Re: Wavy glider wings - baking results

From: Bill Gowen <wdgowen_at_earthlink.net>
Date: Tue, 20 Dec 2005 10:22:10 -0500

Bruce
Only glide testing will tell for sure but my bet is your wing will perform better with more camber in the tips.

Another way to avoid the waves is to use a piece of wood for the flaps that is the final thickness (or close to it) that you want for the flaps. I have gone down to .009 for this on a couple of gliders. You can still feather out the TE if you want to and the flaps will be plenty strong for Cat 1. I've sanded the flaps on my last 2 gliders just because I didn't have the right piece of wood I needed.

Those sub-four pound sheets that Tim puts up occasionally are excellent for this. Expensive but excellent. C-grain sheets are even okay for flaps when thin enough.
Bill Gowen
Decatur, GA USA
  ----- Original Message -----
  From: Bruce McCrory
  To: Indoor_Construction_at_yahoogroups.com
  Sent: Monday, December 19, 2005 11:57 PM
  Subject: [Indoor_Construction] Wavy glider wings - baking results


  Mrs. Scrouge stole my mouse Saturday, so now I'm posting results of
  my
  wavy wings experiment with the steam iron (oven). I posted 3 photos
  in
  the files under a new "Gliders" folder and "Misc. Stuff" a few
  minutes
  ago.

  This is the intended Cat. 2 design. Wood is about 4.5lb, (a/b)-grain
  with ray angle leaning aft at base. I hate first time "success"; but
  is probably not so. Read on. The steam bath exaggerated the waves.
  Very
  little was accomplished with the wing panels after I released them
  from
  the press. I rubbed, but they seem to like the shown shape. I was
  able
  to curl the root end to match the central dip. The two are a pretty
  close match.

  The bath plumped the TE about .004", and made the flap very stiff. 6g
  to 7 grams of loading will flex the curl slightly, before the whole
  panel twists. I'm reworking the sanding block. A better thickness may
  be about .012" through the last inch, or so.

  Kurt, and Bill, I do have your followups to my question, and am
  jumping
  ahead. Your tips and thoughts are encouraging. My assumption is:
  these
  flaps should be fairly flexible, flattening on launch, then tucking.
  Math beyond basic addition will return a glazed, dumb look, so I'll
  just use my standard empirical approach. The model will be
  approximately 2 grams; therefore, the flaps should flatten at
  slightly
  more load on a digital scale.

  Good building,
  Bruce in Seattle





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Received on Tue Dec 20 2005 - 07:22:36 CET