The Kit version was designed by John Miller and the ribs are not the same. I am not sure why they were changed by John, but they were, and as a result the Cardinal Evolution 40 has a thicker wing. This being said the Kit or ARC wings would work fine as well, just blunt the LE and reduce the Flap area by removing 1/8 to 3/16 off the Flap Chord. Brodaks sells Rib Kits for the kit version of the wing.
Hope this helps you.
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Bob's your uncle is basically correct, here are the corrections, and reasoning for the profile kit version's airfoil differences.
First a minor correction, Windy Urtenowski designed the Cardinal series of stunters. I only drew the plans for the profile. I used a hand drawn set of plans that were forwarded to me, by Brodak.
The art of lofting ribs has gone through a series of rather large changes over the years, especially since the digital age began.
In the times past, Draftsmen would carefully loft the ribs by hand, with varying levels of accuracy. there were several methods that came about during this time. using a curved tool, similar to a French Curve, or stack sanding/forming of a balsa sandwich to create rib templates. While these methods end up with pretty accurate lofting the rib shapes, there are often some minor discrepancies.
Often, we can get concerned with minor issues, it's more apparent, that at our sizes, the most important airfoil elements, are, the entry area from the front to the high point, the percentage of thickness, and the location of the high point, are the most important. Modern theory, as I understand it, uses a melding of these elements, so we blend to a slightly thicker percentage, and having the high point moved forward a few percentage points at the tips to help control the tip stall in maneuver's.
There are three methods I know of that can do this. Stack sanding is possibly the least accurate due to errors in the forming process, as well as issues that can occur when tracing around the outline, with different pressures possibly crushing the areas when tracing.
In the last few years, Bob Hunt developed what I believe to be the best, non-digital method of lofting wings for our airplanes. His "Lost Foam" rib, and building jig/cradle. It's a pretty accurate system, but still can suffer minor problems during the tracing stages, if the user is not skilled and careful.
With the advent of, and popularity of Cad drafting programs, we can now use digital lofting programs to create extremely accurate airfoil lofts. There are available libraries of very accurate airfoils to begin with, that can be modified to match up with the sometimes crude, (left Shoe traced) early airfoils. The root and tip airfoils are inputted into the program. these are now lofted, and blended, into the correct shaped and amount of ribs that can be used in digital form to laser cut the ribs, right from the digital. In this case, I found that a 6 digit NACA airfoil presented the closest match to the root rib. I did some slight modifications, and wound up with a very close match to the root rib. next, I checked the tip rib shown on the plans, and found that I could modify the digital root rib by changing the length, moving the high point forward slightly, and making it a bit thicker. This digital tip rib compared well to the one shown on the plans. I lofted the ribs, based on the digital root and tip ribs.
The problem area, the Human interaction is almost eliminated. The ribs for the profile are accurate, based on the info given me to work with.
Many Cardinal profile kits have been built and flown since it was released. I am unaware of problems with the wing ribs, and as Bob has said, the profile wing can be used for the Evolution as well. If there are major differences, They don 't seem to make a problem.
A further note, The entry of the NACA 63A modified airfoil, used as a base for the profile Cardinal, Has an entry that allows better penetration in windy conditions, with less buffeting, while still being able to hold off the stall at our operating speeds. If you want a blunter entry, use the NACA0018 airfoil.
I hope this ex[plains why there are some differences with drawings done by different people, at different times. Without access to the same tools or methods, its nearly impossible to have all of these small details match.
I also hope this helps you.
Topic: Cardinal Profile and Cardinal Evolution 40 wings the same? (Read 2460 times)