Brodhead Pietenpol Association

Original Posted By: "Roman Bukolt"
In a message dated 1/18/2006 7:16:10 PM Central Standard Time, jtextor(at)thepalmergroup.comwrites: He did say it was NOT vertical grain. Spars must be 1/4 sawn, or they warp. Chuck G. NX770CG I have to disagree with you here Chuck and this is based soley on my ownexperience with wood.Generally speaking if a board is straight after kiln dryingit will remain straight after sitting for years ,provided it is kept dry.Woodis usually kiln dried to 6% moisture content and when we get it and sit itin our shop it will pick up moisture and stabilize with its surrounding usuallyaround 9 to 12 % moisture content and it will fluctuate between these figuresbut it will not suddenly develop stresses that want to warp it of its own accord.Youcan introduce a warp if you store it with a twist ,somthing like bendinga cap strip after steaming it and then letting it dry.Different species ofwood are kiln dried at different rates to prevent splits ,checking ,and warping.It'sthe rate of drying that is important.All bets are off if you store thewood where it is directly exposed to water with sun dry cycles in between.Thesun suddenly drying a very wet board will introduce stresses that could eithersplit,check or warp it,where previously it was a perfectly straight board. Where 1/4 sawn wood shines is in it's shrinkage and expantion ,which isvery little as compared to flat sawn wood.It is very stable. Been working with wood for years as a cabinet maker and this has been myexpierience which does not qualify me as a wood expert,just a wood observer,soif there is a wood expert in the house,let us hear from him. Kind regards,Mike ________________________________________________________________________________

Original Posted By: "Dick Navratil"
Hi Everybody.I have been lurking on the list and decided to jump in and ask a question about the spars.I think the original design is great. I also think it makes sense to use modern materials such as epoxy where it makes sense. I know there is a builtup spar that has been designed for the wing.I have been in the yacht building business for 30 years and know that good wood is getting more difficult to find and more expensive. When I build mine I will feel more confident in building the spar with spruce caps and a ply web. Has anybody gone this route, compared finished weights etc.Thanks in advance.Steve G.________________________________________________________________________________

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Steve,Check out http://www.cpc-world.com and have a look at "AirframeConstruction" > "Wings" > "Wing Spars".May give you an idea or two.CheersPeterWonthaggi, Australiahttp://www.cpc-world.com-----Original Message-----

Original Posted By: Steve Ruse

Original Posted By: "Bill Church"
Glenn,Crankshafts have failed in Corvair cars also.But this seems mostly on high HP racing applications.The airplane use of the Corvair engine will produce stress on a crankshaftnot found in Cars.These stress issues are not unique to Corvair, Lycoming has had a number ofAD lately related to crankshaft failures And these are purpose buildairplane engines.It seems the stress cracks appear in the Corvair engine applications in KR2 and Zenair 601, none are yet found in Pietenpol applications.But it seems no one has looked at Pietenpol crankshafts either.As flight profiles are different between KR2 and Pietenpol it is fair toassume the stress on the crank will be different to.There are a lot more Pietenpols flying with Corvair engines than KR2's andZenair combined and a lot of them with 600+ hours and no Crank failures.I would like to see some, 200+ hour, Pietenpol corvair cranks evaluated.None the less I intend to get another crankshaft, and have it nitrated, itis cheap insurance.In the mean time I will fly my old crankshaft, I have only 25 hours on theengine and I am still within the 40 Hour test period.I believe as part of the service William Wynne provides, on modifying thecrankshaft, a inspection (and nitrating) is included.But please check with him.Hans "Glenn Thomas" To Sent by: pietenpol-list(at)matronics.com owner-pietenpol-l cc ist-server@matron ics.com Subject Pietenpol-List: Corvair Crank 01/19/2006 10:23 PM Please respond to pietenpol-list@ma tronics.com I got hooked on the idea of the affordable Corvair motor and bought 2 ofthem, the William Wynne conversion manual and a couple of WW's videos and Ivisit his website a couple times a week. Then last week, he posted newinformation regarding nitrided crankshafts and I'm trying to find out ifanyone knows if these stress fractures and cracks that he's found are everfound in an engine straight out of a car. I'd like to continue with theCorvair motor but his article states that the Embry-Riddle magnafluxmachine he used to see the cracks revealed a lot more than the typicalautomotive magnaflux usually does. ...so my question is if I send him thebest of my 2 to have the safety shaft installed and grinding, andnitriding, how do I know the shaft I'm sending is free of cracks, even if Iget a clean bill of health from the place that will do my magnaflux on the2 of them. This is one of those areas I don't know that much about and I'mhoping someone else does. If the crack! s are something that appear only as a result of spinning a prop then I'lljust have the crank I use nitrided.Anyone ever heard of a Corvair crankshaft failure (nitrided or otherwise?)Thanks,Glenn ThomasRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: RE: Pietenpol-List: Re: wing spar questionDate: Fri, 20 Jan 2006 09:44:51 -0500

Original Posted By: "Steve Glass"
Steve,Send me a self addressed, stamped envelope and I will send you an article on designing built-up spars. The article was published in Sport Aviation in the early 1960's.My address is:Greg Cardinal5236 Shoreview Ave. So.Minneapolis, MN 55417----- Original Message -----

Original Posted By:>----- Original Message ----- "Steve Glass"
Hi GregI just received an article via email from Doug Mundy. It is 5 pages from April 1961 Magazine about the builtup spars. I bet it is the same one.Thank you for your offer.Best regardsSteve G>From: "gcardinal" >Reply-To: pietenpol-list(at)matronics.com>To: >Subject: Re: Pietenpol-List: Re: wing spar question>Date: Fri, 20 Jan 2006 17:32:30 -0600>>>Steve,>Send me a self addressed, stamped envelope and I will send you an article >on designing built-up spars. The article was published in Sport Aviation in >the early 1960's.>My address is:>>Greg Cardinal>5236 Shoreview Ave. So.>Minneapolis, MN 55417>>

Original Posted By: barnstmr(at)aol.com