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DX8 full-range collective modification

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  • #1

    DX8 full-range collective modification

    Hello,

    most people will probably have noticed that the mechanical movement range of the collective stick axis is artificially limited, compared to the elevator axis on the other stick.
    The reason are two little plastic blocks inside.
    The procedure to remove them is explained in the manual, where changing mode 1 <-> mode 2 is discussed.

    I tried to calibrate with the blocks removed, and voilà, got the whole range back. It works!
    Besides the obvious modification and calibration, my DX8 required a slightly longer silver screw to hold back the spring (otherwise the return spring kicks in at the extreme end of the range).

    I just tried it with Phoenix, and I think I'll think I'll stick with the full-range version. It's clearly more accurate.

    IMG_2797.JPG
    Figure 1: TETRIS time
    Last edited by GravityKills; 26-07-2012, 10:07 PM.
    Woohoohoohoohoohoohoohoohoohoohoo -Barbra Streisand
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  • #2
    now that is interesting... I had been wondering about that.....

    why is it limited anyway?..
    Logo 600 3D --- Vortex Vx1n
    JR Forza 700 --- Vortex Vx1e

    Team Macgregor flight team and Magregor industries field rep

    Co-founder of South Hants Helis - and now on Facebook
    And the proud wearer of one

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    • #3
      It's common on most radios for it to be limited. No idea why, but interestingly, the DX6i isn't limited in this way.
      Current fleet: Goblin Thunder Sport (700), Trex 700L, Logo 600, Specter 700, Henseleit TDR, V-Baaa control.
      Next heli: I have pretty much everything I want. Maybe I'll upgrade some electronics or something.

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      • #4
        DX8 full-range collective modification

        Many txs that are single mode heli /plane , have the shortened stick travel on the throttle stick. Whether it was started for plank flyers or heli flyers I don't know. Personally I, and many others are used to and prefer this shortened travel . When changing from full negative pitch to full positive pitch , the normal stick travel seems to be a looooong way whether it is during an auto or inverted to normal flight. I use the pencil hold(finger and thumb) stick control so the long travel is no too bad , with the thumb on top( buggy rc) method I would expect be even worse as the thumb is not as articulate and I suspect an element of rudder stick interaction may take place at the stick limits. Many top 3d pilots us "the thumbs" . Wedges or not, its nice to have the choice built into the Tx.

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        • #5
          Originally posted by bigpops View Post
          It's common on most radios for it to be limited. No idea why, but interestingly, the DX6i isn't limited in this way.
          Its common in Spektrum I think - I removed them from a DX8 I was given to help setup.

          I fly Futaba and never had this issue hence they were removed... if you want to limit your throws in my view thats why you have ATV's...

          http://www.rcheliaddict.co.uk/spektrum/84925-dx8.html
          Last edited by Stuart; 09-11-2012, 10:54 AM.
          Cheers
          Stuart

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          • #6
            at least it seems a pretty efficient way to lock in customers to Spektrum...
            I removed them three months ago and still find myself undercompensating when I pick up the Tx in Phoenix.
            Woohoohoohoohoohoohoohoohoohoohoo -Barbra Streisand

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            • #7
              DX8 full-range collective modification

              Originally posted by GravityKills View Post
              at least it seems a pretty efficient way to lock in customers to Spektrum...
              I removed them three months ago and still find myself undercompensating when I pick up the Tx in Phoenix.
              Under compensating, that's exactly what happens to me when flying a heli with long stick travel .

              Some one called it muscle memory!

              A lot of JR radios that are single mode types, have the short stick travel. Many people don't even notice the different , others its enough to make them sell an otherwise good Tx if it ain't got it.

              The stick travel distance is nothing to do with ATV . Full stick travel is still the same servo travel as normal stick travel once recalibrated. You still have + or - 150% ATV. and 7 point ( or 5 on DX8) pitch and throttle curves.

              I have known people who are so desperate for the short stick travel, they put their own wedges on the throttle stick without calibration and play around with ATV They lose most of the throttle trim function and the two end points. In the past I have had to resort to the "secret menu" that the distributors don't want us to use.

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              • #8
                On a DX8, the pitch (and probably throttle) curves are completely programmable. Both X & Y values. Oh, and 7 point.

                So, if you want, you can compress the range, or even shift it off centre.
                Yes, it's th@ tw@ Scallyb@...

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                • #9
                  Originally posted by scallybert View Post
                  On a DX8, the pitch (and probably throttle) curves are completely programmable. Both X & Y values. Oh, and 7 point.
                  Only if you hack the data file though ... or did I miss a recent update?

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                  • #10
                    Originally posted by Mark_T View Post
                    Only if you hack the data file though ... or did I miss a recent update?
                    My DX8 is less than a month old and was new stock at the shop. I've only got 5 point pitch/ throttle curves as well.cant find anything on how to adjust the x cordinates position . That would be very useful particularly with 7 point pitch/throttle curves . A bit like the old JR PCM 10 35mhz in the past.
                    Could you point us in the right direction .

                    Thanks

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                    • #11
                      DX8 full-range collective modification

                      Found it but don't pretend to understand what you have to do in the text editor.

                      What else can you do?

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                      • #12
                        Personal preference I think! Well it certainly is for me. The more travel you have the more you have to move your fingers to get the same response, so naturally this is a little bit slower in fast collective changes. In my view there is plenty of stick resolution even with the blocks there for a perfect hover.

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                        • #13
                          The X values can only be changed in an editor. If you use 7 points, only the first 5 Y values can be changed from the Tx.

                          I haven't done this, but I reckon playing with the X/Y values in Excel (or such) would let you set the curves up fairly intuitively, then transfer them back.

                          I've got flight modes that have full range symmetrical +/- collective, but still hover mid-stick. The zero is effectively off-set. Not necessarilly a good idea, but it's possible.

                          Four flight modes, inc 'Hold'. (Separate motor on/off switch.)
                          Yes, it's th@ tw@ Scallyb@...

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                          • #14
                            Originally posted by LaurenceGough View Post
                            Personal preference I think! Well it certainly is for me. The more travel you have the more you have to move your fingers to get the same response, so naturally this is a little bit slower in fast collective changes. In my view there is plenty of stick resolution even with the blocks there for a perfect hover.
                            You could argue that if you take the blocks out and adjust via the X values, it all becomes programmable, and you can switch throws between various modes.

                            It's all options...
                            Yes, it's th@ tw@ Scallyb@...

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                            • #15
                              IMO the mechanical feedback when you hit the limit is mandatory. If you limit it in SW, it will be very confusing, once you go out-of-range, for example in autorotations.
                              My own solution is to have a bit of 'über-pitch' on collective that I use only rarely, for example to speed up rainbows etc when the rotor is otherwise relatively unloaded. Otherwise, you can do end-to-end tictocs that are outright scary, but then the ESC overheats 10 seconds later.
                              Must say I'm not too happy with my flying at the moment, had a long break during summer because of work. But the setup seems technically OK.
                              Woohoohoohoohoohoohoohoohoohoohoo -Barbra Streisand

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