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Horsepower problem solved. The R-8720.

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  • Horsepower problem solved. The R-8720.

    Ha-Ha. This could cure the Bears ill's.
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    Last edited by hm66sk; 09-11-2013, 02:17 PM.
    "And if they stare, just let them burn their eyes on your moving."

  • #2
    Re: Horsepower problem solved. The R-8720.

    might need a few old car batteries in the tail for weight & balance issues - otherwise I don't see any reason why not?
    1960 Piper Comanche

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    • #3
      Re: Horsepower problem solved. The R-8720.

      Originally posted by comancheflyer View Post
      might need a few old car batteries in the tail for weight & balance issues - otherwise I don't see any reason why not?
      Well for one thing, the crank length on a 4360 was already approaching torsional stress limits, so I don't see that doubling one up would ever be feasible.

      Along with a whole host of other things...

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      • #4
        Re: Horsepower problem solved. The R-8720.

        I always thought that Lycoming XR-7755 would be a cool power plant - too bad it probably weighs more than the rest of the airplane. Guess you would need to design a really really big boil off system though ...

        1960 Piper Comanche

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        • #5
          Re: Horsepower problem solved. The R-8720.

          If its not a photoshop deal. Then it is a non running hollow engine, meaning the insides are void of moving parts.

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          • #6
            Re: Horsepower problem solved. The R-8720.

            I'm pretty sure you can bolt as many intermediate crankcase sections together as you want and slap jugs on, I'm sure they did it just for grins. Angular separation for the '4360 is 12 6/7 degrees; if it had been a five or six row (configurations Pratt considered) that would have been different. Every jug has a little frontal area in the breeze.

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            • #7
              Re: Horsepower problem solved. The R-8720.

              ....quick, grab the blower & gear set.......
              Mayday51
              Jim Gallagher

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              • #8
                Re: Horsepower problem solved. The R-8720.

                Originally posted by mayday51 View Post
                ....quick, grab the blower & gear set.......
                Probably not even in there. Would make a bitchin' coffee table!
                "And if they stare, just let them burn their eyes on your moving."

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                • #9
                  Re: Horsepower problem solved. The R-8720.

                  Not photoshopped. I took pics of it myself. Two things I noticed and havn't seen on any naked motor before. The cyls seemed to have unique finning on the head area and the valves pushrods were front and rear of each cyl instead of both pushrods being front OR rear of the cyl as in every other P&W or Wright I've seen. I'm not convinced this was just a dummy joke engine and not a genuine project that was never used. Too bad there wasn't some decent info displayed with it.

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                  • #10
                    Re: Horsepower problem solved. The R-8720.

                    GeeBee... what you are seeing is all standard P&W R-4360. As has been said, this is just a lash-up of extra crankcase sections. There are no internals...

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                    • #11
                      Re: Horsepower problem solved. The R-8720.

                      Originally posted by GeeBeeZ1931 View Post
                      Too bad there wasn't some decent info displayed with it.
                      LOL... I believe it came out of Alby's shop.. We wound up sheltering from the rain with a couple of neat ladies (mother daughter) who work for Alby selling shirts... apparently, all you need to know is in the dataplate on the engine. I have a pic.. will find and post, the key element in the model number is the BS at the end of the sequence....
                      Wayne Sagar
                      "Pusher of Electrons"

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                      • #12
                        Re: Horsepower problem solved. The R-8720.

                        I have to give him credit for creating a great conversation piece out of parts from two engines, excluding a crank and internal parts. Sure peaked everyone's interest.

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                        • #13
                          Re: Horsepower problem solved. The R-8720.

                          I think they should have parked it over next to the American Spirit project....

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                          • #14
                            Re: Horsepower problem solved. The R-8720.

                            I remember working on one of those engines back in the mid 50's, for a top secret design at Area 52. There were 3 built. It was designed for the P-56 (designated after the number of cylinders). It was a mid engine design driving a front pusher prop and a rear tractor prop. Two props were needed to absorb the horsepower. A total of 5 flights were made. The main problem was the airplane was approaching the trans sonic region and prop tip speeds were approaching near warp speed. The plane was designed for two crewmembers.......one pilot and one mechanic to change cylinders inflight.
                            The short lived project was shelved after the delivery of the 112 cylinder P&W 17440. Do a Google Search and I'm sure you won't be able to find any additional information.....remember SHHHHhhhhhhhhhhhhhh, it was top secret.
                            Brian

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                            • #15
                              Re: Horsepower problem solved. The R-8720.

                              When I arrived at Stead on the 6th, it was sitting next to the fence. A friend and I were marveling at it, when two fellows with a forklift came to move it out to the spot it was in during the event. One fellow said he had built it, when he discovered you could bolt the cases together and everything fit like it was made to be that way. He said over the years he enjoyed the number of people who told him, often in some detail, how they had worked on this series of engine back in the day in the such and such aircraft....but his favorite one yet was the guy who spent ten minutes explaining to his girlfriend exactly how jet engines like this work....

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