Original Posted By: "jarheadpilot82"
Brent, I am building my Pietenpol using the Riblet 613.5 wing rib profile. It is slightlytaller than even the 612, I believe. I am also using aluminum extruded sparslike are used on a J3 Cub or similar aircraft with wooden ribs. The ribs aretaller than the spars, but also understand this - lift is trying to push theribs up toward the spar, not the other way around (not pushing down from above).That is why many/most people assemble the wings upside down, so that the bottomof the rib, the lower capstrip, is fully against the bottom edge of thespar when the wing is assembled. I don't think that the "spacer" is necessaryfor overall strength, although I did use them. I am a belt and suspenders kindof guy.I am away from home but will be back tomorrow and post a picture or two then. NoI do not think that you need it the whole length of the spar. You are just addingweight by doing so. Also, I am not an engineer, but simply building yourspar taller does not necessarily make it stronger. This is an extreme example,but imagine your spar being 1 inch thick X 5 inches tall. Now imagine how yourspar would be if you tripled its height but left the thickness the same. Idon't believe it would be 3 times stronger. It is a combination of height andthickness that makes it stronger. That is one of the reasons I used aluminum extrudedspars. I don't worry about spar strength at all. As Dan Weseman half-jokinglyput it, "Let's see if I get this right. You have a 9 G spar on a 2 G airplane."Works for me.P.S. Take this for all that it is worth. I am not a structural engineer, NOR didI sleep in a Holiday Inn Express last night.--------Semper Fi,Terry HandAthens, GARead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Corvair Engine Project For Sale on Barnstormers
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