Results 1 to 2 of 2

Thread: Sundowner Wheel Pants - PowerFlow Exhaust - will they help?

  1. #1

    Sundowner Wheel Pants - PowerFlow Exhaust - will they help?

    On Sat Dec 3 20:43 , David Vance sent:



    You might recall my post asking whether the average Musketeer could attain

    2700 rpm at 8000 feet. The reason behind the question is that the PFS

    exhaust is supposed to provide an extra 200 rpm at cruise altitude.

    Obviously if the average Mouse can already attain redline rpm at altitude,

    there is no need for a fancy exhaust system.



    ---

    Hmmm - my Sport is only 150HP, and it has the original 58" prop.



    Level at about 5,500 ft, the engine pulls about 50 RPM over redline (2,700 RPM)

    at wide open throttle (WOT.) I have a 4-cylinder graphic engine analyzer, and

    the mixtures are very even. I bought an electronic tach, and my mechanical tach

    is pretty close.



    If I pull back the throttle that little bit to bring the RPMs back to the

    redline, the mixtures become very uneven.



    So, over several months last year, we all talked about what that meant, and what

    could be done. Obviously, I could get the prop twisted a little bit - out to

    60", but that would make the climb even 'less' than what I get now.



    There's some 'documentation' that indicates that I should actually change the

    prop to 56" or less, or reduce the GW to 2,000 lbs to get better climb. NOT an

    option.



    So, the picture is, if I had more HP, or if the plane was 'sleeker' the same prop

    would be overrevving MORE than before, and I'd have to pull the throttle back

    even more.



    So it seems to me, I can't go any faster than the plane will fly now, even if I

    had more horsepower or a sleeker plane, cause I'd have to pull the throttle back

    to keep from over-revving, with the associated uneven mixtures.



    Jeff, what did you do with your prop?



    Bill Howard

    BeechSportBill

    N1927W 1973 Sport 150

    Beech Aero Club NorthWest Region Director



    P.S. A little birdy told me the prop was OK out to 2,800 RPM, and I know that the

    engine actually LIKES to run WOT (SMOOTH!,) as long as I'm not heading downhill

    aand go any farther over that 2,750 in level flight.

    ---- Msg sent via @bmi.net Mail v4 - http://www.bmi.net
    _______________________________________________
    BAC-Mail mailing list
    BAC-Mail@beechaeroclub.org
    http://www.beechaeroclub.org/mailman/listinfo/bac-mail

  2. #2
    mike at rellihan.com
    Guest

    Sundowner Wheel Pants - PowerFlow Exhaust - will they help?

    When discussing prop performance, keep in mind that pitch isn't the only
    factor at work. Blade length and blade profile also pay an important part.
    One man's 60" may be another man's 56", if the prop having 56" pitch is
    longer than the one having 60; or if the 56" prop has a wider chord with a
    larger thrust area... Time to go to bed and get off this topic, I can
    tell....


    -----Original Message-----
    From: Bill Howard [mailto:bhoward@bmi.net]
    Sent: Sunday, December 04, 2005 1:00 AM
    To: mike@rellihan.com; musketeermail@yahoogroups.com;
    bac-mail@beechaeroclub.org; David Vance
    Subject: Re: Sundowner Wheel Pants - PowerFlow Exhaust - will they help?



    On Sat Dec 3 20:43 , David Vance sent:



    You might recall my post asking whether the average Musketeer could attain

    2700 rpm at 8000 feet. The reason behind the question is that the PFS

    exhaust is supposed to provide an extra 200 rpm at cruise altitude.

    Obviously if the average Mouse can already attain redline rpm at altitude,

    there is no need for a fancy exhaust system.



    ---

    Hmmm - my Sport is only 150HP, and it has the original 58" prop.



    Level at about 5,500 ft, the engine pulls about 50 RPM over redline (2,700
    RPM)

    at wide open throttle (WOT.) I have a 4-cylinder graphic engine analyzer,
    and

    the mixtures are very even. I bought an electronic tach, and my mechanical
    tach

    is pretty close.



    If I pull back the throttle that little bit to bring the RPMs back to the

    redline, the mixtures become very uneven.



    So, over several months last year, we all talked about what that meant, and
    what

    could be done. Obviously, I could get the prop twisted a little bit - out
    to

    60", but that would make the climb even 'less' than what I get now.



    There's some 'documentation' that indicates that I should actually change
    the

    prop to 56" or less, or reduce the GW to 2,000 lbs to get better climb. NOT
    an

    option.



    So, the picture is, if I had more HP, or if the plane was 'sleeker' the same
    prop

    would be overrevving MORE than before, and I'd have to pull the throttle
    back

    even more.



    So it seems to me, I can't go any faster than the plane will fly now, even
    if I

    had more horsepower or a sleeker plane, cause I'd have to pull the throttle
    back

    to keep from over-revving, with the associated uneven mixtures.



    Jeff, what did you do with your prop?



    Bill Howard

    BeechSportBill

    N1927W 1973 Sport 150

    Beech Aero Club NorthWest Region Director



    P.S. A little birdy told me the prop was OK out to 2,800 RPM, and I know
    that the

    engine actually LIKES to run WOT (SMOOTH!,) as long as I'm not heading
    downhill

    aand go any farther over that 2,750 in level flight.

    ---- Msg sent via @bmi.net Mail v4 - http://www.bmi.net



    _______________________________________________
    BAC-Mail mailing list
    BAC-Mail@beechaeroclub.org
    http://www.beechaeroclub.org/mailman/listinfo/bac-mail

Similar Threads

  1. Sundowner Wheel Pants - PowerFlow Exhaust - will they help?
    By BeechSportBill in forum Musketeer-Mail Archive
    Replies: 2
    Last Post: 12-05-2005, 07:49 AM
  2. [musketeermail] Sundowner Wheel Pants - PowerFlow Exhaust -
    By jbryant in forum BAC Mail Archive - DO NOT POST HERE
    Replies: 0
    Last Post: 12-05-2005, 07:48 AM
  3. Sundowner Wheel Pants - Power Flow Exhaust Systems
    By Rellihan in forum BAC Mail Archive - DO NOT POST HERE
    Replies: 1
    Last Post: 12-03-2005, 10:56 PM
  4. Sundowner Wheel Pants - PowerFlow Exhaust Systems
    By Rellihan in forum Musketeer-Mail Archive
    Replies: 1
    Last Post: 12-03-2005, 08:10 PM
  5. [musketeermail] Sundowner Wheel Pants - PowerFlow Exhaust Sy
    By sjcote in forum BAC Mail Archive - DO NOT POST HERE
    Replies: 0
    Last Post: 12-03-2005, 08:09 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Single Sign On provided by vBSSO