Brodhead Pietenpol Association

Original Posted By: "Dortch, Steven D MAJ MIL USA NGB"
Subject: Pietenpol-List: nice looking Scout on BarnstormersAnd a few other items of possible interest.And all this talk about axels.....just build one with a thick wall and be done with it. You'll be fine. Mine has 15 years, 450 hoursand lots of firm arrivals and it hasn't bent. Talk about making more work out of work.Again, my axel is 1.5" OD and 0.188 wall thickness of 4130 and it works just fine.Mike C.[cid:image001.png(at)01CE4683.02025350]________________________________________________________________________________

Original Posted By: "Clif Dawson"
Right! The axle, though a round tube, is a beam, justlike the spars are. Look at the one inch routed spar.The outer "edges" are the full one inch width but thecenter area is only 1/2" thick. The question then is"How does this work?".The answer is that in a beamthe bending strength is mostly in that very small areaat the edges. The center's main function, and in manycases only function, is to hold those two outer bitsin place, simply a seperator. It's a little more complicatedin a true space frame application of joined triangles,and somewhat stronger. This is what Douwe will beattempting.In the drawing below I have illustrated three types of beam.The two outer ones show tension/compressioncaps clearly. Because of the uniform circular homogenious cross section of the tube the "cap" /web concept is not so evident.But it's there.Unfortunately, with a tube, increasing the "cap"crossection automaticaly comes with the penaltyof doing the same with the webs.What all this means is that by stuffing a chunk ofwood down there is really adding more web withoutmuch benefit of cap.Another thingis that just because one wood is harderand heavier than another does not translate into strength. The compression strength of Spruce is 4780 lb/inch=B2 butthe much heavier Oak is 4760 lb/inch=B2.Clif The Monkey Wrench. :-)I prefer drawing to talking. Drawing is faster andleaves less room for lies. LeCorbusier And all this talk about axels...just build one with a thick wall and be done with it. You'll be fine. Mine has 15 years, 450 hours and lots of firm arrivals and it hasn't bent. Talk about making more work out of work. Again, my axel is 1.5" OD and 0.188 wall thickness of 4130 and it works just fine. Mike C.________________________________________________________________________________