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  • Control Joystick Assembly

    Greetings all.

    Before I start drilling the keel tube (or any other part), I'm laying out a 3D CAD model of the airframe in preparation. A critical system is the control rod/joystick linkages. The Gyrobee documentation omits drawings for this system, so I have downloaded and modeled it per the Hornet v14 drawings. There's a couple of things that bother me about that design (the welded bellcranks) and I would like to review other similar "walking beam" type joystick control systems.

    Are there any other drawings available online of similar designs by other manufacturers? I would greatly appreciate any links, and/or feedback about the control yoke welded cranks. Thank you.

    Brian Jackson

  • #2
    Hi Brian.

    I'm taking the same route as you (I have to choose between Inventor and Fusion 360. Draftsight 2017 can be used, if 2D is enough).

    There are several parts that were readily available back then, but not anymore. I have a friend who is certified to weld both steel and aluminum.

    I have a lathe and a tool mill, so I can make a lot, but I need a drawing. I plan on buying the aluminum in Sweden and Starbee sells a hardware pack (AN stuff).

    It'll have a composite tail like the Watson. The walking beam stick could be a bolt-together design like so many others. I don't know what to do for a seat.

    One could build a Hornet, but I like the fact that the Gyrobee is an established design with a twin mast - and I've never read a bad thing about a Gyrobee. Everybody loves it.

    But I need some real stick time, before I buy these things and start building. After all, it could be just a stupid idea I've had for 30+ years.....

    Cheers
    Erik

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    • #3
      A couple of options:
      1. Advertise for a used Brock system.
      2. Find an old Dominator or Air Command system to use as a model. I believe the Air Command system is weld free and can be built with basic tools.
      3. Build a simple "pump handle" system.
      Rick Martin
      Sport Pilot, Gyroplane
      Bradenton, Florida
      Gator Gyro (a Jake Jacob "Everglades Kite") N328RM
      Tandem Dominator
      Follow Your Dreams ;)

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      • #4
        Hi Erik.

        We should stay in touch during our builds. I eventually opted for an overhead stick, though it has a very simple reverser mechanism so the stick control motions aren't backward from the conventional keel-mounted stick.

        Brian

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        • #5
          Brian: Show a pic or drawing of this simple reverser mechanism?

          Comment


          • #6
            Starbees has a nice pic of their cyclic control, you could import it into CAD as a pdf, scale it off a known dimension ex. 1" .125 square, then trace over the pic and fine tune all dims.
            For the seat I used a VW lowback fiberglass buggy seat, I believe I purchased it from CB performance, worked perfect, very light mount same as Gyrobee plans
            http://www.cbperformance.com/product-p/5495.htm
            Last edited by Countach; 05-12-2017, 10:33 PM.

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            • #7
              Originally posted by Kevin_Richey View Post
              Brian: Show a pic or drawing of this simple reverser mechanism?
              Hi Kevin.

              I'm actually finishing the design drawings this week with part numbers, etc. I've seen examples of other reverser systems that use bellcranks, control rods, spherical bearings and a wealth of other items that add complexity. It kept nagging me that a simpler solution was possible. I'll post the drawings here when they're ready to review. The whole system only uses a military grade U-joint and a linear bearing. Very light weight yet bulletproof. I hope the forum will look over the details and scrutinize. Peer review is critical.

              Brian

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              • #8
                Brian: My take on the sense-of-direction of control sticks is this:

                Think of the stick (joy- or overhead-) as one radius of a circle. The center of the circle is the pivot at the opposite end of the stick from your hands (below your seat for the joystick; above your head for the overhead) . Now, understand that your movements of the stick are ARCS of this circle -- just as they are when you turn the steering wheel of your car. These control motions, IOW, are not simple fore-aft or sideways linear movements. They're segments of a circle.

                From that viewpoint, a right bank requires a clockwise movement of the pilot's hand along an arc of the circle. A left bank requires a counter-clockwise arc. As long as you model your control movements this way, there's no difference between a joystick and an UN-reversed overhead. The difference between these sticks is merely the difference between holding the wheel of your car on its top or its bottom. You're gripping the "control circle" at a different location on its circumference.

                In my early gyro days, i intentionally steered my car from the bottom of the wheel when driving to the airport. I imagined that pushing the wheel toward the front of the car would lift its front wheels (disappointingly, it never did).

                i also imagined a little wheel on each end of the T-handle -- the T-handle was a model of the gyro's main-gear axle. The way the T-bar tilts is the way your axle will tilt. You can also imagine the vertical part of the stick to be the mast. The mast follows the stick.

                If, despite all this, you insist on a reverser, I suggest that you NOT use a T-handle; put a grip on the vertical shaft of the stick to more closely simulate the hand position on a joystick. I believe that, for those of us who fly both types of control, the T-handle and the horizontal position of the hands help our brain to call up the appropriate set of reflexes -- to launch the right mental software.

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                • #9
                  Thank you, Doug. I'm glad you mentioned not using a T-handle... it reaffirms the same thought I had. I don't want it being confused for a direct-mounted control stick. Inch-per-degree of motion will mimic a joystick, only on a different swing arc. The control roll-off is gentle at the outer ranges due to the way rotational points are positioned. I hope to have time this weekend to finish the detail drawings. A picture of the 3D model won't show sections and small details.

                  Comment


                  • #10
                    Brian: If you use a joystick leverage ratio (3/4" to 1" per degree), then I suggest making the stick long enough to allow you to rest your forearm on your thigh. Overhead sticks typically have a longer throw than joysticks, and so precision movement of the hands is less critical. E.g. my Gyrobee's overhead has about 2" travel for 1 degree of head travel -- very INsensitive.

                    You can see from old photos that Dr. Bensen had his T-bar up at breast height. You have no fixed reference for your arm if your hand is up that high. If you select joystick-grade sensitivity, though, it will help you make more calibrated movements if you have your arm in your lap and and just move your wrist. This makes overcontrol less likely.

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                    • #11
                      Hi Brian (and Doug).

                      My build has not started in earnest. On the 10/11 of June I'll be going on a gyro week-end trip with a lot of other folks. Island hopping, at least 5 hours in the air with an instructor in the other seat.
                      It'll be in an open gyro, either a MTO or a Magni. Two of those hours will be instruction. This trip should help me decide, if I really want to pursue this hobby, or stay with R/C helicopters...
                      I have started ground school but not taken any tests yet. If this trip goes well, I'll get a UL fixed wing license first and gyro afterwards. It won't be more expensive, as the fixed wing instruction is much cheaper.
                      It will be more fun to build, when I'll be able to fly it myself. And I have the larger, expensive parts so it shouldn't be too big a job to build the Gyrobee.

                      Let's keep in touch.
                      Cheers
                      Erik

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