X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-pb0-f52.google.com ([209.85.160.52] verified) by logan.com (CommuniGate Pro SMTP 6.0c2) with ESMTPS id 5807969 for flyrotary@lancaironline.net; Thu, 11 Oct 2012 20:50:31 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.160.52; envelope-from=rwstracy@gmail.com Received: by mail-pb0-f52.google.com with SMTP id rr13so2155462pbb.25 for ; Thu, 11 Oct 2012 17:49:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=subject:references:from:content-type:x-mailer:in-reply-to :message-id:date:to:content-transfer-encoding:mime-version; bh=pOO3A7PVX4lqyUW6Wjr4XiDRJ6xgTUY45YieOw+PaIA=; b=cRaNPMeL3mJpYN4iFU5+rka/0kE306CU+7xwxGr33FktCp5ZmdYqrA6nVglHS+4pK6 V2z0PcCr4M20ZRhjDKzx1wjLr7YyKoIFA1tAFC5aJbBbGG+83ioY3gxSjEOOFTf20qQ5 BkvOCdlvyiuAOwWegzU8KG/Edfunc6+GYd5e3q1V+hW+t0keivJ7T04IermG5jTnUMcQ 2mXblIPuhyUeH8MVDvhxO0EZx+4kbYcYwaOc5Sze5H0qu+hconhveaig/wpT9QrBxUxY E444JgUTRUSuxBm4LSKotIfErepeVNlvAclAyC1l+ICel7PIdwA0eZ7S/+5LFcFQEarI JY2g== Received: by 10.68.130.194 with SMTP id og2mr8584785pbb.131.1350002996071; Thu, 11 Oct 2012 17:49:56 -0700 (PDT) Return-Path: Received: from [192.168.1.3] (40.sub-70-196-194.myvzw.com. [70.196.194.40]) by mx.google.com with ESMTPS id w4sm3389392pav.27.2012.10.11.17.49.53 (version=TLSv1/SSLv3 cipher=OTHER); Thu, 11 Oct 2012 17:49:55 -0700 (PDT) Subject: Re: [FlyRotary] Re: cooling airflow concepts References: From: Tracy Content-Type: multipart/alternative; boundary=Apple-Mail-7C48E60F-50AD-4C0C-A4A2-68298AFF973A X-Mailer: iPad Mail (10A403) In-Reply-To: Message-Id: <96DCB78F-4052-41CA-92A8-D315DBC97117@gmail.com> Date: Thu, 11 Oct 2012 18:49:52 -0600 To: Rotary motors in aircraft Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) --Apple-Mail-7C48E60F-50AD-4C0C-A4A2-68298AFF973A Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable In my understanding, Airflow dislikes corners so nothing beats a round inlet= . Aircraft design is all about compromises so other factors may require a d= ifferent shape. =20 Tracy Sent from my iPad On Oct 10, 2012, at 6:10 PM, Stephen Izett wrote: > Thanks Tracy. > So given the right inner and outer radius', do you believe creating a circ= ular inlet over the current trapezoid shape? > My concern with the current shape is that the largest area of the inlet is= towards the hub. >=20 > Steve Izett > On 10/10/2012, at 9:54 PM, Tracy wrote: >=20 >> Hi Steve, out here in Colorado again with limited access to internet. = Somewhere in the archives is the report I did on the inlets. They were bas= ed on a NACA study which mainly defined the optimum inner and outer radius f= or the inlets. I found it made a very big difference in capturing off axis= airflow (climb attitude and prop wash) . The difference between the raw tu= be inlet (like a huge pitot tube) and the radiused inlets was very noticeab= le, especially in climb. They were at least a factor of 2 better at captur= ing the prop wash in static conditions as measured by pressure at the face o= f the heat exchangers. >>=20 >> Tracy >>=20 >> Sent from my iPad >>=20 >> On Oct 9, 2012, at 11:45 PM, Stephen Izett wrote: >>=20 >>> Thanks Steve >>> I wonder if Tracy is lurking and can comment on the value of reworking t= he cowl inlets? >>>=20 >>> Cheers >>>=20 >>> Steve Izett >>> On 10/10/2012, at 1:32 PM, Steven W. Boese wrote: >>>=20 >>>> Steve, >>>> =20 >>>> I am not the right person to try to answer your question. Having retai= ned the stock Van's cooling inlets for the coolant exchangers with essential= ly no diffusers, the result appears to be marginal cooling and high drag. S= o I am asking myself the exact same question. >>>> =20 >>>> Steve Boese >>>> RV6A, 1986 13B NA, RD1A, EC2 >>>> =20 >>>> =20 >>>> From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf= of Stephen Izett [steveizett@me.com] >>>> Sent: Tuesday, October 09, 2012 6:39 PM >>>> To: Rotary motors in aircraft >>>> Subject: [FlyRotary] Re: cooling airflow concepts >>>>=20 >>>> Thanks again Steve >>>>=20 >>>> My current snout looks similar to the attached image. >>>> I'm considering going to the trouble of reworking the cowl into two cir= cular duct openings, keeping them as far from the centre of the prop as poss= ible. >>>> Current opening is approx 7'' x 3'' - 21sqin. >>>> Tracy I believe uses (Water Side) 5 1/4" so - 21sqin. >>>> Multiply Tracy's by 2/3 (loose a rotor) + a bit for the extra side exha= ust energy (Renesis) going into the coolant - say 15sqin's or 4 1/2 inch dia= meter. >>>> The other attached photos are modified Glasair snouts >>>> What do you think I should consider given the amount of work involved a= nd the possible improvement factored in? >>>>=20 >>>> Cheers >>>> Steve Izett=20 >=20 --Apple-Mail-7C48E60F-50AD-4C0C-A4A2-68298AFF973A Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
In my understanding, Airflow dislikes c= orners so nothing beats a round inlet.   Aircraft design is all about c= ompromises so other factors may require a different shape.  
=
Tracy

Sent from my iPad

On Oct 10, 2012,= at 6:10 PM, Stephen Izett <steveize= tt@me.com> wrote:

Thanks T= racy.
So given the right inner and outer radius', do you believe creatin= g a circular inlet over the current trapezoid shape?
My concern wi= th the current shape is that the largest area of the inlet is towards the hu= b.

Steve Izett
On 10/10/2012, at 9:54 P= M, Tracy wrote:

Hi Steve,   out here in Colorado again wi= th limited access to internet.   Somewhere in the archives is the repor= t I did on the inlets.  They were based on a NACA study which mainly de= fined the optimum inner and outer radius for the inlets.   I found it m= ade a very big difference in capturing off axis airflow (climb attitude and p= rop wash) .  The difference between the raw tube inlet (like a huge pit= ot tube) and the radiused  inlets was very noticeable, especially in cl= imb.   They were at least a factor of 2 better at capturing the prop wa= sh in static conditions as measured by pressure at the face of the heat exch= angers.

Tracy

Sent from my iPad
=

On Oct 9, 2012, at 11:45 PM, Stephen Izett <steveizett@me.com> wrote:

Thanks Steve
I wonder if T= racy is lurking and can comment on the value of reworking the cowl inlets?

Cheers

Steve Izett
=
On 10/10/2012, at 1:32 PM, Steven W. Boese wrote:

Steve,

 

I am not the right person to try to answer your question.  Having r= etained the stock Van's cooling inlets for the coolant exchangers with essen= tially no diffusers, the result appears to be marginal cooling and high= drag.  So I am asking myself the exact same question.

 

Steve Boese
RV6A, 1986 13B NA, RD1A, EC2
<= p style=3D"margin-top: 0px; margin-bottom: 0px; "> 

 

<= div id=3D"divRpF385011" style=3D"direction: ltr; ">From:=  Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of Stephen Izett [steveizett@me.com]
Sent: Tuesday, October 09, 2012 6:39= PM
To: Rotary m= otors in aircraft
Subject:&n= bsp;[FlyRotary] Re: cooling airflow concepts

Thanks again Steve

My current snout looks sim= ilar to the attached image.
I'm considering going to the trouble o= f reworking the cowl into two circular duct openings, keeping them as far fr= om the centre of the prop as possible.
Current opening is approx 7= '' x 3'' - 21sqin.
Tracy I believe uses (Water Side) 5 1/4" so - 2= 1sqin.
Multiply Tracy's by 2/3 (loose a rotor) + a bit for the ext= ra side exhaust energy (Renesis) going into the coolant - say 15sqin's or 4 1= /2 inch diameter.
The other attached photos are modified Glasair s= nouts
What do you think I should consider given the amount of work= involved and the possible improvement factored in?

Cheers
Steve Izett 


= --Apple-Mail-7C48E60F-50AD-4C0C-A4A2-68298AFF973A--