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Thread: Prop pitch

  1. #11
    Senior Member Wheels's Avatar
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    Oct 2010
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    Spokane Wa
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    Default Re: Prop pitch

    The numbers look similar to mine. Solo Full tanks 65 MPH Im around 1000 FPM.
    My Field elevation is 2160 ft.

    I have heard and experienced that the Rotax RPM gauge is about 200 RPM low. Watch that. Find out if you are safe at max indicated RPM. Probably not. Use a strobe or digital RPM on the prop and do the math. I need help, but my friends are smart so they do the math for me.

    Hope to see you at the fly in at Kitfox fun day.

  2. #12
    Senior Member av8rps's Avatar
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    Oct 2009
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    Junction City, WI
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    Default Re: Prop pitch

    It sounds like you are very close to the optimal setting for a 912 with that prop. My experience with different settings on my IVO IFA on my 912ul Kitfox 4 amphib would completely agree with how you have your Kiev set.

    Maybe I missed it, but what is your prop diameter/ length? If it is a 75 inch Kiev those are GREAT numbers.

    Worth mentioning, I tell friends flying 912's that if they want better STOL and climb but still want to get somewhere at a reasonable cruise, set prop so that you get 5800 rpm with WOT straight and level. You'll have a much better climb than at 5500-5600 WOT, but you won't notice much drop in cruise when you pull it back to 5500 for max cruise. (Plus, if you want to race your buddies 172 or something, the plane will fly fastest at 5800 )
    Last edited by av8rps; 07-04-2017 at 06:48 AM.

  3. #13
    Senior Member
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    Pittsboro,NC
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    Default Re: Prop pitch

    My Kiev is a 67.5" 3 blade.

  4. #14
    Senior Member av8rps's Avatar
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    Default Re: Prop pitch

    Ok, that actually makes more sense to me. I've said for a long time that the best prop diameter for overall recreational flying in these planes is between 68 and 72 inches. Smaller is faster at the loss of some climb, and longer provides better STOL at the loss of some cruise.

    But the reality is that your 68" Kiev makes for a very good performing Kitfox, as you have a nice cruise with a good climb. And on only 80 hp that is pretty impressive.

  5. #15
    Senior Member
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    Mar 2009
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    Pittsboro,NC
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    Wink Re: Prop pitch

    I flew the last 2 mornings, yesterday with a passenger and close to full fuel and I was impressed that I experienced little if any loss of speed after removing a half degree of pitch. I didn't do the math but I'm sure I was pushing my 1200 lb gross weight limit. I was well aware that my take off run was longer and my rate of climb was less but it still performed very well. I think my pitch is just about a perfect compromise of climb and cruise. No more tweeking for me. Thanks for all the good advice. James Thomas

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