X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao104.cox.net ([68.230.241.42] verified) by logan.com (CommuniGate Pro SMTP 5.1.10) with ESMTP id 2177411 for flyrotary@lancaironline.net; Sat, 14 Jul 2007 11:36:52 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.42; envelope-from=alventures@cox.net Received: from fed1rmimpo01.cox.net ([70.169.32.71]) by fed1rmmtao104.cox.net (InterMail vM.7.08.02.01 201-2186-121-102-20070209) with ESMTP id <20070714153615.EGIG1393.fed1rmmtao104.cox.net@fed1rmimpo01.cox.net> for ; Sat, 14 Jul 2007 11:36:15 -0400 Received: from BigAl ([72.192.132.90]) by fed1rmimpo01.cox.net with bizsmtp id PTcE1X0051xAn3c0000000; Sat, 14 Jul 2007 11:36:14 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: FW: Oil cooler air flow Date: Sat, 14 Jul 2007 08:37:39 -0800 Message-ID: <000001c7c635$4b106340$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C7C5F2.3CED2340" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C7C5F2.3CED2340 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable =20 Hi Al, =20 If a "full-strength" Streamline duct were tested under the conditions of = 9.5"H20 at the entranced to the inlet then at the widest part of the = duct=20 you should theoretically measure 9.5*.84 =3D 7.98. =20 Ed; =20 Perhaps you could enlighten me on this. Where does the .84 come from? = Is this static pressure? I thought that as the air was expanded and = slowed, dynamic pressure was converted to static pressure and the value = increased. You=92ve obviously studied this more than I. =20 Regarding your second sketch, since you do have slower moving boundary = layer air moving next to the skin of the fuselage (and duct), the vane would probably help it turn around the corner. However, you are still = ingesting slower moving air with less dynamic pressure to recover from it. It is = my opinion (no experience or hard data) that moving your inlet fuselage = side of your inlet opening approx 1 1/2 - 2"away from the fuselage would make = an improvement. =20 =20 You are very right about that. Actually in the location that it is, = even an inch or less away from the surface would make a big difference. Keep in mind that the scoop is about 23=94 wide with about 1 =BC=94 opening. = How do you get BL diversion with that configuration? Of course this configuration = began the way it did because another Velocity builder had put his standard aircraft oil cooler (for a Lyc) in the same location, and said it worked great without a scoop =96 just the differential pressure above and below = the wing was enough. Go figure. =20 As I as looking over this diagram more carefully (Winginstallation.jpg), = it became apparent that it main point was to show one duct installation = with the inlet stand off (bottom one) and the other without inlet stand off = using a vane to assist the airflow. So, one could draw the conclusion that = you have a choice? either use inlet stand-off OR using a vane. =20 =20 FWIW =20 Where did that diagram come from? Very interesting. I think that my = scoop opening is large enough, and the BL thin enough, that if I can get = effective diffusion in the duct it should work just fine. =20 Thanks for your input on this. =20 Al =20 =20 =20 =20 =20 =20 =20 Thanks, Al ------=_NextPart_000_0001_01C7C5F2.3CED2340 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

 

Hi Al,

 

If a "full-strength" Streamline duct were tested under the = conditions of

9.5"H20 at the entranced to the inlet then at the widest part of the duct =

you should theoretically measure 9.5*.84 =3D 7.98.

 

Ed;

 <= /font>

Perhaps you = could enlighten me on this. =A0Where does the .84 come from?=A0 Is this static = pressure?=A0 I thought that as the air was expanded and slowed, dynamic pressure was converted to static pressure and the value increased. You’ve = obviously studied this more than I.

 <= /font>

Regarding your second sketch, since you do have = slower moving boundary layer air moving next to the skin of the fuselage (and = duct), the vane would probably help it turn around the corner.  However, = you are still ingesting slower moving air with less dynamic pressure to recover = from it.  It is my opinion (no experience or hard data) that moving your inlet fuselage side of your inlet opening   approx  = 1 1/2 - 2"away from the fuselage would make an improvement.  =

 

You are very right about that.=A0 Actually in the = location that it is, even an inch or less away from the surface would make a big difference.=A0 Keep in mind that the scoop is about 23” wide with = about 1 =BC” opening.=A0 How do you get BL diversion with that configuration? Of = course this configuration began the way it did because another Velocity builder had put his standard aircraft oil cooler (for a Lyc) in the = same location, and said it worked great without a scoop – just the = differential pressure above and below the wing was enough.=A0 Go = figure.

 

As I as looking over this diagram more carefully = (Winginstallation.jpg), it became apparent that it main point was to show one duct installation = with the inlet stand off (bottom one) and the other without inlet stand off = using a vane to assist the airflow.  So, one could draw the conclusion that = you have a choice?  either use inlet stand-off OR using a vane.  =

 

FWIW

 

Where did that diagram come from?=A0 Very = interesting. I think that my scoop opening is large enough, and the BL thin enough, = that if I can get effective diffusion in the duct it should work just = fine.

 

Thanks for your input on this.

 

Al

 

 

 

 

 

 <= /font>

 <= /font>

Thanks,=

=A0Al

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