The Long Beach ACO has approved the use of a 74DM6S5-0-58 prop for my sport
at 2150lbs and the 160hp engine. I am waiting for the paperwork from them
with the approval before I run out and get a new prop. Their main concern
was, now get this, NOISE. Changing the prop to 58" will produce more noise
and the ACO was concerned it might not pass FAR 36 requirements. Never mind
that there are 10,000 airplanes out there with an 0-320 and Sensenich 58"
Anyway, that's are Tax dollars at work.
I hope to have the prop by April.
From: firstname.lastname@example.org [mailto:email@example.com]
On Behalf Of Bill Howard
Sent: Saturday, December 03, 2005 10:00 PM
To: firstname.lastname@example.org; email@example.com;
firstname.lastname@example.org; David Vance
Subject: [musketeermail] 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
at wide open throttle (WOT.) I have a 4-cylinder graphic engine analyzer,
the mixtures are very even. I bought an electronic tach, and my mechanical
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
could be done. Obviously, I could get the prop twisted a little bit - out
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
prop to 56" or less, or reduce the GW to 2,000 lbs to get better climb. NOT
So, the picture is, if I had more HP, or if the plane was 'sleeker' the same
would be overrevving MORE than before, and I'd have to pull the throttle
So it seems to me, I can't go any faster than the plane will fly now, even
had more horsepower or a sleeker plane, cause I'd have to pull the throttle
to keep from over-revving, with the associated uneven mixtures.
Jeff, what did you do with your prop?
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
engine actually LIKES to run WOT (SMOOTH!,) as long as I'm not heading
aand go any farther over that 2,750 in level flight.
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