Pattern wing design

[Lance Van Nostrand]

Buddy,
"Eagle One"? I liked Viagara better.  Of course, with carbon fiber reinforcement, that may be a bitof an exaggeration.

Your wing question is not a simple one.  There are many many variables in a wing and the effect of each variable is debatable, even with wind tunnel tests.  Our planes demand uniform performance but very little lift.  they fly at slow speeds (low Reynolds numbers) and they must handle equally well inverted.  There is not much research in this area.  Even airfoil design software, like profoil, is of limited help.  
  This may elicit controversy, but the most important thing in a pattern wing is planform, given the obvious requirement for a symmetrical airfoil.  The airfoil is important, but less so in our application since we are limited to symmetrical airfois and we have very little lift requirements. 
  You need to start with a goal and then make tradeoffs to achieve that goal.  Most people don't want to wade into these variables and test new wing designs.  That's why most planes on the market are Prophecy wings with a different shaped fuse.  Our Entropy made slight mods to the wing,but this is essentially what it is.  The Aries, on the other hand, is the product of a different lineage of development with different goals.  It is an "unconventional" shape: large root chord, large sweep back, small tip.  The larger root increases the drag closer to the CG for speed control and stability.  This also moves the center of lift closer to the fuse.  Along with the small 9 1/4" tip chord this helps the tips initate a snap.  This is necessary to conteract the large wing area - which is there to maintain extra stability at low speed or high alpha.  In comparison to the pattern standard wing, it rolls better and flies slower.
   You want to understand thse variables more?  A good website is http://www.aae.uiuc.edu/m-selig/ at the U of I.  There are lots of others.  Good airfoil performance plots are not available for free anywhere I know of (anyone should fee free to correct me on this point) so you''ll have to buy a good plotting program to nail it. You can have different airfoils at the root and tip to blend characteristics.
  Dihedral is related to wing position relative to the vertical CG and its relation to the stab is super critical.  Don't ignor the stab airfoils either. They can actually affect CG position too.
--Lance

  ----- Original Message ----- 
  From: BUDDYonRC at aol.com 
  To: discussion at nsrca.org 
  Sent: Wednesday, September 03, 2003 11:43 AM
  Subject: Pattern wing design



  I am in the final stages of production on my new "Eagle One" design which is a revised fiberglass fuse.  Version of my "Mirage" ( Changed the name for obvious reasons) .
  The first Fuselage is out of the mold and I am looking at possible revisions to the wings but unfortunately I am wing stupid.   
  If there is anyone out there that will provide some insight on the subject it will be appreciated.
  1. Airfoil? Shape and type with advantages and disadvantages of those currently used on pattern planes  
  2. Plan size and shape? Single tapered and double tapered and why?
  3.  Airfoil thickness and taper? Equal percentage or higher percentage taper and why?
  4. More sweep or less sweep? (expected effect)
  5. Dihedral? Expected effects.
  What are the best being used currently? Why?
  I am currently using a Laminar airfoil 2- 1/8" Max thickness (11.5%), 19" wide at the root and 9" wide at the tip double tapered with a leading edge sweep of 15 degrees and a trailing edge taper of 2-1/2 degrees plan form with equal percentage thickness, 34" long and 7 degrees dihedral.
  The airplane fly's good with some small flight imperfections that I think a revision to wing design may correct.  I just want to make sure that I understand what the expected results of any changes will be before I proceed
  Any and all help will be appreciated.
  Buddy  
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