Original Posted By: Michael Perez
Re: Pietenpol-List: wood vs steel struts
Re: Pietenpol-List: Re: wood vs steel struts
Original Posted By: Michael Perez
Pietenpol-List: Re: wood vs steel struts
Original Posted By: "Mark Roberts"
......added pic's (clearer).......end msg--------L.Metzel KLNCA65-8N2308CAN HardwareAirframe 712TTW72CK-42 SensenichStandard Factory GN-1Read this topic online here:http://forums.matronics.com/viewtopic.p ... ttachments: http://forums.matronics.com//files/1_21 ... ___Subject: Pietenpol-List: Re: wood vs steel struts
......added pic's (clearer).......end msg--------L.Metzel KLNCA65-8N2308CAN HardwareAirframe 712TTW72CK-42 SensenichStandard Factory GN-1Read this topic online here:http://forums.matronics.com/viewtopic.p ... ttachments: http://forums.matronics.com//files/1_21 ... ___Subject: Pietenpol-List: Re: wood vs steel struts
Re: [Shaw Suspected Junk Email] Re: Pietenpol-List: wood vs steel struts
Original Posted By: "Clif Dawson"
Another, much lighter, possibility.http://www.youtube.com/watch?v=DarTJsvb ... .....maybe the entire enchelada, er,airplane even. :-)Clif You may want to buy streamline aluminum struts and then wrap them with a thin wood veneer. Michael Perez________________________________________________________________________________
Another, much lighter, possibility.http://www.youtube.com/watch?v=DarTJsvb ... .....maybe the entire enchelada, er,airplane even. :-)Clif You may want to buy streamline aluminum struts and then wrap them with a thin wood veneer. Michael Perez________________________________________________________________________________
RE: Pietenpol-List: Re: wood vs steel struts
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Fairly simple to calculate. First, figure out what gross weight yourairplane will have (in order to make this calculation conservative, pick anumber higher than you really think it will be). For the purpose of thisexercise, let's say the gross weight is 1300 lbs.Then multiply that by the highest load factor (G-load) you would expect tosurvive in extreme turbulence or maneuvers. 5 G's is a common number forultimate loading (the load that would cause something to break). So thismeans the wing is carrying 1300 x 5 or 6,500 lbs of load.Most of the wing load is carried by the lift struts. A Pietenpol has a 29'wingspan, with a 2' wide centersection, so each wing panel is 13' 6" wideand carries 13.5/29 or 47% of the load, which in this example is 3,025 lbs.Since the lift struts attach in the middle of the wing panel, virtually allof the lift load is transferred to the struts, with very little load carriedby the bolts attaching the wing panel to the centersection (low enough to beignored in this example). So the two lift struts on each side carry 3,025lbs between them.Calculating how much of that load is carried by the front strut and how muchby the rear is a bit more difficult. The distribution of load varies withthe location of the center of pressure, which moves around as the angle ofattack changes, and the location of the center of gravity, which varies withhow the airplane is loaded (fuel and passengers, for example). It isprobably safe to say that the front strut carries up to about 3/4 of thewing load, since it is pretty close to the C.G.So that means with a 1300 lb Pietenpol loaded to 5 G's by turbulence orextreme aerobatics, the front struts each are carrying (3/4)x(3,025) or2,270 lbs.OK, we've found the load the struts carry. The stress is simply that loaddivided by the cross sectional area of the strut. For a round tube, thearea is easy to calculate: Area = =F0(d2outside - d2inside)/4Assuming you are using 1" diameter 4130 steel tubing, with a wall thicknessof 0.049", the cross-sectional area would be =F0 x (1.0002 - .9022)/4 or .146in2 . With 2,270 lbs being carried by .146 in2, the stress in that strutwould be 2270/.146 or 15,505 psi. Since normalized 4130 has an ultimatestrength of 90,000 psi, this is certainly a safe load for that steel strutto carry.So for wood or aluminum struts, you simply need to know the breakingstrength of the material and the cross-sectional area of the strut and youcan calculate the stress.Jack PhillipsNX899JPSmith Mountain Lake, Virginia-----Original Message-----
Fairly simple to calculate. First, figure out what gross weight yourairplane will have (in order to make this calculation conservative, pick anumber higher than you really think it will be). For the purpose of thisexercise, let's say the gross weight is 1300 lbs.Then multiply that by the highest load factor (G-load) you would expect tosurvive in extreme turbulence or maneuvers. 5 G's is a common number forultimate loading (the load that would cause something to break). So thismeans the wing is carrying 1300 x 5 or 6,500 lbs of load.Most of the wing load is carried by the lift struts. A Pietenpol has a 29'wingspan, with a 2' wide centersection, so each wing panel is 13' 6" wideand carries 13.5/29 or 47% of the load, which in this example is 3,025 lbs.Since the lift struts attach in the middle of the wing panel, virtually allof the lift load is transferred to the struts, with very little load carriedby the bolts attaching the wing panel to the centersection (low enough to beignored in this example). So the two lift struts on each side carry 3,025lbs between them.Calculating how much of that load is carried by the front strut and how muchby the rear is a bit more difficult. The distribution of load varies withthe location of the center of pressure, which moves around as the angle ofattack changes, and the location of the center of gravity, which varies withhow the airplane is loaded (fuel and passengers, for example). It isprobably safe to say that the front strut carries up to about 3/4 of thewing load, since it is pretty close to the C.G.So that means with a 1300 lb Pietenpol loaded to 5 G's by turbulence orextreme aerobatics, the front struts each are carrying (3/4)x(3,025) or2,270 lbs.OK, we've found the load the struts carry. The stress is simply that loaddivided by the cross sectional area of the strut. For a round tube, thearea is easy to calculate: Area = =F0(d2outside - d2inside)/4Assuming you are using 1" diameter 4130 steel tubing, with a wall thicknessof 0.049", the cross-sectional area would be =F0 x (1.0002 - .9022)/4 or .146in2 . With 2,270 lbs being carried by .146 in2, the stress in that strutwould be 2270/.146 or 15,505 psi. Since normalized 4130 has an ultimatestrength of 90,000 psi, this is certainly a safe load for that steel strutto carry.So for wood or aluminum struts, you simply need to know the breakingstrength of the material and the cross-sectional area of the strut and youcan calculate the stress.Jack PhillipsNX899JPSmith Mountain Lake, Virginia-----Original Message-----
Re: Pietenpol-List: Re: wood vs steel struts
Original Posted By: Jack Phillips
Excellent explanation.Thank you,Michael----------------------------------------------------------------------------------------------------------------------------------------------------------------
Excellent explanation.Thank you,Michael----------------------------------------------------------------------------------------------------------------------------------------------------------------
Pietenpol-List: Re: Latex Paint Forum
Original Posted By: "Charles Burkholder"
I would be interested in your forum on this subject. Possible to do a video andpost it on YouTube for us not attending?WF2--------Read this topic online here:http://forums.matronics.com/viewtopic.p ... __________
I would be interested in your forum on this subject. Possible to do a video andpost it on YouTube for us not attending?WF2--------Read this topic online here:http://forums.matronics.com/viewtopic.p ... __________
RE: Pietenpol-List: Re: wood vs steel struts
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Oops! Of course you are right, John. I wondered, because I remember doingthe analysis years ago when I built my Pietenpol and it seemed like thestruts were a lot more highly loaded than that. That's what I get fortrying to work from memory, instead of drawing a free body diagram.So in my example, the stress in the steel tube strut would be more like31,000 psi, which is getting into significant stress range.Jack PhillipsNX899JPSmith Mountain Lake, Virginia _____
Oops! Of course you are right, John. I wondered, because I remember doingthe analysis years ago when I built my Pietenpol and it seemed like thestruts were a lot more highly loaded than that. That's what I get fortrying to work from memory, instead of drawing a free body diagram.So in my example, the stress in the steel tube strut would be more like31,000 psi, which is getting into significant stress range.Jack PhillipsNX899JPSmith Mountain Lake, Virginia _____
Pietenpol-List: Re: wood vs steel struts
Original Posted By: "dgaldrich"
Need some help on where to mount the ELT and ELT antenna on my Pietenpol. I had not intended to have an ELT based on reports from this group that they were not required to have one by their DAR because of staying within 25 miles of the home airport for the first 40 hours. Now that my plane is finished (see attached pic), my DAR says I must have one. So, I am essentially having to retrofit an ELT to a plane I didn't design to have one. At this point I am leaning toward putting the ELT between the legs of the passenger on the floor of the front pit. For the antenna, I am leaning toward mounting it on the forward portion of the coaming (tho it will hurt to drill a mounting hole in my finished cowl), as that's the only existing metal that is large enough to act as a ground plane.I know its preferred (but not required) to mount the ELT as far aft as possible, but at this point, I would have to do some major rework to mount the ELT and create a ground plane anywhere behind the pilot, not to mention the negative effect on CG.I've gone through all the Matronics archives without finding a good solution for my situation, so would invite any input on:1. Where you mounted the ELT.2. Where you mounted the ELT antenna.3. What you used as a ground plane.Especially if it's mounted in a forward location. Larry Morlock________________________________________________________________________________Subject: Pietenpol-List: Re: wood vs steel struts
Need some help on where to mount the ELT and ELT antenna on my Pietenpol. I had not intended to have an ELT based on reports from this group that they were not required to have one by their DAR because of staying within 25 miles of the home airport for the first 40 hours. Now that my plane is finished (see attached pic), my DAR says I must have one. So, I am essentially having to retrofit an ELT to a plane I didn't design to have one. At this point I am leaning toward putting the ELT between the legs of the passenger on the floor of the front pit. For the antenna, I am leaning toward mounting it on the forward portion of the coaming (tho it will hurt to drill a mounting hole in my finished cowl), as that's the only existing metal that is large enough to act as a ground plane.I know its preferred (but not required) to mount the ELT as far aft as possible, but at this point, I would have to do some major rework to mount the ELT and create a ground plane anywhere behind the pilot, not to mention the negative effect on CG.I've gone through all the Matronics archives without finding a good solution for my situation, so would invite any input on:1. Where you mounted the ELT.2. Where you mounted the ELT antenna.3. What you used as a ground plane.Especially if it's mounted in a forward location. Larry Morlock________________________________________________________________________________Subject: Pietenpol-List: Re: wood vs steel struts
Original Posted By: "Gary Boothe"
JackAs one of my engineering profs from back in the stone ages used to say about hisexams -- "No free body diagram, no credit!!!"DaveRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________
JackAs one of my engineering profs from back in the stone ages used to say about hisexams -- "No free body diagram, no credit!!!"DaveRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________
RE: Pietenpol-List: ELT Location
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Larry,I can't help you with the ELT, since mine is behind the pilot.but your Pietsure turned out nice!!Gary BootheNX308MB
Larry,I can't help you with the ELT, since mine is behind the pilot.but your Pietsure turned out nice!!Gary BootheNX308MB
Re: Pietenpol-List: Re: engine out..
Original Posted By: gliderx5(at)comcast.net
Jeff,Either those guys that want you to change engines are secretly envious, or theydon't want to admit that they don't have the gonads to build and fly a real experimental!(Not that there's anything wrong with a/c engines...that was simplynot your choice) They sound like some of the same guys from my airport! I'm not an 'A' guy, butI know there are plenty of guys on this list who are quite experienced, and justwaiting for you to ask some direct questions.When you get the bugs worked out, like Dan Helsper did, those guys will be awedby your cool-sounding engine, take credit for helping you to fix it, then moveon to the next airport to beat up on someone else...GaryNX308MBSent from my iPhoneOn Jun 17, 2013, at 7:33 AM, "bender" wrote:> > My spars are douglas fir.. and I found some within an hour from here.> plan to pick of a board or 2 today and start scarfing.> the repair other than scarfing the joint that is still on the plane looks prettyeasy.> A couple of the pilots here at work are asking when i'm going to put an airplaneengine on it. I really hate to do that because the A is really cool.> I do know of an A75 locally that I could get for a good price.. needs overhaul,but that's easy. I hope to keep the A.. going to tear it apart unless I findan ignition or carb prob just to figure this out.> but the wing is first.. gotta have that no matter the engine choice.> I'm thinking a lot about the oil pressure.. or lack of..being the possible issue.> > jeff> > > > > Read this topic online here:> > http://forums.matronics.com/viewtopic.p ... 866#402866> > > > > > > > > > ________________________________________________________________________________Date: Mon, 17 Jun 2013 23:45:42 +0000 (UTC)
Jeff,Either those guys that want you to change engines are secretly envious, or theydon't want to admit that they don't have the gonads to build and fly a real experimental!(Not that there's anything wrong with a/c engines...that was simplynot your choice) They sound like some of the same guys from my airport! I'm not an 'A' guy, butI know there are plenty of guys on this list who are quite experienced, and justwaiting for you to ask some direct questions.When you get the bugs worked out, like Dan Helsper did, those guys will be awedby your cool-sounding engine, take credit for helping you to fix it, then moveon to the next airport to beat up on someone else...GaryNX308MBSent from my iPhoneOn Jun 17, 2013, at 7:33 AM, "bender" wrote:> > My spars are douglas fir.. and I found some within an hour from here.> plan to pick of a board or 2 today and start scarfing.> the repair other than scarfing the joint that is still on the plane looks prettyeasy.> A couple of the pilots here at work are asking when i'm going to put an airplaneengine on it. I really hate to do that because the A is really cool.> I do know of an A75 locally that I could get for a good price.. needs overhaul,but that's easy. I hope to keep the A.. going to tear it apart unless I findan ignition or carb prob just to figure this out.> but the wing is first.. gotta have that no matter the engine choice.> I'm thinking a lot about the oil pressure.. or lack of..being the possible issue.> > jeff> > > > > Read this topic online here:> > http://forums.matronics.com/viewtopic.p ... 866#402866> > > > > > > > > > ________________________________________________________________________________Date: Mon, 17 Jun 2013 23:45:42 +0000 (UTC)
RE: Pietenpol-List: Re: wood vs steel struts
Original Posted By: "Gary Boothe"
Yep - that's a good rule. An FBD tends to point out such little things asvector components, which would have cued me in on this one. I was so busythinking about how to explain how you get from the loading to the stressesin the strut that I neglected to mention the huge effect the strut geometryhas on the loading (and the stresses).As long as we're having this discussion, it's probably appropriate tomention that one of the problems with wooden or aluminum struts is how tomake the attachments to the fittings. Almost invariably such attachmentshave to be made with bolts loaded in shear, so the shear strength of thewood or aluminum must be considered. It is not a trivial exercise.Jack PhillipsNX899JPSmith Mountain Lake, VirginiaA retired engineer, who perhaps should STAY retiredJackAs one of my engineering profs from back in the stone ages used to say abouthis exams -- "No free body diagram, no credit!!!"Dave________________________________________________________________________________
Yep - that's a good rule. An FBD tends to point out such little things asvector components, which would have cued me in on this one. I was so busythinking about how to explain how you get from the loading to the stressesin the strut that I neglected to mention the huge effect the strut geometryhas on the loading (and the stresses).As long as we're having this discussion, it's probably appropriate tomention that one of the problems with wooden or aluminum struts is how tomake the attachments to the fittings. Almost invariably such attachmentshave to be made with bolts loaded in shear, so the shear strength of thewood or aluminum must be considered. It is not a trivial exercise.Jack PhillipsNX899JPSmith Mountain Lake, VirginiaA retired engineer, who perhaps should STAY retiredJackAs one of my engineering profs from back in the stone ages used to say abouthis exams -- "No free body diagram, no credit!!!"Dave________________________________________________________________________________
Re: Pietenpol-List: wood vs steel struts
Original Posted By: "John Greenlee"
Subject: Re: Pietenpol-List: wood vs steel struts UNCLASSIFIEDWay late into this discussion.Think about using aluminium but painting it to look like wood.A buddy building a Spencer AirCar (Huge amphibian) has developed the ability tomodify a paint job so that it looks like wood. you can't tell where the realwood and the plastic or aluminium start.On 06/16/13, Michael Perez wrote:> > > > Hi Paul. I can't answer your question directly, only to say that the aluminumstruts will be lighter than any similar sized steel struts. If you are thinkingof using steel tubes to wrap with wood, than those steel tubes alone will probablyweigh more than the aluminum struts. Aluminum tubes wrapped with wood,T-88, varnish/paint may still weigh more than the plain aluminum struts. > > You may want to buy streamline aluminum struts and then wrap them with a thinwood veneer. (Of course, the added veneer, adhesive, varnish/paint, etc. addweight...) However, gluing down a thin veneer over the streamline tube would beeasy and the shape is already perfect...no wood fabrication required. The veneercan be purchased just about any place you can buy wood.> > FWIW, my aluminum struts, complete with machined aluminum inserts, SS forks andthe nuts/bolts to assemble them, weigh just under 4 lbs. each.> > Michael Perez> Pietenpol HINT Videos> Karetaker Aero> http://www.karetakeraero.com/(blockedht ... aero.com/)> > UNCLASSIFIED________________________________________________________________________________
Subject: Re: Pietenpol-List: wood vs steel struts UNCLASSIFIEDWay late into this discussion.Think about using aluminium but painting it to look like wood.A buddy building a Spencer AirCar (Huge amphibian) has developed the ability tomodify a paint job so that it looks like wood. you can't tell where the realwood and the plastic or aluminium start.On 06/16/13, Michael Perez wrote:> > > > Hi Paul. I can't answer your question directly, only to say that the aluminumstruts will be lighter than any similar sized steel struts. If you are thinkingof using steel tubes to wrap with wood, than those steel tubes alone will probablyweigh more than the aluminum struts. Aluminum tubes wrapped with wood,T-88, varnish/paint may still weigh more than the plain aluminum struts. > > You may want to buy streamline aluminum struts and then wrap them with a thinwood veneer. (Of course, the added veneer, adhesive, varnish/paint, etc. addweight...) However, gluing down a thin veneer over the streamline tube would beeasy and the shape is already perfect...no wood fabrication required. The veneercan be purchased just about any place you can buy wood.> > FWIW, my aluminum struts, complete with machined aluminum inserts, SS forks andthe nuts/bolts to assemble them, weigh just under 4 lbs. each.> > Michael Perez> Pietenpol HINT Videos> Karetaker Aero> http://www.karetakeraero.com/(blockedht ... aero.com/)> > UNCLASSIFIED________________________________________________________________________________
Pietenpol-List: Re: Who's flying from TX, OK to Brodhead
Original Posted By: "curtdm(at)gmail.com"
The technique is referred to as "faux wood finishing" and has been around a LONGtime. VERY common in the colonial days to paint nasty ordinary common hardwoods like cherry and walnut, to look like mahogany. Seriously, they'd paintit brown and fake the entire job! Point being, it really can be convincing, it's well documented and there's quitea number of tools out there that can help. Just start researching faux woodfinishing techniques.Read this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Who's flying from TX, OK to Brodhead
The technique is referred to as "faux wood finishing" and has been around a LONGtime. VERY common in the colonial days to paint nasty ordinary common hardwoods like cherry and walnut, to look like mahogany. Seriously, they'd paintit brown and fake the entire job! Point being, it really can be convincing, it's well documented and there's quitea number of tools out there that can help. Just start researching faux woodfinishing techniques.Read this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Who's flying from TX, OK to Brodhead
Pietenpol-List: Re: wood vs steel struts
Original Posted By: brian.e.jardine@l-3com.com
... or this: hydrographic wood grain--------Read this topic online here:http://forums.matronics.com/viewtopic.p ... __________
... or this: hydrographic wood grain--------Read this topic online here:http://forums.matronics.com/viewtopic.p ... __________
Re: Pietenpol-List: Room reservation for Brodhead
Original Posted By: Marcus Zechini
Due to work again this year I won't be attending Brodhead. I do have aroom reserved in Monroe at the AmericInn. I have till next Wednesday tocancel if anybody is interested in the 2 Queen room, free Breakfast,nice pool.BrianSLC-UT385-315-0127________________________________________________________________________________Date: Wed, 17 Jul 2013 15:50:13 -0400Subject: Re: Pietenpol-List: Room reservation for Brodhead
Due to work again this year I won't be attending Brodhead. I do have aroom reserved in Monroe at the AmericInn. I have till next Wednesday tocancel if anybody is interested in the 2 Queen room, free Breakfast,nice pool.BrianSLC-UT385-315-0127________________________________________________________________________________Date: Wed, 17 Jul 2013 15:50:13 -0400Subject: Re: Pietenpol-List: Room reservation for Brodhead