Pietenpol-List: Plans source...
Posted: Fri Jan 29, 2016 9:04 pm
Original Posted By: Phillip Perry
Subject: Pietenpol-List: Plans source...
Subject: Pietenpol-List: Plans source...
Original Posted By: "Charles N. Campbell"
Semih; since the list has been pretty quiet, I don't feel bad posting a ratherlengthy response. This is copied from something that I sent to another builderwho is considering using an O200.First, I will grant you (and it's important to note) that the weight, CG, and physicalconfiguration of my airframe and engine will by definition of "homebuilt"and "experimental" be different from yours, so anything that works on my airplanemay not work on yours, for obvious reasons. Perhaps more subtly, evenif our airplanes were quite similar in their major aspects, slight differencesin construction and rigging could make mine *aerodynamically* different fromyours so the fine points of trim and rigging that make mine fly straight andlevel may not apply to yours. In that light, I offer my further comments andobservations.With the 3.5 degree downthrust and thrustline offset that are now set on my engineand airframe, in level cruise and with the stick held firmly to keep the airplanesteady in roll and pitch, if I remove my feet from the rudder pedals theairplane will yaw gently to the left. I didn't want to believe it after Ihad made the tweaks and shims and adjustments that I did, but it's true and I'vedemonstrated it time and time again in the smooth calmness of morning air.In the more usual conditions that I fly (bumps and less than smooth air), it'sfar less noticeable but still there. My airplane cannot be flown with feetoff the rudder pedals and still maintain heading. The prop hub is not perfectlycentered in the opening in the engine cowl opening anymore, but the airplaneflies straighter and I'm OK with that. It all adds character, and I don't meanjust to the airplane.In the pitch axis, you can only guess at what to set the downthrust for the wayyou will "mostly" fly the airplane because (for example), with just me in theairplane and full fuel in the tank, I need to hold back stick for about the firsthour or 90 minutes of flight. As fuel burns off, the need for back stickreduces but in any case the back pressure is never really enough for me to wishI had elevator trim. In fact, the snugness in my palm adds a bit of steadinessto things. The downfall comes if I need to let go of the stick to do anything,in which case the nose will drop and I'll see increasing airspeed prettyquickly until I grab the stick again, but it's not instant and it's not frightening.It is, however, unstoppable without the use of hands or the fumblingof knees against the stick ;o) As fuel burns off this tendency decreases untilat some point, in smooth air and in level flight, I can let go of the stickfor perhaps 10 seconds at a time without altitude going nuts. I can't ask moreof the airplane than that.My airplane is pretty stable in roll but if something starts happening in one ofthe other axes, roll is quite willing to go along with the game and pretty soonnone of them are behaving. Pick up an errant wing with rudder and just moveon.Now back to yaw, since that is usually what we're trying to correct with thrustlineoffset. Right now I have a bent aluminum trim tab on the trailing edge ofmy rudder, about 2/3 of the way down from the top. It is 3" tall and standsaway from the rudder 2". Its trailing edge is deflected 1" to port off the axisof the rudder... in other words, it is bent at an angle of 30 degrees to port.Standing behind the airplane, that is to the left. Without this trim tabthe yawing tendency with feet off the pedals is about 40-50% more than it iswith the tab, so as much as I would have liked to have taken it off and leftit off, flight testing showed noticeable improvement with it so I left it on.A kludge, an admission of failure, a sign that things are not as they shouldbe. A necessary evil in my case, but not necessarily in yours.The leading edge of my vertical stabilizer is offset 1/4" to the left (port side)from perfectly in line with the axis of the fuselage. I would have offsetit more than that in order to correct the yawing tendency without the use of thebent metal trim tab but since the tailpost remains fixed as I force the noseof the VS over, the wood and glue joints are all stressed and I didn't likethat so I left it at what I felt comfortable with. It helped get me to wherethe stability is now, but it obviously adds trim drag and if you can keep yourVS aligned with the airframe and make the yaw correction using thrustline offset,I think you would be better off.So now to summarize, I have three kludges all slapped together on my airplane toget the tail to swing to port (rotate the airplane clockwise) and thus get thenose to swing to starboard (rotate the airplane clockwise). Without them,and with feet off the rudder bar, my airplane will yaw to port and rotate theairplane counter-clockwise as I watch the compass heading count down from 360like the Dow Jones on a bad day ;o) I have a bent trim tab on the rudder, I haveoffset in my vertical stabilizer, and I have engine mount shims. You cando better by building in some thrustline offset and if you do, you might be ableto eliminate one, two, or all of these kludges.Now, should you find some shimming to be necessary to correct yaw or pitch trimat your engine mounts after you complete and test-fly the airplane, do not spendthe $11.50 that Aircraft Spruce wants for each of their P/N 21530 engine mountwashers for Continentals. And by all means do NOT use standard AN970-6 largeflat washers for this duty... they are too thin and they will cup when youtighten down the nuts. Don't ask me how I know this ;o) If you need washersthat are perfectly suited for this application, get McMaster-Carr item no. 92140A118black oxided steel washers, $12.36 for a 10-pack, and you will be happy.I wouldn't be surprised if you can't find them in Istanbul, but you get theidea. By the way, several cruise lines have just taken all Turkish ports offtheir Mediterranean cruise itineraries. It's a shame.--------Oscar ZunigaMedford, ORAir Camper NX41CC "Scout"A75 powerRead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Sat, 30 Jan 2016 07:22:44 -0500Subject: Re: Pietenpol-List: Plans source...
> > Along the line of plans and getting started, what is the consensus for reliablehigh-quality wood? We have a local high-end hard wood supplier here in townbut I don't know if they'd be more affordable or even predicable with regardsto aviation quality products. I need to get that sorted out and decide iflocal vs mail-order is best for me. > > Oscar and Jack, I'm located in McGregor, Texas at KPWG (just west of Waco by10-12 miles). The RV-10 is finally getting close to the end. I'm rigging itnow and tying up loose ends. There's a good chance that it will fly this summer. I'll put around 100 hours on it first and then send it to the paint shopafter the bugs have been shaken out. > > Here's a couple of photos of the project. After the -10, which we will lovetraveling in, you can see why the simplistic desire to build a minimalist Pietis so attractive. It's the perfect evening flight airplane while the sungoes down.> > Thanks for the help everyone,> Phil> > > > > > > > Sent from my iPhone> >> On Jan 30, 2016, at 11:41 AM, taildrags wrote:>> >> >> Phil; where are you located? You might have a builder nearby who can spreadhis/her plans out on the workbench so you can see what they look like beforeyou jump in. I have almost everything that the Pietenpol Family website offers,I paid a little less than what they're asking for them now, but it's been worthit to me to have the original plans, the supplement with the Corvair andContinental information, the 3-piece wing supplement, and the builder's manualwith commentary and FAQ.>> >> I have no idea what Spruce offers for the same price, but most of us on thelist have bought our plans from the Pietenpol family out of a bit of pride insaying that both the airplane, the family, and the plans are still around after85-90 years. Not to disparage Jim & Nancy Irwin, but it's just a differentnostalgia to say you bought your plans from the Pietenpol family.>> >> -------->> Oscar Zuniga>> Medford, OR>> Air Camper NX41CC "Scout">> A75 power>> >> >> >> >> Read this topic online here:>> >>