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  1. #1

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    difference in prop types

    not sure if this is the right forum to put this in but what is the difference between all the different types of wooden props. I have seen type a, c, d, and e. I was wanting to order a new prop for my os 70 4 stroke and wasnt sure the difference between all the props.
    thanks
    Jeff

  2. #2
    jeffie8696's Avatar
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    RE: difference in prop types

    Not all props are created equal to put it simply. In general wide bladed props work best with 4 stroke engines while narrow blades work well with screaming 2 strokes. However it seems there are no hard rules, I prefer to grab a handful of props in the general size range and fly each one then decide.
    Club Saito # 677-Team Boca Bearings-Star Collectibles Muscatine-Glowhead Brotherhood #19

  3. #3

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    RE: difference in prop types

    Try a 12x7 and 12x8 on the engine
    AMA # 126183
    Fly light, fly fast and fly low.

  4. #4

    RE: difference in prop types

    Have you looked up the manufacturers specifications to see what is a good starting point???
    www.staustelldmc.org.uk

  5. #5
    SrTelemaster150's Avatar
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    RE: difference in prop types

    Depending on the drag factor of the airframe the engine is to be used in, I prop about 700-1500 RPM less (static) than the maximum RPM of the engine.

    If the engine is to be installed in a WW-I biplane start W/the smaller spec'ed props. If it's going into a P-51 Mustang, go W/the larger spec'ed props.
    Club Saito #785 - FA91S, FA150, FA180, FA180HC/BBC, FA200TI, FA300TTDP: All with CH Ignitions CDI/Glow fuel
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  6. #6
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    RE: difference in prop types

    I like a 13x6 Master Airscrew K Series on my 70 four stroke. As already stated, try a few to see what you like.

    edit
    the K series is plastic, didn't read the original post very well
    - Carrell

  7. #7
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    RE: difference in prop types

    Iuse 10,000 rpm as a limit for static rpms on any prop for mid sized 4S engines.
    In other words I ground test any prop I am interested in trying and if it turns over 10,000 static it might over rev the engine and cause wear, stress on the engine.
    I allow slightly higher rpm limits on smaller 4S engines.
    Club Saito # 677-Team Boca Bearings-Star Collectibles Muscatine-Glowhead Brotherhood #19

  8. #8
    SrTelemaster150's Avatar
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    RE: difference in prop types


    ORIGINAL: jeffie8696

    IĀ*use 10,000 rpm as a limit for static rpms on any prop for mid sized 4S engines.
    In other words I ground test any prop I am interested in trying and if it turns over 10,000 static it might over rev the engine and cause wear, stress on the engine.
    I allow slightly higher rpm limits on smaller 4S engines.
    That's a good bench mark for medium sized 4-strokes.

    My CDI fired Saito FA91S was spinning a 15 x 4 @ 10,300, a bit more than I liked.

    I went to a 15 x 5 & the revs dropped to 9,700, a bit more cushion against overreving in the air.
    Club Saito #785 - FA91S, FA150, FA180, FA180HC/BBC, FA200TI, FA300TTDP: All with CH Ignitions CDI/Glow fuel
    SIG BH #41
    - 1/3 Spacewalker, Rascal 110
    CUB BH #231 - Wings Maker 1/5 J-3 Cub

  9. #9
    1QwkSport2.5r's Avatar
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    RE: difference in prop types


    ORIGINAL: SrTelemaster150


    ORIGINAL: jeffie8696

    IĀ*use 10,000 rpm as a limit for static rpms on any prop for mid sized 4S engines.
    In other words I ground test any prop I am interested in trying and if it turns over 10,000 static it might over rev the engine and cause wear, stress on the engine.
    I allow slightly higher rpm limits on smaller 4S engines.
    That's a good bench mark for medium sized 4-strokes.

    My CDI fired Saito FA91S was spinning a 15 x 4 @ 10,300, a bit more than I liked.

    I went to a 15 x 5 & the revs dropped to 9,700, a bit more cushion against overreving in the air.
    Whats the typical rev range for the average OS or Saito 4-stroke?
    GlowHead Brotherhood #3
    Using Dynamite, Enya, Fox, Jett, K&B, SH, Super Tigre, Thunder Tiger, and Traxxas engines.


  10. #10
    SrTelemaster150's Avatar
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    RE: difference in prop types

    ORIGINAL: 1QwkSport2.5r


    ORIGINAL: SrTelemaster150


    ORIGINAL: jeffie8696

    IĀ*use 10,000 rpm as a limit for static rpms on any prop for mid sized 4S engines.
    In other words I ground test any prop I am interested in trying and if it turns over 10,000 static it might over rev the engine and cause wear, stress on the engine.
    I allow slightly higher rpm limits on smaller 4S engines.
    That's a good bench mark for medium sized 4-strokes.

    My CDI fired Saito FA91S was spinning a 15 x 4 @ 10,300, a bit more than I liked.

    I went to a 15 x 5 & the revs dropped to 9,700, a bit more cushion against overreving in the air.
    Whats the typical rev range for the average OS or Saito 4-stroke?
    Saito FA91S specified max is 11,000 RPM.

    Mine idles @ 1700 RPM W/CDI firing things off 11* BTDC @ idle.

    Initial full advance timing setting is 35* BTDC.
    Club Saito #785 - FA91S, FA150, FA180, FA180HC/BBC, FA200TI, FA300TTDP: All with CH Ignitions CDI/Glow fuel
    SIG BH #41
    - 1/3 Spacewalker, Rascal 110
    CUB BH #231 - Wings Maker 1/5 J-3 Cub


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