Brodhead Pietenpol Association

Original Posted By: "K5YAC"
I see it exactly the opposite of you. The main reason to consider (I'm not saying build) deviating from the plans is to honor the B. Pietenpol spirit of always build safer and better flying aircraft. There is no need to cure the deficiency in the design, reason enough is to make B.P. happy in heavens, as he is known not to build two exactly the same aircraft and to be as far from "purist" as he can be. After all he abandoned one of the most significant marks of his design (Ford engine) as soon as he got a chance to do it. I deeply beleive if he can see someone building Piet with Ford enigne in 2009 he would think for him self "Oh, no, another ..... building by the plans".The amount of hate in the form "Oh, I just flew my Piet, and you morons talk about something better instead to build by the plans like me" is getting quite disturbing. There is no wonder people got annoyed. There is no single thread in which some deviation from the plans is mentioned that is not rapidly shut with flood of "Why, why, why, when this design confirmed it self for 80 years?" messegaes. To honor B.P, is there any other reason needed?Regards, and please don't mind the rough tone, I got excited how this thread is cut of, and I am very interested in building with pushrods for several reasons,Ivan Todorovic =C2- =C2-http://www.matronics.com/Navigator?Piet ... ntribution =C2-________________________________________________________________________________Subject: Pietenpol-List: Re: some thoughts

Original Posted By: Mark Roberts
Subject: Pietenpol-List: And the real work begins...

Original Posted By: Dave and Connie

Original Posted By: Ben Charvet

Original Posted By: Robert Ray
Subject: Re: Pietenpol-List: Re: Push/pull tubes and rod ends

Original Posted By: Douwe Blumberg
Tim: The strut design that Hosie chose for the Chaffinich was a round tube withstream-lining with balsa wood covered with cloth. In all the maneuvers that thisairplane went through I never had one incident of vibrations that were inany way a concern, Something that paralleled Allen's struts, his struts had nojury strut help.Pieti Lowell timothywillis(at)earthlin wrote:> Now I don't want to start anything about a guy who has built eight Piets, butI found very strange his position of the "Chaffinch's" jury struts, very nearthe end of the lift struts. My thought has been that you want to place the jurystrut near, but not at the middle of the lift strut. The "not at the middle"has to do with avoiding the harmonic cited in other posts on our message board.Near the middle is to optimize the reduction of buckling, as also previouslydiscussed.> His other changes seem a matter of taste, esp. since he claims no "Pietenpol"in the plane's name.> Tim in central TX> > --Read this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Sun, 25 Oct 2009 22:19:07 -0400 (EDT)

Original Posted By: Robert Ray
Subject: Re: Pietenpol-List: some thoughts

Original Posted By: "Jack Phillips"
Now you're doing it! Get some T-88 and get crackin. I found the ribs to be alot of fun. Once I figured out how to build them, it was kind of like a littleassembly line. Not a whole lot of study required on those once you get going...just keep putting the little sticks with the big sticks and soon you'll lookup and have a whole pile of em. Not real sure on the 2' x 4' plywood for all the gussets. I burnt through a 4'x 4', and then some. I cut my gussets a little large, but close to what theplans showed... plus I have a vertical in front and behind each spar, so thatconsumed a little more material. Good luck, and keep us posted.--------Mark - working on wingsRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________

Original Posted By: owner-pietenpol-list-server(at)matronics.com [mailto:owner-pietenpol-lis
=9CI see I am not alone in changing the Pietenpol to suit my own personal need/wants=9D=C2-Those are words I can live with. Change =93 Yes, Improve =93 NO. Have you checked out www.cpc-world.com? You will see an excellent job of incorporating push rods.=C2-Gary BootheCool, Ca.PietenpolWW Corvair Conversion, mountedTail done,=C2-Fuselage=C2-on gear(15 ribs down)

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Looking good, Ben! I can hardly wait for a full report of your firstflight.Jack PhillipsNX899JPRaleigh, NC-----Original Message-----

Original Posted By: Ken Howe

Original Posted By: Michael Perez

Original Posted By: Michael Perez

Original Posted By: "Jack Phillips"
Well, I feel real lucky to have had the opportunity to look at your airplane onmy first trip to Brodhead. What a beauty.--------Mark - working on wingsRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Thanks, Mark. I wish I had met you while we were there. Sometimes I thinkBrodhead should last a week and Oshkosh shouldn't be more than two days.Jack PhillipsNX899JPRaleigh, NC-----Original Message-----

Original Posted By: "John Recine"
Actually, we did meet just briefly. You were getting ready for a Saturday flight...I asked a couple of questions about you fuselage and got out of the way.Hopefully I won't feel too intimidated by you veterans next year, and I'll makeit a point to seek some of you guys out. I really didn't have any reasonto feel intimidated... everyone was super nice (except for that bum John Racine),but I didn't really figure that out until late in the event. Just kidding John... I'll see you tomorrow night. Markle said he'll be providingsome pizza and I've got the beer.--------Mark - working on wingsRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Re: Pietenpol-List: Re: some thoughts

Original Posted By: Mark Chunard
I am in route and will catch up with you guys tomorrow night after work. See ya thenJohn------Original Message------

Original Posted By: Matt Redmond
The advantage of the threaded inserts are that the proper materials can be chosen, stress concentrations avoided and rolled threads used. They ought to have excellent fatigue life. On the other hand they are usually either riveted, bolted or welded to the tube, so they do need that joint taken into consideration.However, if the tube is otherwise a suitable size and material, there's no reason why properly-made internal threads can't work nicely. As Michael Perez pointed out correctly they can potentially have enough strength. The tube also will need enough net section to carry the load, and sufficient moment of inertia to avoid Euler buckling, and sufficient wall thickness to avoid local crippling. The threaded hole will need appropriate alignment, of course, and it would be good to have a tapered run-out to the threads.Usually when such elements are designed, there's a threaded insert such as a Helicoil for the actual threads. That's a refinement that is probably unlikely for a homebuilder to install, so it would be desirable to assess why that's such a common design detail, and what the issues are.I think it's unlikely that such a pushrod would be anything like weight-efficient for any serious element of the control system. But it's worth the try, if anyone is interested enough to spend the time to do it. It's not something to be ruled out arbitrarily. It's also not something to be adopted without completely understanding and accounting for all the aspects involved.David Paule

Original Posted By: dpaule(at)frii.com
I had a Robertson B1-RD and the elevator pushrod was done that way. It only had on guide but I'm sure the forces were much less as the cruise speed was only 33mph. In anything but a very light breeze the bicycles passed me=3B-)BTW - these last comments are more like the ones I'm used to on this listDoug DeverIn beautiful Stow Ohio-working on ribs.

Original Posted By: Ben Charvet

Original Posted By: Tim Willis
Subject: Re: Pietenpol-List: Push/pull tubes and rod endsMr.Peitenpol was always making changes, just look at the Sky Scout plans. He talks about changing the gear, the tail wheel, and a brace in the rib. He wanted these changes to be used for the Air Camper and the Scout. People are just always trying to make things better. I believe it's called progress. I hear of those who would not change a thing, but when you talk tothem they really did make some small changes. I guess that doesn't count. Some people don't trust themselves to make a change. Others have the experience or knowledge to feel fine with their changes. We are all different,that's what makes life worth living. I had trouble with my cables between the stick and the bellcrank. The cables were tight when the stick was centered, but loose when I had full stick forward or full stick back. I came close to using a push/pull tube there. My glider has push/pull tubes and they work great. I can't see it adding more then 2 or 3 pounds at tops. Not near as much as a cubby hole with a tie down kit. Howdy________________________________________________________________________________Date: Mon, 26 Oct 2009 15:43:14 -0500 (GMT-05:00)

Original Posted By: Jeff Boatright
This is only my opinion, and we all know what opinions are like...Michael, change your plane to suit your needs and desires. It's YOUR airplane.You will be the one who must trust his life to the design changes, and noneof us are obligated to fly in your plane. I will be building mine as close to the prints as possible, as I don't care tochange things just for the sake of change. However, IF there was a change thatI wanted to make (and there are a few) that I could justify the time/effort/expense,then I would do it. But if there was no logical justification for changingany aspect of MY plane, then that aspect will be built according to theplans. I personally don't see what there is to be gained by going to the push/pull insteadof the pull/pull cables. To me, the external control cables and controlhorns add just as much to the nostalgic air of this timeless airplane as the Jennystyle gear and wire wheels do.If indeed you posed the question of push/pull just from the interest of learningabout the engineering involved, I support your decision to do this. As for the forces in the control system, look for the weakest link in the cablesystem. What it is the breaking strength in tension of a typical turnbucklein the elevator cable system? The threaded portions of the eye or fork ends don'thave a very large cross section... What is the shear strength of the clevispin that hooks the eye of the turnbuckle to the bellcrank/control horn? Howmuch force is required to tear the clevis pin out of the the thin sheet metalbellcrank/control horn? I would think that the pulling force exerted by the elevator on the cables wouldbe the same as the pushing force applied to a pushrod tube, and you could usethat loading to calculate the diameter and wall thickness of the pushrod tubeyou would need to use to prevent buckling in compression loading. You couldbuild a mock-up and test it with weights or scales to simulate the flight loadsencountered, provided you had an accurate way to calculate or measure thoseflight loads. Or you could copy the design of another existing plane that usespush/pull elevator controls. What do the RV's use? I think those are push/pull,and that plane imparts much larger flight loads than a Piet could imposeon the system. Again, just my $.02 on this topic. Returning to lurk mode now...Billy McCaskillUrbana, IL/Baker, LARead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Mon, 26 Oct 2009 21:48:47 -0400

Original Posted By: Matt Redmond
The advantage of the threaded inserts are that the proper materials can be chosen=2C stress concentrations avoided and rolled threads used. They ought to have excellent fatigue life. On the other hand they are usually either riveted=2C bolted or welded to the tube=2C so they do need that joint taken into consideration.However=2C if the tube is otherwise a suitable size and material=2C there's no reason why properly-made internal threads can't work nicely. As Michael Perez pointed out correctly they can potentially have enough strength. The tube also will need enough net section to carry the load=2C and sufficient moment of inertia to avoid Euler buckling=2C and sufficient wall thickness to avoid local crippling. The threaded hole will need appropriate alignment=2C of course=2C and it would be good to have a tapered run-out to the threads.Usually when such elements are designed=2C there's a threaded insert such as a Helicoil for the actual threads. That's a refinement that is probably unlikely for a homebuilder to install=2C so it would be desirable to assess why that's such a common design detail=2C and what the issues are.I think it's unlikely that such a pushrod would be anything like weight-efficient for any serious element of the control system. But it's worth the try=2C if anyone is interested enough to spend the time to do it. It's not something to be ruled out arbitrarily. It's also not something to be adopted without completely understanding and accounting for all the aspects involved.David Paule