Pietenpol-List: spar weight

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Pietenpol-List: spar weight

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Original Posted By: "Rodger & Betty Childs"
To impede the collection of moisture in the wing & tail surfaces, Iinstalled seaplane fittings in each bay. Drainage is enhanced in flightby the negative pressure created by the accelerated airflow over thesurfaces.Mike B Piet N687MB ( Mr Sam )________________________________________________________________________________
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Pietenpol-List: spar weight

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Original Posted By: Michael D Cuy
-- Pietenpol-List message posted by: "Michael Brusilow" To impede the collection of moisture in the wing tail surfaces, I installed seaplane fittings in each bay. Drainage is enhanced in flight by the negative pressure created by the accelerated airflow over the surfaces. Mike B Piet N687MB ( Mr Sam ) ________________________________________________________________________________Date: Tue, 06 Feb 2001 14:51:51 -0500
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Re: Pietenpol-List: spar weight

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Original Posted By:> John McNarry
Hi John, Actually I have not joined the RAA yet, though a friend has invited metoI think that particular meeting. Don't know my work schedule off hand butif I am around I just might go. Your clock has been complete and runningabout 4 weeks now. Looks good in my basement! Let me know if you arecoming to Winnipeg. I expect I won't be going out west for a couple ofmonths. As far as spar weights, my Baltic birch plywood laminated spar came outto15.3 lbs for the rear spar. The front is heavier as I left extra materialon the top to meet the capstrips without using a wedge but I have not yetcut it to exact size so have not weighed it. I weighed a friends freshlycut Sitka spruce spars last night. His rear spar was 10 lbs(3/4x4 3/4) andhis front spar was 14 lbs (1 inch x full height possible - about 4 3/4 onfront edge and 5 1/4 rear face). Based on this I suspect my total weightgain for the Baltic plywood spars will be about 12 -15lbs over usingunrouted Sitka spars, and 20-25 over routed Sitka spars or about 20 over3/4" Sitka. Not real happy with the weight gain as I think I am buildingmost components too heavy. It was about 1/5 the cost of Sitka.Wayne Sippola, Winnipeg
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Re: Pietenpol-List: spar weight

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Original Posted By: "Mike Bell"
Subject: Pietenpol-List: Re: Hardware1 )I have the aluminum hinges for the tail they come with 3/16 steel pins and I am wondering if I switched to stainless steel pins and cotter pins would this reduce the chance of galvanic interaction2 ) I would like to use stainless flat head screws, with nyloc nuts to hold the hinge castings in place in the wood--- ( a ) can I purchase these locally or should they be aircraft quallity specification only ( b ) what is a good source for such hardware3 ) when installing the hinges, is it advisable to varnish them before putting them into the wood - or some other treatment --or none?? thanks for any advice Henry Williams________________________________________________________________________________Subject: Re: Pietenpol-List: spar weight
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Post by matronics »

Original Posted By:> John McNarry
02/06/2001 08:50:03 AMHow long were the spars that you're referring to? I'd like to get aweight per foot to compare methods. I'll be starting to laminatespars soon. I have a big, beautiful piece of ash that will give mesome 1 inch by 1/4 inch cap strips.Thanks,Mike "Wayne Sippola" To: Sent by: cc: owner-pietenpol-list-server@mat Subject: Re: Pietenpol-List:spar weight ronics.com 02/03/2001 10:52 AM Please respond to pietenpol-list Hi John, Actually I have not joined the RAA yet, though a friend hasinvited me toI think that particular meeting. Don't know my work schedule off handbutif I am around I just might go. Your clock has been complete andrunningabout 4 weeks now. Looks good in my basement! Let me know if you arecoming to Winnipeg. I expect I won't be going out west for a coupleofmonths. As far as spar weights, my Baltic birch plywood laminated sparcame out to15.3 lbs for the rear spar. The front is heavier as I left extramaterialon the top to meet the capstrips without using a wedge but I have notyetcut it to exact size so have not weighed it. I weighed a friendsfreshlycut Sitka spruce spars last night. His rear spar was 10 lbs(3/4x43/4) andhis front spar was 14 lbs (1 inch x full height possible - about 4 3/4onfront edge and 5 1/4 rear face). Based on this I suspect my totalweightgain for the Baltic plywood spars will be about 12 -15lbs over usingunrouted Sitka spars, and 20-25 over routed Sitka spars or about 20over3/4" Sitka. Not real happy with the weight gain as I think I ambuildingmost components too heavy. It was about 1/5 the cost of Sitka.Wayne Sippola, Winnipeg
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Re: Pietenpol-List: spar weight

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Original Posted By: "Michael Brusilow"
I have an idea but am not sure what a "seaplane fitting" is. Could you elaborate?Thanks. Dave Boyd, Champaign, IL
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Re: Pietenpol-List: spar weight

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Original Posted By:> Mike Bell
Spars were 13' long for use with a 36" center section. What are you usingfor your web?Wayne Sippola, Winnipeg
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Original Posted By:> Mike Bell
02/07/2001 08:10:40 AMI'm thinking about three layers of 1/8 inch ac birch ply. I haven'tlooked at the AC Spruce catalog to lay out the least expensivecombination to get at least 3/8 in the web.______________|______________|| | | || | | || | | || | | || | | ||______| |_______| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |_____ | | | |______| | | || | | || | | || | | || | | ||______| |_______||______________ |1 - Ash cap 1/4 x 1 top and bottom2 - Spruce 7/16 x 1 1/2 top2 - Spruce 7/16 x 1 bottom3 - AC Birch ply 1/8 inch layers in the web one of which extends tothe capsI'm not entirely happy with the top and bottom of the web. Where 3/8goes to 1/8 should have some spruce overlapping.I laid it out this way to minimize amount of AC BIrch Ply and cost,but I think that the 3/8 ought to go all the way to the caps.I still have the fuse on the work table, so I have a little more timeto think it through.Mike "Wayne Sippola" To: Sent by: cc: owner-pietenpol-list-server@mat Subject: Re: Pietenpol-List:spar weight ronics.com 02/06/2001 01:32 PM Please respond to pietenpol-list Spars were 13' long for use with a 36" center section. What are youusingfor your web?Wayne Sippola, Winnipeg
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Re: Pietenpol-List: spar weight

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Original Posted By: Mike Bell
Sounds like it's time to dig out a copy of Bruhn's "Analysis & Design ofAirplane Structures" or "Stress Without Tears" to do some figuring -- bothof these books have good sections on wood spar design -- just matching thedimensions of a spar doesn't always work out.If you don't mind mixing & matching materials, you might check outwww.continuo.com/marske/carbon/carbon.htm for some info on 1/8" dia. carbonrods -- the rough numbers show that (4) of these are equal to a 1" sq.capstrip in a spar -- added to the top & bottom of the typical Piet sparmakes it twice as strong. 240 ft @ $.60 / ft. At last a hi-tech one piecewing!! ;-)Mike----- Original Message -----
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Re: Pietenpol-List: spar weight

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Original Posted By: "Mike Bell"
Mike,Concerning the built up spar, I wonder, there are two things that don't lookgood.Several years ago, Kitplanes ran an article about built up spars and theyhad suggested that the spar web go all the way thru the cap strips in fullwidth, not stepped down. With the spar web stepped down this wouldconcentrate loadsat the transion point to the thinner web.Also, I think the ash strip on the top and bottom of the spar caps should bethe same material as the cap strips, spruce. The reason for this is, the ashis stronger than the spruce and thus will direct the load to the spruce capstrips and over load them.Ok, there are three things, the ash is going to add alot of extra weight.Rodger ChildsPiet in progress________________________________________________________________________________Subject: Re: Pietenpol-List: spar weight
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Original Posted By: Mike Bell
02/08/2001 08:47:02 AMDo you have an old copy of Bruhn? One that still has the wood designsection? If so, how long is the wood section and will you make acopy?I've been using Stress Without Tears. It's good, but the limitedexamples often leave some doubt.The 3/8 in ply web will handle the shear stress. And the combined capwill be stronger than a one inch AC grade spruce. I looked at thedrawing and considered the small glue area at the top and bottom ofthe two outer layers of the web and didn't like very the limitedsurface area to transfer the stress through. The simplest improvementwould be to make them a little taller and rabbet them into the sprucecap strips. I'm a big fan of laminating stuff. It really diminishesthe possibility of an unseen defect spoiling the spar.The carbon fiber rod sounds great. I had considered a layer of carbonfiber cloth in both caps, but I'm not familiar with using it in alamination combined with wood. I wouldn't know what to expect if thefiber cloth was between wood laminations.By the way, on a related subject, I saw a picture of a jig to use witha router that would make cutting the 15:1 angle for scarfing things abreeze. It's really just a box that carries the router above the worksurface. It was shown as a method for planing small areas or levelingthe ends of odd bits up to logs. But, with a small wedge strip on oneside it would plane at the correct angle. A router gives a muchsmoother surface than I had imagined and I plan to make a lot more useof the one I have.Mike "Michael Conkling" To: Sent by: cc: owner-pietenpol-list-server@mat Subject: Re: Pietenpol-List:spar weight ronics.com 02/07/2001 09:40 PM Please respond to pietenpol-list Sounds like it's time to dig out a copy of Bruhn's "Analysis & DesignofAirplane Structures" or "Stress Without Tears" to do some figuring --bothof these books have good sections on wood spar design -- just matchingthedimensions of a spar doesn't always work out.If you don't mind mixing & matching materials, you might check outwww.continuo.com/marske/carbon/carbon.htm for some info on 1/8" dia.carbonrods -- the rough numbers show that (4) of these are equal to a 1" sq.capstrip in a spar -- added to the top & bottom of the typical Pietsparmakes it twice as strong. 240 ft @ $.60 / ft. At last a hi-tech onepiecewing!! ;-)Mike----- Original Message -----
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Original Posted By: Michael D Cuy
02/08/2001 09:01:07 AMThe thin ash cap strip comes from an old NACA publication that someonewas kind enough to give reference to recently. The stress is greatestat the furthest from the center of the spar. The ash is nearly twiceas strong as spruce at a large penalty in weight, but a small amountused where there is the greatest need gives a lot of bang for theounces added.The glue area of ash to spruce is quite large and will successfullytransfer all of the load. The NACA publication compared solid sparsto laminated spars with a 1/8 or 1/16 inch maple cap strip and got asignificant increase in load before failure with the cap lamination.I think that you're correct about continuing the plywood web further,up to as much as through the caps strips.Thanks,Mikeps. If anyone out there has an old copy of Bruhn, it would be doing agreat favor to make copies of the wood design section available. "Rodger & Betty Childs" To: "Pietenpol List" Sent by: cc: owner-pietenpol-list-server@mat Subject: Pietenpol-List:Spar weight ronics.com 02/07/2001 10:21 PM Please respond to pietenpol-list Mike,Concerning the built up spar, I wonder, there are two things thatdon't lookgood.Several years ago, Kitplanes ran an article about built up spars andtheyhad suggested that the spar web go all the way thru the cap strips infullwidth, not stepped down. With the spar web stepped down this wouldconcentrate loadsat the transion point to the thinner web.Also, I think the ash strip on the top and bottom of the spar capsshould bethe same material as the cap strips, spruce. The reason for this is,the ashis stronger than the spruce and thus will direct the load to thespruce capstrips and over load them.Ok, there are three things, the ash is going to add alot of extraweight.Rodger ChildsPiet in progress________________________________________________________________________________Date: Thu, 08 Feb 2001 09:21:35 -0500
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Re: Pietenpol-List: spar weight

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Original Posted By: Mike Bell
Hi Mike,My "Bruhn" is 1943 copy -- the "Wood Beams and Fittings" chapter is 14pages -- good stuff! $2 should cover coping & postage.Any one else need information for thier archives??Mike in Pretty Prairie, KS----- Original Message -----
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Re: Pietenpol-List: spar weight

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Original Posted By: Christian Bobka
Subject: Re: Pietenpol-List: spar weightIn a message dated 2/8/01 8:40:49 PM Eastern Standard Time, hpvs(at)southwind.net writes:> Mike, if this is not asking too much, could this be scanned and placed on the Web somewhere ? Unless of course its copyrighted________________________________________________________________________________Date: Fri, 9 Feb 2001 00:21:16 -0500
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Re: Pietenpol-List: spar weight

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Original Posted By: Michael Conkling
I'll do it Mike. Get the copies made and send me your address and I'll sendyou a couple bucks.GregGridley, KS----- Original Message -----
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Re: Pietenpol-List: spar weight

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Original Posted By: Greg Yotz
Greg,I'll make up some sets the first part of next week.Mike Conkling21806 S. Broadacres Rd.Pretty Prairie, KS 67570----- Original Message -----
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> Re: Pietenpol-List: spar weight

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Original Posted By: "R deCosta"
> > > > How long were the spars that you're referring to? I'd like to get a> weight per foot to compare methods. I'll be starting to laminate> spars soon. I have a big, beautiful piece of ash that will give me> some 1 inch by 1/4 inch cap strips.> > Thanks,> > Mike________________________________________________________________________________
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Re: Pietenpol-List: spar weight

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Original Posted By: "Mike Bell"
>>>> How long were the spars that you're referring to? I'd like to get a> weight per foot to compare methods. I'll be starting to laminate> spars soon. I have a big, beautiful piece of ash that will give me> some 1 inch by 1/4 inch cap strips.>> Thanks,>> Mike________________________________________________________________________________Subject: Re: Pietenpol-List: spar weight
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> Re: Pietenpol-List: spar weight

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Original Posted By: "Warren D. Shoun"
>>>> How long were the spars that you're referring to? I'd like to get a> weight per foot to compare methods. I'll be starting to laminate> spars soon. I have a big, beautiful piece of ash that will give me> some 1 inch by 1/4 inch cap strips.>> Thanks,>> Mike________________________________________________________________________________Date: Wed, 07 Feb 2001 09:18:47 -0800
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> > Re: Pietenpol-List: spar weight

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Original Posted By: "Rodger & Betty Childs"
> >> > >> >> > How long were the spars that you're referring to? I'd like to get a> > weight per foot to compare methods. I'll be starting to laminate> > spars soon. I have a big, beautiful piece of ash that will give me> > some 1 inch by 1/4 inch cap strips.> >> > Thanks,> >> > Mike>>________________________________________________________________________________
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Re: Pietenpol-List: Spar weight

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Original Posted By: "Mike Bell"
> >> > >> >> > How long were the spars that you're referring to? I'd like to geta> > weight per foot to compare methods. I'll be starting to laminate> > spars soon. I have a big, beautiful piece of ash that will giveme> > some 1 inch by 1/4 inch cap strips.> >> > Thanks,> >> > Mike>>________________________________________________________________________________Subject: Re: Pietenpol-List: Spar weight
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