---------------------------------------------------------- Pietenpol-List Digest Archive --- Total Messages Posted Tue 09/28/04: 13 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:21 AM - Re: "How I carve Propellers" (hjarrett) 2. 05:16 AM - Re: "How I carve Propellers" (Peter W Johnson) 3. 06:30 AM - Fw: "How I carve Propellers" (cgalley) 4. 07:07 AM - Re: Looking for a GN-1... (Joe Krzes) 5. 01:13 PM - engine instrumentation for Corvair (Oscar Zuniga) 6. 01:48 PM - Engine Development Report (Michael Fisher) 7. 03:33 PM - GN-1 project & Continental A-80 4 sale (N321TX@wmconnect.com) 8. 03:50 PM - Re: Pietenpol-List Digest: 19 Msgs - 09/06/04 (CapnAvid@aol.com) 9. 04:57 PM - Re: GN-1 project & Continental A-80 4 sale (DJ Vegh) 10. 05:05 PM - Aircamper w/ Corvair conversion at Copperstate (DJ Vegh) 11. 07:48 PM - Re: engine instrumentation for Corvair (Rick Holland) 12. 08:20 PM - Scimitar Prop (Rcaprd@aol.com) 13. 09:56 PM - Re: Scimitar Prop (Galen Hutcheson) ________________________________ Message 1 _____________________________________ Time: 04:21:40 AM PST US From: "hjarrett" Subject: Re: Pietenpol-List: "How I carve Propellers" --> Pietenpol-List message posted by: "hjarrett" I would really like a copy too if there is a way to get it through the system. Can someone host it on a site? Hank J ----- Original Message ----- From: "cgalley" Subject: Re: Pietenpol-List: "How I carve Propellers" > --> Pietenpol-List message posted by: "cgalley" > > I down loaded the 1st 60 pages and created a 18,250 KB PDF file. I can send > it to you if your request it. > > Cy Galley - Aeronca Aviators Club > Newsletter Editor & EAA TC > www.aeronca.org > Actively supporting Aeroncas every day > > ----- Original Message ----- > From: "Don Morris" > To: > Sent: Sunday, September 26, 2004 7:53 AM > Subject: Pietenpol-List: "How I carve Propellers" > > > > --> Pietenpol-List message posted by: Don Morris > > > > > Hi. > > > > We've talked about the author. Is there any source for the book? (I > > tried downloading from the flying flea web site, but with my slow flakey > > internet connection, I just finally gave up.) > > > > -Don > > > > javcr@prodigy.net.mx wrote: > > > > >--> Pietenpol-List message posted by: javcr@prodigy.net.mx > > > > > > > > >Hi Piets > > > > > >The first prop that i used was homemade 66x38 with ths prop just I can > > >get 2550 rpm's static , after to read the Mr Alvin prop manual I made a > > >64x32 with the shape of the picture of Oscar Zuiga Prop, much better, > > >2950 static rpm's, that with avgas... > > >Javier Cruz > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > ________________________________ Message 2 _____________________________________ Time: 05:16:33 AM PST US From: "Peter W Johnson" Subject: RE: Pietenpol-List: "How I carve Propellers" --> Pietenpol-List message posted by: "Peter W Johnson" Hank, Its available here:- http://www.mykitplane.com/Planes/PeoplesFiles/HowIMakeProp.pdf 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 hjarrett Subject: Re: Pietenpol-List: "How I carve Propellers" --> Pietenpol-List message posted by: "hjarrett" I would really like a copy too if there is a way to get it through the system. Can someone host it on a site? Hank J ----- Original Message ----- From: "cgalley" Subject: Re: Pietenpol-List: "How I carve Propellers" > --> Pietenpol-List message posted by: "cgalley" > > I down loaded the 1st 60 pages and created a 18,250 KB PDF file. I can send > it to you if your request it. > > Cy Galley - Aeronca Aviators Club > Newsletter Editor & EAA TC > www.aeronca.org > Actively supporting Aeroncas every day > > ----- Original Message ----- > From: "Don Morris" > To: > Sent: Sunday, September 26, 2004 7:53 AM > Subject: Pietenpol-List: "How I carve Propellers" > > > > --> Pietenpol-List message posted by: Don Morris > > > > > Hi. > > > > We've talked about the author. Is there any source for the book? (I > > tried downloading from the flying flea web site, but with my slow flakey > > internet connection, I just finally gave up.) > > > > -Don > > > > javcr@prodigy.net.mx wrote: > > > > >--> Pietenpol-List message posted by: javcr@prodigy.net.mx > > > > > > > > >Hi Piets > > > > > >The first prop that i used was homemade 66x38 with ths prop just I can > > >get 2550 rpm's static , after to read the Mr Alvin prop manual I made a > > >64x32 with the shape of the picture of Oscar Zuiga Prop, much better, > > >2950 static rpm's, that with avgas... > > >Javier Cruz > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > ________________________________ Message 3 _____________________________________ Time: 06:30:28 AM PST US From: "cgalley" Subject: Fw: Pietenpol-List: "How I carve Propellers" --> Pietenpol-List message posted by: "cgalley" Thanks. It is much smaller that the other site (11,195) I re-saved using the make smaller option and it is about 9,000 KB for the entire 134 pages. I believe some of the pictures have been left out. I have my smaller version posted on a web site. It will only be up there 2 days. www.qcbc.org/HowIMakeProp.pdf But it still will take a long time. Cy Galley - Bellanca Champion Club Newsletter Editor-in-Chief & EAA TC www.bellanca-championclub.com Actively supporting Bellancas every day > > > ----- Original Message ----- > From: "Peter W Johnson" > To: > Sent: Tuesday, September 28, 2004 7:16 AM > Subject: RE: Pietenpol-List: "How I carve Propellers" > > > > --> Pietenpol-List message posted by: "Peter W Johnson" > > > > > Hank, > > > > Its available here:- > > > > http://www.mykitplane.com/Planes/PeoplesFiles/HowIMakeProp.pdf > > > > 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 hjarrett > > Sent: Tuesday, September 28, 2004 9:21 PM > > To: pietenpol-list@matronics.com > > Subject: Re: Pietenpol-List: "How I carve Propellers" > > > > --> Pietenpol-List message posted by: "hjarrett" > > > > I would really like a copy too if there is a way to get it through the > > system. Can someone host it on a site? > > Hank J > > > > > > ----- Original Message ----- > > From: "cgalley" > > To: ; > > Sent: Monday, September 27, 2004 10:06 AM > > Subject: Re: Pietenpol-List: "How I carve Propellers" > > > > > > > --> Pietenpol-List message posted by: "cgalley" > > > > > > I down loaded the 1st 60 pages and created a 18,250 KB PDF file. I can > > send > > > it to you if your request it. > > > > > > Cy Galley - Aeronca Aviators Club > > > Newsletter Editor & EAA TC > > > www.aeronca.org > > > Actively supporting Aeroncas every day > > > > > > ----- Original Message ----- > > > From: "Don Morris" > > > To: > > > Sent: Sunday, September 26, 2004 7:53 AM > > > Subject: Pietenpol-List: "How I carve Propellers" > > > > > > > > > > --> Pietenpol-List message posted by: Don Morris > > > > > > > > > > > Hi. > > > > > > > > We've talked about the author. Is there any source for the book? (I > > > > tried downloading from the flying flea web site, but with my slow > flakey > > > > internet connection, I just finally gave up.) > > > > > > > > -Don > > > > > > > > javcr@prodigy.net.mx wrote: > > > > > > > > >--> Pietenpol-List message posted by: javcr@prodigy.net.mx > > > > > > > > > > > > > > >Hi Piets > > > > > > > > > >The first prop that i used was homemade 66x38 with ths prop just I > can > > > > >get 2550 rpm's static , after to read the Mr Alvin prop manual I made > a > > > > >64x32 with the shape of the picture of Oscar Zuiga Prop, much > better, > > > > >2950 static rpm's, that with avgas... > > > > >Javier Cruz > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > ________________________________ Message 4 _____________________________________ Time: 07:07:27 AM PST US From: "Joe Krzes" Subject: RE: Pietenpol-List: Looking for a GN-1... --> Pietenpol-List message posted by: "Joe Krzes" Steve, There is a nice one in Conroe, TX (just north of Houston). Check this link to EAA chapter 302 for details and phone number Joe Spring, TX >From: "Steve Ruse" >Subject: Pietenpol-List: Looking for a GN-1... >Date: Mon, 27 Sep 2004 00:02:53 -0500 > >--> Pietenpol-List message posted by: "Steve Ruse" > > >BlankDoes anyone know of any nice ones for sale, preferably not too far >from >Texas? I'd prefer something with a certified engine, possibly a Corvair. >I've been checking controller.com & tradeaplane for the last couple of >months, but haven't found a whole lot. There is what appears to be a nice >GN-1 in Canada, but I'm shying away from that one because I'm afraid the >paperwork & getting a thorough inspection done might be a hassle. > >If you have any pointers on what to look for, both good and bad, please let >me know! I don't know enough myself to ensure that I can avoid getting >burned. > >Thanks for any help or input! > >Steve Ruse >Irving, TX > >Do not archive > >--- >Version: 6.0.769 / Virus Database: 516 - Release Date: 9/24/2004 > > ________________________________ Message 5 _____________________________________ Time: 01:13:28 PM PST US From: "Oscar Zuniga" Subject: Pietenpol-List: engine instrumentation for Corvair --> Pietenpol-List message posted by: "Oscar Zuniga" How do you use the mixture control without an EGT? I always did it by leaning the mixture till the engine started to run rough, then richen back up a tad till it smoothed out. Oscar Zuniga San Antonio, TX ________________________________ Message 6 _____________________________________ Time: 01:48:42 PM PST US From: Michael Fisher Subject: Pietenpol-List: Engine Development Report 2004) --> Pietenpol-List message posted by: Michael Fisher Hi Bert, Congratulations on high speed taxi tests successfully completed. Interesting and exciting times continue. Glad to hear you survived the hurricanes and were able to help with the cleanup. Your friend with a possible interest in pictures of my engine project is a bright guy, willing to innovate and test. It was my pleasure to spend a little time with him at his airfield, just before Sun and Fun last April. I left with the feeling that I should have stayed another day to learn more. I particularly like his ideas on weight saving structures, "T" section rib capstrips, and cooling systems. He told me what happened in the crash that cost a life and totaled a great homebuilt. The passenger squirmed around in the front seat, using the front throttle as a handhold. In so doing, he damaged the pilot's control linkage and reduced power to idle a few hundred feet above the piney woods. Shoulder harnesses were not used, but might have greatly reduced the crash injuries. Years as a charter pilot have taught me that passengers are often credited with more common sense than they actually have. That is why passenger briefings are now the law for air taxi operations and a good idea for everyone else. Since I don't have a digital camera, conventional photo prints of my inverted Ford engine are all I have at present. It is hanging on my shop wall, supported on a mount attached to a Pietenpol Scout forward fuselage hardpoint mockup. --- Looks like a powerplant I might like to fly behind. --- Made in America! Shurely would be fun to have it for the annual gathering at Brodhead Wisconsin. Don't anyone hold their breath waiting for this to happen. There are good reasons why we don't see many inverted auto engine conversions. I'll touch on a few of them below: Oiling --- Oil must be picked up from a low mounted tank, circulated through the engine, and returned to that tank via a scavenge pump or gravity. A pushrod engine would be better than an overhead cam because return oil could run through the pushrod holes. Crank trigger ignition --- I set the entire system up in a lathe and was able to make it work minus the main power control module computer. The same pair of cylinders always fires first. Hand propping will probably work if you pre-rotate the engine with reference to a mark on the camshaft sprocket to take advantage of that fact. The vital parts of these systems can be sheltered behind the firewall, safe from the heat, moisture, and vibration that cause failures. Fuel System --- The factory injectors will be blocked open and pressurized with the factory pump. Mixture control will be via a cockpit controlled needle valve, bypassing fuel rail pressure to the return line. The throttle will have three basic settings: takeoff, cruise, and approach. Emergency fuel will drain from the wing tank to a calibrated orfice just downstream from the throttle valve. My emergency fuel system idea came from the book "Jungle Pilot" by Nate Saint --- recommended reading for those flying light planes through rough country. Happy landings, Mike Fish ________________________________ Message 7 _____________________________________ Time: 03:33:08 PM PST US From: N321TX@wmconnect.com Subject: Pietenpol-List: GN-1 project & Continental A-80 4 sale I'm going to place my GN-1 project on Ebay in a couple of weeks but I wanted folks on the list to have first crack at it. You can see what this project looks like (minus the engine) by visiting D.J.'s website. I think he posted the info and pictures on March 12 and they should still be available for viewing. The GN-1 project has been in storage under a tarp at my hanger here in humid central Texas and I suspect the plywood sideboards on the fuselage went into shock going from an extremely dry desert climate (Mesa, Arizona) to what has almost been a tropical sweatland on my farm. The sides are wavy, almost undetectable ... and the laser cut metal parts I have that are unpainted need a light sanding because of a very thin layer of oxidation. I also detected what looks like some surface mold (dark spots) on a few wood surfaces (originally varnished) and it seems like a light sanding with 320 or 400 grade sandpaper would clean this residue off. This project comes with nearly all the ribs, built by D.J himself, as well as all the wood to finish the wings and D.J.'s original rib jigs. I am keeping the motormount and J3 Cub fuel tank, but everything else goes. I probably will also be selling my Continental A-80 engine, disassembled and now looking better than the day it left the factory. The case was worked by Divco ($820.42) and the accessory case was worked on to new factory limits by Drake Air Parts ($495.00) . I have a brand new camshaft (Sacramento Air Parts $500.00) for this engine and I recently purchased a nice yellow tag crankshaft from Aircraft Engine & Accessory ($650.00) that is 20 under with a new set of bearings ($4.25) . The connecting rods, tappet bodies and rocker arms were reconditioned at Aircraft Engine & Accessory to the tune of $906.59. I also purchased new rod bolts and nuts and cotter pins for $107.22 from Aircraft Specialties Services. I installed a brand new engine dataplate and had the old numbers professionally engraved (not stamped) and have all new cylinder base nuts, cover screws, MOH gasket set, all seals and gaskets and clamps from Fresno Airparts Company ($305.08) to go with the engine. The cylinders are currently undergoing a Cerminil process (best there is and I'll argue this point with ANYBODY) and they should be finished in about three weeks. I can't toss a figure out there for the engine until I have an idea what the cylinders will cost, but this will be a pristine engine with all yellow tags and receipts. The engine case is anodized and looks like a golden treasure trove and the new data plate makes this engine look like a million bucks (hey, maybe that's how much I should ask for it.) Keep viewing Ebay and I'll have this engine on the auction block in the coming weeks. Make a reasonabhle offer on the GN-1 project, and I might just sell it without going on Ebay. Thanks, Sterling Brooks ________________________________ Message 8 _____________________________________ Time: 03:50:00 PM PST US From: CapnAvid@aol.com Subject: Pietenpol-List: Re: Pietenpol-List Digest: 19 Msgs - 09/06/04 For "Leon Stefan" lsutks@webtv.net Re: Root rib covering. You don't have to stitch the root rib as the 2" cap strip is wide enough to make a good fabic bond with the covering glue (Poly Tac, Super Seam, etc.). Be sure that the diagonal braces that keeps the fabric from pulling the rib and cap strip towards the tip are in place; the 2" cap strip & root rib will buckle when you shrink the fabric if they are not braced. Rogers Theetge capnavid@AOL.com ________________________________ Message 9 _____________________________________ Time: 04:57:45 PM PST US From: "DJ Vegh" Subject: Re: Pietenpol-List: GN-1 project & Continental A-80 4 sale I'll add that this GN-1 project was built by the same guy who built the wings I am using on my GN-1. The workmanship is very nice and I would consider it good and safe. It was built from the first day right here in Mesa, AZ. went through 3 owners but always stayed in our dry climate. All of the ribs and wing material are my stuff that I was going to use before I got my beautifully finished wings. I sold all of it to Sterling earlier this year. I used aircraft ply and Sitka Spruce on the ribs. All glued together with T-88. In fact the very same ribs Sterling is selling can be seen in the first entries of my construction log. DJ Vegh www.imagedv.com/aircamper ----- Original Message ----- From: N321TX@wmconnect.com To: pietenpol-list@matronics.com Sent: Tuesday, September 28, 2004 3:32 PM Subject: Pietenpol-List: GN-1 project & Continental A-80 4 sale I'm going to place my GN-1 project on Ebay in a couple of weeks but I wanted folks on the list to have first crack at it. You can see what this project looks like (minus the engine) by visiting D.J.'s website. I think he posted the info and pictures on March 12 and they should still be available for viewing. The GN-1 project has been in storage under a tarp at my hanger here in humid central Texas and I suspect the plywood sideboards on the fuselage went into shock going from an extremely dry desert climate (Mesa, Arizona) to what has almost been a tropical sweatland on my farm. The sides are wavy, almost undetectable ... and the laser cut metal parts I have that are unpainted need a light sanding because of a very thin layer of oxidation. I also detected what looks like some surface mold (dark spots) on a few wood surfaces (originally varnished) and it seems like a light sanding with 320 or 400 grade sandpaper would clean this residue off. This project comes with nearly all the ribs, built by D.J himself, as well as all the wood to finish the wings and D.J.'s original rib jigs. I am keeping the motormount and J3 Cub fuel tank, but everything else goes. I probably will also be selling my Continental A-80 engine, disassembled and now looking better than the day it left the factory. The case was worked by Divco ($820.42) and the accessory case was worked on to new factory limits by Drake Air Parts ($495.00) . I have a brand new camshaft (Sacramento Air Parts $500.00) for this engine and I recently purchased a nice yellow tag crankshaft from Aircraft Engine & Accessory ($650.00) that is 20 under with a new set of bearings ($4.25) . The connecting rods, tappet bodies and rocker arms were reconditioned at Aircraft Engine & Accessory to the tune of $906.59. I also purchased new rod bolts and nuts and cotter pins for $107.22 from Aircraft Specialties Services. I installed a brand new engine dataplate and had the old numbers professionally engraved (not stamped) and have all new cylinder base nuts, cover screws, MOH gasket set, all seals and gaskets and clamps from Fresno Airparts Company ($305.08) to go with the engine. The cylinders are currently undergoing a Cerminil process (best there is and I'll argue this point with ANYBODY) and they should be finished in about three weeks. I can't toss a figure out there for the engine until I have an idea what the cylinders will cost, but this will be a pristine engine with all yellow tags and receipts. The engine case is anodized and looks like a golden treasure trove and the new data plate makes this engine look like a million bucks (hey, maybe that's how much I should ask for it.) Keep viewing Ebay and I'll have this engine on the auction block in the coming weeks. Make a reasonabhle offer on the GN-1 project, and I might just sell it without going on Ebay. Thanks, Sterling Brooks ________________________________ Message 10 ____________________________________ Time: 05:05:08 PM PST US From: "DJ Vegh" Subject: Pietenpol-List: Aircamper w/ Corvair conversion at Copperstate --> Pietenpol-List message posted by: "DJ Vegh" I've talked things over with Pat Panzera, Editor of Contact Magazine. They will have a booth (booth #5) at the Copperstate Fly-in. I will be bringing my nearly completed fuselage with a running Corvair firewall forward installation. I shoudl be arriving on Saturday monring about 8am. Pat will be hosting Corvair conversion discussions every day of the fly-in, but I'll be there with Pat at 2pm on Saturday. After the brief chat we'll run some Corvairs. If anyone lives nearby and is anxious to see a Corvair install please come out and introduce yourself to me. I'll be glad to talk with anyone about it. Just look for the 6'4" 29yr old dude with really shizzle looking sunglasses and spiked hair....that'd be me.... LOL See ya there. DJ Vegh www.imagedv.com/aircamper N74DV Mesa, AZ _ ________________________________ Message 11 ____________________________________ Time: 07:48:59 PM PST US From: Rick Holland Subject: Re: Pietenpol-List: engine instrumentation for Corvair --> Pietenpol-List message posted by: Rick Holland I always did it that way with my RC models but always used an EGT on spam cans. On Tue, 28 Sep 2004 13:51:07 -0500, Oscar Zuniga wrote: > --> Pietenpol-List message posted by: "Oscar Zuniga" > > How do you use the mixture control without an EGT? I always did it by > leaning the mixture till the engine started to run rough, then richen back > up a tad till it smoothed out. > > Oscar Zuniga > San Antonio, TX > > > -- Rick Holland ________________________________ Message 12 ____________________________________ Time: 08:20:30 PM PST US From: Rcaprd@aol.com Subject: Pietenpol-List: Scimitar Prop --> Pietenpol-List message posted by: Rcaprd@aol.com I'm going to see if I can kick up any interest in the design of a 'Scimitar Prop'. I've brought up this subject in years past on this list, but had only limited interest. As we all know, a propeller absorbs the energy of the fuel burned in the engine, and dispenses it in the form of thrust. Whenever energy is transformed from one form to another, some energy is transformed to some other form which is lost to intent of thrust. Energy cannot be created nor destroyed...it's a fact of physics. Therefore, the more efficiently the 'Potential' energy of the fuel that is burned, can be transformed into thrust, the less fuel will be required to perform a given amount of work. A given fixed pitch prop is most efficient at a specific r.p.m., and a specific forward speed. This is why adjustable props came into play, and high performance airplanes usually have Constant Speed Props. Here is where the Scimitar Prop comes in. The blades of the Scimitar Prop will twist to a lower blade angle for the high thrust required for takeoff and climb, then once airborne and power is pulled, the prop unloads and flexes back almost to the blade angle it was carved at. Hence you have an adjustable blade angle prop, with No Moving Parts !! Pretty cool, huh? Wood is the chosen material for this design, because it will not fatigue, it's readily available, and it's relatively easy to work with. Here are the forces imposed upon a Propeller: 1. Centrifugal Force - Most powerful force, tends to pull the blades outward away from the hub. 2. Thrust Bending Force - Blade tips bend forward when put under a load. 3. Torque Bending Force - Blades bend opposite the direction of rotation. 4. Aerodynamic Twisting Force - Twists the blade at the aerodynamic center of pressure. Tends to twist the blades to High Pitch. 5. Centrifugal Twisting Force - The Mass of the blade, under a centrifugal force, tends to twist the blades to a Lower Pitch. 6. Vibration Force (Resonance) - Everything has a resonant frequency, according to the mass, and the location of the mass. A Scimitar design prop takes advantage of these forces to twist the blades to a lower blade angle for takeoff and climb, and then when in cruise flight and power is pulled back, and the prop unloads, the blade angle relaxes back to a higher blade angle, and you have a cruise prop. Steve Wittman certainly understood the potential of a scimitar design, as evidence on the wall of his hanger in Oshkosh. I still can't understand why all props aren't of scimitar design. With enough Research and Development, then mass production could easily bring the additional labor involved, down to a competitive cost. I have searched the library at Oshkosh, lots of web sites, and asked lots of people about scimitar props. By far, the best info I've found on it, is the couple of pages in Eric Clutton's book. I did, however, discover that the concept came about in W.W.I aircraft. The design showed potential, but what happened on several occasions was that in a dogfight, the lead plane would go into a dive, in an effort to escape the aggressor, and the engine / prop would overspeed, then the blades would begin to flutter, and disintegrate. You can imagine the vibration of a broken prop blade, and if power wasn't pulled and shut down the engine, it would then shake the engine right off the plane, and now, with a tail heavy CG condition, the plane would spin to the ground. Even if the pilot was able to shut down the engine in time, he was then a glider pilot...easy prey. I believe when you over-run the prop of a scimitar design, the aerodynamics are what cause the flutter. I have heard stories about how props de-laminate when using thin laminates of wood, however these props had the width of the planks in the conventional direction. The cause of these de-laminations could also have been the technique of construction. The big question, is if any successful props were built using the parameters that Eric Clutton set forth. I do not know the answer to that question. I still plan of building one, but haven't began construction, yet. The method of construction I would use, is laminates of 1/4" or less, bend each laminate in a jig, to match the 'S' shape of the prop, and use T88 exclusively, but to avoid squeezing too much of the adhesive out, by using either scrim cloth between the laminates, or glass beads in the mixture of epoxy. The type of wood would I'll use, is still undecided yet, but the type of types of acceptable prop wood is called out in the AC 43.13-1A. Now, the challenge of designing a reliable Scimitar Prop, using the mass of the blade to twist the blade to a lower blade angle for takeoff and climb, then back almost to the blade angles that they were cut at, when the prop unloads. The laminations would be perpendicular to the direction of conventional props, so as to achieve the dramatic arc of the blades, as set forth by Eric Cluttons design. I'm looking for any input, pros or cons, and especially if anyone is aware of an aircraft that has used this design prop successfully. Chuck Gantzer Pietenpol Aircamper NX770CG ________________________________ Message 13 ____________________________________ Time: 09:56:43 PM PST US From: Galen Hutcheson Subject: Re: Pietenpol-List: Scimitar Prop --> Pietenpol-List message posted by: Galen Hutcheson Chuck, very interesting concept. I would like to follow this with you. I will try to do some research as time permits. Thanks. Doc --- Rcaprd@aol.com wrote: > --> Pietenpol-List message posted by: Rcaprd@aol.com > > I'm going to see if I can kick up any interest in > the design of a 'Scimitar > Prop'. I've brought up this subject in years past > on this list, but had only > limited interest. > As we all know, a propeller absorbs the energy > of the fuel burned in the > engine, and dispenses it in the form of thrust. > Whenever energy is > transformed from one form to another, some energy is > transformed to some other form > which is lost to intent of thrust. Energy cannot be > created nor destroyed...it's > a fact of physics. Therefore, the more efficiently > the 'Potential' energy of > the fuel that is burned, can be transformed into > thrust, the less fuel will be > required to perform a given amount of work. A given > fixed pitch prop is most > efficient at a specific r.p.m., and a specific > forward speed. This is why > adjustable props came into play, and high > performance airplanes usually have > Constant Speed Props. Here is where the Scimitar > Prop comes in. The blades of > the Scimitar Prop will twist to a lower blade angle > for the high thrust > required for takeoff and climb, then once airborne > and power is pulled, the prop > unloads and flexes back almost to the blade angle it > was carved at. Hence you > have an adjustable blade angle prop, with No Moving > Parts !! Pretty cool, huh? > Wood is the chosen material for this design, because > it will not fatigue, it's > readily available, and it's relatively easy to work > with. > > Here are the forces imposed upon a Propeller: > > 1. Centrifugal Force - Most powerful force, tends > to pull the blades > outward away from the hub. > > 2. Thrust Bending Force - Blade tips bend > forward when put under a load. > > 3. Torque Bending Force - Blades bend opposite > the direction of > rotation. > > 4. Aerodynamic Twisting Force - Twists the blade > at the aerodynamic > center of pressure. Tends to twist the blades to > High Pitch. > > 5. Centrifugal Twisting Force - The Mass of > the blade, under a > centrifugal force, tends to twist the blades to a > Lower Pitch. > > 6. Vibration Force (Resonance) - Everything has a > resonant frequency, > according to the mass, and the location of the > mass. > > A Scimitar design prop takes advantage of these > forces to twist the > blades to a lower blade angle for takeoff and climb, > and then when in cruise flight > and power is pulled back, and the prop unloads, the > blade angle relaxes back > to a higher blade angle, and you have a cruise prop. > Steve Wittman certainly understood the potential > of a scimitar design, as > evidence on the wall of his hanger in Oshkosh. > I still can't understand why all props aren't of > scimitar design. With > enough Research and Development, then mass > production could easily bring the > additional labor involved, down to a competitive > cost. I have searched the > library at Oshkosh, lots of web sites, and asked > lots of people about scimitar > props. By far, the best info I've found on it, is > the couple of pages in Eric > Clutton's book. I did, however, discover that the > concept came about in W.W.I > aircraft. The design showed potential, but what > happened on several occasions > was that in a dogfight, the lead plane would go into > a dive, in an effort to > escape the aggressor, and the engine / prop would > overspeed, then the blades > would begin to flutter, and disintegrate. You can > imagine the vibration of a > broken prop blade, and if power wasn't pulled and > shut down the engine, it would > then shake the engine right off the plane, and now, > with a tail heavy CG > condition, the plane would spin to the ground. Even > if the pilot was able to shut > down the engine in time, he was then a glider > pilot...easy prey. I believe > when you over-run the prop of a scimitar design, the > aerodynamics are what > cause the flutter. I have heard stories about how > props de-laminate when using > thin laminates of wood, however these props had the > width of the planks in the > conventional direction. The cause of these > de-laminations could also have been > the technique of construction. The big question, is > if any successful props > were built using the parameters that Eric Clutton > set forth. I do not know > the answer to that question. > I still plan of building one, but haven't began > construction, yet. The > method of construction I would use, is laminates of > 1/4" or less, bend each > laminate in a jig, to match the 'S' shape of the > prop, and use T88 exclusively, > but to avoid squeezing too much of the adhesive out, > by using either scrim > cloth between the laminates, or glass beads in the > mixture of epoxy. The type of > wood would I'll use, is still undecided yet, but the > type of types of > acceptable prop wood is called out in the AC > 43.13-1A. > Now, the challenge of designing a reliable > Scimitar Prop, using the mass > of the blade to twist the blade to a lower blade > angle for takeoff and climb, > then back almost to the blade angles that they were > cut at, when the prop > unloads. The laminations would be perpendicular to > the direction of conventional > props, so as to achieve the dramatic arc of the > blades, as set forth by Eric > Cluttons design. > I'm looking for any input, pros or cons, and > especially if anyone is > aware of an aircraft that has used this design prop > successfully. > > > Chuck Gantzer > Pietenpol Aircamper > NX770CG > > > > > > Contributions > any other > Forums. > > http://www.matronics.com/chat > > http://www.matronics.com/subscription > http://www.matronics.com/FAQ/Pietenpol-List.htm > http://www.matronics.com/archives > http://www.matronics.com/photoshare > http://www.matronics.com/emaillists > > > > > >