X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from zproxy.gmail.com ([64.233.162.201] verified) by logan.com (CommuniGate Pro SMTP 5.0) with ESMTP id 811061 for flyrotary@lancaironline.net; Tue, 01 Nov 2005 16:20:34 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.233.162.201; envelope-from=wdleonard@gmail.com Received: by zproxy.gmail.com with SMTP id i28so1279809nzi for ; Tue, 01 Nov 2005 13:19:41 -0800 (PST) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=DCvfwj7bL93yjjBuf9tqkuu38EARQAj3EfHeqzeF7Y35sDbBz9RawdCrrQdRs7QUXXgamZiN5sqkcwO+0HYGtH4RHF1EJumqneSjlQKexPT6JIiQt4IMHxFQOjY7PcW6f5ef8NWvofvAtzZnvNUhqA1yYb7kvooC/islxZI/AoE= Received: by 10.36.222.75 with SMTP id u75mr4449174nzg; Tue, 01 Nov 2005 13:19:41 -0800 (PST) Received: by 10.36.222.63 with HTTP; Tue, 1 Nov 2005 13:19:41 -0800 (PST) Message-ID: <1c23473f0511011319k4a295622q5fe29c7121469c57@mail.gmail.com> Date: Tue, 1 Nov 2005 13:19:41 -0800 From: David Leonard To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Catto Prop In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_12526_10553077.1130879981744" References: ------=_Part_12526_10553077.1130879981744 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On 11/1/05, Jim Sower wrote: > > <... I need a little more pitch if I am truly going to be ...> > Don't take a chance on getting over-pitched. You can always turn the > engine/prop faster. Makes for more power too. Max prop rpm is >3000 so > you've lots of wiggle room there, but if you're over-pitched ... > Nothing much good can come of that ... Jim S. > > David Leonard wrote: I am turning my 68x74 wood prop at 3000 right now in cruise (if it is cool out) with some room left in the throttle, but usually not a lot of room lef= t in the cooling department when going that fast. However, as I continue to improve on cooling I am finding that I am running up against 3000 rpm. I don't think I should be running it more than that on a regular basis. If I can turn my 2-blade 74" prop at 3000k, will I pick up any speed from = a 3-blade 74" prop turning at the same speed (through reduced slip)? If I mak= e the prop shorter can I turn it faster? I have heard that 900fps prop tip speed is a good upper limit. Is this a good number to use? Should I be usin= g that as my cruise tip speed, not max tip speed? -- Dave Leonard Turbo Rotary RV-6 N4VY http://members.aol.com/_ht_a/rotaryroster/index.html http://members.aol.com/_ht_a/vp4skydoc/index.html ------=_Part_12526_10553077.1130879981744 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline

On 11/1/05, = Jim Sower <canarder@fron= tiernet.net> wrote:
<... I need a little more pit= ch if I am truly going to be ...>
Don't take a chance on getting over= -pitched.  You can always turn the
engine/prop faster.  Makes for more power too.  Max= prop rpm is >3000 so
you've lots of wiggle room there, but if you're= over-pitched ...
Nothing much good can come of that ... Jim S.

D= avid Leonard wrote:
 
I am turning my 68x74 wood prop at 3000 right now in cruise (if it is = cool out) with some room left in the throttle, but usually not a lot of roo= m left in the cooling department when going that fast.  However, as I = continue to improve on cooling I am finding that I am running up against 30= 00 rpm.  I don't think I should be running it more than that on a= regular basis.
 
If I can turn my 2-blade 74" prop at 3000k, will I pick up any sp= eed from a 3-blade 74" prop turning at the same speed (through reduced= slip)?  If I make the prop shorter can I turn it faster?  I= have heard that 900fps prop tip speed is a good upper limit.  Is this= a good number to use?  Should I be using that as my cruise tip s= peed, not max tip speed? 
 
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