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Airfoils, Ordinates, Fat Wings, Harry Riblett and other musings…

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  • #31
    What Jared said...

    While this discussion has been educational, we aren't building an SR-71 or an F-104. In fact, our VNE is lower than the stall speed of both of those :-)

    Also, keep in mind that many of us are scratch building and are hammering our ribs out over a wooden template: there is no way in, well.... you know, that all of our ribs are *exactly* the same as the kit ribs. I would argue that not all of the ribs in a wing are *exactly* the same, although you probably can't tell that by eye. The kit ribs, however, are as close to perfection as you can get WRT the plans/mylar template.

    There are many Bearhawks happily speeding and STOLing around and they couldn't care less about a line width on the plans here or there. The airplanes are wonderful to fly, have great performance, and have no nasty gotchas.

    By all means, carry on with the academic discussions (I'll admit my eyes glazed over a bit after a while...I'm a software guy...) but for those that are concerned/confused, don't be. Bob knows what he is doing and designing. The proof is in the flying (both scratch and kit built) and there is a LOT of proof out there....

    My $0.02
    -------------------
    Mark

    Maule M5-235C C-GJFK
    Bearhawk 4A #1078 (Scratch building - C-GPFG reserved)
    RV-8 C-GURV (Sold)

    Comment


    • stinger
      stinger commented
      Editing a comment
      I did not cut my nose ribs , I wrapped Duck tape around the tip two layers . I think it turned out well. Yes wing ribs may be different however my LAS fly's quite good .I have 21" tires, Cont. 0200 with a top speed of 135 mph at red line of 2750 rpm. Cruise 2450 rpm around 110mph. Stinger

    • NCLSA183
      NCLSA183 commented
      Editing a comment
      stinger. You are wrapping “duck” tape, nborer is getting attacked by “duck” shoes while I’m having trouble keeping my “ducks” in a row… Maybe we need a new topic. LOL Nice performance numbers on your LSA. I truly enjoyed following your progress. Congrats!!

    • NCLSA183
      NCLSA183 commented
      Editing a comment
      rv8bldr. Mark, thank you for adding your 2 cents. I’m glad this conversation got you up from that very comfortable looking chair with the beautiful trees in the background.

      As someone who has endured some very long coding sessions over the years, I submit that your eyes may likely have been glazed over long before you starting reading this topic. (wink)

      I certainly agree with you in regard to the inconsistency of the hammered ribs. But that is an area where we have a bit of control without adding very much to the build time. The airfoil mylar drawing represents the size and shape of the completed wing, cross section. Allowing for rib flange and skin thickness when making the rib form blocks would result in a completed wing that would better match the mylar and, therefore, more likely have the flight characteristics that were originally intended by the designer. And remember, we don’t know the intentions of the Dwg 4 modification.

      Based upon the analysis by nborer, a few line widths don’t appear to make any truly noticeable difference, but yet, Bob considered it important enough to make that small change to the Riblett 30-613.5 airfoil without any flight testing to quantify the design or verify and compare the results. A very talented, current builder of a large wing Bearhawk recently told me that his completed wing came in at 0.210 inch thicker than the mylar drawing. Will this person be just as happy flying around with that extra weight, drag and likely loss of performance or will he be wondering “what if” as he questions whether or not to load that trophy moose into the aircraft? To borrow a slogan from the Army, my little LSA wants to “be all you can be” so I’ll be making every effort to assure that. Due to the reasons I wrote in some other posts, I will now be using LSA Dwg 4 as the profile for my build.

      Mitch

  • #32
    Originally posted by rv8bldr View Post
    What Jared said...

    While this discussion has been educational, we aren't building an SR-71 or an F-104. In fact, our VNE is lower than the stall speed of both of those :-)

    Also, keep in mind that many of us are scratch building and are hammering our ribs out over a wooden template: there is no way in, well.... you know, that all of our ribs are *exactly* the same as the kit ribs. I would argue that not all of the ribs in a wing are *exactly* the same, although you probably can't tell that by eye. The kit ribs, however, are as close to perfection as you can get WRT the plans/mylar template.

    There are many Bearhawks happily speeding and STOLing around and they couldn't care less about a line width on the plans here or there. The airplanes are wonderful to fly, have great performance, and have no nasty gotchas.

    By all means, carry on with the academic discussions (I'll admit my eyes glazed over a bit after a while...I'm a software guy...) but for those that are concerned/confused, don't be. Bob knows what he is doing and designing. The proof is in the flying (both scratch and kit built) and there is a LOT of proof out there....

    My $0.02
    Hear, hear. I do NOT want to steer anyone away from the plans. I was about to start forming my aileron spar web prior to my inadvertent shop "closure," and the plans very clearly say "check for fit with rib" right next to the dimensioned spar height. In order to fit my aileron ribs (without joggling - another religious argument that I won't dive into), my aileron spar web needs to be about 0.1" taller than the dimension showed in the plans. Lack of joggling will only account for half of that variation. Yet, when I lay my ribs on my formblock and compare to the Mylar, they look pretty darn close to me. I guess I went a little more to the outside of the line. I'm not sweating it. When my build comes in heavy, this will be one of the 1000 reasons.

    But seriously, a software guy? That's where all the problems originate! (*Ducks shoe thrown in my general direction.*)

    Nick
    4-Place Model 'B' Serial 1529B (with many years to go...)

    Comment


    • #33
      Originally posted by nborer View Post

      Stuff deleted....

      But seriously, a software guy? That's where all the problems originate! (*Ducks shoe thrown in my general direction.*)

      Nick
      At one time them would have been fightin' words.... However, I'm less than 2 years from pulling the plug on working for a living so I find that aspersions don't stick anymore.

      -------------------
      Mark

      Maule M5-235C C-GJFK
      Bearhawk 4A #1078 (Scratch building - C-GPFG reserved)
      RV-8 C-GURV (Sold)

      Comment


      • nborer
        nborer commented
        Editing a comment
        Said in jest, of course. My brother is a software engineer, so we've been trading barbs for the last several decades.

      • rv8bldr
        rv8bldr commented
        Editing a comment
        And it was taken in jest, Nick :-) No worries....

      • NCLSA183
        NCLSA183 commented
        Editing a comment
        About 10% of my work over the years has been the design, prototyping and building of custom electronic projects for clients’ niche applications. I would design the hardware and code the software and/or firmware and not once have I ever thrown a shoe, of any kind, at my alter ego. You guys should grow up and stop clowning around before someone loses an eye!! Just learn to get along and play nice!! LOL

        Mitch
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