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  • Been given control of a cool project

    I cannot predict what life will throw at me, best I just ride the wave and appreciate things.

    Let me post some images to wet your appetite...



    and




    It is a twin drive with counter rotating propellers, powered via belt reduction to two Mazda 13B rotary engines. This will be going in the nose of a Cessna 185.

    I have been given authority to make changes where I see fit, and engineer certain aspects. I am making all the drawings in Solid Works. Final engineering review will take place with a professional engineer.
    I also will be building it. He has a Smithy 3 in 1 1340 in his hangar with all the basic machine tooling that I will get to use! Ahhh get to make chips again!!!!

    Got tons more work ahead of me, exciting!

  • #2
    General question?
    Who certifies something like that ?

    .
    .

    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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    • #3
      Originally posted by John Stevenson
      General question?
      Who certifies something like that ?

      .
      The FAA has outlined a very lengthy and costly procedure for doing it. I do not know the exact details as it does not apply to this. This airplane is an experimental.

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      • #4
        For a minute there I thought it was a new design for a BOP.

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        • #5
          Gee I thought you were recently out of work? If so, great job of landing on your feet! Good luck on your project.
          - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
          Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

          It is true, there is nothing free about freedom, don't be so quick to give it away.

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          • #6
            Originally posted by Your Old Dog
            Gee I thought you were recently out of work? If so, great job of landing on your feet! Good luck on your project.
            The guy I am working for, his hangar is next to where we park our airplanes from my old job. You know the saying, one thing leads to the next!

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            • #7
              Ah, I see, one engine faces forward, and the other faces to the rear. They drive two propellers through two common shafts, one inside the other.
              Throughout avation history counter-rotating props have been tried repeatedly, and abandoned...mostly due to third order harmonics in the drive system. Using two rotaries for power is certainly not the most economical set-up. Mazda engines aren't noted for fuel economy or long service life.

              Good luck with the project. Keep us posted.
              No good deed goes unpunished.

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              • #8
                Originally posted by saltmine
                Ah, I see, one engine faces forward, and the other faces to the rear. They drive two propellers through two common shafts, one inside the other.
                Throughout avation history counter-rotating props have been tried repeatedly, and abandoned...mostly due to third order harmonics in the drive system. Using two rotaries for power is certainly not the most economical set-up. Mazda engines aren't noted for fuel economy or long service life.

                Good luck with the project. Keep us posted.
                We are looking at TBO's of 3500 hours, much better than a lycombing. Harmonics are an issue we've been discussing.

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                • #9
                  If it works, nice.. no P-factor.

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                  • #10
                    Originally posted by saltmine
                    Throughout avation history counter-rotating props have been tried repeatedly, and abandoned...
                    Various aircraft types have enjoyed long service life with contra-rotating props. Others have used counter-rotating props but that is not what this adaptation appears to be.
                    Last edited by The Artful Bodger; 06-16-2010, 12:18 AM.

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                    • #11
                      Originally posted by The Artful Bodger
                      Various aircraft types have enjoyed long service life with contra-rotating props. Others have used counter-rotating props but that is not what this adaptation appears to be.
                      Contra-rotating, thank you.

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                      • #12
                        Originally posted by John Stevenson
                        General question?
                        Who certifies something like that ?

                        .

                        Smithy.............

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                        • #13
                          Originally posted by A.K. Boomer
                          Smithy.............
                          All the important stuff will be farmed out to local CNC houses. Know of any good ones in the East Bay area of California?

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                          • #14
                            You're barking up the wrong tree.


                            Having quite a bit of internal knowledge about the 1.3L wankel (like I pulled 140hp per litre at the wheels from one without boost on low compression rotors while still running 5 points rich), I can tell you with certainty that what you want to do is build a bigger wankel.

                            2L wankels (3 rotor) are capable of 800hp under boost (lifespan is directly related to ignition timing as blown apex seals due to detonation mean the rotor housings are trashed and that means you're asking for trouble in this application). I'm assuming you want to use two NA engines piggy backed through some kind of clutch, when you could save all that trouble by devising a longer multi-piece eccentric shaft (which are commercially available for higher rpm applications anyway) and simply add more rotors to the primary power plant while supplementing them with center bearings (which the production 1.3L has always lacked). The remaining element is just an appropriate intake manifold and a custom header which are also less than overtly difficult (but runner length can't be too short or you'll lose any semblance of torque).

                            With bearings between all the rotors in their respective intermediate housings, you're looking at an engine that can reliably run at over 12,000rpm without much trouble.

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                            • #15
                              Gannet

                              You are very fortunate to get that job but I daresay that the owner went to a lot of trouble to pick his man for the job.

                              That is no small compliment as regards your skill, personality and reliability and ability to take on projects and work your way through them.

                              You must be well regarded - and that doesn't come without good reason.

                              Congratulations.

                              I had the best part of three years on an OZ aircraft carrier that was out-fitted with Fairey Gannet aircraft with contra-rotating propellers. They could operte or cruise on one engine if needed - especially "on patrol" as it was quite a lot more economical as regards fuel (AV-CAT).

                              http://en.wikipedia.org/wiki/Fairey_Gannet

                              http://www.google.com.au/#hl=en&sour...556ce57ce57d56

                              One of my jobs was the stabilised landing lights and mirrors - on sponsons out-board of the flight deck. I used to service and provide the anti-submarine torpedoes for the Gannets as well as the rocket and bomb lifts. I also had all the guns (17 x 40/60 Bofors) and the small arms and sonar (very simple). So I had a lot of work and time on and out-board of the flight deck and saw a lot of those Gannets. Their stall speed was incredibly slow - as was their take-off speed (no steam catapult needed if necessary). They could land-on without arrestor wires if necessary.

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