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  • #16
    . could of been an a good image for travelling there max.

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    • #17
      Hi Tony,

      Bright Steel, Cheap Chinese compound lathe, guestimating the speed and playing with tool heights.. what could possibly go wrong

      Took a bit to get the combinations right. Chatter was definitely an issue and lost one bit running right to left toward the chuck. In the end, I flipped the tool to the back side and reversed the lathe so the tool was running away from the chuck and could let it run off the stock before I 'declutched' it etc. I have to admit to this being the first time I have cut a thread for a legitimate purpose off this lathe and not being overly experienced in cutting threads anyway it was bloody stressful !!

      P.

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      • #18
        ha ha , yeah that brings back memories. I remember when I was at TAFE a million years ago the instructor was showing how to cut threads. anyway it wouldn't cut at all. not even a bit. there was all these heads looking at the thread cutting tool on the shaft wondering what the hell was wrong. I stood up , as i was also 1 of the heads bending down and straining to see what the hell was going on , and looked and then I could see he had the lathe actually spinning in reverse. I told them what was wrong and everyone laughed , everyone except the instructor. he took it out on me. ahhh well story of my life.

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        • #19
          Hi again,

          Just doing some homework on the 'mixing unit'.. One of the big ticket items is the use of 'Push Pull Control Cables' which are used to invert both the pitch and roll inputs from the overhead control and provides the 'corrected sense' (Cyclic forward for rotor tilt forward, backward for rotor tilt backward, right for right lateral roll, and left for left lateral roll etc).

          I have seen control push pull cables used on small kit helicopters as primary control and there's a few examples being used in commercial aircraft as well, however thought I would ask if anyone has any experience in using them for primary control on gyros.

          Funnily enough, and along the same lines as Tony's advice/suggestion/observations, if they work in the mixing unit at the top of the mast, there's probably no reason why I can't run them from the existing under seat controls up to the head in lieu of the push pull tubes. They are heavier of course, but they will still allow the 'pivoting' mast design by way of being flexible enough to allow the mast to pivot without having to disconnect the flight controls etc.

          A quick disclaimer here as I fully understand the 'folding mast' concerns right now.. the design I'm using allows the mast to pivot laterally on a support bearing/pillar assembly as a single piece, ie it's still a one piece 2.5x2in mast from the keel to the head, but is allowed to disconnect from the keel attachment and pivot around a support bearing/pillar about mid way up. The idea being the gyro can still be stored in the garage, and you can mount the blades by hand before raising the mast and securing etc. Originally my gyro had a folding mast with the split/cheeks at literally 'back of the neck' height. I considered it to be all good for flying around and it's definitely convenient, however in an accident, I can't help but feel if it's going to break, it will do so at the weak point being the cheek plate attachments.. this design will hopefully eliminate that risk whilst providing a safe, strong and ultimately more convenient alternative. That's the reasoning anyway

          Anyway, back to the push pull cables, does anyone have any feedback?

          Ta

          Paul

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          • #20
            G110 has push pull cables, as well as some of the production made gyros, don't they have cables.
            Remember: no matter where you go, there you are

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            • #21
              That's gold Ross, exactly what I was looking for. Any chance of getting contact details of G110s owner (if not on the forums)? Keen to get more info.



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              • RossM
                RossM commented
                Editing a comment
                I have removed the number now, as 4CA has contacted the owner.
                Last edited by RossM; 20-02-2019, 07:14 PM.

            • #22
              would a flexible mounted control system, like push/pull control cables, have less 'stick shake'?
              Remember: no matter where you go, there you are

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              • #23
                Hi Ross,

                Thanks for passing on John's number. Great guy to talk to and had a wealth of info on the use of the cable control system.

                In regards to stick shake through the cables, I don't actually know. The design I'm building has two elastomeric blocks that make up the pivot point/joint on the mast support pillar, plus another at the keel joint to allow the mast to flex a bit. The mixing unit is at the head and includes a rigid section connecting to the cheek plates, and a dynamic section that ends up being the control column. Given there is still essentially a hard connection to the mast, any flex in the mast is still going to show up as stick shake. The cables will invert the inputs and may reduce the feedback through those connections, but the mast shake is probably the thing that ruins the design in the end.. it'll work, but if it's uncomfortable then it's not enjoyable.

                John mentioned that there can be quite a bit of play in the cables which can manifest as 'slop', I guess if you get the right frequencies, it could either snuff out a vibration or build on one. Dual cables cancel out the play so that's the way to go there.

                The good thing about the mixing unit design is that the cables are only about a foot long each with a nominal radius bend that I guess will pre-load the cable to some extend removing some of the play.

                Anyway, difficult to describe without drawings, and it looks like I won't quite get it finished by the nationals (close but not quite), so I'll have to get some progress photo's up instead.

                Paul

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                • #24
                  Hi again,

                  Didn't want this particular thread to become my 'Build Blog', but...

                  I just wanted to share that amazing feeling you get when an engine (in this case an EJ22) you have spent unknown hours rebuilding finally starts for the first time.

                  In particular, after all the angst of cutting/splicing/soldering up a new wiring harnesses for the ECU, adding in the alternator, fitting a new gearbox, sourcing a starter motor that fits it, piping in a new radiator and air filter, dodgying up a token exhaust that gives at least a hint of back pressure, then working out how your going to test it in the airframe before you have instruments or batteries even fitted..

                  Anyway, I have to say, it's a unique feeling when you do get to kick it in the guts for the first time and it fires, idles and accelerates as advertised.

                  Sadly, it was just me in my garage with the door open, but I did look around the street to see if anyone was looking. I mean, a beautifully loud rumble of an un-muffled exhaust, and an engine being revved just for fun should draw a crowd shouldn't it?..

                  Anyway, there was no one around, and my missus just doesn't understand, soooo I have opted to share with you guys instead

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                  • #25
                    Thanks Paul
                    Remember: no matter where you go, there you are

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                    • #26
                      Paul,

                      If you're thinking of push-pull cables from the usual joystick configuration, be aware of the following:

                      C56 Control System Design
                      The primary control system and their attachment points must be designed to be withstand the loads set out below at C60 and also be capable of visual inspection during normal pre-flight checks and regular maintenance. Pitch and roll control inputs will normally be transmitted to the rotor head by push-pull control rods although ASRA recognizes that some builders will opt to use push-pull control cables. A significant shortcoming with the use of push-pull cables is that the condition of the internal cable cannot be inspected, as is their reported less-precise "feel". If a builder-to-order or a home-builder elects to use push-pull cables for pitch and roll in their project, the only approved push-pull cables are Teleflex 60 Series with 5/16" UNF thread ends or Teleflex 80 Series with 3/8" UNF thread ends. Such cables must be fitted strictly in accordance with the manufacturer's directions with particular care taken in relation to bend radii. Push-Pull cable installations used for rudder control must be Teleflex 40 Series push-pull cables with 1/4" UNF thread ends. Such Teleflex cable installations in build-to-order and home-builds have an operational life of 1000 hours. Because of the sealed or sheathed nature of push-pull cables, the visual inspection requirement is waived for: - (a) sheaths (if fitted) for rudder cable systems; and (b) push-pull cables running within sheaths fitted as original equipment by a recognized manufacturer; or (c) Teleflex push-pull cables running within sheaths in builds-to-order or home-builds as specified above.

                      This from the construction standards for both basic and complaint gyros.

                      Regards,

                      Waddles
                      Waddles

                      In aviation, the only stupid question is the one you don't ask!

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                      • #27
                        Thanks Waddles,

                        Yes, that's the direction I am ultimately taking. Push/Pull Cable Control from the conventional cyclic between the legs, and also for the rudder.

                        I'd previously taken note of the Construction Standards for the cables and will happily comply with those directions.

                        I'm also keen to run two cables for each pitch and roll input so I can load them a little against each other and take up any internal slack but will have to see if this is practical and/or the geometry allows for it. I also understand they are heavier than you would expect so will see how it goes. Unfortunately, this build is already 'heavy' so I'm trying to claw back some margin.

                        I did a search on where to get Teleflex cables, and a few places came up. www.controlsandcables.com.au have the Teleflex Marine range so will probably chase them. That said, if anyone knows another good place to source them from, more than happy to run with any recommendations.

                        Keep you posted, but as you can tell.. it's a relatively slow process. Mind you, things start to progress faster with the engine installed etc.

                        Cheers

                        Paul

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                        • #28
                          Mate,

                          Be careful of the marine cables as they may not meet the same specs as the Teleflex "numbered" series.
                          Try this link and search under "Control Cables". You'll find the 40 and 60 series here. http://www.mechanicalcontrolcables.com.au/index-2.html

                          Waddles.
                          Waddles

                          In aviation, the only stupid question is the one you don't ask!

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                          • #29
                            Thanks Waddles,

                            That's really appreciated, I will go through those guys so I can show compliance with the standard.

                            I must admit, I was having trouble finding those numbers linked to the Teleflex name.. looks like Teleflex may have been bought and sold a couple of times and 'new' numbers are being associated with the cables.

                            Anyway, I'll talk to these guys tomorrow.

                            Cheers

                            Paul

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                            • #30
                              Paul it may be wise NOT to mention to the distributor that the cables are going onto an aircraft. I have recently had problems with a bearing distributor.

                              Regards...........Chook.

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