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Foregoing the D Window

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  • Foregoing the D Window

    RE: 4 Place...

    Seems like many, if not most, have opted to change the D window (rear side window) to a more squared version. I'm think I would also prefer a squared style window. My research for examples on how to do this mod did not produce many results. Jared has some good pointers, but I'm still not visualizing a replacement for the existing aluminum D frame that comes with the quick build kit. Do any of you have pictures and experience that you can share?

    Thanks in advance!
    Rob Caldwell
    Lake Norman Airpark (14A), North Carolina
    EAA Chapter 309
    Model B Quick Build Kit Serial # 11B-24B / 25B
    YouTube Channel: http://bearhawklife.video
    1st Flight May 18, 2021

  • #2
    I've personally not heard of folks modifying the window frame from rounded to square. I think that was a change incorporated with the Bravo design but I'm not positive about that. In fact I don't think I've seen any examples of Bravo 4-place kit builds out there so it could be you're just noting the old design.

    I prefer the D look myself, the engineer in me appreciates the removal of stress risers

    Re Jared's design I wanted to do something similar and go floor to ceiling with a window, but that would require welding to the fuselage frame and I'd rather avoid that. So for now the plan is a regular D window on the port side and a larger window starboard on the door. I figure this also gives my passengers options if someone isn't comfortable sitting close to the open side.

    ETA: It immediately occurred to me you might not be talking about Bravo/pre-Bravo designs but rather just what Jared did. He has some pretty good pics of his frame on his site, I recall having to dig a bit for them though.
    Last edited by Archer39J; 10-03-2018, 11:37 AM.
    Dave B.
    Plane Grips Co.
    www.planegrips.com

    Comment


  • #3
    The window and its frame are not really part of the structure assuming what ever you do stays on the plane and does not depart the plane. So no structural issues assuming you execute whatever modification well. However, I would want to have a good, strong reason as all the little things like this delay finishing and flying your BH. And if you do not understand how all the stringers/formers/and fabric interact - you might find what you thought worked actually created some other unexpected issues to deal with. Mark

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    • jaredyates
      jaredyates commented
      Editing a comment
      Agreed 100% here!

  • #4
    I wasn't thinking this mod was B model specific, and maybe there are no B models with this mod. But I personally do not care for the look of the D window.

    These pics demonstrate why I say most of the builds I've seen do not adopt the D window.
    You do not have permission to view this gallery.
    This gallery has 15 photos.
    Rob Caldwell
    Lake Norman Airpark (14A), North Carolina
    EAA Chapter 309
    Model B Quick Build Kit Serial # 11B-24B / 25B
    YouTube Channel: http://bearhawklife.video
    1st Flight May 18, 2021

    Comment


    • #5
      Originally posted by robcaldwell View Post
      I wasn't thinking this mod was B model specific, and maybe there are no B models with this mod. But I personally do not care for the look of the D window.

      These pics demonstrate why I say most of the builds I've seen do not adopt the D window.
      Yeah all of those except 1 seem to be the legacy "A" model design. I don't think anyone has modded a Bravo back to that. If it's important to you I don't see why you couldn't just make a new frame, hopefully that fit the existing standoffs. Though without actually laying it out there could be fit issues like Mark said.

      Though I don't know for sure, I'd guess the change was to reduce the stress concentration in the sharp corners of the window. Good design practice.
      Dave B.
      Plane Grips Co.
      www.planegrips.com

      Comment


      • #6
        On the original BH the window frames were steel and welded in place. On the Model B they are aluminum and made differently. One of the changes Bob wanted for the B model. MG

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        • SimonNicholson
          SimonNicholson commented
          Editing a comment
          My B model fuselage still has the steel window frames. When was the change made? Or is my fuselage actually an A model?

      • #7
        Thanks, Mark. Glad to understand that information and history. Very helpful.
        Rob Caldwell
        Lake Norman Airpark (14A), North Carolina
        EAA Chapter 309
        Model B Quick Build Kit Serial # 11B-24B / 25B
        YouTube Channel: http://bearhawklife.video
        1st Flight May 18, 2021

        Comment


        • #8
          The B model left side rear window, when mounted on the factory standoffs, seems like it has an odd profile. From the rear aluminum door former, it goes concave on the bottom, and then back out to next station. The top side profile looks normal, but the lower edge seems a bit odd. I don't know how many model B's are flying, or have the fuselage covered other than Rob. Is this profile correct? I will try to take a picture and post it.

          Comment


          • robcaldwell
            robcaldwell commented
            Editing a comment
            Mine was the same. I had to move a standoff and adjust the other. Still has a slight "bulge" aft of the window.

          • svyolo
            svyolo commented
            Editing a comment
            Yeah I will talk to Mark about it, but I think just bending the aft lower standoff will fix most of it. I just want to make sure the stock profile isn't necessary for some reason.

        • #9
          I was about to secure the left rear window in place, but then started thinking about how to replace the window if I ever needed to. I assumed the external fabric would terminate on the outside of the window frame. Would it make more sense to terminate the external fabric to the inside piece of the window frame, and then screw the outside frame onto the outside of the window? Is this what was intended?

          I also saw the Patrol recommends mounting angles to the window standoffs, and mounting the frame to that. That doesn't look like it works for the Model B.

          I have found lots of little tidbits of Patrol and Model B window install details, but I can't find anything describing the whole install.

          Comment


          • Mark Goldberg
            Mark Goldberg commented
            Editing a comment
            John, if you will call me I am happy to try and explain. Mark
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