---------------------------------------------------------- Pietenpol-List Digest Archive --- Total Messages Posted Thu 11/19/09: 25 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:52 AM - Re: Re: Upper Flying Strut Fitting, Possibe Plans Error (Robert Ray) 2. 03:51 AM - Re: Prop Choices A-65 () 3. 04:54 AM - rib/spar orientation (vman1922) 4. 05:18 AM - Re: built up spars (Jim Markle) 5. 05:19 AM - Re: rib/spar orientation (Ameet Savant) 6. 05:36 AM - Re: rib/spar orientation (Pieti Lowell) 7. 07:28 AM - Re: built up spars (ivan.todorovic) 8. 08:21 AM - Re: rib/spar orientation (ivan.todorovic) 9. 08:22 AM - Re: shipping aluminum sheet (Gene Rambo) 10. 10:50 AM - Bernard Pietenpol - Corvair Oil Pan Conversion (dwilson) 11. 11:55 AM - Re: Re: rib/spar orientation (David Paule) 12. 01:31 PM - rib/spar orientation (Oscar Zuniga) 13. 02:32 PM - static thrust (skellytown flyer) 14. 02:34 PM - Re: Re: built up spars (Peter W Johnson) 15. 04:22 PM - Re: built up spars (ivan.todorovic) 16. 04:50 PM - Re: static thrust (helspersew@aol.com) 17. 05:36 PM - Re: Re: built up spars (Peter W Johnson) 18. 05:37 PM - Re: static thrust (gliderx5@comcast.net) 19. 06:17 PM - 106 years ago today- Prelude to fight (helspersew@aol.com) 20. 06:18 PM - Re: static thrust (David Paule) 21. 06:22 PM - Re: Re: built up spars (Clif Dawson) 22. 06:52 PM - Re: static thrust (gliderx5@comcast.net) 23. 06:58 PM - G-BUCO engine failure (Douwe Blumberg) 24. 07:45 PM - Re: Re: built up spars (Robert Ray) 25. 08:53 PM - Re: static thrust (David Paule) ________________________________ Message 1 _____________________________________ Time: 12:52:19 AM PST US Subject: Re: Pietenpol-List: Re: Upper Flying Strut Fitting, Possibe Plans Error From: Robert Ray Finer thaan frog hair! On Thu, Nov 19, 2009 at 2:47 AM, wrote: > Seeing as I started this thread I should show what I ended up doing. > > On both sides of the spar under the fitting I added 1/8-inch Birch plywood > plates 12-inches long tapered on both ends to avoid sudden change in spare > cross section. I did not weld the two straps together. > > Chris > Sacramento, CA > WestCoastPiet.com > ________________________________ Message 2 _____________________________________ Time: 03:51:33 AM PST US From: Subject: Pietenpol-List: Re: Prop Choices A-65 I flew an A-65 Champ with a Sensenich W72 CK44 wooden prop, and in the Cincinnati summer heat it was a real dog with two on board. Switching to the recommended metal "climb" prop, a Sensenich 74CK-0-44, transformed that Champ into a real nice performer even a full gross on the hottest summer days! Has anybody tried one of those sweet Sensenich ground adjustable composite props on a Piet? Paul ________________________________ Message 3 _____________________________________ Time: 04:54:42 AM PST US Subject: Pietenpol-List: rib/spar orientation From: "vman1922" In the layout of a 612 rib template I am not sure what to use as a vertical reference for the spar. Should it be 90 degrees from the cord line or 90 degrees from the bottom wing surface???????? I believe this would also affect the angle of incidence. Thanks! You all make this a great place to exchange info! Read this topic online here: http://forums.matronics.com/viewtopic.php?p=273696#273696 ________________________________ Message 4 _____________________________________ Time: 05:18:28 AM PST US From: Jim Markle Subject: Re: Pietenpol-List: built up spars >For us cheapskates still trying to use thinner and >less expensive stock and either scarfing or laminating >things so we don't have to use long expensive pieces of >clear wood, and trying to use plywood for the web rather >than spruce planks, the approach becomes one of >engineering a built-up section with equivalent strength. >This is where I am right now, and Jim Markle knows why ;o) > WHAT? Who, me???? Uhhh, I'll just say that lighter (with equivalent strength) is always better! ________________________________ Message 5 _____________________________________ Time: 05:19:37 AM PST US Subject: Re: Pietenpol-List: rib/spar orientation From: Ameet Savant IMHO, considering incidence is measured with respect to chord line, making the spar perpendicular to the chord would make it easier (mathematically) to select the strut lengths. Having said that, I don't think it is hard at all to figure out what the lengths would be in case the spar was perpendicular to the bottom of the airfoil. Ameet On Thu, Nov 19, 2009 at 6:54 AM, vman1922 wrote: > > In the layout of a 612 rib template I am not sure what to use as a vertical > reference for the spar. Should it be 90 degrees from the cord line or 90 > degrees from the bottom wing surface???????? > > I believe this would also affect the angle of incidence. > > Thanks! You all make this a great place to exchange info! > > ________________________________ Message 6 _____________________________________ Time: 05:36:03 AM PST US Subject: Pietenpol-List: Re: rib/spar orientation From: "Pieti Lowell" Mr V I used the 90 Deg, from the cord line as Mr R. suggested. He also suggested 1 Deg. angle of incidence on the 612. I would go with 1/2 Degree AoI, I also have the short version Piet, My long version worked well with 1-1/2deg. Pieti Lowell Read this topic online here: http://forums.matronics.com/viewtopic.php?p=273701#273701 ________________________________ Message 7 _____________________________________ Time: 07:28:53 AM PST US Subject: Pietenpol-List: Re: built up spars From: "ivan.todorovic" Peter, Please check if I've messed the dimensions for the front spar on the drawings below. Maybe it is a stupid question, but better safe than sorry: spar face with full plywood web goes in the wing-tip direction for both spars, front and rear, right? There is a small drawing near the right edge of your sketch that made me uncertain about that. One other thing: vertical stiffeners position on the spar inside edge would need a hint or two, there are several dimensions (7 1/2), (1/2 + 8 1/2) that are a bit confusing. Regards, Ivan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=273710#273710 Attachments: http://forums.matronics.com//files/frontsparinside_144.jpg http://forums.matronics.com//files/frontspartip_262.jpg ________________________________ Message 8 _____________________________________ Time: 08:21:24 AM PST US Subject: Pietenpol-List: Re: rib/spar orientation From: "ivan.todorovic" Mr Lowell, Have you changed the spar positions when you've changed the airfoil, or you have left them exactly where they are on FC10? Regards, Ivan Todorovic Read this topic online here: http://forums.matronics.com/viewtopic.php?p=273718#273718 ________________________________ Message 9 _____________________________________ Time: 08:22:36 AM PST US From: "Gene Rambo" Subject: Re: Pietenpol-List: shipping aluminum sheet It would look like a Tarantino movie . . . lots of blood and not pretty Gene do not archive ----- Original Message ----- From: Jack Phillips To: pietenpol-list@matronics.com Sent: Wednesday, November 18, 2009 6:52 PM Subject: RE: Pietenpol-List: shipping aluminum sheet Don't you wish you had that on video? Jack Phillips NX899JP Raleigh, NC ------------------------------------------------------------------------- ----- From: owner-pietenpol-list-server@matronics.com [mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Gene Rambo Sent: Wednesday, November 18, 2009 6:08 PM To: pietenpol-list@matronics.com Subject: Re: Pietenpol-List: shipping aluminum sheet 3003 comes in 4x12 too. It can be had in differing hardnesses, I think 1/2 hard is the norm for cowlings, etc (can't say the T_ number). I am going to a local place within the week to buy a piece for my cowlings. Talking about something that unwinds with a fury, though, if anyone is using hard wire (or music wire) for tail bracing or wing drag wires, I made the mistake of holding a roll and cutting off the brass-wire ties. It had the ends bent back 180 degrees, so as it started uncoiling, it dug those sharp ends into my hands. I only then realized that I had no option but to put my foot on it, cover my face, and jump off . . . it slapped me about ten times before I got out of reach. Damn near kilt me! Gene ----- Original Message ----- From: hvandervoo@aol.com To: pietenpol-list@matronics.com Sent: Wednesday, November 18, 2009 4:17 PM Subject: Re: Pietenpol-List: shipping aluminum sheet Gene, Oscar is looking for 4' x 12' sheets, My Piet used less 4' x 4' He is clearly building an all aluminum Pietenpol, or..... B-T-W 3003 is very soft. 6061 is twice as stiff and 2024 is three time stiffer than 6061. Regards Hans All wood Pietenpol NX15KV, with some steel and aluminum parts all wrapped in Polyfiber -----Original Message----- From: Gene Rambo To: pietenpol-list@matronics.com Sent: Wed, Nov 18, 2009 2:16 pm Subject: Re: Pietenpol-List: shipping aluminum sheet why "aircraft grade" aluminum? Regular old 3003 aluminum is what has been used since the Wrights and works perfectly fine for anything on a Piet. Can buy locally, is cheap, and is easy to work with. Gene ----- Original Message ----- From: hvandervoo@aol.com To: pietenpol-list@matronics.com Sent: Wednesday, November 18, 2009 2:52 PM Subject: Re: Pietenpol-List: shipping aluminum sheet What's that Oscar, building a spam can ? I have bought and rolled upto .040 with out a problem. But did not buy from Aircraft spruce, I got my stuff local. Try Trident metals (Houston and Austin locations) they carry aircraft grade aluminum, including mill certification. Pick it up yourself, with sales tax still much less than Aircraft spruce, Wicks or Airparts Good luck Hans NX15KV -----Original Message----- From: Oscar Zuniga > To: Pietenpol List > Sent: Wed, Nov 18, 2009 10:11 am Subject: Pietenpol-List: shipping aluminum sheet > Aircraft Spruce and others indicate that 4'x12' sheetsof aluminum up to about .030" can be shipped as onepiece by rolling and boxing. They caution that theydon't guarantee that the heavier gauge material willunroll completely flat when shipped this way. Hasanyone ordered sheet stock that was shipped rolledthis way, and what was your experience with it? Oscar ZunigaAir Camper NX41CCSan Antonio, TXmailto: taildrags@hotmail.comwebsite at http://www.flysquirrel.net =_blank>www.aeroelectric.comm/" target=_blank>www.buildersbooks.com=_b lank>www.homebuilthelp.com_blank>http://ww w.matronics.com/contributiont" target=_blank>http://www.matronics.com/Navigator?Pietenpol-Listtp://forums.matronics.com = href="http://www.aeroelectric.com">www.ae roelectric.comtitle=http://www.buildersbo oks.com/ href="http://www.buildersbooks.com">www. buildersbooks.comhref="http://www.homebu ilthelp.com">www.homebuilthelp.comhref="http://www.matronics.com/contribution">http://www.matronics.com/ctitle=htt p://www.matronics.com/Navigator?Pietenpol-List href="http://www.matronics.com/Navigator?Pietenpol-List">http://www.matronics.com/Navigator?P ietenpol-Listhref="h ttp://forums.matronics.com">http://forums.m atronics.com =_blank>www.aeroelectric.comm/" target=_blank>www.buildersbooks.com=_blank>www.homebuilthelp.com_blan k>http://www.matronics.com/contributiont" target=_blank>http://www.matronics.com/Navigator?Pietenpol-Listtp://for ums.matronics.com href="http://www.aeroelectric.com">www.aeroelectric.comtitle=http://w ww.buildersbooks.com/ href="http://www.buildersbooks.com">www.buildersbooks.comhref="http:/ /www.homebuilthelp.com">www.homebuilthelp.comhref="http://www.matronics .com/contribution">http://www.matronics.com/ctitle=http://www.matronics .com/Navigator?Pietenpol-List href="http://www.matronics.com/Navigator?Pietenpol-List">http://www.mat ronics.com/Navigator?Pietenpol-Listhref="http://forums.matronics.com">h ttp://forums.matronics.com www.aeroelectric.comwww.homebuilthelp.comhttp://www.matronics.com/contrib ution www.aeroelectric.com www.buildersbooks.com www.homebuilthelp.com http://www.matronics.com/contribution http://www.matronics.com/Navigator?Pietenpol-List ________________________________ Message 10 ____________________________________ Time: 10:50:33 AM PST US Subject: Pietenpol-List: Bernard Pietenpol - Corvair Oil Pan Conversion From: "dwilson" Here are a couple of Pictures of a Corvair Oil Pan that had the ears welded on by Mr. Pietenpol. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=273744#273744 Attachments: http://forums.matronics.com//files/pan2_173.jpg http://forums.matronics.com//files/pan1_189.jpg ________________________________ Message 11 ____________________________________ Time: 11:55:29 AM PST US From: "David Paule" Subject: Re: Pietenpol-List: Re: rib/spar orientation The spars won't care if they are a few degrees one way or the other. But if you happened to get the rib lay-out from the Pietenpol family, it shows where those uprights are intended to be. However, the strength of the wing isn't very sensitive to that angle, as long as it's not too far off. Just to be clear, I'm talking about the angle of the spar with regard to the chord or the bottom of the wing. I'm not talking about the angle of incidence. David Paule > > > I used the 90 Deg, from the cord line as Mr R. suggested..... ________________________________ Message 12 ____________________________________ Time: 01:31:15 PM PST US From: Oscar Zuniga Subject: Pietenpol-List: rib/spar orientation My own take on it is that the spar orientation should be relative to the chord line of the selected airfoil. The quirk in the deal is that some of the older airfoils were referenced to a line along the bottom, which made some sense with flat-bottomed airfoils like the USA35. However, camber and cusp change the picture, plus the fact that all modern airfoils and all analysis programs reference the mean aerodynamic chord (I believe). In any case, the Riblett is not a flat-bottomed airfoil and all of its published characteristics are referenced to the chord. I wish the world was simple again, like it used to be ;o) Oscar Zuniga Air Camper NX41CC San Antonio, TX mailto: taildrags@hotmail.com website at http://www.flysquirrel.net ________________________________ Message 13 ____________________________________ Time: 02:32:09 PM PST US Subject: Pietenpol-List: static thrust From: "skellytown flyer" if anybody is interested enough to spend some money for a tester-there is one on E-bay that looks pretty nice in the aircraft parts site.it has a 400# range.probably imported but should b fairly accurate. Raymond Read this topic online here: http://forums.matronics.com/viewtopic.php?p=273788#273788 ________________________________ Message 14 ____________________________________ Time: 02:34:51 PM PST US From: "Peter W Johnson" Subject: RE: Pietenpol-List: Re: built up spars Ivan, Comments embedded......... Please check if I've messed the dimensions for the front spar on the drawings below. ................all look good. Maybe it is a stupid question, but better safe than sorry: spar face with full plywood web goes in the wing-tip direction for both spars, front and rear, right? There is a small drawing near the right edge of your sketch that made me uncertain about that. ................do you mean the grain of the plywood? If so yes main grain is along the length of the spar One other thing: vertical stiffeners position on the spar inside edge would need a hint or two, there are several dimensions (7 1/2), (1/2 + 8 1/2) that are a bit confusing. ................Not sure what you mean here, the wing join ends are 7 1/2", the center (wing spar strut fitting) 25 1/2", the wing tip 4 1/2". There is blocking at each wing rib position, pulley fixing position and compression strut fitting. ................Does all that help? Cheers Peter ________________________________ Message 15 ____________________________________ Time: 04:22:58 PM PST US Subject: Pietenpol-List: Re: built up spars From: "ivan.todorovic" Peter, I've looked at Piet plans and it helped to clarify some dimensions, I'm drawing on, give me a day or two to finish it. My question was so stupid - you haven't seen what is puzzling me, but let me embarace my self again and put it differently: when you build the whole front spar, and the spar box has so called "U" shape, do you rotate the bottom of the letter "U" towards the tip of the wing, not towards the rear spar? Regards, Ivan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=273802#273802 ________________________________ Message 16 ____________________________________ Time: 04:50:25 PM PST US Subject: Re: Pietenpol-List: static thrust From: helspersew@aol.com Gentlemen, Has anyone done a static thrust test on their flying airplane (or almost flying?). I have measured 265 lbs. with my Model A and my 76/46 prop. I would be curious how this stands up to others. Dan Helsper Poplar Grove, IL. ________________________________ Message 17 ____________________________________ Time: 05:36:08 PM PST US From: "Peter W Johnson" Subject: RE: Pietenpol-List: Re: built up spars Ivan, Sorry, check out page 6 of the build pictures. They show the ply side on the inside of the wing. Cheers Peter Wonthaggi Australia http://www.cpc-world.com -----Original Message----- From: owner-pietenpol-list-server@matronics.com [mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of ivan.todorovic Sent: Friday, 20 November 2009 11:22 AM Subject: Pietenpol-List: Re: built up spars Peter, I've looked at Piet plans and it helped to clarify some dimensions, I'm drawing on, give me a day or two to finish it. My question was so stupid - you haven't seen what is puzzling me, but let me embarace my self again and put it differently: when you build the whole front spar, and the spar box has so called "U" shape, do you rotate the bottom of the letter "U" towards the tip of the wing, not towards the rear spar? Regards, Ivan ________________________________ Message 18 ____________________________________ Time: 05:37:20 PM PST US From: gliderx5@comcast.net Subject: Re: Pietenpol-List: static thrust Dan I have the results of my static thrust testing at http://home.comcast.net/~mmorrison123/engine_test.html. Corvair with a homemade prop. 2500 RPM static giving 280 lbs thrust. I spoke with William Wynne at Oshkosh, and he indicated that for a Piet I should be more like 2700 RPM and 350 lbs thrust. I may look at getting a Warp prop. It is highly likely that the factory can make a better prop than I can. Malcolm Morrison ----- Original Message ----- From: helspersew@aol.com Sent: Thursday, November 19, 2009 7:49:50 PM GMT -05:00 US/Canada Eastern Subject: Re: Pietenpol-List: static thrust Gentlemen, Has anyone done a static thrust test on their flying airplane (or almost flying?). I have measured 265 lbs. with my Model A and my 76/46 prop. I would be curious how this stands up to others. Dan Helsper Poplar Grove, IL. ________________________________ Message 19 ____________________________________ Time: 06:17:18 PM PST US Subject: Pietenpol-List: 106 years ago today- Prelude to fight From: helspersew@aol.com >From the diary of Orville Wright: November 19, 1903 Kitty Hawk, N.C. On arising found ponds about camp frozen, also water in basin. Coldest nig ht we have had so far. Gathered several logs of oak for firewood. Wind blo wing 6 to 8 meters. Too cold for work. "However we are entirely comfortable, and have no trouble keeping warm at nights. In additions to the classifications of last year, to wit, 1,2,3, and 4 blanket nights, we now have 5 blanket nights, and 5 blankets and 2 quilts. Next comes 5 blankets, 2 quilts, & fire, & hot water jug. This is as far as we have got so far. Next comes the addition of sleeping without undressing, then shoes and hats, and finally overcoats. We intend to be comfortable when we are here." (Wilbur Wright to Bishop Milton Wright, No v. 23, 1903.) do not archive ________________________________ Message 20 ____________________________________ Time: 06:18:12 PM PST US From: "David Paule" Subject: Re: Pietenpol-List: static thrust A lower-pitch prop will give you higher static RPM and greater static thrust. If you are otherwise happy with the prop, that's the only change needed. Besides, your next prop will be faster to make and possibly better, right? David Paule ----- Original Message ----- From: gliderx5@comcast.net To: pietenpol-list@matronics.com Sent: Thursday, November 19, 2009 6:37 PM Subject: Re: Pietenpol-List: static thrust Dan I have the results of my static thrust testing at http://home.comcast.net/~mmorrison123/engine_test.html. Corvair with a homemade prop. 2500 RPM static giving 280 lbs thrust. I spoke with William Wynne at Oshkosh, and he indicated that for a Piet I should be more like 2700 RPM and 350 lbs thrust. I may look at getting a Warp prop. It is highly likely that the factory can make a better prop than I can. Malcolm Morrison ----- Original Message ----- From: helspersew@aol.com To: pietenpol-list@matronics.com Sent: Thursday, November 19, 2009 7:49:50 PM GMT -05:00 US/Canada Eastern Subject: Re: Pietenpol-List: static thrust Gentlemen, Has anyone done a static thrust test on their flying airplane (or almost flying?). I have measured 265 lbs. with my Model A and my 76/46 prop. I would be curious how this stands up to others. Dan Helsper Poplar Grove, IL. ________________________________ Message 21 ____________________________________ Time: 06:22:57 PM PST US From: "Clif Dawson" Subject: Re: Pietenpol-List: Re: built up spars Ah, Ivan, When you say "tip" do you mean the "leading edge", or front of the wing? > Peter, when you build the whole front spar, and the spar box has so called "U" shape, do you rotate the bottom of the letter "U" towards the tip of the wing, not towards the rear spar? > > Regards, > Ivan ________________________________ Message 22 ____________________________________ Time: 06:52:58 PM PST US From: gliderx5@comcast.net Subject: Re: Pietenpol-List: static thrust David All true. I must admit that making the prop (per Alvin Schubert) was probab ly my favorite part of building the Piet so far. I did build it 66 inches, with the intent of trimming an inch or two to get more RPM if needed. I wil l have to see what more RPMs but a smaller disk does to the thrust. Experim ental aircraft right! Malcolm Morrison ----- Original Message ----- From: "David Paule" Sent: Thursday, November 19, 2009 9:17:49 PM GMT -05:00 US/Canada Eastern Subject: Re: Pietenpol-List: static thrust =EF=BB A lower-pitch prop will give you higher static RPM and greater static thrus t. If you are otherwise happy with the prop, that's the only change needed. Besides, your next prop will be faster to make and possibly better, right? David Paule ----- Original Message ----- From: gliderx5@comcast.net Sent: Thursday, November 19, 2009 6:37 PM Subject: Re: Pietenpol-List: static thrust Dan I have the results of my static thrust testing at http://home.comcast.net/~ mmorrison123/engine_test.html . Corvair with a homemade prop. 2500 RPM stat ic giving 280 lbs thrust. I spoke with William Wynne at Oshkosh, and he ind icated that for a Piet I should be more like 2700 RPM and 350 lbs thrust. I may look at getting a Warp prop. It is highly likely that the factory can make a better prop than I can. Malcolm Morrison ----- Original Message ----- From: helspersew@aol.com Sent: Thursday, November 19, 2009 7:49:50 PM GMT -05:00 US/Canada Eastern Subject: Re: Pietenpol-List: static thrust Gentlemen, Has anyone done a static thrust test on their flying airplane (or almost fl ying?). I have measured 265 lbs. with my Model A and my 76/46 prop. I would be curious how this stands up to others. Dan Helsper Poplar Grove, IL. href="http://www.aeroelectric.com">www.aeroelectric.com href="http://www.buildersbooks.com">www.buildersbooks.com href="http://www.homebuilthelp.com">www.homebuilthelp.com href="http://www.matronics.com/contribution">http://www.matronics.com/chr ef="http://www.matronics.com/Navigator?Pietenpol-List">http://www.matroni cs.com/Navigator?Pietenpol-List ======= ________________________________ Message 23 ____________________________________ Time: 06:58:14 PM PST US From: Douwe Blumberg Subject: Pietenpol-List: G-BUCO engine failure Darn those certified aircraft engines!! Douwe Do not archive!!! ________________________________ Message 24 ____________________________________ Time: 07:45:34 PM PST US Subject: Re: Pietenpol-List: Re: built up spars From: Robert Ray I think what they are talking about is a d-cell thats an upper case D imagine the D being the leading edge of the wing and the top of the D is a material such as a wooden spare with a thin piece of plywood wrapped around to the bottom of the spare. I imagine that the hold concept would be stronger and more rigid but then I'm not an engineer, On Thu, Nov 19, 2009 at 7:22 PM, ivan.todorovic wrote: > > Peter, > > I've looked at Piet plans and it helped to clarify some dimensions, I'm > drawing on, give me a day or two to finish it. > > My question was so stupid - you haven't seen what is puzzling me, but let > me embarace my self again and put it differently: when you build the whole > front spar, and the spar box has so called "U" shape, do you rotate the > bottom of the letter "U" towards the tip of the wing, not towards the rear > spar? > > Regards, > Ivan > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=273802#273802 > > ________________________________ Message 25 ____________________________________ Time: 08:53:07 PM PST US From: "David Paule" Subject: Re: Pietenpol-List: static thrust As long as the diameter is not too large for the maximum rpm, greater diameter is more efficient. If you imagine a graph of speed on the horizontal axis and efficiency on the vertical axis, increasing the diameter causes the efficiency to go up. Lowering the pitch causes the efficiency to occur at a lower speed. Of course you've got to make sure that your prop isn't too long for the engine. And that takes a balance between pitch and diameter, plus some of the art of building props. And that art, alas, is beyond me. I'm merely an engineer. David Paule ----- Original Message ----- From: gliderx5@comcast.net To: pietenpol-list@matronics.com Sent: Thursday, November 19, 2009 7:26 PM Subject: Re: Pietenpol-List: static thrust David All true. I must admit that making the prop (per Alvin Schubert) was probably my favorite part of building the Piet so far. I did build it 66 inches, with the intent of trimming an inch or two to get more RPM if needed. I will have to see what more RPMs but a smaller disk does to the thrust. Experimental aircraft right! Malcolm Morrison ----- Original Message ----- From: "David Paule" To: pietenpol-list@matronics.com Sent: Thursday, November 19, 2009 9:17:49 PM GMT -05:00 US/Canada Eastern Subject: Re: Pietenpol-List: static thrust =EF=BB A lower-pitch prop will give you higher static RPM and greater static thrust. If you are otherwise happy with the prop, that's the only change needed. Besides, your next prop will be faster to make and possibly better, right? David Paule ----- Original Message ----- From: gliderx5@comcast.net To: pietenpol-list@matronics.com Sent: Thursday, November 19, 2009 6:37 PM Subject: Re: Pietenpol-List: static thrust Dan I have the results of my static thrust testing at http://home.comcast.net/~mmorrison123/engine_test.html. Corvair with a homemade prop. 2500 RPM static giving 280 lbs thrust. I spoke with William Wynne at Oshkosh, and he indicated that for a Piet I should be more like 2700 RPM and 350 lbs thrust. I may look at getting a Warp prop. It is highly likely that the factory can make a better prop than I can. Malcolm Morrison ----- Original Message ----- From: helspersew@aol.com To: pietenpol-list@matronics.com Sent: Thursday, November 19, 2009 7:49:50 PM GMT -05:00 US/Canada Eastern Subject: Re: Pietenpol-List: static thrust Gentlemen, Has anyone done a static thrust test on their flying airplane (or almost flying?). I have measured 265 lbs. with my Model A and my 76/46 prop. I would be curious how this stands up to others. 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