X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from wa-out-1112.google.com ([209.85.146.179] verified) by logan.com (CommuniGate Pro SMTP 5.1.9) with ESMTP id 2097346 for flyrotary@lancaironline.net; Mon, 11 Jun 2007 21:51:24 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.146.179; envelope-from=wdleonard@gmail.com Received: by wa-out-1112.google.com with SMTP id j4so2436330wah for ; Mon, 11 Jun 2007 18:50:46 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=JfiZoF5jyB4lgviLAmZ+6OXrx8r+q8gHDyp0TuIikzHZig5pqsKaAzvVaOyiKSS8xACfiVPUsQWBDpoQu9vChHkYEbJxI6wcO1X5A9XiD7zUXX1geKNfIFvatKfdL74v78MNfCI1jmC/hm37URjiZ/1hC9RMVjmitpM+l/T96MU= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=UmJsFNtwwAcTLFUo3PUBs43RnZUxY4vtUD0mvsncQ/hAMwwNwxDnvu1VIYCfdXDAPMppi/WYR2AihHmP7PGlHmwfmwoEa6NwIPhWHuNT69B60587Eq18LN1fLMOYrCjgBVNpPYAe3Q3R/NUQbrRGVbVGVSvPe+5J3CkUmCBWtDU= Received: by 10.114.194.1 with SMTP id r1mr6149437waf.1181613046608; Mon, 11 Jun 2007 18:50:46 -0700 (PDT) Received: by 10.115.54.9 with HTTP; Mon, 11 Jun 2007 18:50:46 -0700 (PDT) Message-ID: <1c23473f0706111850me1ed74doca428308aaa4562b@mail.gmail.com> Date: Mon, 11 Jun 2007 18:50:46 -0700 From: "David Leonard" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: RV-7A cooling - continued In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_62410_25136627.1181613046582" References: ------=_Part_62410_25136627.1181613046582 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline I had a cowl flap on my first iteration, but I never really ever closed it because I always wanted the extra cooling. It seemed to make a small difference. Bill has a sizable cowl flap that apparently works but is costly in terms of drag. My latest iteration is going back to a full-span cowl flap but I am still not very optimistic that it will make a big difference. Dave Leonard On 6/11/07, Ed Anderson wrote: > > Hi Dennis, > > Yes, had 3 grandsons over yesterday myself - so I understand distraction > {:>) > > Yes, going to more H20 probably helps more than just about anything -well, > more air flow also helps. The normally 50/50 has a Cp of around 0.8 where > as water of course is 1.0 or a 20% improvement right there. But, then you > have to remember to put it back to 50/50 come winter time. Texas gets > cold > as best I remember. > > Several folks have tried cowl flaps with less than overwhelming success. > Not certain why they do not seem to used more - they, of course, do add > complexity and a small bit of weight. In my opinion, they get to be a > real > hassle trying to put them in to a nose gear aircraft - not so much in a > tail > dragger with more room under the lower bottom cowl. > > I can tell when OAT changes by more than 2 -3 degrees F just by how my > cooling temps are running. So you're on the money about relatively small > changes having bigger impact on liquid cooled installations. > > I believe that driving a bit more air to your oil cooler will pay > dividends. > > > Best Regards > > Ed > > Ed Anderson > Rv-6A N494BW Rotary Powered > Matthews, NC > eanderson@carolina.rr.com > http://members.cox.net/rogersda/rotary/configs.htm#N494BW > http://www.dmack.net/mazda/index.html > ----- Original Message ----- > From: "Dennis Haverlah" > To: "Rotary motors in aircraft" > Sent: Sunday, June 10, 2007 11:32 PM > Subject: [FlyRotary] Re: RV-7A cooling - continued > > > > Sorry the pictures were not attached - I got distracted - 5 grand kids > > descended on us for the evening. I'll send the pictures Monday. Your > > idea for a vertical plate to divert more air from the water and to the > oil > > may be the ticket. Also I'm using about 50% water and antifreeze, I'll > > change to 10 % antifreeze, 90 % water and a teaspoon to a tablespoon of > > liquid soap to help lower the water temps more. We have plenty of 95 + > > degree days here in the summer! Air cooled engines have a big advantage > > because the cylinders can run 450 deg F and the delta T between the > > cylinder and fins is much higher. A 10 degree change in max. temp due > to > > ambient temps going up is not nearly as critical for them as compared to > > us when we are trying to control temps at 200 to 215 deg F. I'm > surpassed > > cowl flaps are not standard issue on rotary A/C. I may have to add them > > in the future to enhance full power climb cooling. > > > > Dennis H. > > > UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > -- David Leonard Turbo Rotary RV-6 N4VY www.N4VY.RotaryRoster.net www.RotaryRoster.net ------=_Part_62410_25136627.1181613046582 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline
I had a cowl flap on my first iteration, but I never really ever closed it because I always wanted the extra cooling.  It seemed to make a small difference.  Bill has a sizable cowl flap that apparently works but is costly in terms of drag.  My latest iteration is going back to a full-span cowl flap but I am still not very optimistic that it will make a big difference.
 
Dave Leonard 

 
On 6/11/07, Ed Anderson <eanderson@carolina.rr.com> wrote:
Hi Dennis,

Yes, had 3 grandsons over yesterday myself - so I understand distraction
{:>)

Yes, going to more H20 probably helps more than just about anything -well,
more air flow also helps.  The normally 50/50 has a Cp of around 0.8 where
as water of course is 1.0 or a 20% improvement right there.  But, then you
have to remember to put it back to 50/50 come winter time.  Texas gets cold
as best I remember.

Several folks have tried cowl flaps with less than overwhelming success.
Not certain why they do not seem to used more - they, of course, do add
complexity and a small bit of weight.  In my opinion, they get to be a real
hassle trying to put them in to a nose gear aircraft - not so much in a tail
dragger with more room under the lower bottom cowl.

I can tell when OAT changes by more than 2 -3 degrees F just by how my
cooling temps are running.  So you're on the money about relatively small
changes having bigger impact on liquid cooled installations.

I believe that driving a bit more air to your oil cooler will pay dividends.


Best Regards

Ed

Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda/index.html
----- Original Message -----
From: "Dennis Haverlah" <clouduster@austin.rr.com>
To: "Rotary motors in aircraft" < flyrotary@lancaironline.net>
Sent: Sunday, June 10, 2007 11:32 PM
Subject: [FlyRotary] Re: RV-7A cooling - continued


> Sorry the pictures were not attached - I got distracted - 5 grand kids
> descended on us for the evening.  I'll send the pictures Monday.  Your
> idea for a vertical plate to divert more air from the water and to the oil
> may be the ticket.  Also I'm using about 50% water and antifreeze, I'll
> change to 10 % antifreeze, 90 % water and a teaspoon to a tablespoon of
> liquid soap to help lower the water temps more.  We have plenty of 95 +
> degree days here in the summer!  Air cooled engines have a big advantage
> because the cylinders can run 450 deg F and the delta T between the
> cylinder and fins is much higher.  A 10 degree change in max. temp due to
> ambient temps going up is not nearly as critical for them as compared to
> us when we are trying to control temps at 200 to 215 deg F.  I'm surpassed
> cowl flaps are not standard issue on rotary A/C.  I may have to add them
> in the future to enhance full power climb cooling.
>
> Dennis H.
>
UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html


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



--
David Leonard

Turbo Rotary RV-6 N4VY
www.N4VY.RotaryRoster.net
www.RotaryRoster.net ------=_Part_62410_25136627.1181613046582--