X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from nm2.bullet.mail.sp2.yahoo.com ([98.139.91.72] verified) by logan.com (CommuniGate Pro SMTP 6.0c2) with ESMTPS id 5808695 for flyrotary@lancaironline.net; Fri, 12 Oct 2012 09:56:09 -0400 Received-SPF: none receiver=logan.com; client-ip=98.139.91.72; envelope-from=echristley@att.net Received: from [98.139.91.68] by nm2.bullet.mail.sp2.yahoo.com with NNFMP; 12 Oct 2012 13:55:32 -0000 Received: from [66.94.237.98] by tm8.bullet.mail.sp2.yahoo.com with NNFMP; 12 Oct 2012 13:55:32 -0000 Received: from [127.0.0.1] by omp1003.access.mail.mud.yahoo.com with NNFMP; 12 Oct 2012 13:55:31 -0000 X-Yahoo-Newman-Id: 960825.27280.bm@omp1003.access.mail.mud.yahoo.com Received: (qmail 9000 invoked from network); 12 Oct 2012 13:55:31 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=att.net; s=s1024; t=1350050131; bh=fbFr6QaaZn/WDtTIrRPyBvDXdiALE3VlbMvS4idC9Ps=; h=X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:Received:Message-ID:Date:From:User-Agent:MIME-Version:To:Subject:References:In-Reply-To:Content-Type; b=zVH/AvW1+hEJZzYAU7rI1KBAW9CmL17meAW2+iL8Tc4JKZLuwwK/xhy60RCAzdZkIN76ENx4vY8TSLOfGpDaLxUvQMWR/pjfy0WrOhNUmOdy3R3CasG7kr0flXVdJoTEDTefcIkRhA0BvOgksj9/EEQqlhDDdIQL6fKEGx7wVB8= X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: dYEKkRoVM1kkSeIwMchifmcsdyGCHtDfZJzyv4VUEI7C3ri IUzicvKkzZy7AG8n9D0.SMsXdBCRNkiguYpX9ZciMBSZepXktjL_5DUNyVSw b._JcGKOdWGDfVGxeV_oFp.H4gs9IocwW.4SXYnEtpwDwCP6nBwBQdw2xRdL ccE9vMduIZW8JpXEs1kJKGabQdHcY9Svf_nN29VD5nsmHRcw2oy74EKdXAKE EZtmuEMVnfFOoU5Jrw0CRPWn1Vz16pjY1IoDF5FsEsSLTQ4oomkS0FmEZgFD ifp39xaN8ghG2ztKtsJyJyXsMUc343oHLhUMjHs_TPM0oQ60v3Srt_1kdY8j W4GqSyKmRtBa7dv.uQLVJujQrVjC0fyOI8rqp81r4wme8DBhk4OFr_YgdA3D _YuV8PJH_60kC4wCVKBwfoY.tD_ASBJg.v6hkEo5Ba_i5NEpnjCBsJMk4d.d HBBuH8ZsBmZzYh3oCPM0U X-Yahoo-SMTP: 40RP3pGswBDvPav1a.I8eMv.KS8bdgWBnCloVoKaow-- Received: from [10.62.203.45] (echristley@216.240.30.4 with plain) by smtp111.sbc.mail.mud.yahoo.com with SMTP; 12 Oct 2012 06:55:31 -0700 PDT Message-ID: <5078214D.8010007@att.net> Date: Fri, 12 Oct 2012 09:55:25 -0400 From: Ernest Chrisltey User-Agent: Mozilla/5.0 (X11; Linux i686; rv:15.0) Gecko/20120907 Thunderbird/15.0.1 MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: cooling airflow concepts References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------020101040003060907060304" This is a multi-part message in MIME format. --------------020101040003060907060304 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Must.....resist. Must not start modifying cooling inlets until flight tests prove current setup insufficient. Must...resist...premature....optimization. On 10/11/2012 08:49 PM, Tracy wrote: > In my understanding, Airflow dislikes corners so nothing beats a round > inlet. Aircraft design is all about compromises so other factors may > require a different shape. > > 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 >> circular inlet over the current trapezoid shape? >> My concern with the current shape is that the largest area of the >> inlet is towards the hub. >> >> Steve Izett >> On 10/10/2012, at 9:54 PM, Tracy wrote: >> >>> 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 based on a NACA study which mainly defined the >>> optimum inner and outer radius for 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 tube inlet (like a >>> huge pitot tube) and the radiused inlets was very noticeable, >>> especially in climb. They were at least a factor of 2 better at >>> capturing the prop wash in static conditions as measured by pressure >>> at the face of the heat exchangers. >>> >>> Tracy >>> >>> Sent from my iPad >>> >>> On Oct 9, 2012, at 11:45 PM, Stephen Izett >> > wrote: >>> >>>> Thanks Steve >>>> I wonder if Tracy 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 >>>>> retained the stock Van's cooling inlets for the coolant exchangers >>>>> with essentially 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 >>>>> >>>>> ------------------------------------------------------------------------ >>>>> *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 >>>>> >>>>> Thanks again Steve >>>>> >>>>> My current snout looks similar to the attached image. >>>>> I'm considering going to the trouble of reworking the cowl into >>>>> two circular duct openings, keeping them as far from 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 - 21sqin. >>>>> Multiply Tracy's by 2/3 (loose a rotor) + a bit for the extra side >>>>> exhaust energy (Renesis) going into the coolant - say 15sqin's or >>>>> 4 1/2 inch diameter. >>>>> The other attached photos are modified Glasair snouts >>>>> What do you think I should consider given the amount of work >>>>> involved and the possible improvement factored in? >>>>> >>>>> Cheers >>>>> Steve Izett >>>> >> --------------020101040003060907060304 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit
Must.....resist.
Must not start modifying cooling inlets until flight tests prove current setup insufficient.
Must...resist...premature....optimization.

On 10/11/2012 08:49 PM, Tracy wrote:
In my understanding, Airflow dislikes corners so nothing beats a round inlet.   Aircraft design is all about compromises so other factors may require a different shape.  

Tracy

Sent from my iPad

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

Thanks Tracy.
So given the right inner and outer radius', do you believe creating a circular inlet over the current trapezoid shape?
My concern with the current shape is that the largest area of the inlet is towards the hub.

Steve Izett
On 10/10/2012, at 9:54 PM, Tracy wrote:

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 based on a NACA study which mainly defined the optimum inner and outer radius for 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 tube inlet (like a huge pitot tube) and the radiused  inlets was very noticeable, especially in climb.   They were at least a factor of 2 better at capturing the prop wash in static conditions as measured by pressure at the face of the heat exchangers.

Tracy

Sent from my iPad

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

Thanks Steve
I wonder if Tracy 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 retained the stock Van's cooling inlets for the coolant exchangers with essentially 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

 

 

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

Thanks again Steve

My current snout looks similar to the attached image.
I'm considering going to the trouble of reworking the cowl into two circular duct openings, keeping them as far from 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 - 21sqin.
Multiply Tracy's by 2/3 (loose a rotor) + a bit for the extra side exhaust energy (Renesis) going into the coolant - say 15sqin's or 4 1/2 inch diameter.
The other attached photos are modified Glasair snouts
What do you think I should consider given the amount of work involved and the possible improvement factored in?

Cheers
Steve Izett 



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