Announcement

Collapse
No announcement yet.

Tower height?

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Tower height?

    Is there a formula or spreadsheet on tower/teeter bolt height for the Dragon Wings?
    Bobby Munroe
    Private Pilot (SEL)
    PRA Chapter 62 #42748
    EAA #1160523

  • #2
    This may be of some help. It is a page from 'Flugphysik der Tragschrauber' (Duda/Seewald):

    ​​​​​​


    The formula giving the optimal distance is: hU = rmBl ĚkBl


    Where:

    rmBl is the distance between the point where the prolongations of the blades meet at the rotor head and the center of mass of a blade (CGBl)

    and:

    kBl is the conicity, in radians.

    In the example of the book (an MBO rotor) that distance hU is 12cm. In your case it is probably different. Just insert your numbers and see what happens...

    Good luck...
    Last edited by XXavier; 10-15-2018, 12:01 PM.

    Comment


    • #3
      Does anyone know the coning distance of 27 foot dragon Wings supporting an 830 pound all up weight?
      Bobby Munroe
      Private Pilot (SEL)
      PRA Chapter 62 #42748
      EAA #1160523

      Comment


      • #4
        Originally posted by AirCommandPilot View Post
        Does anyone know the coning distance of 27 foot dragon Wings supporting an 830 pound all up weight?

        Comment


        • #5
          More...


          Comment


          • #6
            Hello Bobby:
            I have a set of 27' Dragonwings on my Dominator.
            I will get by the airfield and get some measurements and post them here for you.
            David McCutchen
            615-390-2228
            Bensen B7m, 90 hp Mac
            Dominator Tandem, 100 hp Hirth
            Kolb Mark III Classic, 80 hp Verner
            Certified - Advanced Master Beef Producer
            EAA Member #0511805
            PRA Member #28866
            PRA Chapter 16 Member
            Secretary & Treasure - PRA Chapter 16
            President / Sylvia - Yellow Creek Volunteer Fire Dept.
            Chairmen - Dickson County Veteran's Day Committee
            Volunteer - Dickson County Airport Aviation Day Committee
            2 busy 2 No!

            Comment


            • #7
              Originally posted by XXavier View Post
              More...

              Thanks XXavier, but that just adds more questions.

              My issue is I have a single place Air Command with a heavy Subaru EA82. With my 200 lbs of weight added to the 635 lbs of machine, and 25' SkyWheels I'm not getting the climb performance I would like (during the summer). Last winter the thing would rise in the air like an elevator. I'm getting around 435 lbs of thrust in the heat, and was getting 455 lbs during the winter.
              My guess is I need a 27' rotor to make up for the weight. I might have access to borrow a set of 27' Dragon Wings from a two place dominator to test out my 'guess', but I would have to use taller tower plates on my head. I'm just trying to figure out where my teeter bolt needs to be if I get to test the 27' rotor.
              I don't know the specifics of the Dragon wing e.g. the blade CG and Blade weight. This info should already be out here. I just haven't been able to find it.
              Bobby Munroe
              Private Pilot (SEL)
              PRA Chapter 62 #42748
              EAA #1160523

              Comment


              • #8
                Originally posted by Gyro28866 View Post
                Hello Bobby:
                I have a set of 27' Dragonwings on my Dominator.
                I will get by the airfield and get some measurements and post them here for you.
                Thanks David. Would it matter if mine is a single place? Your Dominator is tandem right? Or would it just be about the weight?
                Bobby Munroe
                Private Pilot (SEL)
                PRA Chapter 62 #42748
                EAA #1160523

                Comment


                • #9
                  Originally posted by AirCommandPilot View Post

                  Thanks XXavier, but that just adds more questions.

                  My issue is I have a single place Air Command with a heavy Subaru EA82. With my 200 lbs of weight added to the 635 lbs of machine, and 25' SkyWheels I'm not getting the climb performance I would like (during the summer). Last winter the thing would rise in the air like an elevator. I'm getting around 435 lbs of thrust in the heat, and was getting 455 lbs during the winter.
                  My guess is I need a 27' rotor to make up for the weight. I might have access to borrow a set of 27' Dragon Wings from a two place dominator to test out my 'guess', but I would have to use taller tower plates on my head. I'm just trying to figure out where my teeter bolt needs to be if I get to test the 27' rotor.
                  I don't know the specifics of the Dragon wing e.g. the blade CG and Blade weight. This info should already be out here. I just haven't been able to find it.
                  I hope you may solve the problem soon, but (it seems to me) it may be a problem of thrust available, and not of rotor size. Perhaps a different propeller (or a different pitch, if adjustable) could be of help... Good luck...

                  Comment


                  • #10
                    My thrust is only 30 lbs less than one of our AR1s with a 912. The my weight is similar to the AR1 yet it can carry another person and fly just fine. The two differences are the rotor diameter and the drag. Not much I can do about the drag without a total redesign, but I can change the rotor. If it doesn't help, I know what I need to do.
                    Another example is the early RAF with the same engine as me would fly two people, but I think it has a 30' rotor. Am I thinking wrong here?
                    Bobby Munroe
                    Private Pilot (SEL)
                    PRA Chapter 62 #42748
                    EAA #1160523

                    Comment

                    Working...
                    X