Wanted :186 cu in, Radial Y ; (30 hp) @ 1,300 rpm -- !

Discussion in 'The light stuff area' started by Bille Floyd, Jan 5, 2020.

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  1. Jan 26, 2020 #41

    TFF

    TFF

    TFF

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    Actually the RC four stoke was primarily developed for point 3, compared to 2 stokes. Electric sucked for years. To me it still does. As for point one, they are catalytic ignition engines mostly. Regular ignition is always an upgrade but rarely needed for most flying. Low TBO is relative; 300 hours is a lifetime in RC. Point 4. Badge of honor
     
  2. Jan 26, 2020 #42

    Bille Floyd

    Bille Floyd

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    20,5 Hp will get me off the ground, (with Ease) at 2700-ASL , here
    in Las Vegas ; but would it be enough to get me up, at 5,500-ASL
    at King Mt Idaho ? When all done with pod and landing gears, i
    expect my Exxtacy to weigh 240-Lb + 205 for the big-Ass pilot.

    The Exxtacy gets a 17:1 glide , and is rated tandem for 160-Kg total pilot
    weight ; so i'm still within the VNE max weight. I was told by the
    airport owner, (who knows my glider well) ; i'd need 25-Hp to
    do the job with certainty. Less than 25-Hp ; i might need a tow
    assist to get me flying.

    I really do hate 2-strokes ; but as of now i really don't see
    another option than the Moster 185, or Hirth F-33 , to fit
    the HP i'm looking for , and still come in under 40-Lb , with
    the E-start ??

    I guess the Valch Vm 420cc R5 radial, would be a bad choice
    for dependability ; since there's so few of them out there to compare
    with ?

    Bille
     
    Last edited: Jan 26, 2020
  3. Jan 26, 2020 #43

    blane.c

    blane.c

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  4. Jan 26, 2020 #44

    Bille Floyd

    Bille Floyd

    Bille Floyd

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    I would think, that a lower turning rpm engine , would last longer ?
    But Honda makes dirt bike engines , to run a few seasons, if you don't
    abuse them : like the CR-250F 4-stroke, documented 38-Hp at
    11,730 rpm .

    @ blane.c
    I'd like a 28-Hp continuous, radial-Y, that spun 2.5 to 3K-rpm , with electronic
    ignition, EFI, and weighed 40-Lb, with the E-start ! :beer:

    Bille
     
  5. Jan 26, 2020 #45

    Bille Floyd

    Bille Floyd

    Bille Floyd

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    I looked at the first :20-seconds of the video, and the Y radial looks
    to be shaking a Lot , compared to the 25-Hp , 5-cyl radial in this one
    below:


    Are more cylinders on a radial , (smoother) ?

    The Valach VM 420 R5, is getting it's 25-Hp, out of a 420cc engine;
    but it spins too fast at 4500rpm. What would Ya need to do
    to slow the Valach down to 2500rpm ?

    Bille
     
  6. Jan 26, 2020 #46

    blane.c

    blane.c

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    I want Santa Claus to be real! But seriously I don't know anyone that makes that. However there are some possibilities depending on what you want. Do you want to fly or lament?

    You could if you wanted to, get one of the little V engines and make a "fake cylinder" to put on the top or bottom, it could be made out of something light and be used to house something useful. With the help of some nerdy friends you could make a loudspeaker bark out the odd resonance needed to "get that authentic sound". That is the least expensive way. Otherwise suck it up and go on a diet, lose 33lbs … oops you want electric start … lose 41lbs and voilà it's the same difference in weight to buy a Scale Birds little Verner and you only need to use 28hp if that's all you want to use.
     
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  7. Jan 27, 2020 #47

    sotaro

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  8. Jan 27, 2020 #48

    sotaro

    sotaro

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    While technically more complicated, a radial 2 stroke with a standard radial crankcase (no crankcase compression) and a supercharger is more elegant than a geared together 3, 4 or 5 singles geared together. The latter is obviously possible, and in some ways the problems are simpler.
     
  9. Jan 27, 2020 #49

    blane.c

    blane.c

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    Jan Carlson about RPM vs POWER.png

    So if you want decrease RPM to 2500RPM that is decrease to about 55%. The lowest the chart shows is a decrease to 63% were you get 25% of the power.
     
    Last edited: Jan 27, 2020
  10. Jan 27, 2020 #50

    ScaleBirdsScott

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    More cylinders indeed smooths things out. So does higher RPM. On a basic level as you add cylinders to a radial you have shorter time between ignition events per revolution, for a given RPM.

    There's a lot more going on that could factor into it, especially if someone is trying to design an engine, but I'm not actually enough of an engineer to do justice to a technical explanation.
     
  11. Jan 27, 2020 #51

    blane.c

    blane.c

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    "I think" much of the appeal of a radial is the exhaust note. So Low RPM Long Stroke comparative to displacement is what you want even "under square" (bore smaller diameter than stroke length) to get the RPM down in respect to displacement, if you want that sound.
     
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  12. Jan 27, 2020 #52

    Bille Floyd

    Bille Floyd

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    I get , (that part) now ; thanks for your time !!

    Bille
     

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