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  • Pitbull plans/drawings/owner's manual?

    Hi,
    In writing to this forum, I'm appealing to probably the most informed group of gyro enthusiasts in the world. Well, I hope so. Because I would like very much to build a clone of the Pitbull gyro. Actually, not so much a clone, as an evolution of the design, since approximating any design inevitably results in a completely new design anyway. But I admire the Pitbull very much and want one.

    I have seen the pictures and videos of the BTTB Pitbull, and it is an extremely handsome design, but alas, is not in production. I have written to the email address supplied on their website, but have not received a reply.

    So my plea is simple: Does anyone have a set of plans, drawings or an owners' manual on which I might use to more accurately base my design?

    I have expertise in building fixed wing composite, wooden and aluminum aircraft. I see no essential issues with building the glassfibre fuselage, or the metal underpinnings. It's just that I would like to see some actual measurements to put my mind at rest.

    Also, if anyone could offer advice on the idiosyncrasies of tractor gyros, I'd be very appreciative.

    Regards,
    Duncan
    Duncan Meyer
    Brisbane, Australia

  • #2
    Welcome to the Rotary Wing Forum Duncan.

    There are not a lot of Pit Bulls flying and most that I have seen needed to have extensive modifications before they flew.

    Good luck on you project.

    I suggest learning to fly a gyorplane before embarking on a project of this magnitude.
    Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

    Comment


    • #3
      Hi,
      I'm still busy building an AeroMax as well as a small aluminium fixed wing which I designed, so I'm in no hurry. But you know how it is - unless you do your planning well in advance, it inevitably comes back to bite you in the bum. As far as lessons are concerned, yes of course. It is illegal anyway to fly a gyro here without proper training. I have flown a gyro a few times, and loved it. There is a healthy collection of gyro nuts out at Caboolture airfield not too far from me, and I believe instruction can be had there. I am really looking forward to it.

      Regards,
      Duncan
      Last edited by rtfm; 05-09-2017, 03:01 PM.
      Duncan Meyer
      Brisbane, Australia

      Comment


      • #4
        Hi Duncan
        PRA Chapter 31 has a PitBull that was donated to us and we hope to sell to fund our 912 Rotax engine for our club two-place trainer project.
        I believe that he also gave us plans but its somewhere in about 6 boxes of parts and paperwork. I have not looked for it yet, but will next time I'm at the hangar.

        Also Ron Heron the builder of the little wings wrote up how to fly a tractor gyoplane and how they are different than pusshers for PRA and it's on there web-site under the training menu item on the left hand side of the screen.
        ..
        Here is a direct link: http://pra.org/default.aspx?p=How2FlyTractor&i=83

        Last edited by All_In; 05-09-2017, 09:38 PM.
        Resistance is futile…… You will be compiled!
        Cheers,
        John Rountree

        PRA- Director, Secretary
        PRA- Business Manager

        PRA31 - Vice President of S.D. Rotorcraft Club
        http://www.Pra31.org

        U.S. Agent for Aviomania Aircraft... the most stable gyroplane on the market today.
        See: Aviomania USA http://www.AviomaniaUSA.com

        OEM Dealer for MGL Avionics - glass cockpit EFIS for Experimental aircraft Ask about DISCOUNTS for PRA MEMBERS

        Comment


        • #5
          Hi,
          That is extremely helpful. Thank you. I have scoured the web for photos, videos etc, and have just about everything that has been published on the web. But there's nothing like some good old 2-D drawings (however rudimentary) to use as a sanity check.

          My little design is obviously a Pitbull-derivative, but with a few changes, namely the triangulated mast and the clip-on, clip-off cabin enclosure. I'm thinking of the Hirth F30, or maybe the three-pot MZ.

          I've attached some rather rough drawings of my working concept. I tend to start with rough drawings like these, and then work by hand and by eye. When I'm happy with the shape, I make a mold, and then I'm committed. I'll buy as much of the hardware as possible from standard gyro sources.

          The wings are copied from the BTTB Pitbull. A great idea. Doubling as fuel tanks and adding about 120lbs of lift at cruise. At only 6ft span, they shouldn't interfere too much with the aerodynamic downflow from the rotor. It's a pretty basic design, just with a pretty exterior. I have no idea why tractor gyros are scarcer than hen's teeth, because to my eye, they look a whole lot better than pushers.

          Regards,
          Duncan
          Last edited by rtfm; 05-09-2017, 09:06 PM.
          Duncan Meyer
          Brisbane, Australia

          Comment


          • #6
            You may find this old naca report an interesting read.

            http://naca.central.cranfield.ac.uk/...report-523.pdf

            Wings that unload the rotor too much can result in unsafe rotor rpm.

            Comment


            • #7
              Hi. Interesting paper, thank you. The "wings" I propose on my gyro are very small, but learning from the paper, I need to think about the wing AoA. Perhaps the wings can be mounted on a round tube (rather than a rectangular tube, as originally envisaged), with an adjustment on the wing TE to facilitate adjustments in the AoA for in-flight testing purposes.

              One question, though. the wing AoA is measured (in the report) with reference to the plane perpendicular to the rotor axis. Is this a constant angle? And if so, how is this determined?

              Regards,
              Duncan
              Duncan Meyer
              Brisbane, Australia

              Comment


              • #8
                Another option may be to either follow Dick DeGraw's lead and partially power the rotor, or use an over-run clutch on the prerotaror to ensure a minimum rotor speed - the idea being to keep the prerotator powered up in-flight.
                Duncan Meyer
                Brisbane, Australia

                Comment


                • #9
                  Hi rtfm! Our friends Charlie Mara and Warren Traweek built a beautiful Pit Bull here at the San Manuel airport and they both flew it in 2008. They used a BMW motorcycle engine for power. There is a nice write up about it in "Rotorcraft", 2008, Vol 46 #1. Warren wrote the article after Charlie passed. He talked about the flight characteristics, and was impressed with it overall. I witnessed some of the flights, and thought it was going to be a fun gyro to see flying here on a regular basis. When Charlie passed though, Warren was too distraught to continue, and sold it. It is nearby, but to my knowledge, has never been flown again.

                  I searched in the PRA archives, but unfortunately find that particular issue is not included. I have cell phone pictures of the article, but they will not upload here. If you or anyone else is interested, I would be happy to send you pictures of the article.

                  I looked at your post with interest as I am trying to sell a Pit Bull for the family of a friend who recently passed away. You can see the current listing on Barnstormers. This Pit Bull was built by our dear friend, mentor, gyro and fixed wing DPE Terry Brandt. He asked me to sell it for him before he passed, and we tried last fall, had a buyer who was going to have it shipped to Hong Kong, but recently backed out on the sale because the permitting process was too arduous - or so he said. Terry was very distraught that he had to sell the Pit Bull, and I am sure that he would have flown it successfully, had he lived. The workmanship is of course very nice (considering who built it). It has a registration, but no airworthiness document. Terry included plenty of documentation on the build, so the buyer will not have any trouble getting it inspected by a DAR. There are plenty of extra parts, it is all complete, and only needs a few details to finish it. Terry thought it would need a slightly larger radiator, because he was having problems with it overheating. It looks as though he may have used a VW Rabbit radiator. A slightly thicker custom built radiator would no doubt solve the overheating problem. Other than that, he said it ran very well.

                  So yes, a Pit Bull can be made to fly. Have fun with your project! My advice is - don't make it overcomplicated.

                  Comment


                  • #10
                    [QUOTE=rhoadsrunner;n1131316]Hi rtfm! Our friends Charlie Mara and Warren Traweek built a beautiful Pit Bull here at the San Manuel airport and they both flew it in 2008. They used a BMW motorcycle engine for power. There is a nice write up about it in "Rotorcraft", 2008, Vol 46 #1. Warren wrote the article after Charlie passed. He talked about the flight characteristics, and was impressed with it overall. I witnessed some of the flights, and thought it was going to be a fun gyro to see flying here on a regular basis. When Charlie passed though, Warren was too distraught to continue, and sold it. It is nearby, but to my knowledge, has never been flown again.

                    I searched in the PRA archives, but unfortunately find that particular issue is not included. I have cell phone pictures of the article, but they will not upload here. If you or anyone else is interested, I would be happy to send you pictures of the article.
                    ...

                    Here is a picture of the cover from PRA archives. PRA Members can find almost all of the back issues online.
                    Resistance is futile…… You will be compiled!
                    Cheers,
                    John Rountree

                    PRA- Director, Secretary
                    PRA- Business Manager

                    PRA31 - Vice President of S.D. Rotorcraft Club
                    http://www.Pra31.org

                    U.S. Agent for Aviomania Aircraft... the most stable gyroplane on the market today.
                    See: Aviomania USA http://www.AviomaniaUSA.com

                    OEM Dealer for MGL Avionics - glass cockpit EFIS for Experimental aircraft Ask about DISCOUNTS for PRA MEMBERS

                    Comment


                    • #11
                      Here is a link to my friend's BTTB Pit Bull gyro http://www.alphasuite.com/PITBULL/WRITEUP_PB.htm

                      McCulloch J2 fans might recognize the "wing" tanks. This gyro used to be hangared near me.
                      Tom Milton, PRA Director, Need a DAR, Seat tank, Prerotator, Rotor Brake, or Rotor Tach?
                      Have Airworthiness Certification questions?
                      gyroplanes@aol.com or
                      Visit www.calumetair.com

                      Comment


                      • #12
                        Originally posted by gyroplanes View Post
                        Here is a link to my friend's BTTB Pit Bull gyro http://www.alphasuite.com/PITBULL/WRITEUP_PB.htm

                        McCulloch J2 fans might recognize the "wing" tanks. This gyro used to be hangared near me.
                        Thanks for the link, Tom. But something caught my eye. It looks like his Sport Copter head is flipped 180 degrees in order to attach the control rods which are forward of the mast. But doesn't that also flip the arrangement of the offset gimbal? In other words, wouldn't the natural pitching self-regulation that the offset gimbal provides now be pitching the other way and working against him? I'm just curious how that may have been resolved in his build since Jim Vanek had assisted him.

                        Comment


                        • #13
                          Originally posted by Brian Jackson View Post

                          Thanks for the link, Tom. But something caught my eye. It looks like his Sport Copter head is flipped 180 degrees in order to attach the control rods which are forward of the mast. But doesn't that also flip the arrangement of the offset gimbal? In other words, wouldn't the natural pitching self-regulation that the offset gimbal provides now be pitching the other way and working against him? I'm just curious how that may have been resolved in his build since Jim Vanek had assisted him.
                          If you check out the larger pictures of the head you will see that although the control rods attach to the front of the torque bar the gimbal offset is still in its proper place, behind the pitch pivot point. That would make the torque bar a custom bar for this particular gyro.

                          Comment


                          • #14
                            Originally posted by Alan_Cheatham View Post

                            If you check out the larger pictures of the head you will see that although the control rods attach to the front of the torque bar the gimbal offset is still in its proper place, behind the pitch pivot point. That would make the torque bar a custom bar for this particular gyro.
                            Yes, I see now that the pitch pivot is indeed forward of the spindle. My eyes deceived me. Thank you for the explanation.

                            Comment


                            • #15
                              SnoBird's Adventurer 2 place was the same way . Stick action crossed over under the seats.
                              Tom Milton, PRA Director, Need a DAR, Seat tank, Prerotator, Rotor Brake, or Rotor Tach?
                              Have Airworthiness Certification questions?
                              gyroplanes@aol.com or
                              Visit www.calumetair.com

                              Comment

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