---------------------------------------------------------- Pietenpol-List Digest Archive --- Total Messages Posted Sat 02/16/08: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:08 AM - Re: Rib questions (Rick Holland) 2. 08:13 AM - prop for A75 (Oscar Zuniga) 3. 08:19 AM - another wooden trailing edge sketch of possible interest (Cuy, Michael D. (GRC-RXD0)[ASRC]) 4. 02:03 PM - Rear spar to rib fitment (Ryan Mueller) 5. 04:25 PM - Re: Rear spar to rib fitment (Glenn Thomas) 6. 05:04 PM - Re: Rear spar to rib fitment (Rick Holland) 7. 05:47 PM - Re: Rear spar to rib fitment (Ryan Mueller) 8. 06:53 PM - Re: prop for A75 (MikeD) 9. 11:30 PM - Key Style Mag Switch (KMHeide, BA, CPO, FAAOP) ________________________________ Message 1 _____________________________________ Time: 08:08:37 AM PST US From: "Rick Holland" Subject: Re: Pietenpol-List: Rib questions No just the 14" long piece that goes along the back of the entire wing, attached to the back end of all the ribs. Rick On Feb 15, 2008 7:44 PM, Skip Gadd wrote: > Rick, > The trailing edge piece you described, are you talking about the ply > gusset or a spruce filler? > I'm thinking. > Skip > > > ----- Original Message ----- > *From:* Rick Holland > *To: *pietenpol-list@matronics.com > *Sent:* 2/15/2008 12:13:02 AM > *Subject:* Re: Pietenpol-List: Rib questions > > Hey Skip > > I have have the full size 612 drawing in front of me now, the trailing > edge piece is 1 1/4" wide and goes from 3/8" height to 1/8" at the end. > Looks almost identical to the original rib TE. Are you thinking of building > a 612 wing? > > * > > > * > > -- Rick Holland ObjectAge Ltd. Castle Rock, Colorado ________________________________ Message 2 _____________________________________ Time: 08:13:23 AM PST US From: Oscar Zuniga Subject: Pietenpol-List: prop for A75 MikeD wrote- >The torque curves are very close up to A65 rpm levels and if you load it the same >it will perform about the same. You need to load it so that it reaches it's higher >cruise/max rpm to produce full power, therefore you need less load than a 65. Correct. The torque curves should be more than just very close... they should be exactly the same because the A75 is the same engine as the A65. The rods are drilled to provide more oil at the higher rated RPM and the pistons are different (waffle pattern on the underside or some such thing), plus a few minor tweaks, but they are one and the same engine. I've looked at the Continental specs for the carb venturi for the two engines (when using the NA-S3A1) and it is unclear but I believe they both use the 1-1/4" venturi, too. Bottom line is that if I put my Hegy 72x42 prop on the A75 it will perform exactly like my A65 and I'll never see the additional 10HP because I won't be able to crank it up to 2600 RPM to get full rated 75HP out of it. Oscar Zuniga San Antonio, TX mailto: taildrags@hotmail.com website at http://www.flysquirrel.net ________________________________ Message 3 _____________________________________ Time: 08:19:06 AM PST US Subject: Pietenpol-List: another wooden trailing edge sketch of possible interest From: "Cuy, Michael D. (GRC-RXD0)[ASRC]" ________________________________ Message 4 _____________________________________ Time: 02:03:11 PM PST US From: Ryan Mueller Subject: Pietenpol-List: Rear spar to rib fitment Good afternoon everyone, So today I am engaged in fitting blocks to the rib jig (I have glued the full size print down with spray adhesive). I cut two pieces of pine down to 4 3/4" x 1" to represent the front and rear spars. The front spar block looks to fit properly into the space on the plan. The rear spar, however, doesn't quite fit. I've read a number of posts about what to do, from notching the upper capstrip to beveling the spar. I thought about positioning the rear spar so the top is properly aligned, and trimming the bottom at the shallow angle of the lower capstrip, but not having a flat surface on the bottom of the spar could play havoc with fittings I would think. If I position the rear spar with proper alignment on the bottom then I can either bevel the top or just trim it square and use small wedges between the spar and ribs. Or, I could just leave the spar the way it is and align it with one side, accepting the small change in airfoil shape that results. I.E., align it on the bottom and screw the block in place, place my wood blocks everywhere but near the aft part of the top capstrip, and then put a piece of spruce in the jig and see where it wants to bend. This would result in the top capstrip being at most 1/8" (more likely around 1/16") higher above the rear spar than the print shows. Would a 1/8 to 1/16 inch of a change there matter? And finally....on the plans (sheet no. 5) it shows the bottom of the rear spar meeting flush with the capstrip. The bottom capstrip is descending at a shallow angle, making the bottom of the spar look like it would need to beveled to maintain that contact. Does the bottom of the spar need to be beveled to meet flush with that lower capstrip, or is that something else that you just don't have to worry about? Thanks for the help, Ryan --------------------------------- Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. ________________________________ Message 5 _____________________________________ Time: 04:25:13 PM PST US From: "Glenn Thomas" Subject: Re: Pietenpol-List: Rear spar to rib fitment I faced the same problem. After going around and around with different approaches I decided to just trim the top of the rear spar to the right angle. There is barely any interference so I only have to shave off a whisker. Today I used my new jointer for the first time. I'm thinking it will be the perfect tool to do this. Just tilt the fence to the correct angle and pass the spar through. Much safer than trying to do it with a tablesaw since you control the depth of the cut and an accidental dive past the cut line is virtually impossible. I don't think you want to notch the capstrip. There's structural strength that would be lost if you did that. Are you building the one piece wing? You might consider the 3/4" spar which is strong enough. That way there is less spar interfering with rib. (and the spar is cheaper). Thats my opinion for what it's worth. On 2/16/08, Ryan Mueller wrote: > > Good afternoon everyone, > > So today I am engaged in fitting blocks to the rib jig (I have glued the > full size print down with spray adhesive). I cut two pieces of pine down to > 4 3/4" x 1" to represent the front and rear spars. The front spar block > looks to fit properly into the space on the plan. The rear spar, however, > doesn't quite fit. I've read a number of posts about what to do, from > notching the upper capstrip to beveling the spar. > > I thought about positioning the rear spar so the top is properly aligned, > and trimming the bottom at the shallow angle of the lower capstrip, but not > having a flat surface on the bottom of the spar could play havoc with > fittings I would think. > > If I position the rear spar with proper alignment on the bottom then I can > either bevel the top or just trim it square and use small wedges between the > spar and ribs. > > Or, I could just leave the spar the way it is and align it with one side, > accepting the small change in airfoil shape that results. I.E., align it > on the bottom and screw the block in place, place my wood blocks everywhere > but near the aft part of the top capstrip, and then put a piece of spruce in > the jig and see where it wants to bend. This would result in the top > capstrip being at most 1/8" (more likely around 1/16") higher above the rear > spar than the print shows. Would a 1/8 to 1/16 inch of a change there > matter? > > And finally....on the plans (sheet no. 5) it shows the bottom of the rear > spar meeting flush with the capstrip. The bottom capstrip is descending at a > shallow angle, making the bottom of the spar look like it would need to > beveled to maintain that contact. Does the bottom of the spar need to be > beveled to meet flush with that lower capstrip, or is that something else > that you just don't have to worry about? > > Thanks for the help, > > Ryan > > ------------------------------ > Be a better friend, newshound, and > > * > > * > > -- Glenn Thomas Storrs, CT http://www.flyingwood.com ________________________________ Message 6 _____________________________________ Time: 05:04:29 PM PST US From: "Rick Holland" Subject: Re: Pietenpol-List: Rear spar to rib fitment I just angled the top of the rear spar by ripping it through a table saw, left the bottom square. Rick On Feb 16, 2008 3:00 PM, Ryan Mueller wrote: > Good afternoon everyone, > > So today I am engaged in fitting blocks to the rib jig (I have glued the > full size print down with spray adhesive). I cut two pieces of pine down to > 4 3/4" x 1" to represent the front and rear spars. The front spar block > looks to fit properly into the space on the plan. The rear spar, however, > doesn't quite fit. I've read a number of posts about what to do, from > notching the upper capstrip to beveling the spar. > > I thought about positioning the rear spar so the top is properly aligned, > and trimming the bottom at the shallow angle of the lower capstrip, but not > having a flat surface on the bottom of the spar could play havoc with > fittings I would think. > > If I position the rear spar with proper alignment on the bottom then I can > either bevel the top or just trim it square and use small wedges between the > spar and ribs. > > Or, I could just leave the spar the way it is and align it with one side, > accepting the small change in airfoil shape that results. I.E., align it > on the bottom and screw the block in place, place my wood blocks everywhere > but near the aft part of the top capstrip, and then put a piece of spruce in > the jig and see where it wants to bend. This would result in the top > capstrip being at most 1/8" (more likely around 1/16") higher above the rear > spar than the print shows. Would a 1/8 to 1/16 inch of a change there > matter? > > And finally....on the plans (sheet no. 5) it shows the bottom of the rear > spar meeting flush with the capstrip. The bottom capstrip is descending at a > shallow angle, making the bottom of the spar look like it would need to > beveled to maintain that contact. Does the bottom of the spar need to be > beveled to meet flush with that lower capstrip, or is that something else > that you just don't have to worry about? > > Thanks for the help, > > Ryan > > ------------------------------ > Be a better friend, newshound, and > > * > > * > > -- Rick Holland ObjectAge Ltd. Castle Rock, Colorado ________________________________ Message 7 _____________________________________ Time: 05:47:58 PM PST US From: Ryan Mueller Subject: Re: Pietenpol-List: Rear spar to rib fitment Glenn, I'm going with the 3/4 spar, yes, but in lieu of modifying the ribs I'm just going to build them to 1" and glue the 1/8" plywood strips where the ribs end up. Based on what I've been thinking, and what you and Rick have stated, I think aligning via the bottom of the spar and ripping the excess out of the top will work well enough. Time to build a rib! Ryan Glenn Thomas wrote: I faced the same problem. After going around and around with different approaches I decided to just trim the top of the rear spar to the right angle. There is barely any interference so I only have to shave off a whisker. Today I used my new jointer for the first time. I'm thinking it will be the perfect tool to do this. Just tilt the fence to the correct angle and pass the spar through. Much safer than trying to do it with a tablesaw since you control the depth of the cut and an accidental dive past the cut line is virtually impossible. I don't think you want to notch the capstrip. There's structural strength that would be lost if you did that. Are you building the one piece wing? You might consider the 3/4" spar which is strong enough. That way there is less spar interfering with rib. (and the spar is cheaper). Thats my opinion for what it's worth. On 2/16/08, Ryan Mueller wrote: Good afternoon everyone, So today I am engaged in fitting blocks to the rib jig (I have glued the full size print down with spray adhesive). I cut two pieces of pine down to 4 3/4" x 1" to represent the front and rear spars. The front spar block looks to fit properly into the space on the plan. The rear spar, however, doesn't quite fit. I've read a number of posts about what to do, from notching the upper capstrip to beveling the spar. I thought about positioning the rear spar so the top is properly aligned, and trimming the bottom at the shallow angle of the lower capstrip, but not having a flat surface on the bottom of the spar could play havoc with fittings I would think. If I position the rear spar with proper alignment on the bottom then I can either bevel the top or just trim it square and use small wedges between the spar and ribs. Or, I could just leave the spar the way it is and align it with one side, accepting the small change in airfoil shape that results. I.E., align it on the bottom and screw the block in place, place my wood blocks everywhere but near the aft part of the top capstrip, and then put a piece of spruce in the jig and see where it wants to bend. This would result in the top capstrip being at most 1/8" (more likely around 1/16") higher above the rear spar than the print shows. Would a 1/8 to 1/16 inch of a change there matter? And finally....on the plans (sheet no. 5) it shows the bottom of the rear spar meeting flush with the capstrip. The bottom capstrip is descending at a shallow angle, making the bottom of the spar look like it would need to beveled to maintain that contact. Does the bottom of the spar need to be beveled to meet flush with that lower capstrip, or is that something else that you just don't have to worry about? Thanks for the help, Ryan --------------------------------- Be a better friend, newshound, and -- Glenn Thomas Storrs, CT http://www.flyingwood.com --------------------------------- Never miss a thing. Make Yahoo your homepage. ________________________________ Message 8 _____________________________________ Time: 06:53:49 PM PST US Subject: Pietenpol-List: Re: prop for A75 From: "MikeD" taildrags(at)hotmail.com wrote: > MikeD wrote- > > > > The torque curves are very close up to A65 rpm levels and if you load it the same > > it will perform about the same. You need to load it so that it reaches it's higher > > cruise/max rpm to produce full power, therefore you need less load than a 65. > > > > > > Correct. The torque curves should be more than just very close... they should be exactly the same because the A75 is the same engine as the A65. The rods are drilled to provide more oil at the higher rated RPM and the pistons are different (waffle pattern on the underside or some such thing), plus a few minor tweaks, but they are one and the same engine. I've looked at the Continental specs for the carb venturi for the two engines (when using the NA-S3A1) and it is unclear but I believe they both use the 1-1/4" venturi, too. > > Bottom line is that if I put my Hegy 72x42 prop on the A75 it will perform exactly like my A65 and I'll never see the additional 10HP because I won't be able to crank it up to 2600 RPM to get full rated 75HP out of it. > > Oscar Zuniga > San Antonio, TX > mailto: taildrags@hotmail.com > website at http://www.flysquirrel.net You know, I never did get a concrete answer on the issue of the carb throat diameter by asking around, so I said "should be very close" versus "is the same" just to be safe. I know there are internal differences like you mention, but I've heard several versions of the carb story. But I wasn't worried enough about it so far to give it more than a passing effort at investigation. I was certain about the need to reduce load relative to the A65 though. I have seen 70-38, 70-40, 72-38 listed as suitable props for the 75, which are all a tad lower in load factor than the usual selections for the A65. At this point I have not made a concrete choice for our Piet/A75 combo, but 72-38 seemed about right according to what I have learned so far, if I am off then I suspect 70-38 or 72-36 would be the way to go. We are not interested in pushing our Piet past 75mph or so cruise, but better climb performance is always a good thing. I'll talk to the prop mfg before the final decision is rendered. I wonder how many Piets are out there fitted with A75's? Mike -------- Piet-builder-who-hopes-to-be-flying-next-summer Read this topic online here: http://forums.matronics.com/viewtopic.php?p=164501#164501 ________________________________ Message 9 _____________________________________ Time: 11:30:55 PM PST US From: "KMHeide, BA, CPO, FAAOP" Subject: Pietenpol-List: Key Style Mag Switch Members of the list: Anyone have information as to where I could purchase a Keyed Mag Switch? I viewed some of these mag switches in Brodhead, WI last year and would like to purchase one.......if one can be had! I like the style and design....... Ken H Kenneth M. Heide, BA, CPO, FAAOP "Once you have flown, you will walk the earth with your eyes turned skyward, for there you have been, there you long to return, to break the surly bonds of earth and touch the face of God!" -da Vinci/John Gillespie Magee --------------------------------- ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message pietenpol-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Pietenpol-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/pietenpol-list Browse Digests http://www.matronics.com/digest/pietenpol-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.