerp/AI?ARTN=33620.XT90
    http://shop.graupner.de/webuerp/AI?ARTN=33620


    I know they did research and the info they haid ( based on what they read from graupenr manual ) looked promising but unfortunally this is not the case and could not be blamed for what happened. We have 300+ drones in air with the air module and it never failed. (fingers crossed I did not jinx somebody now).

    And the bottom part is that it is installed for 1 battery only not to so even if it would fail in any way it still would not be possible to get a spike or something in the components. I have electronics background and in my opinion it just is not possible.
    If that was the case then it would only be possible that it would spike the receiver which it connects to with servo cable. But only signal wire and ground. (+ is not soldered in the air module.).
     

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