---------------------------------------------------------- Pietenpol-List Digest Archive --- Total Messages Posted Sun 09/17/17: 7 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:51 AM - Help with Spar Decision (Ozzietx) 2. 09:37 AM - Re: Help with Spar Decision (Jack Textor) 3. 01:35 PM - Re: Help with Spar Decision (braywood) 4. 02:11 PM - Re: Help with Spar Decision (Greg Cardinal) 5. 03:13 PM - Re: Cont. 0200 prop pitch (pjb) 6. 08:48 PM - Re: Sky Scout Plans (taildrags) 7. 09:52 PM - Re: Help with Spar Decision (John Woods) ________________________________ Message 1 _____________________________________ Time: 08:51:55 AM PST US Subject: Pietenpol-List: Help with Spar Decision From: "Ozzietx" I am in the process of building my rib jig, and need to make a decision on what size spar slot to incorporate. My priorities are Safety, Weight and cost in that order. I weigh a little over 200 lbs, and will likely have passengers in that range. I am attempting to keep my weight down as low as possible. Yes, I know if I were to lose some weight, that would also help me. I had initially decided on a 1" routed spar. My concerns with that are weight, and my ability to rout an expensive blank without screwing it up. I also hate to waste the wood that will be routed out. Ultimately, I'm sure I can eventually determine how to rout it out. I have seen mention, and some drawings of the "UK box spar" I have spent hours using the search function, but have not seen a solid opinion, and explanation of this design. >From what I understand, this is a required method in the UK for Piet builders. Apparently it is quite light, and strong. From my model airplane experience, it seems like a great option, that includes a strong D box. >From what I have read, this is a modification that has actually been properly stress analyzed. I have read many times, just build it as Bernard designed it. I get that, and may very well do exactly that. I am seeking qualified opinions on the UK box spar idea. In my mind (sometimes a dangerous place) this seems stronger, lighter, and less expensive option. I do have a complete woodworking shop to fabricate any type of spar. I would appreciate any input form people that truly understand the box spar design. Here are a couple of links in which it was discussed: http://forums.matronics.com/viewtopic.php?t=65138&postdays=0&postorder=asc&start=0&sid=c79b4120a295a0875655e3c1870c5f8a http://pietenpol.cpc-world.com/?page_id=4376 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=472946#472946 ________________________________ Message 2 _____________________________________ Time: 09:37:43 AM PST US From: Jack Textor Subject: Re: Pietenpol-List: Help with Spar Decision This what I did, not flying. Design was checked by engineer. http://textors.com/SparSketch2.jpg Other pictures here http://textors.com/PietProject.html Jack Textor Sent from my iPad > On Sep 17, 2017, at 10:51 AM, Ozzietx wrote: > > > I am in the process of building my rib jig, and need to make a decision > on what size spar slot to incorporate. > My priorities are Safety, Weight and cost in that order. > I weigh a little over 200 lbs, and will likely have passengers in that ran ge. > I am attempting to keep my weight down as low as possible. Yes, I know if I were to lose some weight, that would also help me. > I had initially decided on a 1" routed spar. > My concerns with that are weight, and my ability to rout an expensive blan k > without screwing it up. I also hate to waste the wood that will be routed o ut. > Ultimately, I'm sure I can eventually determine how to rout it out. > I have seen mention, and some drawings of the "UK box spar" > I have spent hours using the search function, but have not seen a solid > opinion, and explanation of this design. >> =46rom what I understand, this is a required method in the UK for Piet bu ilders. Apparently it is quite light, and strong. =46rom my model airplane > experience, it seems like a great option, that includes a strong D box. >> =46rom what I have read, this is a modification that has actually been pr operly stress analyzed. > I have read many times, just build it as Bernard designed it. I get that, a nd may very well do exactly that. > I am seeking qualified opinions on the UK box spar idea. In my mind (somet imes a dangerous place) this seems stronger, lighter, and less expensive opt ion. > I do have a complete woodworking shop to fabricate any type of spar. > I would appreciate any input form people that truly understand the box spa r design. > Here are a couple of links in which it was discussed: > > http://forums.matronics.com/viewtopic.php?t=65138&postdays=0&postorder =asc&start=0&sid=c79b4120a295a0875655e3c1870c5f8a > > http://pietenpol.cpc-world.com/?page_id=4376 > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=472946#472946 > > > > > > ========================== ========= ========================== ========= ========================== ========= ========================== ========= ========================== ========= > > > ________________________________ Message 3 _____________________________________ Time: 01:35:43 PM PST US Subject: Pietenpol-List: Re: Help with Spar Decision From: "braywood" Here is a part of the UK spar drawing - gives you an idea of how it is built - similar to Jack's, but the web is on the front side of the spar. Several areas are blocked in with additional spruce between the caps and some sections of 1/8" ply on the backside as well. I have not built mine yet, but will use this design, as it requires much smaller pieces of wood! I am told it has been analysed, but have not been able to get any of that info. It is supposed to be good to 1200lb. Mark Read this topic online here: http://forums.matronics.com/viewtopic.php?p=472954#472954 Attachments: http://forums.matronics.com//files/front_spar_section_detail_431.jpg ________________________________ Message 4 _____________________________________ Time: 02:11:24 PM PST US From: "Greg Cardinal" Subject: RE: Pietenpol-List: Help with Spar Decision Not UK box spar but worth investigating... http://www.westcoastpiet.com/images/Construction/I%20Beam%20Analysis.pdf Greg Cardinal Minneapolis -----Original Message----- From: owner-pietenpol-list-server@matronics.com [mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Ozzietx Sent: Sunday, September 17, 2017 10:52 AM Subject: Pietenpol-List: Help with Spar Decision I am in the process of building my rib jig, and need to make a decision on what size spar slot to incorporate. My priorities are Safety, Weight and cost in that order. I weigh a little over 200 lbs, and will likely have passengers in that range. I am attempting to keep my weight down as low as possible. Yes, I know if I were to lose some weight, that would also help me. I had initially decided on a 1" routed spar. My concerns with that are weight, and my ability to rout an expensive blank without screwing it up. I also hate to waste the wood that will be routed out. Ultimately, I'm sure I can eventually determine how to rout it out. I have seen mention, and some drawings of the "UK box spar" I have spent hours using the search function, but have not seen a solid opinion, and explanation of this design. >From what I understand, this is a required method in the UK for Piet >builders. Apparently it is quite light, and strong. From my model >airplane experience, it seems like a great option, that includes a strong D box. >From what I have read, this is a modification that has actually been properly stress analyzed. I have read many times, just build it as Bernard designed it. I get that, and may very well do exactly that. I am seeking qualified opinions on the UK box spar idea. In my mind (sometimes a dangerous place) this seems stronger, lighter, and less expensive option. I do have a complete woodworking shop to fabricate any type of spar. I would appreciate any input form people that truly understand the box spar design. Here are a couple of links in which it was discussed: http://forums.matronics.com/viewtopic.php?t=65138&postdays=0&postorder=asc&s tart=0&sid=c79b4120a295a0875655e3c1870c5f8a http://pietenpol.cpc-world.com/?page_id=4376 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=472946#472946 ________________________________ Message 5 _____________________________________ Time: 03:13:53 PM PST US Subject: Pietenpol-List: Re: Cont. 0200 prop pitch From: "pjb" Heavy Iron wrote: > Hi Patricia, > > I have a McCauley 71-46 that turns about 2275 static on a C85 if you want to try it. I am based at CGV2 which I think is near you. > > Cheers, > Ron Hi Ron, That's very nice of you to let me try your 71-46 but I think it would be a little too coarse a pitch. So far I've tried: The original wood 74-38 which was way too fine. Overspeeded on take-off and in level flight. A wood 72-40 which produced full throttle static rpm of 2625 [ we also flight tested this one and it overspeeded in level flight but not on take-off. A metal 73-45 which produced full throttle static rpm of 2375 [ we didn't flight test this one] Yes, CGV2 is near me. Cheers, Patricia Read this topic online here: http://forums.matronics.com/viewtopic.php?p=472957#472957 ________________________________ Message 6 _____________________________________ Time: 08:48:10 PM PST US Subject: Pietenpol-List: Re: Sky Scout Plans From: "taildrags" Back on Sept. 7, Doug wrote- >By my estimate your pilot CG at 49.64" from the leading edge leaned back 4" >would be about 11" forward of the seat back and bottom intersection if your >plane is built according to the long fuselage plans. Or about 7.5" if the seat >back is at a 15 degree angle as Ray built his Sky Scout. I imagine it is >somewhere between those two values. OK, today I spent some time taking measurements of my airplane with the fuselage leveled and plumb bobs dropped off the leading and trailing edges of the wing. Some very interesting findings, some that surprised even myself. 1. The wing chord on NX41CC is actually 60.5", apparently due to the metal trailing edge piece extending an extra 1/2" past the tails of the ribs as compared to plans. All this time I've been using 60" and never checked it. Lesson No. 1. 2. The cabanes are 23-1/4" (front) and 22-1/2" (rear) between pivot points, which makes them 2" taller (front) and 2-1/4" taller (rear) than plans. This raises the wing a little and subtracts 1 degree from the angle of incidence. Again, I never knew this about my airplane, so Lesson No. 2. I do know that it is very difficult to ever get a sharp or crisp stall, especially power-off, so perhaps slightly less wing incidence is the cause. 3. The cabanes are actually tilted back 3-1/2" from the vertical, and I've always thought that they were tilted back 4". Lesson No. 3. Boy, why did I ever think I knew this airplane? ;o) This gives me just a bit of encouragement that I can still incline the cabanes back a tad if I ever need to adjust the CG to get it forward a bit more. 4. The rear seat back on NX41CC is not perfectly square in both directions so all I can say is that it's somewhere between 83.7 and 84 degrees from the vertical (inclined back about 6 degrees), which places it just about exactly where the geometry works out from the plans. I fly very little of the time sitting in the complete upright position, so I have never felt like the seat back is too straight for me. My seat back has a little bit of naugahyde-covered foam padding and that seems to be fine. 5. The corner where the pilot's seat back meets the pilot's seat bottom is 1.5" forward of the wing trailing edge. With the pilot's CG at a measured/computed 49.64" aft of the wing leading edge, that places the pilot's CG 9.36" forward of the bottom corner of the seat bottom. Doug said it would be somewhere between 7.5" and 11" forward of the corner. Halfway between those two values would be 9.25", so his math was wayyyy off... a good 7/64" off ;o) Doug, you're *good* with numbers-!! -------- Oscar Zuniga Medford, OR Air Camper NX41CC "Scout" A75 power, 72x36 Culver prop Read this topic online here: http://forums.matronics.com/viewtopic.php?p=472969#472969 ________________________________ Message 7 _____________________________________ Time: 09:52:59 PM PST US From: John Woods Subject: Re: Pietenpol-List: Help with Spar Decision Just a word of caution. If you decide to build the Jim Will's "UK Box Spar" then be aware that the wing design has changed from the original. The Jim Will's design has a different strut attachment point on the wing and four bay's per wing panel rather than three. I'm sure the strut attachment location is significant in the Will's spar design. Whether the four bay has any significance to the final design strength, I'm not sure. I am building my wing using Jim will's design as I can't afford to purchase solid spruce spars here in Australia. JohnW On 17 September 2017 at 23:51, Ozzietx wrote: > > I am in the process of building my rib jig, and need to make a decision > on what size spar slot to incorporate. > My priorities are Safety, Weight and cost in that order. > I weigh a little over 200 lbs, and will likely have passengers in that > range. > I am attempting to keep my weight down as low as possible. Yes, I know if > I were to lose some weight, that would also help me. > I had initially decided on a 1" routed spar. > My concerns with that are weight, and my ability to rout an expensive blank > without screwing it up. I also hate to waste the wood that will be routed > out. > Ultimately, I'm sure I can eventually determine how to rout it out. > I have seen mention, and some drawings of the "UK box spar" > I have spent hours using the search function, but have not seen a solid > opinion, and explanation of this design. > >From what I understand, this is a required method in the UK for Piet > builders. Apparently it is quite light, and strong. From my model airplane > experience, it seems like a great option, that includes a strong D box. > >From what I have read, this is a modification that has actually been > properly stress analyzed. > I have read many times, just build it as Bernard designed it. I get that, > and may very well do exactly that. > I am seeking qualified opinions on the UK box spar idea. In my mind > (sometimes a dangerous place) this seems stronger, lighter, and less > expensive option. > I do have a complete woodworking shop to fabricate any type of spar. > I would appreciate any input form people that truly understand the box > spar design. > Here are a couple of links in which it was discussed: > > http://forums.matronics.com/viewtopic.php?t=65138& > postdays=0&postorder=asc&start=0&sid=c79b4120a295a0875655e3c1870c5f8a > > http://pietenpol.cpc-world.com/?page_id=4376 > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=472946#472946 > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message pietenpol-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Pietenpol-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/pietenpol-list Browse Digests http://www.matronics.com/digest/pietenpol-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.