SpainCub
Registered User
OK 25 posts of people giving their best guess. Let's go to "the" source, Clyde Smith, Jr. - The Cub Doctor. Quoting from the Sept/Oct 2005 Cub Clues newsletter A Study of Piper Ribs Clyde says in part:
"All fabric Piper ribs employed one airfoil design, the USA 35B, but were modified by increasing the upper coordinates by 4%. Thus the terminology "USA 35B Modified" was the typical description of the Piper rib and the chord was 63 inches. All the ribs were similar from the J2 through the PA-25 Pawnee.
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In my weekend siminars, I divide the wings into two classes, the "Cruiser Wing" and the "Cub Wing". The Cruiser wing was used on the J4, J5, PA-12 and PA-14. The Cub wing was used on the J3, PA-11, PA-18, PA-25 and all the short wingers. The differences here were that the Cruiser wing had the "S" or "Sloped" type of false spar and had a stamped nose plate rivited into the leading edge or nose section of each rib, rather than the individual truss type bracing.
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The Cruiser wing panels did not have the short nose rib sections between each main rib either
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The Cub type wing had the concave type false spar and the nose of each rib had the individual brace members. These wings also utilized the short nose rib sections, forward of the main spar, between tha main ribs."
John Scott
John, missed your post, looking for that quote now. Thank you!
If it weren't for the fact that I have two J3 cub ribs and a 12 and 14 rib, I would have never considered this, however the two j3 line up pretty good as do the 12 and 14, but the 14 and 12 are slightly larger at the cord that the j3, however they don´t perfectly line up to the original piper drawing as the j3 is slightly small and the 14 is slightly larger cord. Only the 12 lines up the closes to the drawing... I guess this is all has to do because of the jig differences... 4% is very subtle expect at stations where the cord is thickest at station 18.9... right now from my notes, j3 is 7.53 and 7.56 inches and the 12 is 7.68 inches and the 14 is 7.74 inches... :/