THREE BLADE PROPS

[Wayne Galligan]

Dave,

The Cleveland 16x11 c.fiber prop works good but is does have a funky sound
to it at WOT like you said but is pretty smooth in the 1/4 to 3/4 throttle
range.  The Bolly is even worse and almost sounds like the engine is not
running right.

Wayne

  ----- Original Message ----- 
  From: David Lockhart
  To: discussion at nsrca.org
  Sent: Sunday, June 12, 2005 9:59 PM
  Subject: Re: [SPAM] Re: Three blade size


  WRT the APC 3 15.75-13 3 blade -

  In practice, it works well re-pitched to 10 or 11 for the 140 engines.
For the 160/170s, it works well at 10, 11, or 12.  Very strong 160/170s (ie,
tip the nitro) can effectively handle the stock prop.

  Setup of the engine/pipe is a huge factor - as is the priority a given
pilot might have on peak power vs midrange throttle response.  Longer pipes
and less prop loads contribute to better throttle response (but less power).
Given 30% nitro, relatively short pipe, and a clean light plane, the
15.75-13 will provide reasonable performance on a 140 - it will be super
quiet, but not have the best throttle response - and it will be very
sensitive to having the needles setu just right.

  I've not run the Mejlik / Cleveland props.  I do know the 16-11 Bolly 3
blade is less load than the 15.75-11 APC 3 blade.  The APC is quieter,
faster, and pulls better.  The Bolly is louder for 2 reasons - higher RPM,
and the CF material transmits noise more than the FG/nylon - and the noise
is a different quality of noise - the CF tends to be more tinny/raspy - not
as mellow and smooth - this idea applies to all CF props I've used (compared
to the APC stuff).

  Regards,

  Dave


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