Original Posted By: "C N Campbell"
Subject: Pietenpol-List: Re: Kevin's new Cloudcars propKevin, that prop is beautiful. Great idea to keep the warp drive for the Brodhead trek - guess that means you're planning on flying up this year. Heck, I'd have sold you a special clip-tip Cloudcars prop, especially modifiedand including mud and grass stains. Matt Paxton________________________________________________________________________________
Pietenpol-List: Re: Kevin's new Cloudcars prop
Re: Pietenpol-List: Wood Lift Struts
Original Posted By: Gboothe5
Gary, I can buy a set of T-craft struts that a friend of mine had to take off his plane and replace with new. He says the old ones are perfectly sound -- he had to replace because of an STC or something. Do you think they would be as serviceable as laminated wooden struts? I am planning to use wooden landing gear legs. Chuck ----- Original Message -----
Gary, I can buy a set of T-craft struts that a friend of mine had to take off his plane and replace with new. He says the old ones are perfectly sound -- he had to replace because of an STC or something. Do you think they would be as serviceable as laminated wooden struts? I am planning to use wooden landing gear legs. Chuck ----- Original Message -----
RE: Pietenpol-List: Wood Lift Struts
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Chuck,Most Piet builders would love to stumble upon a set of used struts, as youhave! My choice of wood is merely personal. Carry on, young man!!Gary from CoolNX308MB
Chuck,Most Piet builders would love to stumble upon a set of used struts, as youhave! My choice of wood is merely personal. Carry on, young man!!Gary from CoolNX308MB
Pietenpol-List: Re: Wood Lift Struts
Original Posted By: "tools"
It seems to me that the main issue with wood struts is how you attach the end fittings.The issue there is preventing elongation of the holes, and minimizingany structural integrity issues that may arise if they do.First, nearly all wood/metal interfaces rely on friction between the fitting andthe wood to prevent the penetrating bolts from relying on shear force. Thebolt can handle the shear, the metal fitting can handle the shear, the wood isclearly the weakest link. In the case of mounting a wood prop, Sensenich's documentation clearly states thatthe bolts should hold the prop to the shaft and crush plates to the pointthat the prop can't rotate and put the bolts in shear, which will elongate theholes in the prop. In the case of a wood strut, the thing is in tension, so this is especially important.Wood moves a lot. It grows and shrinks in all three axises with moisture variation.If a board has the growth rings basically parallel to the face of the board,it's "flatsawn". It will expand and contract across the width (in percentage)the most. Next the thickness, and last by a margin is the length. If you turn a flatsawn board into a quartersawn board (like Gary describes), youwill maximize the stability of the board. The metal fitting will not changeit's width enough to matter. The board will, and will thusly elongate the holesaccordingly (if the bolts are a tight fit). By using quartersawn wood youminimize this.The only part of the board that matters where a hole goes through it near the end,is the little piece between that hole, and the end of the board. In the caseof quartersawn, it seems that it could much more easily be broken out, thanif the board were flatsawn. If you can hang on to a board well enough, flatly pulling it apart is simply notthe issue. If you can stabilize it well enough, so that column bucking doesn'tcome into play, flatly squashing it isn't much of an issue either. If a board is dried correctly, then milled correctly, warpage, cupage and twistreally aren't a concern (as they are negligable). They don't affect the strengthof the wood anyway enough to matter. I think if you can't get wood that at least approches aircraft quality (basicallymeaning no knots and straight grain without major growth defects) you needto laminate up a piece. I don't think it matters if you laminate to width orthickness, just however you like the look or need to for available wood. If youdo have decent quality wood, I think it's fine as a solid piece. No matter how you do it, properly engineered ends and properly installed, REALLYREALLY matter.ToolsRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Wood Lift Struts
It seems to me that the main issue with wood struts is how you attach the end fittings.The issue there is preventing elongation of the holes, and minimizingany structural integrity issues that may arise if they do.First, nearly all wood/metal interfaces rely on friction between the fitting andthe wood to prevent the penetrating bolts from relying on shear force. Thebolt can handle the shear, the metal fitting can handle the shear, the wood isclearly the weakest link. In the case of mounting a wood prop, Sensenich's documentation clearly states thatthe bolts should hold the prop to the shaft and crush plates to the pointthat the prop can't rotate and put the bolts in shear, which will elongate theholes in the prop. In the case of a wood strut, the thing is in tension, so this is especially important.Wood moves a lot. It grows and shrinks in all three axises with moisture variation.If a board has the growth rings basically parallel to the face of the board,it's "flatsawn". It will expand and contract across the width (in percentage)the most. Next the thickness, and last by a margin is the length. If you turn a flatsawn board into a quartersawn board (like Gary describes), youwill maximize the stability of the board. The metal fitting will not changeit's width enough to matter. The board will, and will thusly elongate the holesaccordingly (if the bolts are a tight fit). By using quartersawn wood youminimize this.The only part of the board that matters where a hole goes through it near the end,is the little piece between that hole, and the end of the board. In the caseof quartersawn, it seems that it could much more easily be broken out, thanif the board were flatsawn. If you can hang on to a board well enough, flatly pulling it apart is simply notthe issue. If you can stabilize it well enough, so that column bucking doesn'tcome into play, flatly squashing it isn't much of an issue either. If a board is dried correctly, then milled correctly, warpage, cupage and twistreally aren't a concern (as they are negligable). They don't affect the strengthof the wood anyway enough to matter. I think if you can't get wood that at least approches aircraft quality (basicallymeaning no knots and straight grain without major growth defects) you needto laminate up a piece. I don't think it matters if you laminate to width orthickness, just however you like the look or need to for available wood. If youdo have decent quality wood, I think it's fine as a solid piece. No matter how you do it, properly engineered ends and properly installed, REALLYREALLY matter.ToolsRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Wood Lift Struts
Pietenpol-List: Re: Wood Lift Struts
Original Posted By: "tools"
Oh by the way, if you think you need to laminate, but like the look of solid...with careful selection of how you orient the wood, you can do A LOT of laminatingthat basically isn't noticeable.When I was a severely broke young lad, I had to rely on gluing up FIVE pieces ofwood for a drawer front that was only about 4 inches tall. You can't tell it'snot one piece of wood. How the grain is oriented to prevent warps and stuff, really won't matter in aboard as wide as a strut. I routinely glue boards together up to 36" widths andhave never had a problem with them cupping or warping or anything. I've donethis in environments from the dessert to the southeast. ToolsRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Wood Lift Struts
Oh by the way, if you think you need to laminate, but like the look of solid...with careful selection of how you orient the wood, you can do A LOT of laminatingthat basically isn't noticeable.When I was a severely broke young lad, I had to rely on gluing up FIVE pieces ofwood for a drawer front that was only about 4 inches tall. You can't tell it'snot one piece of wood. How the grain is oriented to prevent warps and stuff, really won't matter in aboard as wide as a strut. I routinely glue boards together up to 36" widths andhave never had a problem with them cupping or warping or anything. I've donethis in environments from the dessert to the southeast. ToolsRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Wood Lift Struts
Original Posted By: "Gboothe5"
http://www.rader.org/beginning.htmThere's half a dozen more creatively spelled words in there, keep looking!ToolsRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________
http://www.rader.org/beginning.htmThere's half a dozen more creatively spelled words in there, keep looking!ToolsRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________
RE: Pietenpol-List: Re: Wood Lift Struts
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Lest anyone considering using wood struts were to get squeamish based on theconcerns presented below, let me remind you of the following:1) The "pull-through strength" of most woods is well-known and published.Clif Dawson presented me with one of these tables, which I have publishedbefore, and assume can be found in the archives. Interestingly, the numbersare irrespective of grain direction, and are impressive.2) Remember those engine mounts on the front of your plane? They rely solelyon the clamping pressure of 3 #3 bolts, and grain direction is never evenmentioned; nor does the type of wood seem to matter either, whether spruce,fir, poplar, pine, etc.3) Kevin Purtee just posted the changes he has made, one of which was toremove and replace his previous wood struts. Those struts had suffered somewear, not due to workmanship or design, but with over 200 hours on them.Kevin went on to point out that there was zero elongation in the holes, andhis connection design is extremely simple.Gary from CoolNX308MB-----Original Message-----
Lest anyone considering using wood struts were to get squeamish based on theconcerns presented below, let me remind you of the following:1) The "pull-through strength" of most woods is well-known and published.Clif Dawson presented me with one of these tables, which I have publishedbefore, and assume can be found in the archives. Interestingly, the numbersare irrespective of grain direction, and are impressive.2) Remember those engine mounts on the front of your plane? They rely solelyon the clamping pressure of 3 #3 bolts, and grain direction is never evenmentioned; nor does the type of wood seem to matter either, whether spruce,fir, poplar, pine, etc.3) Kevin Purtee just posted the changes he has made, one of which was toremove and replace his previous wood struts. Those struts had suffered somewear, not due to workmanship or design, but with over 200 hours on them.Kevin went on to point out that there was zero elongation in the holes, andhis connection design is extremely simple.Gary from CoolNX308MB-----Original Message-----