Original Posted By: "walter evans"
Subject: Pietenpol-List: "a little play in the lower end of lift strut"This was mentioned in a past issue of the BPANews. The comment given was"better use jury struts". I assumed the flexing was due to the lack ofjurystruts, Apparently in the "old days", streamlined tubing had ribsformed in them for stiffness. That's how BHP got away with no jurystruts. evidently there was still some vibration flexing he wasconcerned about. Now days streamline tubing don"t have the extrastiffener ribs(like shown on the plans) and everyone uses jury struts.Perhaps some engineer could tell us if this cristalising problem is athing of the past with jury struts at mid length holding the lift strutsfirmly. Leon S.________________________________________________________________________________
Pietenpol-List: "a little play in the lower end of lift strut"
> Pietenpol-List: "a little play in the lower end of lift strut"
Original Posted By: "Gene Rambo"
I'm not an engineer but i think that the jury strut is supposed to resist compression loads . A compression load will/should cause the strut to collaps at its least supported location...the middle.The compression strut then acts to shorten the length on the unsupported wing strut by half. Causing any compression loads to be concentrated at two new centers...each of those at the half way point from the jury strut .In effect causing the wing strut to be 1/2 as long as what you see, and causing the stresses to concentrate at two places, each at the 1/4 full strut length points from each end.It seems to me that we could still eliminate the jury strut. The solution may be to incert a piece of tubing say 3ft feet long or so, with its center at the center of the area of greatest compression load.That being the at the jury strut location.By doubling the thickness of the strut at this area of greatest compressive stress...then tapering the tube like the lever end of a cloths pin at both ends...so to allow stress to flow away from a potential stress riser, one could send the compressive stress concentration to two new centers,,, both at the 1/2 way... away location of the jury strut. ( 2 , 1/4 locations if one were looking at the full length strut)The effect should be the same as a jury strut, in that stress would in effect be acting upon a strut that is as far as the compressive stress is concerned is 1/2 its origonal lenght.If what I said makes any sence that is...>From: leonstefanhutks(at)webtv.net (Leon Stefan)>Reply-To: pietenpol-list(at)matronics.com>To: Pietenpol-List(at)matronics.com>Subject: Pietenpol-List: "a little play in the lower end of lift strut">Date: Fri, 26 May 2000 08:40:43 -0500 (CDT)>>Stefan)>>This was mentioned in a past issue of the BPANews. The comment given was>"better use jury struts". I assumed the flexing was due to the lack of>jurystruts, Apparently in the "old days", streamlined tubing had ribs>formed in them for stiffness. That's how BHP got away with no jury>struts. evidently there was still some vibration flexing he was>concerned about. Now days streamline tubing don"t have the extra>stiffener ribs(like shown on the plans) and everyone uses jury struts.>Perhaps some engineer could tell us if this cristalising problem is a>thing of the past with jury struts at mid length holding the lift struts>firmly. Leon S.>>________________________________________________________________________________
I'm not an engineer but i think that the jury strut is supposed to resist compression loads . A compression load will/should cause the strut to collaps at its least supported location...the middle.The compression strut then acts to shorten the length on the unsupported wing strut by half. Causing any compression loads to be concentrated at two new centers...each of those at the half way point from the jury strut .In effect causing the wing strut to be 1/2 as long as what you see, and causing the stresses to concentrate at two places, each at the 1/4 full strut length points from each end.It seems to me that we could still eliminate the jury strut. The solution may be to incert a piece of tubing say 3ft feet long or so, with its center at the center of the area of greatest compression load.That being the at the jury strut location.By doubling the thickness of the strut at this area of greatest compressive stress...then tapering the tube like the lever end of a cloths pin at both ends...so to allow stress to flow away from a potential stress riser, one could send the compressive stress concentration to two new centers,,, both at the 1/2 way... away location of the jury strut. ( 2 , 1/4 locations if one were looking at the full length strut)The effect should be the same as a jury strut, in that stress would in effect be acting upon a strut that is as far as the compressive stress is concerned is 1/2 its origonal lenght.If what I said makes any sence that is...>From: leonstefanhutks(at)webtv.net (Leon Stefan)>Reply-To: pietenpol-list(at)matronics.com>To: Pietenpol-List(at)matronics.com>Subject: Pietenpol-List: "a little play in the lower end of lift strut">Date: Fri, 26 May 2000 08:40:43 -0500 (CDT)>>Stefan)>>This was mentioned in a past issue of the BPANews. The comment given was>"better use jury struts". I assumed the flexing was due to the lack of>jurystruts, Apparently in the "old days", streamlined tubing had ribs>formed in them for stiffness. That's how BHP got away with no jury>struts. evidently there was still some vibration flexing he was>concerned about. Now days streamline tubing don"t have the extra>stiffener ribs(like shown on the plans) and everyone uses jury struts.>Perhaps some engineer could tell us if this cristalising problem is a>thing of the past with jury struts at mid length holding the lift struts>firmly. Leon S.>>________________________________________________________________________________
Re: Pietenpol-List: "a little play in the lower end of lift strut"
Original Posted By:> oil can
However true all of this may be, the jury strut also prevents excessivevibration of the strut (and therefore destruction at the ends) just likethe javelin in the flying wires of a biplane.----------
However true all of this may be, the jury strut also prevents excessivevibration of the strut (and therefore destruction at the ends) just likethe javelin in the flying wires of a biplane.----------
> > Pietenpol-List: "a little play in the lower end of lift strut"
Original Posted By: leonstefanhutks(at)webtv.net (Leon Stefan)
> > > > I'm not an engineer but i think that the jury strut is supposed to resist> compression loads . A compression load will/should cause the strut to > collaps at its least supported location...the middle.> > The compression strut then acts to shorten the length on the unsupported > wing strut by half. Causing any compression loads to be concentrated attwo > new centers...each of those at the half way point from the jury strut .> In effect causing the wing strut to be 1/2 as long as what you see, and > causing the stresses to concentrate at two places, each at the 1/4 full > strut length points from each end.> > It seems to me that we could still eliminate the jury strut. The solution> may be to incert a piece of tubing say 3ft feet long or so, with itscenter > at the center of the area of greatest compression load.> That being the at the jury strut location.> > By doubling the thickness of the strut at this area of greatestcompressive > stress...then tapering the tube like the lever end of a cloths pin atboth > ends...so to allow stress to flow away from a potential stress riser, one> could send the compressive stress concentration to two new centers,,,both > at the 1/2 way... away location of the jury strut. ( 2 , 1/4 locationsif > one were looking at the full length strut)> > The effect should be the same as a jury strut, in that stress would in > effect be acting upon a strut that is as far as the compressive stress is> concerned is 1/2 its origonal lenght.> > If what I said makes any sence that is...> > >From: leonstefanhutks(at)webtv.net (Leon Stefan)> >Reply-To: pietenpol-list(at)matronics.com> >To: Pietenpol-List(at)matronics.com> >Subject: Pietenpol-List: "a little play in the lower end of lift strut"> >Date: Fri, 26 May 2000 08:40:43 -0500 (CDT)> >> >Stefan)> >> >This was mentioned in a past issue of the BPANews. The comment given was> >"better use jury struts". I assumed the flexing was due to the lack of> >jurystruts, Apparently in the "old days", streamlined tubing had ribs> >formed in them for stiffness. That's how BHP got away with no jury> >struts. evidently there was still some vibration flexing he was> >concerned about. Now days streamline tubing don"t have the extra> >stiffener ribs(like shown on the plans) and everyone uses jury struts.> >Perhaps some engineer could tell us if this cristalising problem is a> >thing of the past with jury struts at mid length holding the lift struts> >firmly. Leon S.> >> >> > > > ________________________________________________________________________________
> > > > I'm not an engineer but i think that the jury strut is supposed to resist> compression loads . A compression load will/should cause the strut to > collaps at its least supported location...the middle.> > The compression strut then acts to shorten the length on the unsupported > wing strut by half. Causing any compression loads to be concentrated attwo > new centers...each of those at the half way point from the jury strut .> In effect causing the wing strut to be 1/2 as long as what you see, and > causing the stresses to concentrate at two places, each at the 1/4 full > strut length points from each end.> > It seems to me that we could still eliminate the jury strut. The solution> may be to incert a piece of tubing say 3ft feet long or so, with itscenter > at the center of the area of greatest compression load.> That being the at the jury strut location.> > By doubling the thickness of the strut at this area of greatestcompressive > stress...then tapering the tube like the lever end of a cloths pin atboth > ends...so to allow stress to flow away from a potential stress riser, one> could send the compressive stress concentration to two new centers,,,both > at the 1/2 way... away location of the jury strut. ( 2 , 1/4 locationsif > one were looking at the full length strut)> > The effect should be the same as a jury strut, in that stress would in > effect be acting upon a strut that is as far as the compressive stress is> concerned is 1/2 its origonal lenght.> > If what I said makes any sence that is...> > >From: leonstefanhutks(at)webtv.net (Leon Stefan)> >Reply-To: pietenpol-list(at)matronics.com> >To: Pietenpol-List(at)matronics.com> >Subject: Pietenpol-List: "a little play in the lower end of lift strut"> >Date: Fri, 26 May 2000 08:40:43 -0500 (CDT)> >> >Stefan)> >> >This was mentioned in a past issue of the BPANews. The comment given was> >"better use jury struts". I assumed the flexing was due to the lack of> >jurystruts, Apparently in the "old days", streamlined tubing had ribs> >formed in them for stiffness. That's how BHP got away with no jury> >struts. evidently there was still some vibration flexing he was> >concerned about. Now days streamline tubing don"t have the extra> >stiffener ribs(like shown on the plans) and everyone uses jury struts.> >Perhaps some engineer could tell us if this cristalising problem is a> >thing of the past with jury struts at mid length holding the lift struts> >firmly. Leon S.> >> >> > > > ________________________________________________________________________________