X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 13 Mar 2009 06:07:46 -0400 Message-ID: X-Original-Return-Path: Received: from QMTA08.westchester.pa.mail.comcast.net ([76.96.62.80] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3545897 for lml@lancaironline.net; Thu, 12 Mar 2009 23:28:54 -0400 Received-SPF: pass receiver=logan.com; client-ip=76.96.62.80; envelope-from=nrgarvin@comcast.net Received: from OMTA12.westchester.pa.mail.comcast.net ([76.96.62.44]) by QMTA08.westchester.pa.mail.comcast.net with comcast id SRQB1b00D0xGWP858TUK07; Fri, 13 Mar 2009 03:28:19 +0000 Received: from nrggateway508 ([71.234.116.252]) by OMTA12.westchester.pa.mail.comcast.net with comcast id STUJ1b0045SotVj3YTUJuy; Fri, 13 Mar 2009 03:28:19 +0000 From: "neal garvin" X-Original-To: "'Lancair Mailing List'" References: Subject: RE: [LML] Re: oil cooling/vernatherm X-Original-Date: Thu, 12 Mar 2009 23:28:21 -0400 X-Original-Message-ID: <24D57133F27E4763A755569125A103C4@nrggateway508> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0128_01C9A36A.3B92FF40" X-Mailer: Microsoft Office Outlook 11 In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 Thread-Index: AcmjHygrsgwpHw9sTeWr9/XnucJ4egAa7zWg This is a multi-part message in MIME format. ------=_NextPart_000_0128_01C9A36A.3B92FF40 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit The Long-Ez uses a reverse scoop under the oil cooler air exit on the bottom of the wing close in to the fuselage. The scoop creates a low pressure area directly behind it to help pull air through the oil cooler. There was a paper in the LongEZ builder hints or such about 15 - 20 years ago that showed how effective it was even though it covered 1/3 of the exit. _____ From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of randy snarr Sent: Thursday, March 12, 2009 10:31 AM To: lml@lancaironline.net Subject: [LML] Re: oil cooling/vernatherm Ron, Thanks for the kind words. I really appreciate it. I had someone else say basically the same thing about the oil cooler inlet. Maybe there is something to that. I will try that and post my results. Randy Snarr --- On Tue, 3/10/09, Ron Laughlin wrote: From: Ron Laughlin Subject: [LML] Re: oil cooling To: lml@lancaironline.net Date: Tuesday, March 10, 2009, 8:36 PM Hi Randy, I read an article once about a Velocity builder (canard pusher) who used NACA ducts behind the cabin to cool his whole engine. As you can imagine, he had some trouble getting adequate air flow through the cowl. He tried many different modifications (short of bonding on some big scoops) but nothing worked. He finally determined that the boundary layer air was just skipping over the NACA ducts and very little was being drawn into the cowl. His solution ended up being very simple. He bonded a small triangular ridge (think similar to a stall strip) on the cowl surface just ahead of the NACA inlet to "trip" the boundary layer so that it would tumble into the duct opening. IIRC, the final shape that worked best for him was a "V" shaped (like a chevron) 3/8" ridge placed about an inch forward of the ducts pointing toward the nose. This might not work in your case but it would be easy to test. Just tape on some balsa strips and go fly. I wish I had a picture for you but I can't remember where I read it. BTW, I'm still very impressed with the unbelievable quality of your work. RonL On Mon, Mar 9, 2009 at 12:41 PM, wrote: > Posted for randy snarr : > > All, > Thanks for the good suggestions on the oil cooler. > I flew again today and my oil temps are at 208 F flying in 35 f air. > They will be 215 or 220 this summer. > I will try a few solutions that do not need to cut the cowl. I will most > likely make a duct to carry the exhaust air from the oil cooler down to the > lower aft part of the cowl. I have also heard that the aft vertical edge of > the naca opening should be shaped like an air foil. Mine is flat and fairly > sharp. The easiest way to test will to be construct a piece to give it a > little airfoil made from balsa or foam taped in place and flight tested. If > that does not work, I will make a duct from the cooler to the low pressure > area on the bottom of the cowl and lastly would be a small lip on the bottom > of the cowl aft. > every producton airplane I have seen with an opening on the bottom of the > cowl has 45 deg lip to create a low pressure area. I should have done that > before I painted.... > > > I will post my findings when I get them. > > Randy Snarr > N694RS > > > -- > > For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html ------=_NextPart_000_0128_01C9A36A.3B92FF40 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

The Long-Ez uses a reverse scoop = under the oil cooler air exit on the bottom of the wing close in to the fuselage. = The scoop creates a low pressure area directly behind it to help pull air through = the oil cooler. There was a paper in the LongEZ builder hints or such about 15 = – 20 years ago that showed how effective it was even though it covered 1/3 = of the exit.

 

From: = Lancair Mailing List = [mailto:lml@lancaironline.net] On Behalf Of randy snarr
Sent: Thursday, March 12, = 2009 10:31 AM
To: = lml@lancaironline.net
Subject: [LML] Re: oil = cooling/vernatherm

 

Ron,
Thanks for the kind words. I really appreciate it.

I had someone else say basically the same thing about the oil cooler = inlet. Maybe there is something to that.
I will try that and post my results.

Randy Snarr

--- On Tue, 3/10/09, Ron Laughlin = <ronlaughlin@gmail.com> wrote:


From: Ron Laughlin <ronlaughlin@gmail.com>
Subject: [LML] Re: oil cooling
To: lml@lancaironline.net
Date: Tuesday, March 10, 2009, 8:36 PM

Hi Randy,
I read an article once about a Velocity builder (canard pusher) = who
used NACA ducts behind the cabin to cool his whole engine. As you = can
imagine, he had some trouble getting adequate air flow through the
cowl. He tried many different modifications (short of bonding on = some
big scoops) but nothing worked. He finally determined that the
boundary layer air was just skipping over the NACA ducts and very
little was being drawn into the cowl.

His solution ended up being very simple. He bonded a small = triangular
ridge (think similar to a stall strip) on the cowl surface just = ahead
of the NACA inlet to "trip" the boundary layer so that it = would tumble
into the duct opening. IIRC, the final shape that worked best for = him
was a "V" shaped (like a chevron) 3/8" ridge placed = about an inch
forward of the ducts pointing toward the nose. This might not work = in
your case but it would be easy to test. Just tape on some balsa = strips
and go fly. I wish I had a picture for you but I can't remember = where
I read it.

BTW, I'm still very impressed with the unbelievable quality of your = work.

RonL



On Mon, Mar 9, 2009 at 12:41 PM,  <marv@lancair.net> wrote:
> Posted for randy snarr <randylsnarr@yahoo.com>: >
>  All,
>  Thanks for the good suggestions on the oil cooler.
>  I flew again today and my oil temps are at 208 F flying in = 35 f air.
>  They will be 215 or 220 this summer.
>  I will try a few solutions that do not need to cut the = cowl. I will most
> likely make a duct to carry the exhaust air from the oil cooler = down to the
> lower aft part of the cowl. I have also heard that the aft = vertical edge of
> the naca opening should be shaped like an air foil. Mine is flat = and fairly
> sharp. The easiest way to test will to be construct a piece to = give it a
> little airfoil made from balsa or foam taped in place and flight = tested. If
> that does not work, I will make a duct from the cooler to the low pressure
> area on the bottom of the cowl and lastly would be a small lip on = the bottom
> of the cowl aft.
>  every producton airplane I have seen with an opening on the = bottom of the
> cowl has 45 deg lip to create a low pressure area. I should have = done that
> before I painted....
>
>
>  I will post my findings when I get them.
>
>  Randy Snarr
>  N694RS
>
>
> --
>
> For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html

--
For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html

 

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