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Changing blade pitch to reduce static RPM

in General Tech Discussion 11 years ago
I have a 3 bladed composite prop on a Rotax 582. According to the POH, the MAX static RPM should be 6500 (based on a 2 bladed wooden prop). Mine was 6850.

How many degrees of pitch change should I try to reduce the RPM by 350?

Thanks,
Mike

  • Re: Changing blade pitch to reduce static RPM

    by » 11 years ago

    Start with 1.5 degrees and that should put you in the ballpark. A second fine tune may be in order after that.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: Changing blade pitch to reduce static RPM

    by » 11 years ago

    Roger, thank you! I was going to start with .5 degrees. So you potentially have saved me 2 extra adjustments!

    And I can tell you, after having adjusted 2 of the 3 blades this morning, there is nothing easy about tightening the bolts without changing the pitch!

    So your reply is greatly appreciated!
      
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  • Re: Changing blade pitch to reduce static RPM

    by » 11 years ago

    The main reason people have the blade pitch change when tightening is usually because they were too loose to start. Only make them loose enough so when you turn the blade you have to use some pressure or muscle. You don't want every thing too loose.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report

  • Re: Changing blade pitch to reduce static RPM

    by » 11 years ago

    First, the blade doesn't rotate smoothly, even when loosened up.

    Second, the pitch changes as you tighten the bolts. The blade that I am adjusting is in a horizontal position. So there are two bolts on top and two on the bottom.

    I wish I knew which bolts (top vs bottom or inner vs outer) changes the pitch higher or lower. I'm sure there must be some logical answer but I haven't figured it out yet!

    Mike
      
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  • Re: Changing blade pitch to reduce static RPM

    by » 11 years ago

    I usually don't have pitch changes when tightening. I didn't say it has never happened. I loosen them only enough that I have to apply some muscle to rotate them. They will be hard to turn, but will turn.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report
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