Brodhead Pietenpol Association

Original Posted By: "Mike Bell"
As Mike C. points out, there is a lot of mythology out thereabout this.I have flown four different Piets over the years (including myown) with the "flop" in place and with it removed. I flew my Piet for two years with a cutout extending to about six or se-ven inches aft of the rear spar. Then I modified the center sec-tion to incorporate the "flop" and it has been in this configura-tion ever since. Frankly, I have been unable to detect any real difference inperformance between configurations. But I think the airflowover the tail is less turbulent with the "flop" in place. As Mikesaid, there is little resistance felt when moving it upward byhand while in flight. Moving it up, however, causes the nose to pitch down quite dramatically (at least, on my a/c). Testing aPiet in a wind tunnel, as suggested by a member of the group, should give some clues regarding the cause.I guess the whole thing will remain vague until wind tunnel test-ing is done. In the meantime, I like the "flop". It accentuates the"Hershey Bar" image of the wing and provides some shade from the sun!Graham Hansen (Pietenpol CF-AUN)________________________________________________________________________________Subject: Pietenpol-List: RE: Pietenpol Pitching moment

Original Posted By: Wizzard187(at)aol.com
03/07/2001 01:25:33 PMI ran some models of the Pietenpol air foil a year or so ago. I canstill find them somewhere. These were mathematical models but theysupported what you see when you look at the wing. It is slightlyreflexed and has very little pitching moment. I ran this on a website that supports airfoils for model aircraft. I ran it withReynolds numbers appropriate to full size flying at about 80 mph. Iwon't dig for them now, but I know that I will run into them.. If youdo a search on airfoils you'll find the site without too much effort.The name just eludes me right now.Mike Christian Bobka To: "INTERNET:pietenpol-list(at)matronics.com" Sent by: owner-pietenpol-list-server@mat cc: ronics.com Subject: RE: Pietenpol-List:Cutout vs. Flaps 03/07/2001 12:32 PM Please respond to pietenpol-list Greg Cardinal and I were pushing for some info a few years ago. Itseemswe were in the throes of trying to properly design a plywood web,built upspar and one of the first pieces of info you need to plug into theformulaswas the pitching moment ranges of the airfoil at various angles ofattackand aircraft loadings. This is normally easily obtained from "thecurves"of the various airfoils. Unfortunately, since the Piet's airfoil ishomegrown, no such data exists. We could make an assumption but we wereunwilling to make such an important assumption so early in theanalysis.So we gave up.If we can't get a full scale pietenpol into a wind tunnel, maybesomeoneout there can take a full or scale airfoil section and run the tests?Wecould supply the model of the airfoil. Any one studying aerodynamicsat auniversity?Chris BobkaTC________________________________________________________________________________

Original Posted By: "ED GRENTZER"
Subject: Re: Pietenpol-List: Wing center section cutouts.Hi Gang, I am building a piet and am 200 # about 5'8 and 65 years old and am worring about getting in and out and have built a step. I am wondering about making the flop from the rear spar back and slant the flop out to get more head room. I haven't climb in one any suggestion would be helpful________________________________________________________________________________