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sdickinson1-Visitor
1-Visitor
April 29, 2008
Question

NACA aerofoil profiles

  • April 29, 2008
  • 1 reply
  • 1320 views
Has anyone on the forum ever created an equation driven curve to represent an NACA 5 series aerofoil profile? If so would you be prepared to share your equation?

Thanks,

Sam

      1 reply

      S
      sdickinson1-VisitorAuthor
      1-Visitor
      June 8, 2008
      I have now solved this problem and we now have a very good working solution.



      The issue which we encountered with using point data was that it is inherently an approximation to the true profile (and therefore inaccurate). If you try to use too many points when creating curves through points then the resulting geometry is very “heavy” and therefore difficult to work with (subsequent curve and surface offsets etc often fail). If you use too few points then the curves and surfaces are not accurate to the design. There are a number of software packages that will output aerofoil point data or even DXF approximations but all of these suffer with the same issues around inaccuracy.



      The best route to creating accurate (and smooth) profiles is to use equation driven curves. It is possible to find the correct equations for whatever profile you want to create through online searches etc. Using equation driven curves leads to much more robust and “light” geometry. We have had no issues with curve and/or surface offsets having used this technique to create the basic aerofoil sections.



      One other issue is than some profiles (the more complex ones) require a number of separate equations for each part of the profile. In these cases I have then used curve copy (approximate) to make a composite curve which ensures tangency/curve continuity. This does introduce a certain amount of approximation but so far it has been extremely small (less than manufacturing tolerances).



      Sam

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