At 07:24 AM 5/4/2005, you wrote: >Something puzzles me. I found by chance, over the Internet, a 'ribs >generator' program, designed for radio-controlled models, wih more than a >thousand profiles available. You just enter the profile type, the chord of >the first rib, the chord of the last rib, and the number of ribs, and >voila! You get a PDF file that goes to your printer, with "assembly marks" >to help you glue the paper sheets together. > >I used it to make a RAF 48 profile, with a 48" chord, as per KR2 specs. >The trouble is, what I get is different from the KR2 Scale 1 drawing. The >KR2 profile is slightly thicker.
A long time ago, I measured the as-drawn RAF and compared it with the as-published data and I remember that they do not agree exactly. The paper may have changed dimension and/or the copying process may not be a true one-to-one. Small differences can be because of the way the smooth line joining coordinate points is generated. The software uses a mathematical spline fit and the paper version used manual drafting tools. It is also possible that slightly different coordinate data was used to generate the different versions. Unless the differences are significant, the flying differences will be inconsequential. Don Reid - donreid "at" peoplepc.com Bumpass, Va Visit my web sites at: AeroFoil, a 2-D Airfoil Design And Analysis Computer Program: http://aerofoilengineering.com KR2XL construction: http://aerofoilengineering.com/KR/KR2XL.htm Aviation Surplus: http://aerofoilengineering.com/PartsListing/Airparts.htm EAA Chapter 231: http://eaa231.org Ultralights: http://usua250.org VA EAA State Fly-in: http://vaeaa.org
