Brodhead Pietenpol Association

Original Posted By: JamesJboyer(at)aol.com
I am getting ready to cover my horizontal stabilizer and have a last minutequestion. Should the holes for mounting the VSTAB be drilled to have theVSTAB perfectly straight and aligned with the fuselage? Or should it beoffset a little one way or the other to compensate for P factor or prop wash(or something else!)?TedLearning that just when you think you understand welding you find out youdon't.________________________________________________________________________________

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Hi Ted,I covered both ends. I drilled two sets of holes for the forward mount forthe vertical fin - one set centered and one set offset to the left by about1 degree, which worked out (as I remember) to about 3/4'" . With the rearmount attached it is still possible to shift the leading edge oversufficiently to attach to the offset holes. I will start off with itcentered, but if I find it needs right rudder in level flight, I can shiftit over fairly easily.Jack -----Original Message-----

Original Posted By: "Tom & Michelle Brant"

Original Posted By: "Robert Haines"
Ted:I started out with the virt stab 1/2" off center, added another 1/2" with little or no change in rudder pressure. Ended up adding a 4" x 6" alum trim tab to the rudder with a very slight angle on it. This easily took care of it.My Opinion: Virt stab is so small that changes in it's position have little effect. Rudder is so large that a small trim tab has a large effect. (My first setting of the trim tab had me holding lots of opposite rudder to correct for the correction!)Any other thoughts from you Piet flyers?NX799JK>From: "Jack Phillips" >Reply-To: pietenpol-list(at)matronics.com>To: >Subject: RE: Pietenpol-List: VSTAB alignment>Date: Wed, 16 Jan 2002 21:31:42 -0500>>>>Hi Ted,>>I covered both ends. I drilled two sets of holes for the forward mount for>the vertical fin - one set centered and one set offset to the left by about>1 degree, which worked out (as I remember) to about 3/4'" . With the rear>mount attached it is still possible to shift the leading edge over>sufficiently to attach to the offset holes. I will start off with it>centered, but if I find it needs right rudder in level flight, I can shift>it over fairly easily.>>Jack>> -----Original Message----->From: owner-pietenpol-list-server(at)matronics.com>[mailto:owner-pietenpol-list-server(at)matronics.com] On Behalf Of Ted>Brousseau>Sent: Wednesday, January 16, 2002 8:16 PM>To: pietenpol-list(at)matronics.com>Subject: Pietenpol-List: VSTAB alignment>>>I am getting ready to cover my horizontal stabilizer and have a last minute>question. Should the holes for mounting the VSTAB be drilled to have the>VSTAB perfectly straight and aligned with the fuselage? Or should it be>offset a little one way or the other to compensate for P factor or prop >wash>(or something else!)?>>Ted>>Learning that just when you think you understand welding you find out you>don't.>>MSN Photos is the easiest way to share and print your photos: http://photos.msn.com/support/worldwide ... __________

Original Posted By: Michael D Cuy
Subject: RE: Pietenpol-List: VSTAB alignment My Opinion: Virt stab is so small that changes in it's position havelittle effect. Rudder is so large that a small trim tab has a large effect. (My first setting of the trim tab had me holding lots of opposite rudderto correct for the correction!) Any other thoughts from you Piet flyers? NX799JK ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ I agree. That is exactly how I did it. Mike B Piet N687 MB (Mr Sam )________________________________________________________________________________Date: Thu, 17 Jan 2002 13:47:45 -0500

Original Posted By: "Graham Hansen"
Jim,Your observations regarding the ineffectiveness of offsettingthe vertical stabilizer, or fin, are consistent with my experiencewith Pietenpols.The VSTAB area is too small to have much effect, and a tab on the rudder trailing edge is quite effective. Initially I attached a tab to the rudder (on the left side because the a/c tended toturn that way) and it worked fine for years. Then I removed the tab when I recovered my Piet about 16 years ago and never got around to re-installing it. In cruise, a touch of right rudder isrequired to correct the left yaw, but this isn't really a bother be-cause a Pietenpol is an airplane you have to fly all the time--- particularly in rough air. (Directional stability isn't great in Piets,particularly with the longer nose and raked-back wing requiredfor balance with the lighter engines.)Cheers,Graham Hansen (CF-AUN) ________________________________________________________________________________

Original Posted By: "Jim Kinsella"
It is always better to move the stab than to try to displace a controlsurface. Reasons are numerous but first: Trim tabs are ugly. Second, adisplaced surface allows more control surface displacement from neutral inmore direction than the other. Third, it is very easy on a piet to find andinstall the correct trim tab-less setting for cruise flight by making a fewnew fittings. (you always adjust for trim neutral in cruise). Fourth, adisplaced surface causes more drag (hey, if you can find ten places to getone mile per hour, then you are going ten miles per hour faster) andincreases fuel burn.Fifth, it is in bad taste.Chris bobka----- Original Message -----

Original Posted By: Larry Neal
Chris,You are absolutely correct in your analysis regarding adjustingthe fixed surface rather than using a tab to displace the controlsurface.However, in my experience with five different Pietenpols overthe years I have found the vertical stab. (fin) needed to be offsetbeyond the limits imposed by the position of the fitting holes inthe forward horizontal stab. (tailplane). On a completed airplane,drilling extra holes wasn't felt to be a good thing to do and wetherefore resorted to the "trim tab trick" (say this fast!).I have found that the control surface (the rudder, in this case) ona Piet is large and needs to be displaced very little---particularlywhen the gap between the VSTAB and rudder is sealed (withfabric on my a/c)--- to correct yaw. (In fact, I sealed all control sur-faces with fabric on my Piet after trying it without gap seals.) Asa result, one doesn't need a very large tab to do the job and theugliness factor is reduced accordingly.A friend built the first post-war Pietenpol in these parts in the early1960's. Initially, he built the VSTAB and rudder according to theplans. He wasn't satisfied with the small VSTAB and built a newVSTAB which was much larger to improve directional stability. Off-setting it only slightly easily corrected left yaw in cruise---which didn'thappen with the standard surface. The downside was that it didn'tlook like a Pietenpol tail anymore.The horizontal stabilizer, on the other hand, is comfortably large andit is possible to achieve "hands-off" cruise by adjusting its incidence.The limiting factor here is the alignment of the lower rudder hinge onthe stern post because the VSTAB is attached to the horizontal stab.and moves with it when the incidence is changed. A possible fix forthis is to have a ball-type rod end attached to the fuselage sternpostfor a self-aligning lower rudder hinge. (I didn't think of this when I builtmy Piet, but wish I had.)When you find ten places to gain one mile per hour, for a total of tenmph on a Pietenpol, please tell me because it seems this design hasa "hull speed" which is difficult to improve upon. (Actually, one shouldnever be in a hurry when flying a Pietenpol or sailing a sailboat, in anycase.) And if I were to install fairings, etc. it wouldn't look like aPieten-pol anymore.But your observations are certainly correct. I have a Piper Vagabond("Wag-A-Bond") I built a few years back and it flies "hands and feet off"in cruise without any tabs anywhere, in support of your post. However,it is an advanced design compared to the Pietenpol.Cheers,Graham Hansen (CF-AUN)________________________________________________________________________________Date: Sat, 19 Jan 2002 22:13:23 -0600

Original Posted By: "Ted Brousseau"
Thanks to everyone who shared their thoughts on alignment of the VSTAB. Icovered the HSTAB. I can't put into words how exciting it was to see allthat woodwork come to life when fully dressed. As it tightened with heatthe thrill grew. I brought it home but my wife wouldn't let me sleep withit. Somehow she didn't understand. It wasn't quite the same as my firstsolo, but just about. Those of you who aren't there yet don't know what youare about to experience. Those of you who have done it know what I mean.Builders, keep the faith and keep up that progress.Ted BrousseauNaples, FL________________________________________________________________________________

Original Posted By: ANNCARLEK(at)aol.com
> >> >> >> >Hi Ted,> >> >I covered both ends. I drilled two sets of holes for the forward mountfor> >the vertical fin - one set centered and one set offset to the left byabout> >1 degree, which worked out (as I remember) to about 3/4'" . With therear> >mount attached it is still possible to shift the leading edge over> >sufficiently to attach to the offset holes. I will start off with it> >centered, but if I find it needs right rudder in level flight, I canshift> >it over fairly easily.> >> >Jack> >> > -----Original Message-----> >From: owner-pietenpol-list-server(at)matronics.com> >[mailto:owner-pietenpol-list-server(at)matronics.com] On Behalf Of Ted> >Brousseau> >Sent: Wednesday, January 16, 2002 8:16 PM> >To: pietenpol-list(at)matronics.com> >Subject: Pietenpol-List: VSTAB alignment> >> >> >I am getting ready to cover my horizontal stabilizer and have a lastminute> >question. Should the holes for mounting the VSTAB be drilled to have the> >VSTAB perfectly straight and aligned with the fuselage? Or should it be> >offset a little one way or the other to compensate for P factor or prop> >wash> >(or something else!)?> >> >Ted> >> >Learning that just when you think you understand welding you find out you> >don't.> >> >>>> MSN Photos is the easiest way to share and print your photos:> http://photos.msn.com/support/worldwide ... __________