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  • greenman407
    Admiral
    • Feb 2009
    • 7530

    Thats interesting. Most other Torps that I have seen are contra props
    IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

    Comment

    • He Who Shall Not Be Named
      Moderator
      • Aug 2008
      • 12321

      Counter rotating propellers and a properly designed pump-jet do the same thing:

      They both recover swirl energy and impart zero net torque onto the vehicle.

      David,
      Who is John Galt?

      Comment

      • greenman407
        Admiral
        • Feb 2009
        • 7530

        I SPY A CELEBRITY. Who is the famous man coming up out of this submarine? Heres a hint. His initials are STClick image for larger version

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        IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

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        • He Who Shall Not Be Named
          Moderator
          • Aug 2008
          • 12321

          Spencer Tracy
          Who is John Galt?

          Comment

          • spankey
            Lieutenant Commander
            • Aug 2010
            • 103

            I suspect that underneath that duct/shroud is a pair of contra props.... Or another means to keep that device from torque rolling all the way to target.

            ...Late post...
            Last edited by spankey; 09-26-2011, 11:23 AM.

            Comment

            • He Who Shall Not Be Named
              Moderator
              • Aug 2008
              • 12321

              Under that shroud is a single rotor, and behind that, a single stator.



              David,
              Last edited by He Who Shall Not Be Named; 09-26-2011, 11:37 AM.
              Who is John Galt?

              Comment

              • spankey
                Lieutenant Commander
                • Aug 2010
                • 103

                Ok, so its the stators that are imparting the counter-torque to compensate for the rotor torque roll. Good to know. I always wondered if there was a single or double rotor.

                Comment

                • He Who Shall Not Be Named
                  Moderator
                  • Aug 2008
                  • 12321

                  More than that: the stator translates swirl flow to axial flow resulting in more thrust than if there were no stator involved. It's the stator(s) that differentiates a pump-jet from a ducted (Kort) nozzle propulsor.

                  David
                  Who is John Galt?

                  Comment

                  • spankey
                    Lieutenant Commander
                    • Aug 2010
                    • 103

                    Right, because the duct, along with the stator is taking all the tip vortecies (wasted energy that normally would be spinning/swirling radially off of the blades) and shoving it backward...

                    Comment

                    • spankey
                      Lieutenant Commander
                      • Aug 2010
                      • 103

                      In the same vein, Does anyone know what (US) submarine they tried this ducting on before they actually employed it on the Seawolf boats? Like most things, it seems like this stuff was probably tested on boats before it was employed on a new build boat.....Unless the Brit's were kind enough to give us a bunch of data on their stuff..?

                      Comment

                      • greenman407
                        Admiral
                        • Feb 2009
                        • 7530

                        Great pictures Dave!! I think that it was one of the 688I that did some testing on that.
                        IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

                        Comment

                        • He Who Shall Not Be Named
                          Moderator
                          • Aug 2008
                          • 12321

                          That's right, is was one of the DevGroups out of New London. One or two boats had not only the propulsor, but some of the engineering plant elements designed for the SEAWOLF class.

                          David,
                          Who is John Galt?

                          Comment

                          • NavyICman
                            Lieutenant
                            • Jun 2010
                            • 60

                            USS Pittsburgh was the test bed for the PJ design. I worked with a gentleman at my last command who was there when it was installed. He is currently a retired CPO working as a Govt Contractor. He said that the design while very sound was not a good fit on the ship and they had many problems. other boats who did testing for things (most out of DEVRON 12): USS Augusta - First WAA Array, ARCI Sonar/Fire control, Thinline arrays, USS Memphis - DiHedral stabilizers and external countermeasures, and a host of other things that shall not be named, USS Cheyenne - Seawolf Propulsion Plant, USS Phoenix and several others - NHP Photonics masts, USS Boise - Increased torque shaft line and thrust bearings. Some of these I was stationed on, some I know people from.

                            Tim

                            Comment

                            • greenman407
                              Admiral
                              • Feb 2009
                              • 7530

                              Yeah........what he said.
                              IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

                              Comment

                              • spankey
                                Lieutenant Commander
                                • Aug 2010
                                • 103

                                very cool. Thanks! ...The navy usually doesnt just DO stuff for new boats without having at least fiddled around with it before!

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