Pietenpol-List: Struts

matronics · Post by **matronics** » Mon Jul 20, 1998 6:05 pm

Original Posted By: Owen Davies
John Could you provide us with the source of your ultra-light streamlinedaluminum flying struts. Sounds like a good idea, maybe even with a whole lengthof 4130 square and end fittings?Thanks in advance.Warren________________________________________________________________________________

matronics · Post by **matronics** » Tue Jul 21, 1998 1:06 am

Original Posted By: dswagler(at)cobkf.ang.af.mil
Subject: Pietenpol-List: Re: Struts>>>John> Could you provide us with the source of your ultra-light streamlined>aluminum flying struts. Sounds like a good idea, maybe even with a wholelength>of 4130 square and end fittings?>>Thanks in advance.>Warren>>________________________________________________________________________________

matronics · Post by **matronics** » Tue Jul 21, 1998 1:06 am

Original Posted By: steve(at)byu.edu
Subject: Pietenpol-List: Re: Struts>>>John> Could you provide us with the source of your ultra-light streamlined>aluminum flying struts. Sounds like a good idea, maybe even with a wholelength>of 4130 square and end fittings?>>Thanks in advance.>Warren>>________________________________________________________________________________

matronics · Post by **matronics** » Tue Jul 21, 1998 2:24 pm

Original Posted By: Richard DeCosta
SteveE,What kind of struts are those on your ship?The flying struts I mean.John-----Original Message-----

matronics · Post by **matronics** » Tue Jul 21, 1998 3:47 pm

Original Posted By: John Greenlee
-----Original Message-----John GreenleeSent: Tuesday, July 21, 1998 1:25 PMSubject: Pietenpol-List: StrutsSteveE,What kind of struts are those on your ship?The flying struts I mean.JohnJohn, I got lucky and found some aluminium extrusions that look very closeto streamline tubing. They were supposed to be chair parts, but gotredirected to my workshop when I realized how well they would work forstruts.Stevee________________________________________________________________________________

matronics · Post by **matronics** » Tue Jul 21, 1998 4:38 pm

Original Posted By: steve(at)byu.edu
Steve,I did something similar. I got some extruded aluminum (6061t6) struts fromthe ultralite industry. Basic stress analysis showed they were not near asstrong as 4130 but plenty strong enough. Inside they are squared off and Imade fittings to slip inside from square 4130 tubing. It slips inside andis bolted. These were dirt cheap compared to current manufacture 4130streamline tubing.John-----Original Message-----

matronics · Post by **matronics** » Tue Jul 21, 1998 8:12 pm

Original Posted By: Aron(at)hrn.bradley.edu
Chair parts?! (I resist the urge to use all-capswith some difficulty.) What kind of aluminum arethey made from? Given the original use, it's toughto believe this is anything you'd want your wings,and life, depending on. If you don't know for sure,please find out what this stuff is.Owen Davies>-----Original Message----->From: Maiser(at)adena.byu.edu On Behalf Of John Greenlee>John, I got lucky and found some aluminium extrusions that look very close>to streamline tubing. They were supposed to be chair parts, but got>redirected to my workshop when I realized how well they would work for>struts.________________________________________________________________________________

matronics · Post by **matronics** » Wed Jul 22, 1998 9:00 am

Original Posted By: Warren D. Shoun
Warren,I don't have the data here at the office. I had planned an article for theBPAN but have not got around to writing it. There are at least twodifferent companies advertising in the classifieds of either/or Kitplanesand Sport Aviation selling them.You certainly could use a whole length of 4130 but I thing it would be abunch of needless weight. We calculated (somewhat rough round numbers butclose enough) that the aluminum struts are nearly twice (1.91 times) asstrong as required even with a safety factor of 1.5 already figured in.They are larger in dimension and thicker in wall than the typically used4130 strut which calculates to 3.34 times as strong as necessary. There isno lack of adequate strength in the aluminum strut, only less overkill.John-----Original Message-----

matronics · Post by **matronics** » Wed Jul 22, 1998 9:47 am

Original Posted By: Owen Davies
Owen, sorry to alarm you. They are 6061T6 extrusions with a .095 wall anda .095 internal "T" section. The 4130 sleeves in each end are bolted onwith two bolts on each end. The bolts go through two thicknesses of the4130, and three of the aluminium. In other words very strong.Stevee-----Original Message-----Owen DaviesSent: Tuesday, July 21, 1998 7:13 PMSubject: Pietenpol-List: Re: StrutsChair parts?! (I resist the urge to use all-capswith some difficulty.) What kind of aluminum arethey made from? Given the original use, it's toughto believe this is anything you'd want your wings,and life, depending on. If you don't know for sure,please find out what this stuff is.Owen Davies>-----Original Message----->From: Maiser(at)adena.byu.edu On Behalf Of John Greenlee>John, I got lucky and found some aluminium extrusions that look very close>to streamline tubing. They were supposed to be chair parts, but got>redirected to my workshop when I realized how well they would work for>struts.________________________________________________________________________________

matronics · Post by **matronics** » Wed Jul 22, 1998 11:08 am

Original Posted By: steve(at)byu.edu
Gee, that does sound more interesting. If youcan suggest a source for this stuff, I probablywouldn't be the only one who'd like to hearabout it. If not, at least it's a nice reminder tobe open of eye and mind. Thanks.Owen Davies-----Original Message-----

matronics · Post by **matronics** » Fri Jul 24, 1998 2:36 am

Original Posted By: John Greenlee
Subject: Pietenpol-List: Re: Re: Struts>also it is not good to combine aluminum with 4130. This creates a>problem with corrosion. I would not like this either on my struts.>> -=Ron=->________________________________________________________________________________

matronics · Post by **matronics** » Fri Jul 24, 1998 7:33 pm

Original Posted By: Craig Lawler
also it is not good to combine aluminum with 4130. This creates aproblem with corrosion. I would not like this either on my struts. -=Ron=-________________________________________________________________________________

matronics · Post by **matronics** » Sat Jul 25, 1998 9:31 am

Original Posted By: PTNPOL(at)aol.com
Ron,You are correct. Airplane building and design is a series of compromises.Ideal struts would be the 4130 streamline tubing. However, my goal was tosave a few dollars here, and it does have other effects. I plan to coat the4130 pieces good with epoxy primer before slipping into the aluminum tube.Probably some periodic inspection would be a good idea.You've got to look up the going price for the 4130 streamline and then pricethe aluminum streamline. The aluminum is probably about 1/3 the cost. Idon't mind inspecting from time to time.John-----Original Message-----

matronics · Post by **matronics** » Mon Aug 10, 1998 5:17 am

Original Posted By: John Greenlee
Subject: Pietenpol-List: Re: Struts>John, I appreciated your comments on the use of aluminum struts.>However, i am unable to find a source. Can you help? Did you stick with>the same elliptical cross section? Or go larger? What was the cost per>foot? I have been on vacation and am just wading through 105 e-mails.>Thanks.>-=Ian=->________________________________________________________________________________

matronics · Post by **matronics** » Mon Aug 10, 1998 5:18 am

Original Posted By: LanhamOS(at)aol.com
Subject: Pietenpol-List: Re: Struts>John, I appreciated your comments on the use of aluminum struts.>However, i am unable to find a source. Can you help? Did you stick with>the same elliptical cross section? Or go larger? What was the cost per>foot? I have been on vacation and am just wading through 105 e-mails.>Thanks.>-=Ian=->________________________________________________________________________________

matronics · Post by **matronics** » Mon Aug 10, 1998 1:12 pm

Original Posted By: Ed0248(at)aol.com
John, I appreciated your comments on the use of aluminum struts.However, i am unable to find a source. Can you help? Did you stick withthe same elliptical cross section? Or go larger? What was the cost perfoot? I have been on vacation and am just wading through 105 e-mails.Thanks.-=Ian=-________________________________________________________________________________

matronics · Post by **matronics** » Tue Aug 11, 1998 9:52 am

Original Posted By: steve(at)byu.edu
Thanks, John. I will dig back through. It sounds very attractive.________________________________________________________________________________

matronics · Post by **matronics** » Wed Aug 19, 1998 1:11 am

Original Posted By: Ian Holland
Subject: Pietenpol-List: Re: Struts>Speaking of struts, here's a URL of a company that sells an extrudedaluminum>streamline tube. Sounds like its intended to fit over a more structurally>significant bar stock for use as lift struts. Kind of heavy when added to4130>square stock, but not terribly expensive. I assume this kind of materialcan't>be used without more support...does anyone out there think otherwise?>>http://www.sky-tek.com/struts.html>>--P ... __________

matronics · Post by **matronics** » Wed Aug 19, 1998 1:11 am

Original Posted By: Peter P Frantz
Subject: Pietenpol-List: Re: Struts>Speaking of struts, here's a URL of a company that sells an extrudedaluminum>streamline tube. Sounds like its intended to fit over a more structurally>significant bar stock for use as lift struts. Kind of heavy when added to4130>square stock, but not terribly expensive. I assume this kind of materialcan't>be used without more support...does anyone out there think otherwise?>>http://www.sky-tek.com/struts.html>>--P ... __________

matronics · Post by **matronics** » Wed Aug 19, 1998 4:51 pm

Original Posted By: Ian Holland
rans aircraft in kansas will sell you streamlined struts that willwork in 1200 gross and under, there phone, do search on ransaircraft they are also resaonable on price! i still haven't completelygot the hang of this here email so bar with a poor ozark boy!-----Original Message-----

matronics · Post by **matronics** » Wed Aug 19, 1998 6:08 pm

Original Posted By: oil can
Speaking of struts, here's a URL of a company that sells an extruded aluminum streamline tube. Sounds like its intended to fit over a more structurally significant bar stock for use as lift struts. Kind of heavy when added to 4130square stock, but not terribly expensive. I assume this kind of material can'tbe used without more support...does anyone out there think otherwise?http://www.sky-tek.com/struts.html--Pet ... __________

matronics · Post by **matronics** » Thu Aug 20, 1998 7:35 am

Original Posted By: John Greenlee
Subject: Pietenpol-List: Re: Struts>I found some of my notes re: aluminum struts.>>I ordered the 'small' strut from:>>Carlson Aircraft Inc>50643 SR 14>PO Box 8804>East Palestine, OH 44413>>Fax 330-426-1144>330-426-3934>e-mail: mlc@sky-tec.com>>6061T6 stremline strut extrusion>Major axis 2.44">Minor axis 1.00">Flat area inside accomodates 3/4" square tube. In the thickest wall, the>wall is 1/8", and varies down to something like .058.>Length is 10'6" but will cut to 107" for UPS.>>Last year's price was $35.70 each. (Compare to 4130!)>>Basic rough stress analysis:>>Assuming a 1100 lb gross weight Piet for an even number, and 6 gs (4gstimes>1.5 safety factor?) for a design load:>>1100 / 4 struts * 6 = 1650.>>In other words each strut must withstand a tension load of 1650 lbs.>>With a .049 wall 4130 steel equivalant to 1.5" round circumfrence strut we>figure something like this:>>.049 * 1.5 * 75000 yield = 5512.50 which is 3.34 times the necessary>strength of 1650.>>With a .058 wall 6061T6 strut we get something like this:>>.058 * 1.5 * 35000 yield = 3150 which is 1.91 times the necessary strength>of 1650.>>So we conclude that though the aluminum strut is significantly less strong>than the 4130 strut, it is almost twice as strong as necessary. Pleasenote>portions of the wall thickness are significantly thicker than the .058 we>used for calculation.>>Some of you engineers (I ain't one) might want to clean this up. I seam to>recall the yield we used for 6061T6 might not be precise. One of you may>have the exact figure available.>>What I did was use a bolted 4130 square tube fitting in each end of the>strut. They appear to be plenty ample to use without a full length steel>tube inside them. You do what you think is prudent.>>Your comments are welcome. I saved all these notes for an article I have>never got around to writing for the BPAN.>>John>>>-----Original Message----->From: Peter P Frantz >To: Pietenpol Discussion >Date: Wednesday, August 19, 1998 6:11 PM>Subject: Re: Struts>>>>Speaking of struts, here's a URL of a company that sells an extruded>aluminum>>streamline tube. Sounds like its intended to fit over a more structurally>>significant bar stock for use as lift struts. Kind of heavy when added to>4130>>square stock, but not terribly expensive. I assume this kind of material>can't>>be used without more support...does anyone out there think otherwise?>>>>http://www.sky-tek.com/struts.html>>>>- ... __________

matronics · Post by **matronics** » Thu Aug 20, 1998 12:32 pm

Original Posted By: Peter P Frantz
I found some of my notes re: aluminum struts.I ordered the 'small' strut from:Carlson Aircraft Inc50643 SR 14PO Box 8804East Palestine, OH 44413Fax 330-426-1144330-426-3934e-mail: mlc@sky-tec.com6061T6 stremline strut extrusionMajor axis 2.44"Minor axis 1.00"Flat area inside accomodates 3/4" square tube. In the thickest wall, thewall is 1/8", and varies down to something like .058.Length is 10'6" but will cut to 107" for UPS.Last year's price was $35.70 each. (Compare to 4130!)Basic rough stress analysis:Assuming a 1100 lb gross weight Piet for an even number, and 6 gs (4gs times1.5 safety factor?) for a design load:1100 / 4 struts * 6 = 1650.In other words each strut must withstand a tension load of 1650 lbs.With a .049 wall 4130 steel equivalant to 1.5" round circumfrence strut wefigure something like this:.049 * 1.5 * 75000 yield = 5512.50 which is 3.34 times the necessarystrength of 1650.With a .058 wall 6061T6 strut we get something like this:.058 * 1.5 * 35000 yield = 3150 which is 1.91 times the necessary strengthof 1650.So we conclude that though the aluminum strut is significantly less strongthan the 4130 strut, it is almost twice as strong as necessary. Please noteportions of the wall thickness are significantly thicker than the .058 weused for calculation.Some of you engineers (I ain't one) might want to clean this up. I seam torecall the yield we used for 6061T6 might not be precise. One of you mayhave the exact figure available.What I did was use a bolted 4130 square tube fitting in each end of thestrut. They appear to be plenty ample to use without a full length steeltube inside them. You do what you think is prudent.Your comments are welcome. I saved all these notes for an article I havenever got around to writing for the BPAN.John-----Original Message-----

matronics · Post by **matronics** » Thu Aug 20, 1998 9:41 pm

Original Posted By: rdecosta(at)autoeurope.com (Richard DeCosta)
Subject: Pietenpol-List: Re: Struts>On Fri, 21 Aug 1998, John Greenlee wrote:>>> Peter,>>>> I dunno much about measuring compression loads. My friend the engineerwho>> helped me with this said that is hard to predict and calculate. Do youknow>> how to do it?>>>> I do not know how many negative gs to plan for though I am sure it isless>> than the positive gs. Piets are flying many hours with wood struts whichI>> guess are weaker in compression than the aluminum struts. I am told the>> jury struts (which I am using) are the key. It would appear mostpotential>> negative gs might be in a hard landing. If the wings collapsed there it>> would be messy and embarrasing, but probably not fatal.>>>> One last note on tension loads. I decided to use 1/8" cable on the wings>> for additional peace of mind.>>>> John>>OK, I read the original e-mail from John and now this one. There have been>a couple of false assumptions made. These can be dangerous as there may be>a greater load being applied to the struts than they are capable of.>>1. the priginal post divided the ENTIRE wing loading at 6 g's across the>four struts. Depending on the Geometry of the struts/wing, this is>unlikely to be the case. Since there is an UNEVENLY distributed load both>across the wing spanwise and chordwise, The front strut usually takes more>of the load than the rear.>>2. it was also assumed that the load on both struts per side would be 550>lbs at 1 g. First, the wing root fittings take some of this load. Second,>depending on the wing geometry, the strut load can actually be GREATER>than the wing load. The wing and fuselage can actually work like a lever>against the strut. The Schwitzer 2-33A would be a good example of this. It>has a long wing but a relatively short strut.>>3. The calculations also assume that the struts are VERTICAL, which they>are not. The Load on the strut increases since it's on an angle (vector>forces).>>Fortunately, the Piet's geometry is such that approximately half of the>flight loads are transmitted through the struts and the rest goes through>the root fittings. At 6 g's, only about 1200 lbs force is imposed on the>front struts and about 600 lbs through the rear.>>The compression loads are no more difficult to work out than the tensile>loads. However, the buckling model could be a little tougher. Buckling is>usually based on shape as opposed to tensile or compressive strength. In>fact, Considering that wooden struts are solid, the buckling strength>would be about the same or better than hollow aluminum tubing.>>Anyway, I hope this helps.>Ken>>________________________________________________________________________________

matronics · Post by **matronics** » Fri Aug 21, 1998 7:40 am

Original Posted By: Peter P Frantz
Subject: Pietenpol-List: Re: Struts>John,>>Thanks for posting your analysis of 6061-T6 strut strength. I'm glad tohear>that there exists streamlined material for less cash than the 4130 stuff,and>that it is being thoughtfully applied to the Piet airframe. You've shownme>that its stronger than I thought. I'll make a note of this for when I getto>that point in construction (by the time we'll all be flying hypersonicfusion>powered vehicles).>>Just one question (and remember, I'm not an engineer, but I play one atwork):>I thought that the struts were primarily used in compression, and thecables>were there to support tension stresses. Seems like the yield stress of the>strut wouldn't be terribly important under compression, but since theconcern>would be for buckling (hence, jury struts) then some factor dependent uponthe>cross section would be important (compare the compression behavior of a bar>with that of a large diameter tube of the same wall thickness). I dunno.>Also, keep in mind that your calculations assume gravitational accelerationof>1g, and turbulence could increase that (by how much, I don't know, but Iwould>guess that you're plenty safe).>>If anything that I've said above is true, then I suppose its good newssince>the compression stress will probably be much less than tension (and cablesare>real good at supporting tension: 1/8" cable has 2000lb breaking strength).>Hmmm, can anyone recommend anything for me to learn more about this;something>like "Aerodynamic Structural Analysis for Beginners"?>>--Peter>________________________________________________________________________________

matronics · Post by **matronics** » Fri Aug 21, 1998 9:52 am

Original Posted By: Peter P Frantz
Peter,Just looked up the url you gave. The same strut I am talking about and thesame vendor.John-----Original Message-----

matronics · Post by **matronics** » Fri Aug 21, 1998 11:21 am

Original Posted By: Peter P Frantz
John,Thanks for posting your analysis of 6061-T6 strut strength. I'm glad to hear that there exists streamlined material for less cash than the 4130 stuff, and that it is being thoughtfully applied to the Piet airframe. You've shown me that its stronger than I thought. I'll make a note of this for when I get to that point in construction (by the time we'll all be flying hypersonic fusion powered vehicles).Just one question (and remember, I'm not an engineer, but I play one at work):I thought that the struts were primarily used in compression, and the cables were there to support tension stresses. Seems like the yield stress of the strut wouldn't be terribly important under compression, but since the concern would be for buckling (hence, jury struts) then some factor dependent upon thecross section would be important (compare the compression behavior of a bar with that of a large diameter tube of the same wall thickness). I dunno. Also, keep in mind that your calculations assume gravitational acceleration of1g, and turbulence could increase that (by how much, I don't know, but I wouldguess that you're plenty safe).If anything that I've said above is true, then I suppose its good news since the compression stress will probably be much less than tension (and cables arereal good at supporting tension: 1/8" cable has 2000lb breaking strength). Hmmm, can anyone recommend anything for me to learn more about this; somethinglike "Aerodynamic Structural Analysis for Beginners"?--Peter________________________________________________________________________________

matronics · Post by **matronics** » Fri Aug 21, 1998 11:25 am

Original Posted By: John Greenlee
Oops, sorry John, just noticed that you specified 6g in your strut analysis asa safety factor. Sounds like plenty of room for error there!--Peter________________________________________________________________________________

matronics · Post by **matronics** » Fri Aug 21, 1998 1:20 pm

Original Posted By: Peter P Frantz
Peter,I dunno much about measuring compression loads. My friend the engineer whohelped me with this said that is hard to predict and calculate. Do you knowhow to do it?I do not know how many negative gs to plan for though I am sure it is lessthan the positive gs. Piets are flying many hours with wood struts which Iguess are weaker in compression than the aluminum struts. I am told thejury struts (which I am using) are the key. It would appear most potentialnegative gs might be in a hard landing. If the wings collapsed there itwould be messy and embarrasing, but probably not fatal.One last note on tension loads. I decided to use 1/8" cable on the wingsfor additional peace of mind.John-----Original Message-----

matronics · Post by **matronics** » Fri Aug 21, 1998 2:47 pm

Original Posted By: Peter P Frantz
On Fri, 21 Aug 1998, John Greenlee wrote:> Peter,> > I dunno much about measuring compression loads. My friend the engineer who> helped me with this said that is hard to predict and calculate. Do you know> how to do it?> > I do not know how many negative gs to plan for though I am sure it is less> than the positive gs. Piets are flying many hours with wood struts which I> guess are weaker in compression than the aluminum struts. I am told the> jury struts (which I am using) are the key. It would appear most potential> negative gs might be in a hard landing. If the wings collapsed there it> would be messy and embarrasing, but probably not fatal.> > One last note on tension loads. I decided to use 1/8" cable on the wings> for additional peace of mind.> > JohnOK, I read the original e-mail from John and now this one. There have beena couple of false assumptions made. These can be dangerous as there may bea greater load being applied to the struts than they are capable of. 1. the priginal post divided the ENTIRE wing loading at 6 g's across thefour struts. Depending on the Geometry of the struts/wing, this isunlikely to be the case. Since there is an UNEVENLY distributed load bothacross the wing spanwise and chordwise, The front strut usually takes moreof the load than the rear.2. it was also assumed that the load on both struts per side would be 550lbs at 1 g. First, the wing root fittings take some of this load. Second,depending on the wing geometry, the strut load can actually be GREATERthan the wing load. The wing and fuselage can actually work like a leveragainst the strut. The Schwitzer 2-33A would be a good example of this. Ithas a long wing but a relatively short strut. 3. The calculations also assume that the struts are VERTICAL, which theyare not. The Load on the strut increases since it's on an angle (vectorforces).Fortunately, the Piet's geometry is such that approximately half of theflight loads are transmitted through the struts and the rest goes throughthe root fittings. At 6 g's, only about 1200 lbs force is imposed on thefront struts and about 600 lbs through the rear. The compression loads are no more difficult to work out than the tensileloads. However, the buckling model could be a little tougher. Buckling isusually based on shape as opposed to tensile or compressive strength. Infact, Considering that wooden struts are solid, the buckling strengthwould be about the same or better than hollow aluminum tubing. Anyway, I hope this helps. Ken________________________________________________________________________________

matronics · Post by **matronics** » Fri Aug 21, 1998 2:53 pm

Original Posted By: "Lee L. Schiek"
John,I've said all I know about structural engineering... nay, even more than I know. There are some real engineer types around here. I'll ask around. Anyways, it sounds like this is just an academic excecise. I noticed that Aircraft Spruce sells something very similar (at a higher price, page 149 of 1998 catalog) for use on the Citabria and Piper without internal bracing. I'msure they've done the math. --Peter________________________________________________________________________________

matronics · Post by **matronics** » Fri Aug 21, 1998 4:06 pm

Original Posted By: "D.J.H."
> Now we're into the 6g range for struts. Hopefully, someone out there has > experienced +6 g's in a Piet & can add to the conversation-> Lee in MI> The only reason I used 6 g is as a basis for the ULTIMATE load. Designersfrequently use a safety factor of 1.5 between the limit load and theultimate load. For example, if a limit load of +6/-3 g is published, theplane is actually tested or designed to break at +9/-4.5g.Ken________________________________________________________________________________

matronics · Post by **matronics** » Fri Aug 21, 1998 6:34 pm

Original Posted By: Peter P Frantz
Ken Beanlands wrote:> > On Fri, 21 Aug 1998, John Greenlee wrote:> > > Peter,> >> > I dunno much about measuring compression loads. My friend the engineer who> > helped me with this said that is hard to predict and calculate. Do you know> > how to do it?> >> > I do not know how many negative gs to plan for though I am sure it is less> > than the positive gs. Piets are flying many hours with wood struts which I> > guess are weaker in compression than the aluminum struts. I am told the> > jury struts (which I am using) are the key. It would appear most potential> > negative gs might be in a hard landing. If the wings collapsed there it> > would be messy and embarrasing, but probably not fatal.> >> > One last note on tension loads. I decided to use 1/8" cable on the wings> > for additional peace of mind.> >> > John> > OK, I read the original e-mail from John and now this one. There have been> a couple of false assumptions made. These can be dangerous as there may be> a greater load being applied to the struts than they are capable of.> > 1. the priginal post divided the ENTIRE wing loading at 6 g's across the> four struts. Depending on the Geometry of the struts/wing, this is> unlikely to be the case. Since there is an UNEVENLY distributed load both> across the wing spanwise and chordwise, The front strut usually takes more> of the load than the rear.> > 2. it was also assumed that the load on both struts per side would be 550> lbs at 1 g. First, the wing root fittings take some of this load. Second,> depending on the wing geometry, the strut load can actually be GREATER> than the wing load. The wing and fuselage can actually work like a lever> against the strut. The Schwitzer 2-33A would be a good example of this. It> has a long wing but a relatively short strut.> > 3. The calculations also assume that the struts are VERTICAL, which they> are not. The Load on the strut increases since it's on an angle (vector> forces).> > Fortunately, the Piet's geometry is such that approximately half of the> flight loads are transmitted through the struts and the rest goes through> the root fittings. At 6 g's, only about 1200 lbs force is imposed on the> front struts and about 600 lbs through the rear.> > The compression loads are no more difficult to work out than the tensile> loads. However, the buckling model could be a little tougher. Buckling is> usually based on shape as opposed to tensile or compressive strength. In> fact, Considering that wooden struts are solid, the buckling strength> would be about the same or better than hollow aluminum tubing.> > Anyway, I hope this helps.> Ken> I just LUV this type of debate & opinion exchange! It makes the siteworthwhile & gives us all something to think about as we all pursue ourdreams of the perfect Piet. To you guys that have a working ortheoretical knowledge of this stuff, PLEASE keep it coming.........I'm just wondering where the line needs to be drawn so we can all geton with certified spruce/approved glue/4130 steel and other thingsthat Bernie never considered when he first started out. For example,I have NO intention of running down to True-Value for some gate straphinges to hold my ailerons on, but by damn, it DID work, didn't it?Now we're into the 6g range for struts. Hopefully, someone out there has experienced +6 g's in a Piet & can add to the conversation-Anyway, this is not to be construed as critisism, just an observation.For my personal plans, if Will Graff used ash & mahogany ply sandwich w/ jury struts, and is still alive & flying after all this time, maybe,just maybe, alternatives DO WORK in the real world of Piet flight.Keep up the debate! Every point raised makes me think & double-think,and that's one of the great values of web discussion groups.Low & Slow,Lee in MI________________________________________________________________________________

matronics · Post by **matronics** » Fri Aug 21, 1998 7:03 pm

Original Posted By: Ken Beanlands
Ken,Thanks for the insight. It sounds like at 1200 lbs force, the aluminumstrut is 2.63 times strong enough! I got mild steel streamline tube for thecabanes.My education is all in business. (Accounting, actually). Maybe that's whymy mind is always looking for a cheaper way.......John-----Original Message-----

matronics · Post by **matronics** » Fri Aug 21, 1998 7:14 pm

Original Posted By: rdecosta(at)autoeurope.com (Richard DeCosta)
Ken Beanlands wrote:> > > Now we're into the 6g range for struts. Hopefully, someone out there has> > experienced +6 g's in a Piet & can add to the conversation-> > Lee in MI> >> > The only reason I used 6 g is as a basis for the ULTIMATE load. Designers> frequently use a safety factor of 1.5 between the limit load and the> ultimate load. For example, if a limit load of +6/-3 g is published, the> plane is actually tested or designed to break at +9/-4.5g.> > Ken> Good points! That's why I really appreciate this theory talk.......>From my personal knowledge, I have to think that +9 -4.5 g's inANY airplane will be a moot point - my rib cage, lungs and arteriesto my brain will have given up the ghost about 5-6 g's before that!I guess it's nice to know my airplane will disintergrate long aftermy tired 52 year old, out-of-condition body does. Keep up the contributions - I really enjoy them. By the time I've absorbedall the postings, maybe Boeing will be after me!Low & SlowLee in MI________________________________________________________________________________

matronics · Post by **matronics** » Mon Aug 31, 1998 12:15 pm

Original Posted By: Ian Holland
I can't remember the source though I have their papers in my stuffsomewhere. It is not eliptical stuff but true streamline stuff. They arenot sold by the foot but in I think 8 ft lengths. Something like 25 or 35bucks a piece. I bought the smallest size they had which is similar to thestruts drawn on the Piet plans and ample strong enough for a Piet. The wallthickness is heaver than a comparable steel strut.Look in the back of Sport Aviation and Kitplanes and there are a couple ofdealers listed. One in Ohio and one in Arizona I think. I used the guy inOhio I think. This stuff is intended for the ultralite industry probably.John-----Original Message-----

matronics · Post by **matronics** » Sun May 07, 2000 11:44 pm

Original Posted By: Eugene Hubbard

matronics · Post by **matronics** » Mon May 08, 2000 1:38 am

Original Posted By: Kirk Huizenga
Subject: Pietenpol-List: StrutsHello Warren Shoun::Do you happen to know the wall thickness of theSky-tec struts? I didn"t see it marked on the Sky tec page you gave us,and if it was the print was to small to read. I have a a set of alum.struts with .049 wall. I'm worried I should go with a heavier thickness.Thank you Leon S.________________________________________________________________________________Date: Mon, 8 May 2000 10:04:18 -0500

matronics · Post by **matronics** » Sun Jun 22, 2014 7:21 am

Original Posted By: Bill
Small error in my post below. The wall thickness of the struts is .065, not .035.SorryScott K. Sent from my iPhone> On Jun 21, 2014, at 7:23 AM, "Scott Knowlton" wrote:> > > For those builders who do not yet have struts for their project I know of a verynice set that are available in Ontario, Canada. They were purpose built fora plans built Pietenpol with .035 streamlined 4130 and all four have properaircraft fork ends. They were epoxy primed and are painted black. The aircraftowner has opted for J3 style sealed struts instead so these (according to theAME who is building the Piet) are surplus to the owner's requirements. > I know the AME and can put anyone interested in touch with him for more details.Contact me off list if interested. > Happy flying this weekend!> > Scott Knowlton> Builder in Burlington Ontario> > Sent from my iPhone> > > > ________________________________________________________________________________Date: Sun, 22 Jun 2014 11:21:53 -0400