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  • #16
    Rehan said: "Your gyro will not do it on its own, unlike HTL gyros which actually went into a PPO in straight and level flight with out and warning.
    A bit of technic will be required to make a Sportcopter PPO."

    No gyro will do it on its own. To develop a PPO is needed a previous and sustained low g environment. And this can only be met by a pilots action (a possitive an large push on the stick when flying with any airspeed, or by doing some aerobatics).

    If anyone creates this situation and does not have an HTL gyro, he will meet a reduction in rotor rpm than may produce a hit of the retreating blade in gyro's tail.

    All teetering rotor gyros (including the most stable ones) have a serious low g limitation. Sometimes it seems that some people are defending the idea that an stable gyro cannot have any problem. This is not true. The best gyro in the world can kill you if you put it in a low g environment. But, of course, it won't be a PPO...



    • #17
      I thought you were already flying.
      As a newbie, I think you are over the hard part. The flying part is easy.


      • #18
        Hi guys, I just found this on the web ( It id a beautiful, concise and illustrative discussion of gyro pitch stability.

        Enjoy, -- Chris.

        P.S.: Nothing new, just better worded and illustrated :-)
        Read about my trip across the USA in an MT03 gyro here.


        • #19
          Originally posted by barnstorm2 View Post
          I sometimes try to help my friends visualize bunt over like this.

          Imagine someone sitting in a rocking chair.

          If you have a high thrust line it is like someone pushing from behind against the head rest. They will push forward and you will fall forward out of the chair on your face.

          The person pushing from behind is the engine applying thrust above your center of gravity. If the rotordrag does not stop them they will push you over.

          CLT is like someone behind your zero gravity chair pushing low, near your butt or about level with your belly button.

          What happens? They just push you and the chair forward. You don't topple over forward.

          Thus.. The only thing holding the person pushing on your headrest from pushing you over (bunting you over) is the drag from the rotors.

          What stops the rotors from dragging ( and stopping the high thrust line from bunting you)?

          Keeping your rotor disk spinning fast which will keep your rotors coned and dragging.

          Anything that can cause you to loose rotor rpm RRPM can cause you to bunt.

          Quick dramatic changes in the rotor disks angle of attack can do this. Going into a near zero G attitude can do this a I assume a few people can list other ways as well.

          I hope that helps.

          When I look at a stock RAF or early Air Command I can see the engine looks like it is pushing against the top back of the pilots head. Also, lots of heavy stuff is under this line and lots of wide body.

          When I look at a Twinstarr, Bee, or Bensen the push is more like around your shoulders or between sholders or belly button. These seem to be what people call Near Centerline Thrust NCLT

          When I look at a Center Line Thrust machine New Air Command, Dominator, Butterfly.. it looks like the thrust line goes through the belly button.

          This is an over simplification but it works alot of the time.

          Apparently a large and effective Horizontal Stabilizer does not help the thrust offset but can stabilze the pitch reactions of the pilot and help the pilot from unloading the rotors as easily. The danger is still there to a certain degree.
          Could a decrease in the vertical distance between the rotor and the center of gravity of the fuselage become a problem?

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