Original Posted By: "ALAN LYSCARS"
Re: Pietenpol-List: Re: CONTACT! Magazine, Pietenpol
RE: Pietenpol-List: Roman Bukolt's Riblett Airfoil
Original Posted By: "Phillips, Jack"
RE: Pietenpol-List: Roman Bukolt's Riblett Airfoil
Original Posted By: "Bill Church"
Alan;The spar strength, dimensions, and materials are selected by the designer basedon the wing span, chord, weight of the aircraft, and design G-loading. If you'renot changing the location of the spars relative to the leading edge, notchanging the wing chord, not changing any of the other factors- if a 3/4" thickspar was OK with the Pietenpol airfoil I would think it would be OK with anotherfoil.Sure, there are other factors that play into the selection such as pitching moment(twist) and other effects that change when the airfoil is changed, but nonethat would affect the spar thickness OTHER THAN THE SPAR DEPTH, which is ofcourse a very big consideration. I thought that the Riblett was a thicker airfoilthan the Piet, in which case the spars are deeper... even more reason whythe 3/4" should be acceptable if they were OK on the Pietenpol airfoil.Disclaimer: I'm not an aerodynamicist, a structural engineer, or an aero engineer!Oscar ZunigaAir Camper NX41CCSan Antonio, TXmailto: taildrags(at)hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________Subject: RE: Pietenpol-List: Roman Bukolt's Riblett AirfoilDate: Mon, 21 Jan 2008 14:37:38 -0500
Alan;The spar strength, dimensions, and materials are selected by the designer basedon the wing span, chord, weight of the aircraft, and design G-loading. If you'renot changing the location of the spars relative to the leading edge, notchanging the wing chord, not changing any of the other factors- if a 3/4" thickspar was OK with the Pietenpol airfoil I would think it would be OK with anotherfoil.Sure, there are other factors that play into the selection such as pitching moment(twist) and other effects that change when the airfoil is changed, but nonethat would affect the spar thickness OTHER THAN THE SPAR DEPTH, which is ofcourse a very big consideration. I thought that the Riblett was a thicker airfoilthan the Piet, in which case the spars are deeper... even more reason whythe 3/4" should be acceptable if they were OK on the Pietenpol airfoil.Disclaimer: I'm not an aerodynamicist, a structural engineer, or an aero engineer!Oscar ZunigaAir Camper NX41CCSan Antonio, TXmailto: taildrags(at)hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________Subject: RE: Pietenpol-List: Roman Bukolt's Riblett AirfoilDate: Mon, 21 Jan 2008 14:37:38 -0500
Pietenpol-List: Re: Roman Bukolt's Riblett Airfoil
Original Posted By: "Don Emch"
I believe that one of the methods of determining Vne is that it is set at 90% of dive speed, Vd, and that Vd is required to be 1.4 times design cruise speed for certification in the normal category.Let's take an example... my airplane. I think I redlined my airspeed indicator at 95MPH (based on somebody else's info), which would mean it should have been designed for Vd of 105MPH but I have no idea if it was. It also means that cruise speed should be about 75MPH and that's pretty close to where I cruise, if a little high. But here's better information: the Pietenpol family website shows the original Piet "high speed" as 90MPH. That would hint at a designer's approved Vd of 100MPH and a cruise of 71MPH, which sounds more like reality for this airplane.I have heard that in order to flight-test to determine Vne, you'd have to fly at Vd for three minutes with no damage or flutter, then redline your Vne at 90% of the tested Vd. I'm not sure I'd want to hold 41CC at 105MPH for three minutes, or that it even could do that without me climbing waaayyy on up there to get enough altitude for the dive. It would really be coming down at that speed.Oscar ZunigaSan Antonio, TXmailto: taildrags@hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________Subject: Pietenpol-List: Re: Roman Bukolt's Riblett Airfoil
I believe that one of the methods of determining Vne is that it is set at 90% of dive speed, Vd, and that Vd is required to be 1.4 times design cruise speed for certification in the normal category.Let's take an example... my airplane. I think I redlined my airspeed indicator at 95MPH (based on somebody else's info), which would mean it should have been designed for Vd of 105MPH but I have no idea if it was. It also means that cruise speed should be about 75MPH and that's pretty close to where I cruise, if a little high. But here's better information: the Pietenpol family website shows the original Piet "high speed" as 90MPH. That would hint at a designer's approved Vd of 100MPH and a cruise of 71MPH, which sounds more like reality for this airplane.I have heard that in order to flight-test to determine Vne, you'd have to fly at Vd for three minutes with no damage or flutter, then redline your Vne at 90% of the tested Vd. I'm not sure I'd want to hold 41CC at 105MPH for three minutes, or that it even could do that without me climbing waaayyy on up there to get enough altitude for the dive. It would really be coming down at that speed.Oscar ZunigaSan Antonio, TXmailto: taildrags@hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________Subject: Pietenpol-List: Re: Roman Bukolt's Riblett Airfoil
RE: Pietenpol-List: determining Vne
Original Posted By: "Phillips, Jack"
Alan, I'll just add my 2 cents worth, even though we all know how little 2 cents isworth nowadays. When Pietenpol designed his wing, he designed it based on trialand error. Probably lots of error. He built it with a 1" thick spar routedto an I beam. Later on he had trouble finding suitable 1" x 4 3/4" boards.So he opted to laminate smaller pieces into a 3/4" x 4 3/4" non-routed spar.He felt, as many do, that a properly laminated spar is somewhat stronger thanone of the same size but solid. As far as I can tell in researching, he didnot use solid 3/4" spars. I could be wrong though. I believe the 3/4" sparswe see in the 3-piece wing plans were of the built up laminated type. I knowthere are lots of ships out there with solid 3/4" spars and as far as I know,none have fallen out of the sky, so I guess my point might very well not meanmuch of anything. I just thought I'd share what I've come across in my Pietenpolexperiences. As a side note Frank Pavliga is recovering Sky Gypsy and should be done withit in the Spring. He bought Lowell Frank's Lambert engine to power it. He flewMr. Frank's airplane just before he bought the engine off of it and told methat the performance was very good. He also said he could tell the wing wasdifferent ( has a Riblett airfoil). He mentioned it felt very pitch sensitive.And that's coming from a pilot with 1400 hours in his own Piet. Just a thoughtto those thinking about changing the airfoil. But of course I'm very biasedabout the Pietenpol design!Don EmchNX899DERead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: RE: Pietenpol-List: determining VneDate: Mon, 21 Jan 2008 15:20:23 -0500
Alan, I'll just add my 2 cents worth, even though we all know how little 2 cents isworth nowadays. When Pietenpol designed his wing, he designed it based on trialand error. Probably lots of error. He built it with a 1" thick spar routedto an I beam. Later on he had trouble finding suitable 1" x 4 3/4" boards.So he opted to laminate smaller pieces into a 3/4" x 4 3/4" non-routed spar.He felt, as many do, that a properly laminated spar is somewhat stronger thanone of the same size but solid. As far as I can tell in researching, he didnot use solid 3/4" spars. I could be wrong though. I believe the 3/4" sparswe see in the 3-piece wing plans were of the built up laminated type. I knowthere are lots of ships out there with solid 3/4" spars and as far as I know,none have fallen out of the sky, so I guess my point might very well not meanmuch of anything. I just thought I'd share what I've come across in my Pietenpolexperiences. As a side note Frank Pavliga is recovering Sky Gypsy and should be done withit in the Spring. He bought Lowell Frank's Lambert engine to power it. He flewMr. Frank's airplane just before he bought the engine off of it and told methat the performance was very good. He also said he could tell the wing wasdifferent ( has a Riblett airfoil). He mentioned it felt very pitch sensitive.And that's coming from a pilot with 1400 hours in his own Piet. Just a thoughtto those thinking about changing the airfoil. But of course I'm very biasedabout the Pietenpol design!Don EmchNX899DERead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: RE: Pietenpol-List: determining VneDate: Mon, 21 Jan 2008 15:20:23 -0500
Pietenpol-List: determining Vne
Original Posted By: "ALAN LYSCARS"