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It was all going so well.....

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  • It was all going so well.....

    Well guys, put the 600L in today.

    Mixed emotions really, kinda glad its out of the way, its only my second crash, the last one being 2 to 3 years ago. But gutted a little not crashed heli is now crashed!

    Will need a bit of help to sus out what went wrong!

    I was between 1 to 2 mins into the third flight of the day on the 600l. I was hovering inverted about 100ft up, as I went to bring it back to upright hover, I heard a strange noise. It sounded like the motor had shut down. My friend with me seems to think he heard a crunch before he recognised the motor had shut down. But I don't recall hearing that.

    in the heat of the moment I held it in the hover, I think at that point I was feeding in positive collective as it held its altitude. Then I think I was at full stick and it began to come down. It didn't fall like straight down, but I was coming down fast (as I recall in the moment).

    As it came down, I didn't feel I had any cyclic control, but I think this is down to bleeding all the head speed. As it dropped I moved the collective to just below mid stick. As it got to around 3 to 4 meters I went full positive. I don't recall the heli responding to this, but it may of done.

    It hit the hard compact soil skids down, but leaning forward, so the bottom front left took the impact.

    I didn't hit throttle hold until it was on the deck and stopped.

    I collected it and brought it back to the pit without unplugging anything. All servos were responding normally, and no beeps or anything from the ESC. I then powered down.

    The good news is the damage - Skids, Canopy and that looks about it . It popped both links of the swash from the main blades. Tail blades, mains, boom all undamaged. Main gearing, tail gearing again all ok. Servos seem to be operational also, pending a closer look.

    So pulled the logs, I need to sus the logging on the brain because it does not add up. the last log in it showed a 6min flight!

    Anyways attached are screenshots of the castle and jeti (logs brain also).

    I initially thought the system had lost its throttle signal, but the timing of the throttle going to zero does not coincide with my pitch inputs. So I am not sure. What I know for sure is there was no over amp, no under voltage, no signal loss (signal strength averages 5 or 6, with it dropping to 3 for a blip. But signal quality stays 100%). No RX power loss either.

    Attached Files
    Last edited by cjm180; 15-08-2017, 08:48 PM.
    Kr
    Craig

    Goblin 700 KSE, Trex 700x, Goblin 770 Sport - Build in progress
    Armattan Chameleon, Losi 5T, HPI Baja
    Aj Laser 60" - Build in progress

    Jeti DS-16

  • #2
    Sorry about the crash, but by the sounds of it it's not too bad.

    The one way bearing coming loose and spinning in the housing is not uncommon on the Trex 600. This is just one of the possibilities but it's consistent with what happened. It's easy enough to check, just try to turn the blades backward while holding the motor still, if you can turn the rotor backward without the motor turning that's the OWB slipping.

    PS.. the images of the logs are too small to read.
    Goblin Kraken, SoXos Strike 7, XLPower Specter, Goblin Black Thunder T, Goblin 700 Speed, Goblin 770 Comp Carbon, Trex 700X, Kasama Dune, Henseleit TDR

    Comment


    • #3
      Castle Log 1 by Craig Mason, on Flickr

      Castle Log 2 by Craig Mason, on Flickr

      Castle Log 3 by Craig Mason, on Flickr

      Castle Log 4 by Craig Mason, on Flickr


      Castle Log 5 by Craig Mason, on Flickr

      Jeti Log 1 by Craig Mason, on Flickr

      Jeti Log 2 by Craig Mason, on Flickr

      Jeti Log 3 by Craig Mason, on Flickr
      Kr
      Craig

      Goblin 700 KSE, Trex 700x, Goblin 770 Sport - Build in progress
      Armattan Chameleon, Losi 5T, HPI Baja
      Aj Laser 60" - Build in progress

      Jeti DS-16

      Comment


      • #4
        Thanks Grumpy

        I have just done that test, turning the head while holding the motor, spins one way, solid the other way. However I will pull the main gear out tomorrow for a look anyways.
        Kr
        Craig

        Goblin 700 KSE, Trex 700x, Goblin 770 Sport - Build in progress
        Armattan Chameleon, Losi 5T, HPI Baja
        Aj Laser 60" - Build in progress

        Jeti DS-16

        Comment


        • #5
          Craig,

          The Castle log does look very much like a slipping OWB. At 2479 seconds you have a rapid drop in power coupled with an initial surge in (motor) RPM then a perfectly flat line RPM, but with very little power being transmitted. This is consistent with the motor spinning with little resistance against a slipping OWB. Then about 15 seconds after the initial event you hit throttle hold.

          Sometimes the OWB will grip again after it comes to a stop which could explain why it wont turn backward.

          I had it happen on my own Trex 600. in my case the OWB itself was ok, it was spinning in the housing. Some Loctite bearing retainer did the trick, probably good practice to change the OWB anyway if you do take it out.
          Last edited by Grumpy; 15-08-2017, 10:14 PM.
          Goblin Kraken, SoXos Strike 7, XLPower Specter, Goblin Black Thunder T, Goblin 700 Speed, Goblin 770 Comp Carbon, Trex 700X, Kasama Dune, Henseleit TDR

          Comment


          • #6
            The OWB on the 600 is notoriously unreliable.
            Tron 7.0 advance Vbar evo V Control
            Foamy plank
            icharger 3010b, Coolice 24v psu
            Member of MK Heli Club and LMAC

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            • #7
              pinion slipping on output shaft of motor ?

              Comment


              • #8
                Thanks for the replies.

                What I have done:

                1) removed the main gear assembly and main shaft. I have looked at the OWB and all looks to be In order. No bits of metal anywhere. I reassembled it on the main shaft outside of the heli. With my hands on the head and gear, I have pulled so hard the OWB jumped. The OWB does not appear to of spun. However I have put a scribe line on it. So I can check after a few flights on it. One owb is not flush with the tip of the gear. There is a radial bearing in the top, and below it the owb. The radial is slightly below the surface of the gear hub. On the bottom, the owb is slightly proud. But the owb OD is not visible. Its just the radius on the edge.

                2) Removed the motor to check if the pinion has slipped. I have removed the grub screw that was deepest ( on the flat ). The flat is visible with no damage. the only mark is the circle from the end of the grub screw.

                Cant immediately see anything else.
                Kr
                Craig

                Goblin 700 KSE, Trex 700x, Goblin 770 Sport - Build in progress
                Armattan Chameleon, Losi 5T, HPI Baja
                Aj Laser 60" - Build in progress

                Jeti DS-16

                Comment


                • #9
                  Craig, if the OWB 'jumped' (as in slipped slightly) then it's faulty. You should be able to put all your strength into it without it budging.
                  Goblin Kraken, SoXos Strike 7, XLPower Specter, Goblin Black Thunder T, Goblin 700 Speed, Goblin 770 Comp Carbon, Trex 700X, Kasama Dune, Henseleit TDR

                  Comment


                  • #10
                    I had my castle 160 shutdown during some tic tocs but the castle log was in conclusive. Found the owb had a lot of oil in it from a rebuild which I cleaned out but this time adding less oil. Since then the problem went away.

                    Comment


                    • #11
                      Hey Guys

                      Sorry for the slow reply, i finally got the 600l rebuilt last night. Just new skids for now, the canopy can come another time!

                      Fitted a brand new OWB as per grumpy's comments. I scribed a line on it to the hub, to see if it spins in the future.

                      Connected a flight pack to test all servos and everything looked good.

                      Got to the field this morning, again all looked good on the pre-flight tests. Carried it put, and started to apply collective. Nothing happened!

                      I could see what appeared to be the swash moving up. Then i begun to lower the collective to see what was happening. As i did it suddenly lent forward. Chopped it down before it tipped over.

                      Anyways another bench test shows the rear cyclic servo is sticky, jumpy. So will get a replacement servo installed that i have and open up the old one. Fun and games!
                      Kr
                      Craig

                      Goblin 700 KSE, Trex 700x, Goblin 770 Sport - Build in progress
                      Armattan Chameleon, Losi 5T, HPI Baja
                      Aj Laser 60" - Build in progress

                      Jeti DS-16

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                      • #12
                        Just crap you found out then and not on the bench. Oh well I'm sure you had a nice trip anyway lol
                        Yes the big sigpic is coming back

                        Comment


                        • #13
                          Hey Up

                          Finally got round to changing the rear cyclic servo today, and promptly took it for a test flight. All seems well! Will get a fair few flights on it tomorrow for a better test!

                          Kr
                          Craig
                          Kr
                          Craig

                          Goblin 700 KSE, Trex 700x, Goblin 770 Sport - Build in progress
                          Armattan Chameleon, Losi 5T, HPI Baja
                          Aj Laser 60" - Build in progress

                          Jeti DS-16

                          Comment


                          • #14
                            Hey

                            Had 32 flights on the 600 and all seems ok. The only thing I had was the head shakes came back again occasionally, particularly after a sudden head move. I have been messing with the gains and it seems to of stopped. Maybe I was just on the limit.

                            I reviewed the vibration logging from the brain and it shows everything is very low, so def sounds like the head gain.

                            I think grumpy had the original cause nailed with a slipped OWB in its housing.

                            Definitely learnt a few things with this crash, which is a good thing

                            Thanks for the help
                            Kr
                            Craig

                            Goblin 700 KSE, Trex 700x, Goblin 770 Sport - Build in progress
                            Armattan Chameleon, Losi 5T, HPI Baja
                            Aj Laser 60" - Build in progress

                            Jeti DS-16

                            Comment

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