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  • #31
    This is my corvair 3.0 liter aircraft conversion minus the starter

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    • #32
      Tallow what is the weight of the engine as pictured?
      BH plans #963
      Patrol plans #P330
      LSA plans #L063

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      • Tallow98
        Tallow98 commented
        Editing a comment
        About the weight of a similarly equipped 0200

    • #33
      It is a 120HP engine though

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      • JimParker256
        JimParker256 commented
        Editing a comment
        Tallow, have you seen any "dyno" verification of the 120 HP claim? I've tried to find it with no luck.

        The reason I'm asking is that at least one acquaintance who has flown behind one for several years recently flew an almost identical airplane with an O-235 (118 HP). His report was that the O-235 plane climbed better and flew faster than his Corvair-powered one. I certainly realize there could be MANY reasons for that (more efficient prop, for one), but it got me wondering, especially since the Corvair guys typically turn a bit higher RPM for max power than does a Lycosaurus... And, of course, a well-built Corvair conversion can be had for a fraction of what a Lycoming costs... And 120 HP is probably overkill for an LSA anyway!

    • #34
      No, I have not seen dyno verification, but I built this myself and I do know that the jugs and pistons are larger than stock jugs and pistons. I actually tore down the original engine and compared the jugs and pistons. I will contact William Wynne and and SPA, LLC for dyno numbers. My case had to be machined for the larger jugs. Usually more cubic inches usually means more HP. A stock engine from the year era of this one is 100hp.
      Also, I have $7800 in a zero time engine

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      • #35
        120 hp gets me off the ground faster for just a couple of pounds more weight. I almost built the 3.3 stroker 130hp

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        • #36
          I certainly "get it" about the Corvair being less expensive!

          I'm just curious about the torque/HP curve at the "lower-than-automotive rating" RPM. I believe the Corvair was redlined at 3600 in automotive trim, and that William Wynne says the Corvair O-190 is good for 120 HP at 3200 RPM (redline), and 110 HP at 3000 ("max continuous power"). Peak torque of 200 lb-ft comes at 2800 RPM. But he doesn't publish any figures or torque curves that show how quickly it falls once you go above or below that 2800 RPM "max" rating.

          That extra 10-20 HP should help get you launched faster than an O-200 powered LSA, provided that the torque doesn't fall off too quickly on either side of the peak torque RPM. (By the way, an O-200 produces over 190 lb-ft of torque over a wide range of "normal" RPM - like from 2200 all the way up to 2850 or so... Peak is roughly 193 lb-ft, so you can see that the torque curve is REALLY flat! There's just not much drop-off.)

          One "down side" to the Corvair is that it does turn at a bit faster RPM than the O-200, and thus will require a shorter prop than they do... A prop that turns 3200 RPM would have a max prop diameter of about 68" to avoid near-supersonic tip speeds that wreak havoc with prop efficiency. (Not to mention how badly the "popping" sound will annoy your neighbors!) For the O-200, which has a max RPM of 2750, that "ideal" prop diameter is around 76 inches. (Note that as a general rule, longer props are more efficient than shorter props.)

          And to comply with the LSA rule that your max cruise airspeed cannot exceed 120 knots (132 mph) at max continuous power (3000 RPM) and sea level ISA conditions, your most aggressive "cruise prop" for your Corvair would likely be a 68x46. That would give you a theoretical max airspeed of about 139 mph at 3200 RPM (presumed redline), and about 132 mph at 3000 RPM (max continuous power - the only setting the LSA rules care about).

          Mark G runs a 76x44" pitch prop on his O-200. This is well below the "132 mph max cruise" pitch (which would be roughly 52"), but it gives Mark's plane great initial acceleration and amazing climb performance, while it also limits its max airspeed to around 115 mph (well below the 132 mph LSA limit). If Mark were to run a 76x52" so he could get cruise speeds up to 132 mph, he would likely be turning a LOT lower static RPM, and thus have a LOT less power available during the initial takeoff roll and climb out.

          But what would that 66x46 "cruise prop" for your Corvair do for STOL performance? The thing is - that's REALLY hard to tell without actual experimentation. Given Mark G's results, where an 8" reduction in pitch gave the best STOL performance, we might "assume" the same for your Corvair engine and argue for the use of a 66x40 (or maybe even 66x38) prop for STOL purposes. But that really depends a LOT on the torque curve, and it would impact your cruise speeds dramatically (114 mph @ 3000 RPM, and 106 mph @ 2800 RPM). Still, that might be a compromise worth making, just as Mark decided on his LSA...

          If I were building a Corvair-powered LSA, I'd be highly tempted to go with a Sensenich ground-adjustable prop... You'd still be limited to around 66-68" for the length (that's purely a function of the 3200 RPM max that the engine will produce), but being able to set the pitch for the "mission du jour" would be pretty cool. Flying cross-country? Set the prop to 46" pitch for 132 kt cruise at 3000 RPM (or 120+ mph at 2800 RPM). Planning to join a STOL competition or go backcountry flying in Idaho? Set the prop to a much finer setting (like 38-40", or whatever keeps you just below redline on climbout) and have a ball. Best of both worlds.
          Jim Parker
          Farmersville, TX (NE of Dallas)
          Patrol Quick-Build Serial # P312

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          • #37
            Actually sensenich is what I will be using. Spa LLC carries them.

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            • JimParker256
              JimParker256 commented
              Editing a comment
              Excellent choice. Looking forward to PIREPS when you're flying!

          • #38
            Originally posted by JimParker256 View Post

            If I were building a Corvair-powered LSA, I'd be highly tempted to go with a Sensenich ground-adjustable prop...
            Sorry, am a late-comer to the discussion... I'd thought about the same combination, but have been on their site several times and can't seem to find such a prop in the Corvair rotation... I know you can use a warp-drive ground adjustable on the Corvair, but it seems from what I read that the Sensenich is an order of magnitude more effective...

            Maybe their site doesn't list all the options -- does anyone know if Sensenich has a model in the Corvair rotation?

            Thanks...

            -- Larry

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            • #39
              Originally posted by dcstrng View Post

              Sorry, am a late-comer to the discussion... I'd thought about the same combination, but have been on their site several times and can't seem to find such a prop in the Corvair rotation... I know you can use a warp-drive ground adjustable on the Corvair, but it seems from what I read that the Sensenich is an order of magnitude more effective...

              Maybe their site doesn't list all the options -- does anyone know if Sensenich has a model in the Corvair rotation?

              Thanks...

              -- Larry
              When I asked about an adjustable pitch one on their rack at OSH today, they said that it was for a Corvair.

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              • #40
                Here's a link to some testing done on the combination.

                Builders, Yesterday, Dan Weseman, Paul Salter and myself drove 150 miles south with the Panther prototype to Sensenich Propellers. The task was to have their engineering staff test the combination of their Composite ground adjustable prop blades on the most powerful Corvair, Dan's 3.3 liter stroker engine. It was a productive and interesting day. Dan had long…

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                • #41
                  Ah, that is very interesting -- I guess their site doesn't have all their R&D on it... I'd looked several times for the newer designed props that are getting good reviews, but after inquiries of props made in the former communist countries, they didn't want their products used on direct-drive engines -- but never asked Sensenich; appears that was shortsighted of me...

                  Thanks for posting...

                  -- Larry

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                  • #42
                    Just picked up a Corvair for our LSA project here and I'd love to see some "number's" from the 100hp all the way up to the 3.3's. Certainly can't be the only one since it seems there is a bit of interest in the combination. Surfed a good bit of time trying to track down some flight reports, but there isn't much out there it seems. Any flying CorvairLSA'ers out there, love to hear from you.

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