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Setting Pitch on Flight Adjustable Prop

in General Tech Discussion 8 years ago
Hi All Flight Adjustable Prop Users:

(originally submitted on wrong forum (912is Technical Questions)


With my flight adjustable prop....5700-5800RPM at WOT is my best climb (for a limited time of course)--full fine. AND I make sure I throttle back before leveling out so that I don't overspeed the engine!

At 5800RPM WOT in straight and level flight (at normally flown altitude)and throttling back to between 5100-5500 RPM, this would obtain my best cruising speeds.

If I want to use my prop without adjusting it (using it like a fixed pitch prop) I set RPM at 5600-5650 at WOT straight and level at my normal operating altitude, and throttle back between 5100-5500.

Manifold pressure is of little importance.

Have I got this straight Roger??
Does anyone else have any suggestions?

Performance seems good, but are these settings the best use of my flight adjustable prop?

Ron

  • Re: Setting Pitch on Flight Adjustable Prop

    by » 8 years ago

    Hi Ron,

    If it will be operated as a fixed pitch then 5600-5650 is a really good balance point between climb, cruise and fuel economy. Set this for you average altitude. Many of us that are setup like this cruises between 5100-5400 rpm. That part is just personal preference.

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

    Thank you said by: Ron Lalonde
      
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  • Re: Setting Pitch on Flight Adjustable Prop

    by » 8 years ago

    Flying out of a pretty nice airfield, so constantly changing prop pitch is not a necessity.
    Sure is nice to have the option when needed. Will set up for 5650RPM.
    As always, thanks for advice.

    Ron
      
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  • Re: Setting Pitch on Flight Adjustable Prop

    by » 8 years ago

    Well you can do that if you want to but you are definitely not making the best use of your in-flight adjustable prop.
    I assume that you have a CS controller?...or are you just using as a VP prop with Manual/button adjustment of Prop pitch on the stick or wherever?
    Set the Prop for 5500/5600 for takeoff and land (in case of go-around) and cruise at 4800rpm/24-26MAP or 5000rpm/26MAP depending on how fast you want to go or you want the fuel burn to be. MAP does matter!
    What is the highest ground static rpm you can achieve?
      
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  • Re: Setting Pitch on Flight Adjustable Prop

    by » 8 years ago

    It is a Arplast PV50 electric in-flight adjustable. Not CS.
    I can get 5100/5200 static, enabling me to climb at 5800 rpm if need be. (For 5 mins). When leveling out I throttle back as to not exceed 5800.Have not recorded the MAP at that setting.
    Always stay between 5100-5500 in cruise.

    Ron
      
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  • Re: Setting Pitch on Flight Adjustable Prop

    by » 8 years ago

    I am not familar with the PV50 but 5100/5200 ground static sounds quite low to me. It would have been good to have checked with the manufacturer but I think Arplast have now gone out of business but I think the fine pitch stop needs adjusting.

    If you look in the Rotax Operators manual Page 5-3 it gives you performance data for use with a VP prop.
    For cruise it gives 5000rpm/27MAP which is 75%power. Personally I use 4800rpm/26MAP I find it gives the best combination of speed and fuel burn which Rotax say is 65% power. Staying within MAP parameters in the cruise will avoid overstressing the engine.

    Rotax also say any rpm over 5500 is restricted to 5mins only. I personally wouldn't run any engine flat out at 5800rpm for 5mins.
      
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