Brodhead Pietenpol Association

Original Posted By: "Christian Bobka"
Just three quick things that I have gleaned from scanning the entries from thepast several days:1. The lift struts on the Piet don't (or shouldn't) do anything during flight otherthan create drag. It's the crossed wires that carry the load, the strutsjust keep the wings from moving DOWNWARD during landings or other negative G loadactivities.2. Ted B. take a look at the Panther Electronics website if you feel you just absolutelycan't fly your Piet without radio communications.3. Try to get a copy of "History By Contract" to find out how the Wright Bros madesure they were credited as being the "first".4. I have a set of Flitzer plans (I thought this was a Pietenpol site?) that Iwould GLADLY part with. There are so many different revisions for so many of theparts that it's absolutely baffling to try to make any sense out of. Mr. Williamswould be well served IMHO to take out all the wordiness and minute detailsof the various evolutions and just print up some simple plans that one couldbuild an airplane from. And no, it's not at all built like a Piet. I wouldguess the parts count is at least three times as great.HO-HO-HOLarry________________________________________________________________________________

Original Posted By: LAWRENCE WILLIAMS [mailto:lnawms(at)msn.com]
Larry,The lift struts will also keep the outer panels of the wing from twistingduring flight. Now let's see if we we're really willing to tighten thewires enough to make this true. Assume a gross weight of 1000 lb, liftstrut angle of 30 degrees with respect to the wing, all of the force on theforward spar, and 4 g loading. All reasonable numbers for the Piet. If weprestress the cables to keep the struts in compression, the cables need tohave TWO TONS of preload EACH. That's 500 lb load to a side, times 4g,divided by sin(30)= 0.5 to get the resultant of the vertical load and thespanwise force that we have to live with. As I remember, the nominal loadcapacity of a 1/8 inch cable is about 2000 lb, but I don't have my AS&S bookhere. At any rate, it sure sounds like we'll be depending on some tensionstrength from the lift struts, at least at the high end of the design load.If we back off and only ask that the struts be in tension during "normal"flight--bank angle < 60 degrees, we're down to "only" 2000 lb preload.Level flight is 1000 lb. My suspicion is that anyone who tightens the wiresuntil they "feel right" isn't going to put anywhere near that much tensionon them, and that the struts are going to carry most of the load during allflight phases.Gene HubbardSan Diego-----Original Message-----