Original Posted By: "Steve Ruse"
Subject: Re: Pietenpol-List: Re: lift struts for GN-1 /Pietenpol this is a longoneThat would be great, thanks. Not to diminish the important's of what's been said regarding the wooden struts. I believe 2 years ago at brodhead the Canadian Goose had wooden struts. They looked great. Mine are already made and are 3 linear layers of wood clear white ash in the middle with black walnut on the outer sandwich. They were laminated using the T88, clamped straight and allowed to set cure under clamp and Jig in a square shape largerthan the streamline tubing. The lamination has metal imbedded into the middleof the lamination at 3 locations each and at the connection point of the jury strut to prevent the bolts from pulling out of thru or splitting out the wood. The struts were shaped using the dimensions of the tubing in the drawings except slightly wider and longer than the metal tubing.Understanding the relationship of the wing to the strut and relative loading and stresses created during normal flight. Here is where my non engineering background really comes into play. If there wing in normal conditionexerts a static load of X lets say for argument sake x is = to 160 lbs over all. And at 8 loading connections two at the flying strut, 2 at the jury strut and 2 at the cabane struts that static load exerted by a non flying wing on the struts would be Y. Lets also assume in gross numbers the fuse at full capacity weighs 700 lbs. what is the static load on the struts?Now that we have a static load on the struts shared by all 8 connections not calculate the dynamic loads positive and negative or compression and extension in flight, that value being SL. The strut load would be that amountof weight or pressure that the strut system is required to support in and under normal flight conditions now to calculate side loads and combined loads to determine then highest amount of loading the struts will ever be exposed to by an aircraft who's total weight is 1000 lbs at full load and flying. That becomes the comparator for strut materials selection. The strut must be capable of handling loads of a value we call UL ultimate loading.Now we can look at the strut material separately as a beam or structural member and either copy form the materials book the load capacity of 4130 round and streamline, T6 aluminum round pipe or streamline, composite and laminated wood.All of which are arbitrary values based on none other than the design weights in the Bernerd POA specs section of the instructions. So if airplane 1weighs 1050 at the curb how much stress will the struts be required to safely and regularly handle?Again not being a computer scientist, however just barely able to type a cogent paragraph my self. We are all using a device that is not less than 10,000 times more capable sophisticated and faster than the computers used toput a man on the moon. It sounds almost cook book type to come up with the equations that when we builders now and in the future want to look at a specific Piet design or system that we can punch in some easy numbers and getout an answer from the computer. Seems like with all the talent real and inferred that 2 engineers with AutoCAD to model and excel to come up with a series of questions that when answered with real data will provide an answer. At a bare minimum then the builder can select an amount of over build as a margin of safety and have a clue as to what's needed for his or her build.That's where I am going with this, there is no need for each of us to try to reinvent the wheel each time someone has an idea or a question that goes contrary to the conventional build or design. After all we are talking experimental here. The It Girl of the Sky put it best, " you're both starvin, why not try to help each other"Go in peace the service has endedNo for the other news I just got my copy of Barnstormers and watched it a n hour ago, wow that was great I am impressed and want to be invited if I can survive my own creative experimental endeavors and the did pay homage to TGW when they looked towards the heavens and asked WWD? What Would Waldo Do the answer was a resounding the show must go on!JohnIn a message dated 10/20/2009 10:28:42 P.M. Eastern Daylight Time, rray032003(at)gmail.com writes:I remember some one did this and there was a picture of the plane in the experimenter. I'll see if I can find the issue and get your address I will mail the picture to you if I can find it.RussellOn Tue, Oct 20, 2009 at 9:44 PM, Bill Church wrote:John (PM Danger),Here I was, thinking that you wanted to know a simple method to determine whether a certain size of round 4130 tubing could be substituted for the 1934 special streamline tubing shown in the plans, and I was thinking about how there is NO SIMPLE ANSWER or formula to give, and then you tell us you're talking about wooden struts. There are so many variables (without evengetting int the specifics of your unique plane)! There's the species of wood,the "quality" of the particular pieces of wood used, the size and shape of the struts, the thickness and number of laminations, the glue used, not to mention the "metal inserts".You mention that you are not an engineer. Well, as you know, I am an engineer, but I'm not an aeronautical engineer. Despite my background, I do notfeel qualified to determine the suitability of wooden flying struts for my Piet, let alone someone else's. I think your best option would be to track down a builder that has successfully built and flown (for a significant amount of time) a wooden-strutted Piet, and borrow that design (if they are willing to share it with you).It sounds like you have built a set of struts based on "that looks about right". The flying struts are WAY too important to be approached in that manner. Like you say, a catastrophic failure in flight would really screw up your day. Be very careful with this stuff.As much as I like the look of wooden struts I will be using steel struts on my plane.Bill C.Read this topic online here:_http://forums.matronics.com/viewtopic.php?p=268755#268755_ (http://forums.matronics.com/viewtopic.p ... 755#268755) s List Un/Subscription,www.matronics.com/Navigator?Pietenpol-List" target="_blank">http://www.matronics.com/Navigator?Piet ... onics.com/" target="_blank">http://forums.matronics.comMatt Dralle, List Admin.====(http://www.matronics.com/Navigator?Pietenpol-List) (http://www.matronics.com/contribution) ________________________________________________________________________________