Had my first Major Crash today

Discussion in 'Cinestar 8' started by David N Atkisson, Jan 17, 2013.

  1. Steve Maller

    Steve Maller UAV Grief Counselor

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    Jei, were you using PH or AH at the time? Do you have a GPX file from that flight?
     
  2. Jei Swan

    Jei Swan Member

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    To be honest with you i have no idea how to get GPX from the system.

    I was flying with both PH an AH on
     
  3. Steve Maller

    Steve Maller UAV Grief Counselor

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    So I assume you don't have a microSD card in your Navi controller? You should get one. You need a 2GB microSD card (no bigger) formatted in FAT16 (not FAT32) and inserted into the slot in the Navi board. It's super important in order to diagnose things that have gone wrong. For example, I had a crash a month or two ago, and by looking at the data, I found that I had accidentally turned on Care Free mode, and I didn't know it. That made the copter seem like it was out of control. I never would have known if I didn't have the card in there.

    I'm beginning to suspect that AH and PH are much better at staying parked in one place than they are at being "dynamic". Dave's crash also happened when he was flying with at least AH on (not sure if he had PH on, too).
     
  4. Dave King

    Dave King Well-Known Member

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    Steve you know what also would help alert you if you hit a switch by accident is enable the voices in your radio (provided your radio supports it). I use the MX20. In addition to being able to have parameters repeat, if you do anything such as turn on/off any of these variables it will tell you (AH, PH, CH, CF, motors on or off) I have the output of my radio going to my FPV monitor and it works really well.
     
  5. Steve Maller

    Steve Maller UAV Grief Counselor

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    I definitely rely on the voice telemetry, but there's a couple problems with it. One is that often the switch alerts ("GPS ON") don't come through if the repeating function ("INPUT VOLTAGE 15.4 VOLTS") is on. This is a serious deficiency IMHO. I'd love to have somebody fix this. Secondly, I would love to have the repeating announcements cycle through all the telemetry items (for me, voltage, current, altitude, etc...) instead of being limited to just one. And as I mentioned before, have anything else (warnings, switch changes) take precedence and interrupt this flow.
     
  6. Dave King

    Dave King Well-Known Member

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    Hmm...When I have battery voltage on repeat for example, I can hit GPS on and it will come through right away. I know Graupner has put out a new firmware update just last week if you want to give that a try? Thats what I am running because I was troubleshooting my RF on issues.
     
  7. Steve Maller

    Steve Maller UAV Grief Counselor

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    How do we all feel about bumping the TX firmware without changing the FC and NC firmware? Has anybody heard from Holger about whether he's "certified" this new code with his firmware?

    I'm really hesitant to mess with this stuff, as I know there's really tight integration between the Graupner and the MK stack.
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I think it's likely the result of flow soldering -- and does no harm as those pads are probably isolated -- but might do some good in terms of mechanical support of the sensor.

    Agreed. Let's look at the evidence.

    I agree. My comments should not be construed as saying the pressure sensor IS the problem. But I am saying that people should (a) check that there is no fatigue damage on the pressure sensor legs and (b) use a dab of hot glue between the sensor and the FC board to reduce the chance of vibration waggling the sensor back and forth and causing fatigue damage. Remember: If it flies, it vibrates. :)

    I agree.

    No argument from me on that one either.
    In the computer business we use the acryonym: PEBKAC to describe a lot of failure causes.
    Problem Exists Between Keyboard and Chair. ;)

    Actually, my experiences have been the opposite. On the impulse impact, I've seen booms rotated, and motors move along the booms.

    All good advice.

    Agreed.

    True. Those are both other possible ways that you can be in AH and plummet. However, I think we've got to factor in eyewitness evidence to some degree. That's where only Dave can tell us what he thinks he might have done (if anything).

    PEBKAC! :)

    Yeah. I make extensive use of checklists and labeling things with color coding to avoid making pre-flight mistakes turn into in-flight disasters. Which is why I'm have to ask passers-by not to ask questions when I'm preflighting...
    Andy.
     
  9. Steve Maller

    Steve Maller UAV Grief Counselor

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    In the firmware update notes:
    "Vario sounds no longer block out the voice output"
    Maybe this will fix my complaints above!
    :rolleyes:
     
  10. Steve Maller

    Steve Maller UAV Grief Counselor

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    The mx20 can record data, but I believe it does not do so unless you use one of the Graupner timers (which I, for one, do not use). I just looked at my mx20's SD card, and as I suspected, its log folder is empty, too.
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I think you can arrange for the timer to start based on a control setting, e.g. throttle. I seem to recall reading that somewhere in the manual.

    Andy.
     
  12. Dave King

    Dave King Well-Known Member

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    I hope so!!
     
  13. Dave King

    Dave King Well-Known Member

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    Interesting points about the motor mounts moving that far up the boom upon impacts! You learn something new everyday which is why I am here as much as possible as I am inexperienced in flying these little flying saucers. If you don't mind, it would be great to see your check list.
     
  14. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    You've not crashed as much as I have -- that's the only difference, Dave.
    The checklists aren't really fit for human consumption (handwritten). Let me see if I can sort them out.
    In the interim: http://forum.freeflysystems.com/ind...nance-work-what-is-recommended.316/#post-3040

    Andy.
     
  15. Gary Haynes

    Gary Haynes Administrator
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    Dave, saw the photo but when I looked at the damage of my own crash and the force that drove boom 5 into the center hug destroying the power distribution ring in the process, even the tightest clamps will allow slippage. That's why FreeFly is working on aluminum clamps for the roll bar to support heavier cameras. The plastic clamps will and do slip regardless of how tight they are even under normal flight conditions/landings with a heavy camera. Can't imagine the forces when they hit the ground.
     
  16. Gary Haynes

    Gary Haynes Administrator
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    Yes the Graupner logging is tied to the flight timers. They are pretty easy to setup. I have mine setup with the top one being a stopwatch with the time at 6:00 with a 30 second warning while the bottom is Flight time. They start when the throttle moves above a -86% level. From the Graupner manual:

    Data acquisition / storage
    The storage of data on the SD card is coupled to the
    fl ight timer. If this timer is started – when a suitable
    memory card is inserted in the card slot and a telemetry
    link to the receiver exists – both the timer and data
    acquisition will stop when the fl ight timer is stopped. The
    fl ight timer is started and stopped as described in the
    section "Timers (general)" on page 138.

    While data acquisition is ongoing, the on-screen card
    image will blink continuously at a slow rate.
     
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  17. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I suspect there's a positive benefit in having the plastic clamps slip on impact -- it dissipates the energy of the impact rather than transmitting it into the structure and causing things to break. Technically I suspect they may be providing the equivalent of a "crush zone" one finds in an automobile.

    As you say, Gary the impulse G-forces are probably pretty high.

    Andy.
     
  18. Mark Melville

    Mark Melville Member

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    Guys I do not trust that molex cable. If it wiggles free and looses contact.........
     
  19. Mark Melville

    Mark Melville Member

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    Also very shaky footage. What type of setup do you have for your gimbal?
     
  20. Gary Haynes

    Gary Haynes Administrator
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    Mark I have read that some folks add a bit of glue/RTV to the molex so that it is more secure. Still removable but less likely to unplug. But haven't read posts elsewhere that have shown many reports of that happening. And as you did on your direct wire can eliminate the worry of it coming loose.

    For gimbals there seems to be a plethora of solutions. Starting point is always to make sure the props and motors are balanced. Then balancing the CG of the gimbal, with the belts removed, then balance the position of the gimbal on the ship while suspending it in the air. Videos for this can be seen HERE. Complete list of gimbal videos.

    After those basic steps have been done then the forum is full of things like number/types of O-rings, tie wraps around the vibration unit, stiffer/thicker gimbal star plate, spacers grommets around the vibration hex posts and the list continues.
     

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