Speaking of power

[Jeff Hughes]

I'm on my second year using a 15.5X12 four blade on my OS1.40. Turns around
7,700 on 15%. Oh, yeah, I"m on a bolly muffler, not a tuned pipe. This prop
really slows the plane on down lines.Sounds like a sewing machine!

----- Original Message -----
From: David Lockhart <DaveL322 at comcast.net>
To: <discussion at nsrca.org>
Sent: Thursday, May 29, 2003 9:01 PM
Subject: Re: RE: Speaking of power


> Jon,
>
> The APC part number is LP3157513 and it is available on the apcprop.com
> website.  The prop has actually been around for about (?) 3 years.  It
> has not gained much popularity (yet) as it is a pretty heavy load, and
> it is only a limited number of flyers seeking "more quiet" and willing
> to experiment outside of the currently popular 15.5-1#W, 16.5-12,13W,
> and 17-10,12.  I suspect more 3 and 4 blade props will be seen in
> future as the engines continue to get stronger (and louder if the RPM
> is not kept in check) and the ground clearance continues to get shorter.
>
> Regards,
>
> Dave Lockhart
> DaveL322 at comcast.net
>
> ----- Original Message -----
> From: Jon Uhler <juhler at jfmolloy.com>
> Date: Thursday, May 29, 2003 10:40 pm
> Subject: RE: Speaking of power
>
> > David,
> >
> > Where does one get a 15.75x13 3 blade prop?
> >
> > Thanks,
> >
> > Jon
> >
> > -----Original Message-----
> > From: David Lockhart [DaveL322 at comcast.net]
> > Sent: Thursday, May 29, 2003 9:05 PM
> > To: discussion at nsrca.org
> > Subject: Re: Speaking of power
> >
> >
> > I previously ran both the 17-12 and 17-12N on my 140EFI.  The 17-
> > 12 was
> > only about 100 RPM less on the ground.  In the air, it was a very
> > different story - the 17-12 actually unloads quite a bit more and
> > is
> > louder in the air.
> >
> > The 15.75-13 3 blade - it is a little too much load for the 140EFI
> > unless you run a lot of nitro.  That prop de-pitched to 11" turns
> > right
> > about 8,000.  Set rich, at 7,700, I think the last time I db'd
> > with a
> > good meter it was 89 db.  Very quiet and my favored prop for P03
> > and
> > F03.
> >
> > Dave Lockhart
> > DaveL322 at comcast.net
> >
> >
> >
> > ----- Original Message -----
> > From: wgalligan <wgalligan at cnbcom.net>
> > Date: Thursday, May 29, 2003 2:23 pm
> > Subject: Re: Speaking of power
> >
> > > OS 1.40RX  17x12N APC 15% Cool Power on our own homemade c.f. 4
> > > chamber pipe = 94 db    I think going to the regular 17x12 would
> > > be quiter.   Lots of carb and prop noise at this rpm level.
> > >
> > > Wayne
> > >
> > >  ----- Original Message -----
> > >  From: Bob Kane
> > >  To: discussion at nsrca.org
> > >  Sent: Thursday, May 29, 2003 12:09 PM
> > >  Subject: Speaking of power
> > >
> > >
> > >  Has anyone measured the sound levels of the larger two strokes
> > > turning the big props?  We measured a YS140DZ with ES pipe
> > turning
> > > a 17X12 APC and came up with 96dB, right on the limit.   Just
> > curious.>
> > >
> > >  Bob Kane
> > >  getterflash at yahoo.com
> > >
> > >
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