X-Virus-Scanned: clean according to Sophos on Logan.com From: "Christamarmc" Received: from mail-pd0-f179.google.com ([209.85.192.179] verified) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTPS id 6998263 for flyrotary@lancaironline.net; Fri, 25 Jul 2014 02:17:30 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.192.179; envelope-from=christamarmc@gmail.com Received: by mail-pd0-f179.google.com with SMTP id ft15so5116872pdb.10 for ; Thu, 24 Jul 2014 23:16:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=subject:references:from:content-type:in-reply-to:message-id:date:to :content-transfer-encoding:mime-version; bh=aMueUi2a/pj1Q0qP6iDL4H4SPWC+PsYaUoz0+lQ+Tf8=; b=shM2ho267ngKcDFGNvXjFN8yQiXZ9sqDRiF1g9INMxJ8Nl1JVJOYs3hOviulgG+Hu0 ikX7T/3JAf9GLXi29Gq/Vp57i7saHHwPC16P2Q5QjXLa0/9OTi69P6iGQwWK/PDGluka vxYjL0XB4tDL4c9Azh5DW43B8OOr87NQaAOjZNl1NVdbrH1D/fK85qxRULEmviU/gIg2 +lGCOzhVNU+5WiBnP4VWmGhmRtptCMwPznFXVUo+VW2lwlsdGj+J9tv6vpvAO64DnoCl P4Lg/4uhiifdHuzgzBBlK7XpH3zi8SN9gTa6lLmGOrX3/aQAkG3HKwSbCQVSrYwj0JcQ hoJw== X-Received: by 10.70.38.203 with SMTP id i11mr40949pdk.162.1406269014349; Thu, 24 Jul 2014 23:16:54 -0700 (PDT) Return-Path: Received: from [192.168.0.3] (210.88.215.218.dyn.commander.net.au. [218.215.88.210]) by mx.google.com with ESMTPSA id fj2sm10157446pdb.66.2014.07.24.23.16.52 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 24 Jul 2014 23:16:53 -0700 (PDT) Subject: Re: [FlyRotary] Re: Rv7 renises p port References: Content-Type: multipart/alternative; boundary=Apple-Mail-CA92F5BA-4925-4D23-A091-0201750313BC X-Mailer: iPad Mail (11D201) In-Reply-To: Message-Id: Date: Fri, 25 Jul 2014 16:16:49 +1000 To: Rotary motors in aircraft Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) --Apple-Mail-CA92F5BA-4925-4D23-A091-0201750313BC Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Hi Tracy Hey that's excellent well that's made up my mind as to what size I wish to s= tick on, will keep al posted when I can get a whirlwind on the front and see= what difference that makes. Cheers Christian Sent from my iPad > On 25 Jul 2014, at 9:41 am, "Tracy" wrote: >=20 > Hi Christian, > No problem with the 74" prop even on my early model RV4 with the short mai= n gear. My home field is grass and 95% of my flying is on grass strips. >=20 > Tracy >=20 > Sent from my iPad >=20 >> On Jul 24, 2014, at 17:07, "Christamarmc" w= rote: >>=20 >> Hi Tracy >> That's excellent results, I've heard that running the 74 " prop on a tail= dragger rv isn't recommended, how have you found it on yours for ground cle= arance, would like to go the 74 over the 72 as I operate from a grass strip a= ll year round. >>=20 >> Cheers >> Christian >>=20 >> Sent from my iPad >>=20 >>> On 25 Jul 2014, at 2:09 am, "Tracy" wrote:= >>>=20 >>> Charlie is right. Consider that an airplane flying with the wing at 0 d= eg. AOA does not fall out of the sky :-) >>>=20 >>> My average speed in the 2004 Sun 100 race was 217.58 mph which includes s= tanding start takeoff and climbout. Prop was a 74 x 88, RPM was 7250 with a= 2.85 : 1 drive. If you calculate that out it comes to 212 mph with zero 's= lippage'. Draw your own conclusions! >>>=20 >>> Tracy >>>=20 >>> Sent from my iPad >>>=20 >>>> On Jul 23, 2014, at 22:59, "Charlie England" wrote: >>>>=20 >>>> Ice sails, desert sails, and now, even unlimited class sailboats can sa= il faster than the wind. 'Negative slippage'. :-) >>>>=20 >>>> A more significant point might be that pitch numbers are virtually mean= ingless, unless you're comparing two props from the same prop maker with the= same blade plan form. Even then, it just tells you which has a finer pitch t= han the other. >>>>=20 >>>> Variables can be: whether the pitch is measured on the back side of the= blade or through the chord line, where along the diameter the pitch angle i= s measured (due to blade twist), and no doubt others I'm not smart enough to= think of at the moment.=20 >>>>=20 >>>> Bottom line is that unless there's an identical airframe flying an iden= tical prop, the pitch number isn't a reliable indicator of speed. >>>>=20 >>>> FWIW, >>>>=20 >>>> Charlie >>>>=20 >>>>=20 >>>>=20 >>>>> On 7/23/2014 7:45 PM, James Osborn wrote: >>>>> I don't know jack about slippage, but I think it is the percentage dif= ference between actual distance traveled and theoretical distance traveled i= f your propeller corkscrewed through the air with no thrust. I found a prop= slip calculator online and for 86 inch pitch, 2.85 gear ratio, 7000 rpm, 18= 0 mph, I get 10% slip. Granted the calculator was for boat propellers, but I= don't think it matters as long as the units are correct. There has to be s= ome slip because there would be no thrust otherwise. So what is considered a= reasonable or good amount of slip? Using Bill's numbers 86 inch pitch, 2.8= 5 gear ratio, 7000 rpm, 200 mph, I get 0% slip. That can't be right! >>>>>=20 >>>>>=20 >>>>>> On Fri, Jul 4, 2014 at 7:19 AM, Bill Bradburry wrote: >>>>>> Christian, >>>>>>=20 >>>>>> It seems that you have a lot of prop slippage at cruise. I think tha= t at >>>>>> that prop rpm you should be getting 200mph if you had no slippage. >>>>>>=20 >>>>>> Bill >>>>>>=20 >>>>>> -----Original Message----- >>>>>> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] >>>>>> Sent: Thursday, July 03, 2014 4:01 PM >>>>>> To: Rotary motors in aircraft >>>>>> Subject: [FlyRotary] Rv7 renises p port >>>>>>=20 >>>>>> Well hi all >>>>>> Just thought I'd throw out there the mods I,ve done to the renises in= an >>>>>> rv7'. >>>>>> Well the p ported engine is now back in the plane and running well, o= ver the >>>>>> standard short manifold that was originally in the plane I have gaine= d >>>>>> around 400 static rpm, same prop and gearbox combo, 2.85 ratio, this e= quates >>>>>> to allot more hp at takeoff, just shy of 2300 prop rpm, I'm running a= prince >>>>>> p tip prop at 68" x 86" pitch, >>>>>> At 8000 ft it is turning 7000 at 180 mph tas which is an improvement o= f 25 >>>>>> mph on previous tests, . So next plan is bigger prop and less pitch t= o let >>>>>> it rev to 7500 in strait and level. >>>>>>=20 >>>>>> Cheers >>>>>> Christian >>>>>> Rv7 renises Aus >>>>>>=20 >>>>>>=20 >>>>>> Sent from my iPad >>>>>> -- >>>>>> Homepage: http://www.flyrotary.com/ >>>>>> Archive and UnSub: >>>>>> http://mail.lancaironline.net:81/lists/flyrotary/List.html >>>>>>=20 >>>>>>=20 >>>>>> -- >>>>>> Homepage: http://www.flyrotary.com/ >>>>>> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary= /List.html >>>>=20 --Apple-Mail-CA92F5BA-4925-4D23-A091-0201750313BC Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Hi Tracy
Hey that's excellen= t well that's made up my mind as to what size I wish to stick on, will keep a= l posted when I can get a whirlwind on the front and see what difference tha= t makes.

Cheers
Christian

Sent fro= m my iPad

On 25 Jul 2014, at 9:41 am, "Tracy" <flyrotary@lancaironline.net> wrote= :

Hi Christian,
No p= roblem with the 74" prop even on my early model RV4 with the short main gear= .   My home field is grass and 95% of my flying is on grass strips.

Tracy

Sent from my iPad

On Jul 24= , 2014, at 17:07, "Christamarmc" <flyrotary@lancaironline.net> wrote:

Hi Tracy
That's excellent results, I've heard t= hat running the 74 " prop on a tail dragger rv isn't recommended, how have y= ou found it on yours for ground clearance, would like to go the 74 over the 7= 2 as I operate from a grass strip all year round.

C= heers
Christian

Sent from my iPad

On 25 Jul 2= 014, at 2:09 am, "Tracy" <= flyrotary@lancaironline.net> wrote:

Charlie is right.  Consider that an airplane flying with th= e wing at 0 deg. AOA does not fall out of the sky :-)

My average speed in the 2004 Sun 100 race was 217.58 mph which includes s= tanding start takeoff and climbout.  Prop was a 74 x 88, RPM was 7250 w= ith a 2.85 : 1 drive.  If you calculate that out it comes to 212 mph wi= th zero 'slippage'.   Draw your own conclusions!

Tracy

Sent from my iPad

On Jul 23, 2014, at 22:59, "= Charlie England" <flyrotar= y@lancaironline.net> wrote:

=20 =20 =20
Ice sails, desert sails, and now, even unlimited class sailboats can sail faster than the wind. 'Negative slippage'. :-)

A more significant point might be that pitch numbers are virtually meaningless, unless you're comparing two props from the same prop maker with the same blade plan form. Even then, it just tells you which has a finer pitch than the other.

Variables can be: whether the pitch is measured on the back side of the blade or through the chord line, where along the diameter the pitch angle is measured (due to blade twist), and no doubt others I'm not smart enough to think of at the moment.

Bottom line is that unless there's an identical airframe flying an identical prop, the pitch number isn't a reliable indicator of speed.

FWIW,

Charlie



On 7/23/2014 7:45 PM, James Osborn wrote:
I don't know jack about slippage, but I think it is the percentage difference between actual distance traveled and theoretical distance traveled if your propeller corkscrewed through the air with no thrust.  I found a prop slip calculator= online and for 86 inch pitch, 2.85 gear ratio, 7000 rpm, 180 mph, I get 10% slip.  Granted the calculator was for boat propellers, but I don't think it matters as long as the units are correct.  There has to be some slip because there would be no thrust otherwise.  So what is considered a reasonable or goo= d amount of slip?  Using Bill's numbers 86 inch pitch, 2.85 gear ratio, 7000 rpm, 200 mph, I get 0% slip.  That can't be right!<= /div>


On Fri, Jul 4, 2014 at 7:19 AM, Bill Bradburry <flyrotary@lancaironli= ne.net> wrote:
Christian,
=
It seems that you have a lot of prop slippage at cruise.  I= think that at
that prop rpm you should be getting 200mph if you had no slippage.

Bill

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.n= et]
Sent: Thursday, July 03, 2014 4:01 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Rv7 renises p port

Well hi all
Just thought I'd throw out there the mods I,ve done to the renises in an
rv7'.
Well the p ported engine is now back in the plane and running well, over the
standard short manifold that was originally in the plane I have gained
around 400 static rpm, same prop and gearbox combo, 2.85 ratio, this equates
to allot more hp at takeoff, just shy of 2300 prop rpm, I'm running a prince
p tip prop at 68" x 86" pitch,
At 8000 ft it is turning 7000 at 180 mph tas which is an improvement of 25
mph on previous tests, . So next plan is bigger prop and less pitch to let
it rev to 7500 in strait and level.

Cheers
Christian
Rv7 renises Aus


Sent from my iPad
--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:
http://mail.lancaironl= ine.net:81/lists/flyrotary/List.html


--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html


=20
= = --Apple-Mail-CA92F5BA-4925-4D23-A091-0201750313BC--