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  • Dominator axles


    I currently have the original hollow core axles on my single place Dominator. I recently bent one in a squirrelly landing, so it's the perfect opportunity to upgrade my axles. I have spoken to a number of people regarding this, and received numerous suggestions. One, is to simply insert a snug grade #8 bolt (9/16" fits) and tighten it down with washers and locknuts, effectively creating something approaching a solid core axle. The prevailing view is to ream out the current axles and welds from both downstruts and weld in place a solid 3/4" axle. I also have a friend who has offered to take a 3/4" O1 grade drill rod and machine one end down to 5/8" and insert it into the current hollow axle (cut off near the weld), securing it with collars on both ends. Effectively, this gives me a 5/8" solid axle with the wheels secured to the 3/4" outboard portion. But is O1 drill rod too brittle for use as an axle?

    I welcome all comments and suggestions.

    Thanks,

    Russ

  • #2
    In my opinion Russ; a heavier axle is not an upgrade.

    Part of why a Dominator is so much fun to fly is because it is light.

    Making one part stronger just puts a bigger load on other parts when a landing goes bad.
    Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

    Comment


    • #3
      The reason some have used a bolt going through the tube, is not to make is stronger. There have been some who have lost the collet/collar and the tire and rim come off. A bolt and nyloc nut and a fender washer to keep the collet from leaving, basically you never loose a wheel.
      David McCutchen
      615-390-2228
      Bensen B7m, 90 hp Mac
      Dominator Tandem, 100 hp Hirth
      Kolb Mark III Classic, 80 hp Verner
      Certified - Advanced Master Beef Producer
      EAA Member #0511805
      PRA Member #28866
      PRA Chapter 16 Member
      Secretary & Treasure - PRA Chapter 16
      President / Sylvia - Yellow Creek Volunteer Fire Dept.
      Chairmen - Dickson County Veteran's Day Committee
      Volunteer - Dickson County Airport Aviation Day Committee
      2 busy 2 No!

      Comment


      • #4
        OK I, hear what you are saying about keeping the gyro light. Full disclosure, when we tried to put a torch to the hollow bent axle and straighten it, we deformed the axle, probably by applying too much heat. A replacement main strut with hollow welded axle is about $155 plus shipping from Ernie. The drill rod repair will only run me $30, and only add about 1 pound per axle at most. So this seems like a reasonable approach. I was more concerned about O1 drill rod being too brittle, and about having a stress point where it is milled down to fit inside the current axle.

        Comment


        • #5
          I would use a piece of 9/16" O.D. DOM, say .065 or .095 thick. Insert it through the existing axle and when you put the collars on, just drill all the way through the collar and axle and pin or bolt it.
          Jerry
          435-201-9888

          Comment


          • #6
            Russ,
            The $155 strut is a sure fix for your gyro . If you or somone repairs it for $30 and it snaps off your $30 repair could cost you thousands of $$$$ My thinking is I would get the strut from RFD to protect my investment .
            Rodney

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            • #7
              Good point. And the consensus from several people who know metals (which I do not) is that drill rod is in fact, much too brittle to be used in an axle.

              Comment


              • #8
                I'm sure your life is worth at least $155. Aviation is no place to be cheap. Landing gear is a pretty important part of the machine and bad things can happen if not fixed correctly.
                BarryK

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                • #9
                  3/4" Chromoly (4130) hollow axles are good to 1232 pounds provided they are 0.120" wall thickness and they are properly heat treated to HRc 38 - 40 Rockwell hardness and then plated and properly Hydrogen de-embrittled using a standard like ASTM B633-15 or equivalent. Without that a Part 23 drop test would fail miserably on the axles alone before it gets to use the shocks.

                  Comment


                  • #10
                    I find it very interesting that those that DO NOT always seem to have all the answers.
                    Fara how many axles have you tested, by what means, and how do you figure the load path to the springs? It is too easy to read a bunch of techno-babble out of a book , then profess knowledge, but quite another to have built 100's and seen the actual results!
                    I will bet that you have NEVER welded a piece of 4130 in your life, but you still profess expertise, amazing isn't it!
                    For the rest of us that have figured the load paths, and forces, YES the axle will break off when you reach a certain load, better that than your back bone absorbing the energy!
                    but thats just my way of thinking!
                    BTW you do have a very nice looking Euro-clone!
                    "Ignorance is curable, Arrogance is Terminal"
                    Ernie Boyette

                    Comment


                    • #11
                      WOW.... That didn't take long for someone to start slinging mud.
                      And we wonder why people don't visit this forum much anymore.
                      Bobby Munroe
                      Private Pilot (SEL)
                      PRA Chapter 62 #42748
                      EAA #1160523

                      Comment


                      • #12
                        The best thing for a self repair would be to use another piece of 4130 tubing that would fit inside

                        the existing axle. hollow axles are normally stronger than solid ones.

                        But it sounds like the axle has been messed with and a new one would be the best way to go,
                        Best Regards,
                        Eddie Sigman,Polvadera,nm
                        (575) 835-4921

                        Comment


                        • #13
                          The new axle from Ernie has been received, painted and installed. In the end, you cannot go wrong with OEM parts.

                          Thanks to to everyone for their input. It definitely helped me make an informed decision.

                          Russ

                          Comment


                          • #14
                            Good choice!!!
                            David McCutchen
                            615-390-2228
                            Bensen B7m, 90 hp Mac
                            Dominator Tandem, 100 hp Hirth
                            Kolb Mark III Classic, 80 hp Verner
                            Certified - Advanced Master Beef Producer
                            EAA Member #0511805
                            PRA Member #28866
                            PRA Chapter 16 Member
                            Secretary & Treasure - PRA Chapter 16
                            President / Sylvia - Yellow Creek Volunteer Fire Dept.
                            Chairmen - Dickson County Veteran's Day Committee
                            Volunteer - Dickson County Airport Aviation Day Committee
                            2 busy 2 No!

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