X-Virus-Scanned: clean according to Sophos on Logan.com From: "Tracy" Received: from mail-yk0-f179.google.com ([209.85.160.179] verified) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTPS id 6998051 for flyrotary@lancaironline.net; Thu, 24 Jul 2014 19:42:10 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.160.179; envelope-from=rwstracy@gmail.com Received: by mail-yk0-f179.google.com with SMTP id 142so2275490ykq.10 for ; Thu, 24 Jul 2014 16:41:37 -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=ILxFsl0msRL37FDX3crcQSSXBgMW9MpfdHl/dPwAj58=; b=oov5hrFQl6WYy+hzJu5a+Uq2fhIl7+QKWQuDMyFx8pFUOL+t0umfBpVpacC9gZScEI okRD3G9K/D12jJ7Inrsx6PLfK/d2TXDPDLmmrdR/hsuAKKCUxmghRnGxaFMeYlbYF7J4 73gMek3tBuchcJMA4DOzdUqLo24v2mMzW697RRoYm+vU3YoPK5gOD4jJmyZqiVZDcaZd VnM9YUHvSlx8CKjJZwX2gGGQ+HGrJWNdMovUkS25fFnEhSKw102IPG0rb6rr4TwPve87 wsUkEGpRu/K4vs3OM6u3Vi6zwCZ2cWSLSRBPlRKwWvv+KFkj3BXc+5uSYnXwaG73ut5S QoOA== X-Received: by 10.236.134.208 with SMTP id s56mr16815432yhi.4.1406245297052; Thu, 24 Jul 2014 16:41:37 -0700 (PDT) Return-Path: Received: from [192.168.1.4] (62.sub-70-209-18.myvzw.com. [70.209.18.62]) by mx.google.com with ESMTPSA id a36sm17057813yho.48.2014.07.24.16.41.35 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 24 Jul 2014 16:41:35 -0700 (PDT) Subject: Re: [FlyRotary] Re: Rv7 renises p port References: Content-Type: multipart/alternative; boundary=Apple-Mail-2376C4BB-4798-4348-AD70-4B171E3D9292 X-Mailer: iPad Mail (11D257) In-Reply-To: Message-Id: <8DB0C64F-E91B-471E-B2B9-5E2D80769E31@gmail.com> Date: Thu, 24 Jul 2014 19:41:33 -0400 To: Rotary motors in aircraft Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) --Apple-Mail-2376C4BB-4798-4348-AD70-4B171E3D9292 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Hi Christian, No problem with the 74" prop even on my early model RV4 with the short main g= ear. 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" wr= ote: >=20 > Hi Tracy > That's excellent results, I've heard that running the 74 " prop on a tail d= ragger rv isn't recommended, how have you found it on yours for ground clear= ance, would like to go the 74 over the 72 as I operate from a grass strip al= l 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 de= g. 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 sai= l faster than the wind. 'Negative slippage'. :-) >>>=20 >>> A more significant point might be that pitch numbers are virtually meani= ngless, unless you're comparing two props from the same prop maker with the s= ame blade plan form. Even then, it just tells you which has a finer pitch th= an the other. >>>=20 >>> Variables can be: whether the pitch is measured on the back side of the b= lade or through the chord line, where along the diameter the pitch angle is m= easured (due to blade twist), and no doubt others I'm not smart enough to th= ink of at the moment.=20 >>>=20 >>> Bottom line is that unless there's an identical airframe flying an ident= ical 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 diff= erence between actual distance traveled and theoretical distance traveled if= your propeller corkscrewed through the air with no thrust. I found a prop s= lip calculator online and for 86 inch pitch, 2.85 gear ratio, 7000 rpm, 180 m= ph, I get 10% slip. Granted the calculator was for boat propellers, but I d= on't think it matters as long as the units are correct. There has to be som= e slip because there would be no thrust otherwise. So what is considered a r= easonable or good amount of slip? Using Bill's numbers 86 inch pitc= h, 2.85 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 that= 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 a= n >>>>> rv7'. >>>>> Well the p ported engine is now back in the plane and running well, ov= er 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 e= quates >>>>> to allot more hp at takeoff, just shy of 2300 prop rpm, I'm running a p= rince >>>>> 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 to= 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-2376C4BB-4798-4348-AD70-4B171E3D9292 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Hi Christian,
No problem wit= h the 74" prop even on my early model RV4 with the short main gear.   M= y 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" <fl= yrotary@lancaironline.net> wrote:

Hi Tracy
That's excellent results, I've heard that runn= ing the 74 " prop on a tail dragger rv isn't recommended, how have you found= it on yours for ground clearance, would like to go the 74 over the 72 as I o= perate from a grass strip all year round.

Cheers
Christian

Sent from my iPad

On 25 Jul 2014, at 2= :09 am, "Tracy" <flyrotary= @lancaironline.net> wrote:

<= div>Charlie is right.  Consider that an airplane flying with the wing a= t 0 deg. AOA does not fall out of the sky :-)

My av= erage speed in the 2004 Sun 100 race was 217.58 mph which includes standing s= tart takeoff and climbout.  Prop was a 74 x 88, RPM was 7250 with a 2.8= 5 : 1 drive.  If you calculate that out it comes to 212 mph with zero '= slippage'.   Draw your own conclusions!

Tracy<= br>
Sent from my iPad

On Jul 23, 2014, at 22:59, "Charlie E= ngland" <flyrotary@lancair= online.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-2376C4BB-4798-4348-AD70-4B171E3D9292--