Original Posted By: "Glenn Thomas"
Pietenpol-List: Rear spar to rib fitment
Re: Pietenpol-List: Rear spar to rib fitment
Original Posted By: "Rick Holland"
Re: Pietenpol-List: Rear spar to rib fitment
Original Posted By: Ryan Mueller
Pietenpol-List: Re: prop for A75
Original Posted By: "KMHeide, BA, CPO, FAAOP"
taildrags(at)hotmail.com wrote:> MikeD wrote-> > > > The torque curves are very close up to A65 rpm levels and if you load it thesame> > it will perform about the same. You need to load it so that it reaches it'shigher> > 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 shouldbe exactly the same because the A75 is the same engine as the A65. The rodsare 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 minortweaks, but they are one and the same engine. I've looked at the Continentalspecs for the carb venturi for the two engines (when using the NA-S3A1) andit 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 exactlylike my A65 and I'll never see the additional 10HP because I won't be ableto crank it up to 2600 RPM to get full rated 75HP out of it.> > Oscar Zuniga> San Antonio, TX> mailto: taildrags(at)hotmail.com> website at http://www.flysquirrel.netYou know, I never did get a concrete answer on the issue of the carb throat diameterby 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'veheard several versions of the carb story. But I wasn't worried enough aboutit so far to give it more than a passing effort at investigation. I was certainabout 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 areall a tad lower in load factor than the usual selections for the A65. At thispoint I have not made a concrete choice for our Piet/A75 combo, but 72-38 seemedabout right according to what I have learned so far, if I am off then I suspect70-38 or 72-36 would be the way to go. We are not interested in pushing ourPiet past 75mph or so cruise, but better climb performance is always a goodthing. 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-summerRead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Sat, 16 Feb 2008 23:26:25 -0800 (PST)
taildrags(at)hotmail.com wrote:> MikeD wrote-> > > > The torque curves are very close up to A65 rpm levels and if you load it thesame> > it will perform about the same. You need to load it so that it reaches it'shigher> > 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 shouldbe exactly the same because the A75 is the same engine as the A65. The rodsare 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 minortweaks, but they are one and the same engine. I've looked at the Continentalspecs for the carb venturi for the two engines (when using the NA-S3A1) andit 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 exactlylike my A65 and I'll never see the additional 10HP because I won't be ableto crank it up to 2600 RPM to get full rated 75HP out of it.> > Oscar Zuniga> San Antonio, TX> mailto: taildrags(at)hotmail.com> website at http://www.flysquirrel.netYou know, I never did get a concrete answer on the issue of the carb throat diameterby 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'veheard several versions of the carb story. But I wasn't worried enough aboutit so far to give it more than a passing effort at investigation. I was certainabout 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 areall a tad lower in load factor than the usual selections for the A65. At thispoint I have not made a concrete choice for our Piet/A75 combo, but 72-38 seemedabout right according to what I have learned so far, if I am off then I suspect70-38 or 72-36 would be the way to go. We are not interested in pushing ourPiet past 75mph or so cruise, but better climb performance is always a goodthing. 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-summerRead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Sat, 16 Feb 2008 23:26:25 -0800 (PST)