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  • #1

    Near crash.....explanation?

    Hi all,

    It was a beautiful evening so I took out the 550e for a flight in the windless conditions. It started off great and I enjoyed myself very much for about 4 minutes. I was doing elevatior tic tocs when all of a sudden I lost complete control of the heli and it did two crazy flips all on its own. The first thought I had was a screw or ball link must have come loose but the heli stopped spinning and I had control again and I landed it safely. Phew!

    The first thing I noticed on inspection was the main gear was quite badly worn away with white nylon shavings covering parts of the heli. Also, the motor seemed rather hot and the battery (opti 6s 5000) seemed warmer than usual for the time I flew (nothing unhealthy). I had just replaced a motor pinion after I managed to some how strip the first one. This made me think that I had set the mesh too high even though I had done the paper test with no breaks in the paper as well as having a little play in the mesh. Could this have something to do with the loss of control?

    My next thought was the bec. I'm using the Castle 10A bec:

    Castle 10A BEC Switching Regulator CASTLEBEC

    I have had a few issues with this bec in the past where when I quickly move the cyclic up and down the servos (Align DS610's) will either twitch or pause for a few seconds. Is this a brown out? Another brown pants moment was while I was flying and going into idle up 1 the heli badly banked to the right and almost hit the ground before I regained control and recovered. I couldn't really explain this and didn't think it was bec related but it's worth a thought. Is there usually problems with this bec? Is it underated for what I'm doing with the heli?

    I've tried to tell you all I can of the problem. Can someone please tell me what I have done wrong? I certainly won't be flying my 550 again until I know what the problem is.

    Thanks,
    David.
    Tags: None
  • #2
    Hi Dave,im not familiar with that bec but i'd say its probably a bit small for the 550,especially fbl.

    I run a life pack direct to the vbar on mine.
    T- rex 600n V-bar
    Logo 550sx V-bar
    Logo 600sx V-bar
    Logo 600sx V-bar night flyer

    VBControl, but not the gay white version as i'm simply not gay enough to pull it off!

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    • #3
      Hey.

      Yep, sounds like a brownout to me. As you can replicate this on the bench by cycling the servos quickly, then your BEC is the problem and at 5 amps continuous it is a little low for FBL use.

      If you want to stick to using a BEC, the CC BEC PRO is the one to fit, with a constant 10amps easily achievable.
      .
      Ian Contessa
      Robbe SchluterUK / Midland Helicopters / Align



      Coolice Power Supplies
      Coolice Custom Built Charge Case's

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      • #4
        Originally posted by coolice View Post
        Hey.

        Yep, sounds like a brownout to me. As you can replicate this on the bench by cycling the servos quickly, then your BEC is the problem and at 5 amps continuous it is a little low for FBL use.

        If you want to stick to using a BEC, the CC BEC PRO is the one to fit, with a constant 10amps easily achievable.
        .
        +1 on the BEC Pro. Great little devices!
        Very proud to be an Align-Trex.co.uk Team Pilot!

        SAB        Goblin 700 / V-Bar Blueline 5.3 Pro
        Trex 600 EFL Pro / V-Bar Silverline 5.3 Pro
        Trex 500 FBL /         Beast X
        Futaba 8FG

        Proud Owner of 2 EGS Awards

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        • #5
          5 amps should be enough unless something is pulling loads of current.

          Having said that I run 10 amps on two leads. The servo style connectors are only rated at 5A

          Check for binding first or bad servo. Possibly even bearings allowing the main gear to touch the frame or meshing badly. Perhaps this causes vibration and upsets the fbl controller

          sigpic Trex 700 OS91,Vbar,S9254,DS610,NHP
          Trex600LE, OS50,Vbar,LTG6100,DS610X4,NHP
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          • #6
            Lots of possibilities. The good news is that you have a fault on the ground, the bad news is that you still flew. Any component may be faulty, it could even be your power lead, especially if this is a new fault, on a heli that was working ok. I'd start with two new power leads as Mslater says. It could easily be a dirty connector dropping too many volts at high current. Also could be a wiring fault with high current wires going too close to the rx. You could check the rx volts when you move the collective. Hopefully you will see it drop. Telemetry is handy for these faults as you can see the volts change on the tx and usually you can set an alarm.
            Flasher 450 Sport. Assan GA250 with 520 tail servo, MKS DS450 cyclic.
            Multiplex Cockpit Tx, DX7, DX6i
            Blade 130-X, MSR, MSRX
            Phoenix Sim

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            • #7
              Thanks for the suggestions,

              I forgot to mention that it is a FB 550e, not FBL, I don't know if this changes much?

              If possible I would like to stick with a bec so if the bec is the problem I'll consider the castle bec pro.

              I'll look over all my wires and servos to check for binding.

              Thanks,
              David.

              Comment

              • #8
                The castle is small for a 550, think 600 size bec and you should be fine.
                Remember all the gear in that Heli is the same as in a 600/700 size Heli so treat its power demands as such.

                Joe
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                I'm not controlling it, just preventing it from crashing
                http://mangled-rc.com/

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                • #9
                  Ok, time for an update, sorry It's been so long sice the last post but I've been buisy.

                  The castle bec pro has only just come into stock at Fastlad and has arrived at my door today. I have one question though: where on a T-rex 550e are you guys putting your bec pros. It seems tight for space but I was thinking of putting it somewhere around the lower back of the frames? If someone could post a picture of where there bec pros are that would be great.

                  I will update later on when I get the bec up and running.

                  Thanks,
                  David.

                  Comment

                  • #10
                    I'm not sure if you know about keeping the high current wiring away from the rx aerials. Different rxs have different sensitivities to interference but it is a good idea to keep all high current and high current switched away from rxs and rx aerials. Any time a current is switched on or off a radio wave is generated and can cause problems especially if the wire is run alongside another wire that goes to the rx.
                    Flasher 450 Sport. Assan GA250 with 520 tail servo, MKS DS450 cyclic.
                    Multiplex Cockpit Tx, DX7, DX6i
                    Blade 130-X, MSR, MSRX
                    Phoenix Sim

                    Comment

                    • #11
                      Hi Dave
                      I'm running a castle bec pro on my 550e flybarred, ive got the bec under the battery mount its a bit of a squeeze but it fits, if you fit it there just be careful that your wires dont catch the motor, did you get a link cable so you can up the voltage if need be?

                      Comment

                      • #12
                        Yes thanks, I was going to keep the distance between the bec and the reciever in mind.

                        Yes I have a link cable, i'll get round to that later today. I will also have a look at fitting the bec under the battery tray like you said.

                        Thanks for the advice, my 550 is almost back in the air after being grounded for a month.
                        David.

                        P.s. I got the bec soldered up and no matter how much input I gave it I couldn't get a brown out so the bec is a success.
                        Last edited by daveman; 14-06-2012, 06:23 PM.

                        Comment

                        • #13
                          Lets hope you have cured the right problem. Don't be too p1ssed off it there's another. You needed to sort out the bec and testing before flying is boring, but does lead to more flying.
                          Flasher 450 Sport. Assan GA250 with 520 tail servo, MKS DS450 cyclic.
                          Multiplex Cockpit Tx, DX7, DX6i
                          Blade 130-X, MSR, MSRX
                          Phoenix Sim

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                          • #14
                            I ran that little castle bec on a 600 fbl for about 2 years before it failed(and then it went pop when it was plugged in, not during a flight)It ran a skookum 360 a csm 720 and 4x bls451 so it should be (just about) adequate for a 550 fb. As has been said check for a faulty or binding servo first before upgrading the bec. Where is the bec situated at the moment? Cooling always helps electronics and heat build up doesn't.
                            Mikes Place - Home of the golden dump.

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                            • #15
                              With all these things one faulty unit doesn't mean much. I had problems with a Twister Storm esc, but it did work most of the time. Turns out it has 80Amp fets in it but only a 1 amp linear bec regulator. 1 amp is the current it switches off at. One of the fets was missing heatsink paste. The fet wasn't even touching the heatsink but it survived. I'm even more surprized that the regulator was only 1 amp for 4 servos and a gyro.
                              Flasher 450 Sport. Assan GA250 with 520 tail servo, MKS DS450 cyclic.
                              Multiplex Cockpit Tx, DX7, DX6i
                              Blade 130-X, MSR, MSRX
                              Phoenix Sim

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