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First Crash but why???

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  • First Crash but why???

    Hi All.
    Had my first crash on the weekend. (Trex500EFL) Really disappointing as just rolled over on take off and not really sure why. 3rd flight of the day it started rolling left. I back off and it settled and took off no problems. 4th flight it rolled right I backed off but too late and the blades hit.
    Have done about 45-50 flights, last dozen with no training skids. I have 2 thoughts why it went bad.
    1st) The training skids put a wobble through the heli so I had to turn the Gains down a lot to stop bob. With out them I was slowly increasing the gains (Aileron and Elevator) to trim to the new setup. Currently on 12 O'clock on the 3GX box. Read the 3Gx settings after the crash and both total gains on 70. Would too high a Aileron gain make it tip on take off?
    2nd) When going from idle up to normal to land I felt the head speed was to low. Made it not so easy to land. So I increased the throttle curve to 0,50,75,85,95 and pitch was left the same 30,35,50,75,100. In idle up pitch is 0,25,50,75,100. I raised the normal mode pitch so I couldn't get too much negative pitch when landing. center stick is 0 pitch. Afterwards was thinking maybe the throttle curve is too step and will have 50% power at -3 deg pitch. Did this cause the problem? It seem to start to roll a long way before it was close to taking off.
    I think I read you shouldn't use any stick inputs with the 3Gx until it is airborne as can mess it up. Shouldn't the swash plate level itself? I carried it to take off point after tuning on. Can this mess it up? Really not sure why I crashed and what to do to prevent it in the future which is the frustrating part.

    Stripped 3 servos, bend tail boom, very slight bent main shaft, landing gear, bearing in tail boom unit. Link rod x1 Main blades just a few scratches on the tips and small ding when it folded back into blade grip. I think repairable. Fairly major rebuild. Canopy didn't have a scratch on it. Was surprised at how much damage got done under the hood.

    any thoughts greatly appreciated.
    cheers




    Goblin 700, Vbar Silverline, Savox SC-1267MG / SB-2272MG.Scorpion opto 130. Align 750mx /450kv
    Trex 500 EFL Pro, DFC, Vbar 5.3 Full Pro.
    CopterX 250 SE FBL, With Align upgrades and 3GX
    JR XG 7
    Mini CP, Heading for retirement.

  • #2
    Mine tipped over on landing once. While spooling down it flopped left. Its a "quirk" of the 3gx system I think. Hopefully coolice will chime in at some point, he knows what he is doing with these things - I don't; I just copied his settings for the 3gx box.

    Your curve settings sound ok. I use exactly the same; Except I have a flat throttle curve in normal mode.

    The trick is to lift off pretty quick I think, lessens the amount of time for this to happen. I normally plug her in, carry her over and put the heli down on the ground; Go instantly to mid stick and let the soft start do its thing, then go instantly to about 75% stick and pop it off the ground - flick on idle up and off I go. Sorry to hear about damage. Did you strip all 3 cyclic servos? Surprised at that, I thought they were metal geared.

    If you managed to bend the main shaft then I wouldnt re-use the blades mate, for the sake of $35 is it worth not replacing and having one disintigrate mid air?
    NONE OF THE BELOW HELI'S ARE OWNED BY ME ANY MORE
    TT Raptor G4 + Vbar
    | MCPX V1 + HP05 Brushless & All the upgrades | 130x Stock | Henseleit TDR 2013 +Vbar | 450L DOMINATOR 6S + Mini Kbar | Logo 550SX +Vbar Mini
    Proud wearer of the EGS award!

    Comment


    • #3
      Thanks for the reply. 3GX does scare me. I have had it reset on the bench several times by just touching the metal case. I was bringing the throttle to about 1/3 letting it settle then bring more power in. Maybe too slow. I would have thought the rolling motion was only caused as the throttle is increasing not once it reaches it set point? Also this rolled to the right. Shouldn't motor torque make it go left??
      Main shaft is bent by maybe .05mm so have ordered a new one. almost impossible to tell so small but might cause a nasty vibe. Ill upload a picture of the blade when I get home.
      Tail servo totally stripped but they are plastic, One Aileron servo had a metal tooth broken off the big gear. The other aileron servo broke the top cover where the 3 gear pins lock in. Broke the side of the locating hole out that locates the pin when the cover is put on. Gears look ok but have ordered a new servo. Not sure if you can get the top cover only? Would recover the rest of the servo for the sake of one silly plastic bit.

      Cheers




      Goblin 700, Vbar Silverline, Savox SC-1267MG / SB-2272MG.Scorpion opto 130. Align 750mx /450kv
      Trex 500 EFL Pro, DFC, Vbar 5.3 Full Pro.
      CopterX 250 SE FBL, With Align upgrades and 3GX
      JR XG 7
      Mini CP, Heading for retirement.

      Comment


      • #4
        Ah ok, I think the 3gx tends to do things like this when its not experiencing the forces it expects.

        If you are at negative pitch and its not experiencing a "drop" senstation then it freaks out. Because its on the ground it cannot move, so this may send it haywire.

        Ive never had my 3GX reset before, you may want to send yours back if it resets by touching the case, sounds to me like some kind of earthing problem.

        Shame it did so much damage, you dont want to have to deal with these things through no fault of your own do you?!?!
        NONE OF THE BELOW HELI'S ARE OWNED BY ME ANY MORE
        TT Raptor G4 + Vbar
        | MCPX V1 + HP05 Brushless & All the upgrades | 130x Stock | Henseleit TDR 2013 +Vbar | 450L DOMINATOR 6S + Mini Kbar | Logo 550SX +Vbar Mini
        Proud wearer of the EGS award!

        Comment


        • #5
          Originally posted by Delarado View Post
          If you are at negative pitch and its not experiencing a "drop" senstation then it freaks out. Because its on the ground it cannot move, so this may send it haywire.


          Helimadness

          There is a big thread on helifreak with videos documenting the reset touching case issue and it appears to be a design fault that effects some units or users.

          Can't find the actual thread but info on it picks up from here.
          http://helifreak.com/showthread.php?t=332506&page=16

          Video here.

          http://helifreak.com/showthread.php?t=332506&page=16
          Last edited by ChrisB; 27-02-2012, 08:20 AM.

          Comment


          • #6
            Hi Guys. Thanks for the replies. So sounds like I should just go hard center stick like Delarado does to over come the spooling up with negative pitch problem. what happen if you use cyclic when on the ground. Does this mess up the 3GX because it cant correct? Might drop my throttle curve back as well. I think that was when the problem started as the flight before was a bit iffy and that was when I upped the lower stick power.
            Cheers.




            Goblin 700, Vbar Silverline, Savox SC-1267MG / SB-2272MG.Scorpion opto 130. Align 750mx /450kv
            Trex 500 EFL Pro, DFC, Vbar 5.3 Full Pro.
            CopterX 250 SE FBL, With Align upgrades and 3GX
            JR XG 7
            Mini CP, Heading for retirement.

            Comment


            • #7
              I go to mid stick in IU and then flip the throttle hold switch off. Nice smooth spinup and then a small but fast input on the collective to get airborn. Works well on the 550 and the 600 (3GX on both)
              Gaui X7/X5, Logo 480, Trex 600EFL, Trex 250DFC - DX18/8

              Comment


              • #8
                Most FBLs do not like the cyclic messed with on the ground and will try to counter any input. Best to spool up without touching cyclics. Once off the deck it's fine ;-)
                sigpic


                Rave ENV Nitro
                New Logo 550
                Synergy N5c
                TSA 700E night flier
                I use VBar control because it's feckin awesome I use NEO rescue when I remember to
                5 x EGS thingys and a Platinum star doo dah

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                • #9
                  Hey.

                  Subscribed, back later with a reply on a full size keyboard and not my phone.
                  .
                  Ian Contessa
                  Robbe SchluterUK / Midland Helicopters / Align



                  Coolice Power Supplies
                  Coolice Custom Built Charge Case's

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                  • #10
                    I use a flat throttle curve on mine, 0-80-80-80-80.

                    Always have always will. That way it spools up to full power at mid stick then it's just a case of using collective to get 'er up!
                    NONE OF THE BELOW HELI'S ARE OWNED BY ME ANY MORE
                    TT Raptor G4 + Vbar
                    | MCPX V1 + HP05 Brushless & All the upgrades | 130x Stock | Henseleit TDR 2013 +Vbar | 450L DOMINATOR 6S + Mini Kbar | Logo 550SX +Vbar Mini
                    Proud wearer of the EGS award!

                    Comment


                    • #11
                      Here is a picture of my blades. Doesn't look like in a structural part and no delam outside the ding. Was thinking I could repair with some epoxy and would be ok? Or am I just wasting my time? When I looked at the high res picture I realized it has what looks to be compression fracture around the bolt pin. I guess from when it bottomed out. I put the bolt in and tried to move but still solid. This looks to be more a problem to meBlade tip.jpgBlade top.jpg.
                      More pics coming.
                      Cheers
                      Attached Files




                      Goblin 700, Vbar Silverline, Savox SC-1267MG / SB-2272MG.Scorpion opto 130. Align 750mx /450kv
                      Trex 500 EFL Pro, DFC, Vbar 5.3 Full Pro.
                      CopterX 250 SE FBL, With Align upgrades and 3GX
                      JR XG 7
                      Mini CP, Heading for retirement.

                      Comment


                      • #12
                        I would not risk flying those blades again. If they let go it will be a more expensive crunch.
                        Gaui R5 + 14S + Tribunus 200 + Scorpion 4530/540 + Bavarian Demon Axon
                        Gaui X3L + Bavarian Demon 3SX
                        Jeti DS-16, Citizen 625
                        iMac + AccuRC =
                        Member of East Fortune Aeromodellers

                        Jeti Sensors and Apps: https://github.com/AlCormack

                        Comment


                        • #13
                          No way would I fly on those blades.' mine are damaged but nowhere near as bad as that.
                          Attached Files
                          NONE OF THE BELOW HELI'S ARE OWNED BY ME ANY MORE
                          TT Raptor G4 + Vbar
                          | MCPX V1 + HP05 Brushless & All the upgrades | 130x Stock | Henseleit TDR 2013 +Vbar | 450L DOMINATOR 6S + Mini Kbar | Logo 550SX +Vbar Mini
                          Proud wearer of the EGS award!

                          Comment


                          • #14
                            ok so 2 votes for the bin good enough for me. Don't want to see my heli in this state again over something stupid. This crash (my first :-( ) has made me realize you REALLY REALLY don't want to crash that often. Once again this was the frustrating thing with learning. Have the hovering, figure 8's not so bad, happy landing, its just the taking off that seems to be the hard bit. Hopefully from the comments above I have learnt enough to not have the same mistake again.
                            I think the damage in that area of the blades is not that structural. maybe ill get a trex clone and test them on that.
                            Adding new blades to the repair list..
                            Thanks for the comments.
                            Cheers




                            Goblin 700, Vbar Silverline, Savox SC-1267MG / SB-2272MG.Scorpion opto 130. Align 750mx /450kv
                            Trex 500 EFL Pro, DFC, Vbar 5.3 Full Pro.
                            CopterX 250 SE FBL, With Align upgrades and 3GX
                            JR XG 7
                            Mini CP, Heading for retirement.

                            Comment


                            • #15
                              Glad you are not going to risk those blades.

                              Re: Take offs.. With my 3GX it hated me trying to fly it off the ground (as I would do with my flybarred). The first time I was lucky and had the training skids on. I followed the general advice and popped it in the air quickly and that always seems to work. Spent a whole pack just doing takeoff and landings non stop to make sure it was not a once off

                              BTW. My throttle curves are much flatter on both my helis (Normal: 0 57 80 80 80 and IU1: 80 80 80 80 80) I found if they were not it was much harder to get good tail control (gyro gain tends to change with RPM).
                              Gaui R5 + 14S + Tribunus 200 + Scorpion 4530/540 + Bavarian Demon Axon
                              Gaui X3L + Bavarian Demon 3SX
                              Jeti DS-16, Citizen 625
                              iMac + AccuRC =
                              Member of East Fortune Aeromodellers

                              Jeti Sensors and Apps: https://github.com/AlCormack

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