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  • reggie_obe
    replied
    Originally posted by brian Rupnow View Post
    I clicked on the photo/link and it didn't take me anywhere.
    Try: https://www.use.com/supersize.pl?set...7e96f7b21e684b
    Without two "figure eight" cams, I'd think the piston would tend to skew and want to jam in the bore. Or drag or scuff or maybe not?

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  • aostling
    replied
    Originally posted by brian Rupnow View Post
    I clicked on the photo/link and it didn't take me anywhere.
    I hope you get the photo/link to work. The engine is uniquely strange. Instead of a crankshaft it has a large central cam, which is driven by a cam "follower" mounted on a wrist pin inside each of the four pistons.

    It may not be practical, but if it is not suited to high speed or loading, perhaps it could form the basis of a Stirling engine, with regenerators to increase the efficiency. A Stirling design would obviate the necessity of valve gear (which might be complicated).
    Last edited by aostling; 12-05-2017, 01:31 AM.

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  • brian Rupnow
    replied
    I clicked on the photo/link and it didn't take me anywhere.

    Leave a comment:


  • kendall
    replied
    Think that would function best as a vertical shaft engine or in an X configuration from a lubrication viewpoint. possibly in a rotary (not wankel) configuration.

    Some models I like to build functional so they can actually power something, others I build just because the operation is fun to watch, this falls into the second set.

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  • BCRider
    replied
    The design seems like it'll have a tendency to rather heavy pistons. Especially if they end up being made longer. I know that the weights are opposing so there would not be very much outward vibration. But the stress from all that reciprocating weight on the linkage points would limit RPM rather strongly. Getting a good flow of oil to those points would be an issue also in a real engine as opposed to a low stress low revving model version. And if it's not a dry sump style of engine that would mean that the bottom piston would be operating submerged in a pool of oil. And that would effectively make the lower piston heavier which would affect the vibration issue. Or if the engine were arranged as an X instead of a + then the two lower pistons would have that issue. In fact even with a dry crankcase arrangement the lower piston(s) would tend to hold more oil and be heavier as a result anyway. Likely to the point where those pistons would need to be made slightly lighter based on testing in a real world engine used to power cars or whatever.

    As a concept it's easy to see. But to put such a setup into a real living and working engine has a LOT of issues.

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  • Toolguy
    replied
    I saw that too. I'm thinking longer pistons would keep the link arms out of the bottom of the cylinders.

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  • TGTool
    replied
    It also looks like it might be tricky working out practical dimensions. The link arms need to pass up into the cylinder a ways at TDC, and the piston rings look perilously close to the bottom of the cylinder at BDC. Still, it would be really fun to see one actually working in the flesh, figuratively speaking.

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  • bob_s
    replied
    Neat, but limited by the bearing area of the central cam.

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  • aostling
    replied
    This is clever, a 4-cylinder engine with perfect primary and secondary balance. I hope Brian gives it a go!

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  • Cuttings
    replied
    Looks to me like a great new project for Brian!

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  • rkepler
    replied
    Hey - this is a *family* oriented website!

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  • Black Forest
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    engine for you model builders

    Click on the animation and it will take you to a larger size.

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