Pietenpol-List: I wish it could fly!
Posted: Fri Jan 20, 2012 10:52 am
Original Posted By: "Piet2112"
Michael,I found this, but haven't been able to find the actual STC if it exists. I waslucky enough to buy a C85-8 so no mods required.Curt MerdanFlower Mound, TXhttp://www.bowersflybaby.com/tech/fenton.htm#C ... 5-12C-85-8 vs. C-85-12I have a Air knocker with a C-85-8. I believe I need to convert this to a -12 configurationto mount a starter. What parts are involved other than changing outthe accessory case using one from a C-85-12,C-90.or a 0-200?The C-85-8 and C85-12 engines are significantly different. The crankcase, accessorycase, accessory gears, and magnetos are different, among other details.The hole spacing and pattern on the -8 accessory case is different than the -12case, so the -12 accessory case does not bolt right up to the -8 crankcase.I am not aware of any approvals to convert from a -8 configuration to -12. The good news is that your engine is quite desirable, and the C85-12 is not aspopular. The -8 is so desirable that there is an STC to convert -12 enginesto -8 status (but not the other direction). You would be money ahead to sellyour -8 and buy a -12.Unfortunately, there is no easy way to install a starter on the -8 series engine.I have looked at several methods, but the expense and complexity of the conversionis simply too high.I'm converting my Champ to a C-85-12 (but no electrics) and I'm using the LasherSTC because it provides the least amount of restrictions for engine choice.The Lasher STC works for the C-85 series of engines, but not for the O-200. You will need some factory drawings and an entirely new cowling to legally installthe O-200.Sorry I don't have a better answer, but this is the straight story.HarryFollow-UpYou are suggesting to me that the -8 engine is a better engine than the -12. DidI understand this correctly?I guess the -8 engine could be lighter, therefore has a better hp to weight ratio.The -8 is preferred because it is lighter than the -12 and less complicated. Internally,the two engines are similar, but the electrical accessories, wiringand battery adds a lot of weight and reduces engine power output a bit becausethe mechanical drag of the accessories eat up a couple of horsepower. Also,within the Cub and Aeronca groups, there is a certain feeling that the -8 is better.Most of the guys who think the -8 is better really don't know why, itis really just what they have "heard". The -8 is also a more historically accurateengine for the more perfect restorations.However, it is all a point of view. If you want electrics, then the -12 is morevaluable. If your preference is simple and light, then the -8 is a better engine.Basically, they are both 85 hp engines, the -12 is about 5 lbs heavier,plus the added weight of the generator, starter, battery, battery box, wiring,etc which adds another 30-35 lbs or so the airframe.I split the difference by building a -12 minus electrics, which is an approvedinstallation. My engine weighs about 5 lbs more than a -8, but I do have theoption of installing electrics at a later time. I probably won't as I don't mindhand propping my engine. Maybe in 20 years I won't, but that is a way offyet.If you are not on the lists, join the Fearless Aeronca Aviator list and the NationalAeronca Association discussion. These two groups will have a ton of informationon the pros and cons of the -8 vs the -12 installation in terms of impacton aircraft performance.HarryRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: I wish it could fly!
Michael,I found this, but haven't been able to find the actual STC if it exists. I waslucky enough to buy a C85-8 so no mods required.Curt MerdanFlower Mound, TXhttp://www.bowersflybaby.com/tech/fenton.htm#C ... 5-12C-85-8 vs. C-85-12I have a Air knocker with a C-85-8. I believe I need to convert this to a -12 configurationto mount a starter. What parts are involved other than changing outthe accessory case using one from a C-85-12,C-90.or a 0-200?The C-85-8 and C85-12 engines are significantly different. The crankcase, accessorycase, accessory gears, and magnetos are different, among other details.The hole spacing and pattern on the -8 accessory case is different than the -12case, so the -12 accessory case does not bolt right up to the -8 crankcase.I am not aware of any approvals to convert from a -8 configuration to -12. The good news is that your engine is quite desirable, and the C85-12 is not aspopular. The -8 is so desirable that there is an STC to convert -12 enginesto -8 status (but not the other direction). You would be money ahead to sellyour -8 and buy a -12.Unfortunately, there is no easy way to install a starter on the -8 series engine.I have looked at several methods, but the expense and complexity of the conversionis simply too high.I'm converting my Champ to a C-85-12 (but no electrics) and I'm using the LasherSTC because it provides the least amount of restrictions for engine choice.The Lasher STC works for the C-85 series of engines, but not for the O-200. You will need some factory drawings and an entirely new cowling to legally installthe O-200.Sorry I don't have a better answer, but this is the straight story.HarryFollow-UpYou are suggesting to me that the -8 engine is a better engine than the -12. DidI understand this correctly?I guess the -8 engine could be lighter, therefore has a better hp to weight ratio.The -8 is preferred because it is lighter than the -12 and less complicated. Internally,the two engines are similar, but the electrical accessories, wiringand battery adds a lot of weight and reduces engine power output a bit becausethe mechanical drag of the accessories eat up a couple of horsepower. Also,within the Cub and Aeronca groups, there is a certain feeling that the -8 is better.Most of the guys who think the -8 is better really don't know why, itis really just what they have "heard". The -8 is also a more historically accurateengine for the more perfect restorations.However, it is all a point of view. If you want electrics, then the -12 is morevaluable. If your preference is simple and light, then the -8 is a better engine.Basically, they are both 85 hp engines, the -12 is about 5 lbs heavier,plus the added weight of the generator, starter, battery, battery box, wiring,etc which adds another 30-35 lbs or so the airframe.I split the difference by building a -12 minus electrics, which is an approvedinstallation. My engine weighs about 5 lbs more than a -8, but I do have theoption of installing electrics at a later time. I probably won't as I don't mindhand propping my engine. Maybe in 20 years I won't, but that is a way offyet.If you are not on the lists, join the Fearless Aeronca Aviator list and the NationalAeronca Association discussion. These two groups will have a ton of informationon the pros and cons of the -8 vs the -12 installation in terms of impacton aircraft performance.HarryRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: I wish it could fly!
--------Jake Schultz - curator,Newport Way Air Museum (OK, it's just my home)Read this topic online here: