X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.101] (HELO ms-smtp-02-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTP id 936125 for flyrotary@lancaironline.net; Sat, 07 May 2005 19:11:31 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.101; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-189-178.carolina.res.rr.com [24.74.189.178]) by ms-smtp-02-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j47NAg0W017969 for ; Sat, 7 May 2005 19:10:44 -0400 (EDT) Message-ID: <000701c5535a$051bfed0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Flow Separation Date: Sat, 7 May 2005 19:10:54 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0004_01C55338.7DC9FA70" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0004_01C55338.7DC9FA70 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Ok, Bill I have some "model aircraft" fiberglass cloth which sounds like it = should be about right. Ed ----- Original Message -----=20 From: William=20 To: Rotary motors in aircraft=20 Sent: Saturday, May 07, 2005 7:02 PM Subject: [FlyRotary] Re: Flow Separation Ed, Consider putting a light layer of fiberglass on the inside, it will = greatly strengthen the structure, andprevent pieces from falling out. = (real light cloth) Bill Schertz KIS Cruiser # 4045 ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Saturday, May 07, 2005 4:08 PM Subject: [FlyRotary] Flow Separation Flew with the new duct this morning for 45 minutes. Cooling was = much better but not as good as I had expected with the enlarged inlet - = after I landed and examined the duct I discovered why. I glue foam sheets together to build up the depth of the duct I = need, shape the foam to get the contour I want and then fiberglass the = out side and put a protective layer of resin over the foam inside the = duct.. Well, this morning before going out to the hangar, I found out = a seam had opened between two sheets of foam - so I filled it with some = bondo type stuff, sanded it down, painted it and took it out and = installed in on the aircraft and went flying. After leveling off the coolant stayed between 190F and 200F - a bit = higher than I expected. So I limited the rpm to 6500 rpm. Throttling = back to 5000 rpm produced 170F. After landing I took the duct off and found what you see in = Separation1s.jpg photo. The seam had opened up again and the filler = material and not helped either. Can you spell FLOW SEPARATION? The = red lines enclose the area I suspect that I had flow separation due to = the obstruction. White arrow indicates direction of air flow. =20 My research indicates that slowing down the boundary layer (such as = these obstructions would) has a much more significant impact on cooling = than you might first think. The slowing of the boundary layer as it = encounters the positive pressure gradient (created as the duct expands = radically) can lead to a portion of the main flow "tumbling" over the = slower moving boundary layer forming "eddies" and effecting a much = larger area of flow than the small ridges would indicate. So I think a sizable area of the right half of the core(looking at = it from the front) may have been blocked or at least had its cooling = impaired by flow separation. Will fix the problem and fly again to see = if the cooling changes. Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com -------------------------------------------------------------------------= --- >> Homepage: http://www.flyrotary.com/ >> Archive: http://lancaironline.net/lists/flyrotary/List.html ------=_NextPart_000_0004_01C55338.7DC9FA70 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Ok, Bill
 
I have some "model aircraft" fiberglass = cloth which=20 sounds like it should be about right.
 
Ed
----- Original Message -----
From:=20 William=20
Sent: Saturday, May 07, 2005 = 7:02=20 PM
Subject: [FlyRotary] Re: Flow=20 Separation

Ed,
Consider putting a light layer of = fiberglass on=20 the inside, it will greatly strengthen the structure, andprevent = pieces from=20 falling out. (real light cloth)
Bill Schertz
KIS Cruiser # 4045
----- Original Message -----
From:=20 Ed Anderson
To: Rotary motors in = aircraft=20
Sent: Saturday, May 07, 2005 = 4:08=20 PM
Subject: [FlyRotary] Flow=20 Separation

Flew with the new duct this morning = for 45=20 minutes.  Cooling was much better but not as good as I had = expected=20 with the enlarged inlet - after I landed and examined the duct I = discovered=20 why.
 
I glue foam sheets together to = build up the=20 depth of the duct I need, shape the foam to get the contour I want = and then=20 fiberglass the out side and put a protective layer of resin over the = foam=20 inside the duct..  Well, this morning before going out to the = hangar,=20  I found out a seam had opened between two sheets of foam - so = I filled=20 it with some bondo type stuff, sanded it down, painted it and took = it out=20 and installed in on the aircraft and went flying.
After leveling off the coolant = stayed between=20 190F and  200F - a bit higher than I expected.  So I = limited the=20 rpm to 6500 rpm.  Throttling back to 5000 rpm produced=20 170F.
 
After landing I took the duct off = and found=20 what you see in Separation1s.jpg photo.  The seam had opened up = again=20 and the filler material and not helped either.  Can you spell = FLOW=20 SEPARATION?   The red lines enclose the area I suspect = that I had=20 flow separation due to the obstruction. White arrow indicates = direction=20 of air flow.  
 
 My research indicates that = slowing down=20 the boundary layer (such as these obstructions would) has a much = more=20 significant impact on cooling than you might first think.  The = slowing=20 of the boundary layer as it encounters the positive pressure = gradient=20 (created as the duct expands radically) can lead to a portion of the = main=20 flow "tumbling" over the slower moving boundary layer forming = "eddies"=20 and effecting a much larger area of flow than the small ridges would = indicate.
 
So I think a sizable area of the = right half of=20 the core(looking at it from the front) may have been blocked or at = least had=20 its cooling impaired by flow separation.  Will fix the problem = and fly=20 again to see if the cooling changes.
 
Ed Anderson
Rv-6A N494BW Rotary=20 Powered
Matthews, NC
eanderson@carolina.rr.com

>>  Homepage: =20 http://www.flyrotary.com/
>>  Archive:  =20 = http://lancaironline.net/lists/flyrotary/List.html
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