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Trex 700N geometry with v-bar

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  • #1

    Trex 700N geometry with v-bar

    Hi guys,

    I have just got my first v-bat should be here this week, looking forward to giving it a go!

    Ok i have a question i have fitted the shorter shaft ( FBL version) and i kept the 700n bell cranks the and the nitro A-arm as its only the pitch links i needed to adjust to get my pitch 0, on my 3gx this works well!

    Ok i also have the align FBL servo horns on the inner hole! now will all this be ok with the v-bar as i did read that the trex700 geometry is not correct for the v-bar??


    many thanks in advance!
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  • #2
    I ran mine just changing the resolution on the servo horns. Pretty sure ball to ball was 21mm, but will have to re-check.

    To get it spot on in the 'green zone', you want the 700E bell cranks and A-arm but I personally wouldnt bother.
    x 3

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    • #3
      The main blade grip is the real problem on most Align FBL models. The distance the ball is from the mast is not enough. For example I have just put a 500EFL together using v-bar. I have modified the blade grip to get the ball 30 mm from the mast. I now get a value of 80 on the collective slider for 12 degrees of pitch. The supplied blade grips has the distance at 25mm which will take out of the green on the v-bar slider. If I move the ball in on the servos the balls hit the servo. I have them at 17mm out using QUK servo arms. The Align servo horn has the distance at 18mm which would take the slider out of the v-bar optimal value.

      Without question the model will still fly fine with values as low as 70 but it is whether you are looking to get the optimal setup on the v-bar.
      Last edited by Andy from Sandy; 02-01-2012, 02:47 PM.
      Member of Mk Heli Club



      GRAMMAR: The difference between knowing your shit and knowing you're shit!

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      • #4
        I would like to get the best out of the v-bar! So If I get the quick uk servo horns I will be getting the best from it??

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        • #5
          Originally posted by jayfrs View Post
          I would like to get the best out of the v-bar! So If I get the quick uk servo horns I will be getting the best from it??
          Doesn't the 700N have a push-pull system, i.e. 2 rods are connected to the servo horn? I don't know if QUK make them. For best results when using push-pull the rods need to be parallel. If you move the rods in at the servo horn and they are no longer parallel then you are actually creating a binding situation. As the rods move in they no longer form a 90 degree angle to the turning moment. The only way to get the turning moment correct again is to move the balls back. Look at the picture, this is the correct way to do it.
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          Last edited by Andy from Sandy; 02-01-2012, 03:45 PM.
          Member of Mk Heli Club



          GRAMMAR: The difference between knowing your shit and knowing you're shit!

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          • #6
            Agree with the above, and the 700E bell cranks and elevator arms will give you the perfect 90 degree setup..

            ..but from what I have read, nobody can tell the difference in flight between going in a hole on the servo horns; and forking out on replacement A-arms/bell-cranks.
            x 3

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            • #7
              Been having a bit of a think would these not work? Futaba Servo Horn Pack Type A SO1236 sure i have seen this set up with a 700 n V-bar i maybe wrong!

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              • #8
                Thats what I had on mine

                Last edited by sacko; 02-01-2012, 06:21 PM.
                x 3

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                • #9
                  someone say fastlad order!! LOL Sacko you positng my v-bar tomorrow??

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                  • #10
                    All good to go Was hoping they were open today, but obviously weren't..

                    If you get stuck with it, give me a bell.
                    x 3

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                    • #11
                      If you want it to fly as good as possible, you'll need to fix the geometry so that the software shows collective and cyclic near the target point.

                      BTW, there is nothing wrong with non-parallel push-pull linkages.
                      Woohoohoohoohoohoohoohoohoohoohoo -Barbra Streisand

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                      • #12
                        Originally posted by sacko View Post
                        All good to go Was hoping they were open today, but obviously weren't..

                        If you get stuck with it, give me a bell.
                        You better charge your fone now! LOL what hole did you have the balls in on them servo horns??

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                        • #13
                          It 20mm-21mm from ball to ball from memory.

                          Lol.. Ill leave it plugged into the mains
                          x 3

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                          • #14
                            BTW, there is nothing wrong with non-parallel push-pull linkages.
                            No there isn't and there is a correct way to ensure operation without any binding at the extremes of travel.
                            Member of Mk Heli Club



                            GRAMMAR: The difference between knowing your shit and knowing you're shit!

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                            • #15
                              I am going to use these 21.5 centre of balls, you can also get these spot on, only any good for Futaba splines though......PV1603 Metal Cyclic Servo Horn Set
                              Heli central...Basildon RC helis...strictly helis only...




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