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  • Dominator measurement needed

    Hi fellow Dominator owners. I need a measurement on a Dom single. With the rotor blades all the way tilted back, how much room is there between the bottom of the rotor blade and the support which runs from the mast to the top of the rudder? In other words, how close does the rotor come from touching that top rudder support in the area around the prop.
    "Never skimp on toilet paper or condoms"
    EAA member # 1102638
    Sport pilot Gyroplane

  • #2
    Hello, is this thing on????
    "Never skimp on toilet paper or condoms"
    EAA member # 1102638
    Sport pilot Gyroplane

    Comment


    • #3
      I'm in the same situation. It's like anything Dominator related is a tight kept secret. I'm looking for the assy instructions for a Dom tail.
      Bobby Munroe
      Private Pilot (SEL)
      PRA Chapter 62 #42748
      EAA #1160523

      Comment


      • #4
        I am trying to get you an answer. It may take a few days. Russ Smith here in NC has a live dominator in captivity. I will call and ask him to measure.
        Scott Waggoner

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        • #5
          For the Dominator; I do not know!
          For most Gyros the answer is, "There is No clearance at all."

          https://www.youtube.com/watch?v=DJ4EpCphp18

          With the Cyclic fully back and the Rotor at the Teeter Stop limits, The rotor WILL strike the tail.
          This is what is mistakenly called "Rotor Flapping". In helicopters, it is called "Mast Bumping."
          In gyros, It is really "Teeter Stop Bumping" and has nothing to do with anything "Flapping" other than the flapping caused by the bumping.
          Rotor Blades do not "Flap" because the Rotor Speed is too low. They Flap because the Teeter Stops are being Bumped.

          Under normal flight aerodynamics, it will not occur.
          The problem is when the Rotor Speed is not sufficient to absorb the excessive incoming airflow.
          The Right Advancing Blade climbs in the higher airflow and the Left Retreating Blade descends in the lower airflow.
          This causes the roll to the left that Juan de la Cierva cured with the invention of the Teetering hinge.

          The initial assumption would be that the rotor disk would tilt to left. Not so.
          The Advancing blade reaches its highest point in the front and then become the retreating blade and begins descending.
          This is why the Rotor tilts Backwards.

          The Teeter Stop Bumping commonly happens in the takeoff phase with low rotor speed and high ground speed.
          Pre-Spinning the Rotor up to sufficient RPM before the takeoff roll will limit the amount of teetering and prevent Rotor Strike.

          It also can occur in normal flight with normal rotor speed coupled with high airspeed.
          The faster you go, the further the rotor disk teeters backward.
          At some speed, the rotor will start bumping the teeter stops.
          This is what determines the Vne (Never Exceed) Airspeed of the Gyro.

          It would not surprise me at all that the Dominator Rotor is capable of striking the top of the Rudder.
          It's what they do!
          It is also why Rotor Speed management is important.
          Last edited by Uncle Willie; 07-14-2017, 08:13 PM.

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          • #6
            A general rule of thumb is with full aft tilt of the head and full aft teeter of the rotor, and with the blade pulled lightly down, there should be no less that one inch of clearance.

            If it is possible for the rotor to geometrically strike the tail or prop then centrifugal teeter limiters should be considered if not down right required to help prevent a low rpm strike.

            Comment


            • #7
              Originally posted by Capt'n Gator View Post
              Hi fellow Dominator owners. I need a measurement on a Dom single. With the rotor blades all the way tilted back, how much room is there between the bottom of the rotor blade and the support which runs from the mast to the top of the rudder? In other words, how close does the rotor come from touching that top rudder support in the area around the prop.
              When rotor isn't rotating at 150+ RPM then it will hit the tail/upper tail support. This is why prerotation starts with stick kept full forward. After RRPM reaches 100-120 RPM stick should be slowly pulled back so that it is full back at 150-160 RPM. When rotor is rotating at 150+ RPM then with stick full aft there should be at least 3-4" clearance.
              Alex Lameko
              Russian gyroforum
              Visit my collection of gyro videos

              Comment


              • #8
                Rotorblades 22'-28' Dragon Wings - all-aluminum, bonded skins
                Length 10'
                Height 8'1"
                Width 5'6"

                From The RFD site
                I'm a gyro Dude now! Bensen FTW

                FRANK

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                • #9
                  So Wayne, I took some measurements this morning on my Dominator single. I have 24' Dragon Wings. With the stick full back and the blades at rest, my rotors actually sit about 3 to 4 inches BELOW my tail. See pic below. I spoke to a couple of very experienced gyro pilots who said this was not unusual and was also true of their two place Dominator. It seems to me that an adjustment of the teeter stops so the blade would clear the tail would result in reduced flair control during landing. One more reason correct rotor/stick management on the ground is so critical, as has been drilled into me by my instructor.

                  Russ

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                  • #10
                    My single Dominator has 5-6" clearance between the blades and the top of the tail. Stick full back on the stop and blades back on the teeter stop.

                    Comment


                    • #11
                      Back to Dom roots: a piece of original drawing.
                      Click image for larger version

Name:	dom tail clrnce.jpg
Views:	1
Size:	167.3 KB
ID:	1122400
                      Alex Lameko
                      Russian gyroforum
                      Visit my collection of gyro videos

                      Comment


                      • #12
                        Bill (uncle Willie) your explanation about rotor flap is the best one ever,very clear, easy to understand, and to the point .

                        Great job of writing.Thank you!
                        Best Regards,
                        Eddie Sigman,Polvadera,nm
                        (575) 835-4921

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                        • #13
                          OK everyone, I appreciate all the input. If everyone will look at post #11 by Twistair. Now if someone could give me the measurement between the rudder stabilizer bar running to the mast and the bottom of the rotor right there above where it says 3/4" prop clearance, I need to know how much clearance there is between the rotor blade and that rudder upper stabilizer bar right above the prop tip area. Thanks.
                          "Never skimp on toilet paper or condoms"
                          EAA member # 1102638
                          Sport pilot Gyroplane

                          Comment


                          • #14
                            Originally posted by Capt'n Gator View Post
                            OK everyone, I appreciate all the input. If everyone will look at post #11 by Twistair. Now if someone could give me the measurement between the rudder stabilizer bar running to the mast and the bottom of the rotor right there above where it says 3/4" prop clearance, I need to know how much clearance there is between the rotor blade and that rudder upper stabilizer bar right above the prop tip area. Thanks.
                            If I am understanding your question correctly Wayne, it looks like one inch of clearance is required from the rotor bad to the bolt.

                            The bolt appears to me to be the high point of the upper rudder brace.
                            Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

                            Comment


                            • #15
                              Originally posted by Uncle Willie View Post
                              For the Dominator; I do not know!
                              For most Gyros the answer is, "There is No clearance at all."

                              https://www.youtube.com/watch?v=DJ4EpCphp18

                              With the Cyclic fully back and the Rotor at the Teeter Stop limits, The rotor WILL strike the tail.
                              This is what is mistakenly called "Rotor Flapping". In helicopters, it is called "Mast Bumping."
                              In gyros, It is really "Teeter Stop Bumping" and has nothing to do with anything "Flapping" other than the flapping caused by the bumping.
                              Rotor Blades do not "Flap" because the Rotor Speed is too low. They Flap because the Teeter Stops are being Bumped.

                              Under normal flight aerodynamics, it will not occur.
                              The problem is when the Rotor Speed is not sufficient to absorb the excessive incoming airflow.
                              The Right Advancing Blade climbs in the higher airflow and the Left Retreating Blade descends in the lower airflow.
                              This causes the roll to the left that Juan de la Cierva cured with the invention of the Teetering hinge.

                              The initial assumption would be that the rotor disk would tilt to left. Not so.
                              The Advancing blade reaches its highest point in the front and then become the retreating blade and begins descending.
                              This is why the Rotor tilts Backwards.

                              The Teeter Stop Bumping commonly happens in the takeoff phase with low rotor speed and high ground speed.
                              Pre-Spinning the Rotor up to sufficient RPM before the takeoff roll will limit the amount of teetering and prevent Rotor Strike.

                              It also can occur in normal flight with normal rotor speed coupled with high airspeed.
                              The faster you go, the further the rotor disk teeters backward.
                              At some speed, the rotor will start bumping the teeter stops.
                              This is what determines the Vne (Never Exceed) Airspeed of the Gyro.

                              It would not surprise me at all that the Dominator Rotor is capable of striking the top of the Rudder.
                              It's what they do!
                              It is also why Rotor Speed management is important.

                              It is my understanding that rotor "flap" is when the critical angle of attack of the rotor blade airfoil is exceeded and one of the blades stalls.

                              I feel this happens when too much forward speed is combined with insufficient rotor rpm.

                              It is not unusual for the rotor to hit the stops in this situation and hitting the stops makes it easier to feel rotor flap in the cyclic.

                              In my experience in most gyroplanes I have flown the rotor will hit the tail when the rotor blades flap on takeoff and hitting the stops is the result of the rotor flap rather than the cause of the tail strike.

                              I have not flown a gyroplane where the rotor hub bar hits the teeter stops past VNE.

                              I have flown gyroplanes where the rotor becomes less manageable as the speed increases.

                              I suspect the VNE in most gyroplanes is set by the test pilot over stability issues rather than the rotor hitting the teeter stops.
                              Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

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