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Thread: Thorp T211 corrugated wing skins

  1. #1
    Registered User handprop's Avatar
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    Thorp T211 corrugated wing skins

    Hey guys, In my quest for learning about the stress in wings I remembered the good ol Thop designs. On some of his airplanes like the T211 he used corrugated aluminum for the skins. What was the reason for this? Is that because it helps with skin buckling and stress or did it have something to do with the manufacturing process. Mike
    Where am I? Charles Lindbergh, upon arrival in Paris.

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    Re: Thorp T211 corrugated wing skins

    Lots of other airplanes have had this feature. Almost a Junkers trademark, though of course many other manufacturers used the trick.

    Photos: Junkers J-9 (D-1) Aircraft Pictures | Airliners.net

    http://www.geocities.com/CapeCanaver...ront-Left2.jpg

    http://cdn-www.airliners.net/aviatio.../8/1412812.jpg

    http://www.eaa.org/wallpaper/images/..._640_plain.jpg

    I think it's mostly to stiffen up the skin.

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    Registered User djschwartz's Avatar
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    Re: Thorp T211 corrugated wing skins

    The idea was to reduce the number of ribs to save weight and manufacturing cost. Rolling corrugations into the skin was supposed to be cheaper than forming and attaching ribs. I suspect it was draggy. As Orion has explained in other threads, airflow is not exactly straight from front to back over much of the wing. There is a spanwise component even on an unswept wing, especially near the tip. Also, the corrugations completely eliminate the ability of the skin to carry any of the bending loads of the wing and may even have made it less stiff torsionally as these loads are approximately at 45 degrees to the span or chord. In fancy engineering terms the corrugations turn the skin into an anisotropic material, one that has more strength and stiffness in one direction than another. This can be an advantage in some cases but it also can make stress analysis more complicated.
    Last edited by djschwartz; May 14th, 2009 at 10:17 PM. Reason: spelling

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    Super Moderator orion's Avatar
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    Re: Thorp T211 corrugated wing skins

    And the corrugation increases the whetted area so although it may reduce the need for as much internal structure, overall it may be a significant aero-based penalty.
    "To live is to learn; to learn is to live" (author unknown)

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    Moderator addaon's Avatar
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    Re: Thorp T211 corrugated wing skins

    Another plane with corrugated skin is the SR-71, although there you can overcome the aero penalty by sheer brute force.

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    Registered User bmcj's Avatar
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    Re: Thorp T211 corrugated wing skins

    Quote Originally Posted by addaon View Post
    Another plane with corrugated skin is the SR-71, although there you can overcome the aero penalty by sheer brute force.
    Yes, but I believe what you percieve as corrugations is actually a ridge pattern placed to allow for thermal expansion.

    Bruce

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    Registered User Norman's Avatar
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    Re: Thorp T211 corrugated wing skins

    Yeah, the ridges get higher as the plane gets hotter. At room temperature they look like embossed ribbons.
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    Re: Thorp T211 corrugated wing skins

    And the fuel tanks don't seal completely until the metal warms up and the expansion closes the gaps. Leaks JP-7 all over the place on the ground.

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    Registered User Mad Man Mike's Avatar
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    Re: Thorp T211 corrugated wing skins

    Of military aircraft it has often been said --if they aint leaking they must be empty!
    MadManMIke --my new E-Mail address is mls211@qwest.net

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