X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2359147 for flyrotary@lancaironline.net; Sat, 29 Sep 2007 11:20:03 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([24.74.103.61]) by cdptpa-omta02.mail.rr.com with SMTP id <20070929151924.PQVZ3965.cdptpa-omta02.mail.rr.com@edward2> for ; Sat, 29 Sep 2007 15:19:24 +0000 Message-ID: <001701c802ac$1f028b30$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: RV-7A Cooling Date: Sat, 29 Sep 2007 11:19:25 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0014_01C8028A.97A49FF0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_0014_01C8028A.97A49FF0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Glad to hear that increasing the exit area appears to have been the = magic bullet. Dealing with air flow is a bit like magic. There are so = many factors that can be interacting that its tough to get a handle on = it even with data collection and analysis. But, your results shows the 1st order effects. Sufficient intake area (which you have) Sufficient core area (which you have) sufficient exit area (which you now have). Easy said, sometimes hard to figure out though. =20 Good work, Dennis Ed ----- Original Message -----=20 From: Dennis Haverlah=20 To: Rotary motors in aircraft=20 Sent: Saturday, September 29, 2007 9:20 AM Subject: [FlyRotary] Re: RV-7A Cooling Ed had asked the following: I still believe you need to divide you plenum vertically - have you = tried that, I know you tried several things, but I don't recall whether = you tried that approach. Perhaps as you suggested having more exit = opening would help as well as your cowl pressure seemed a bit high near = your core exits. Ed You asked if I had divided my inlet plenum to divert more of the water = cooling air into the oil cooler. The attached picture shows a 1/8 inch = thick foam board with a thin layer of glass cloth covering it. I = installed the diverter and flew several times. No measurable = improvement was noted. It probably helped some but I needed quite a bit = more! The picture also shows some white vanes I installed on the rear = half of the oil cooler - left side in plenum. I had thought that the = air flow was having to make too big a direction change at the radiator = face. The vanes did not improve cooling of the oil significantly = either. Bobby H. brought over a spare radiator and we tested it on our = improvised wind-tunnel at 90 deg. to the air stream and 30 deg to the = air stream. The duct leading to the radiator was shaped so that the = radiator surface area receiving the air flow was kept the same in both = tests. Using a very sensitive velocity measuring device Bobby provided = we found that the exit velocity was 28.7 mph at 90 deg - in this test = the air went straight through the radiator fins. With the radiator at = 30 deg. to the air stream the air had to turn 60 deg to go through the = radiator. The air speed behind the radiator at 30 deg was 28.0 mph. = This test proved my suspicion that the radiator fins were causing = turbulent flow at the surface of the radiator was WRONG! This was Good = News to me because it meant my oil/water cooling system probably could = be made to cool without major redesign. I have made 3 flights recently with static pressure, dynamic pressure = and temperature probes under the cowl. After reviewing the data, I made = a change to the cowl outlet area and flew again. The cooling was GREAT. = My oil/water cooling system will work. I'll post pictures and results = soon. I need to do some more flight tests to determine if I will need = any sort of cowl flap or not. My water was much cooler and the oil = stayed below 210 deg. F. while climbing at 25 in MP. to 6500 ft. Also = additional tests may show that I can blank off some of the water = radiator surface to force more air into the oil cooler. Only testing = will tell! Some time ago I modified the James cowl by cutting the upper inlet = hole just below the spinner. This opening provides combustion air to = the engine. A fiberglass plate was installed to separate this = combustion air inlet from the oil/water plenum. This increased my = manifold pressure in cruise significantly. Ed Anderson wrote:=20 Ed -------------------------------------------------------------------------= ----- -------------------------------------------------------------------------= ----- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_0014_01C8028A.97A49FF0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Glad to hear that increasing the exit area = appears to have=20 been the magic bullet.  Dealing with air flow is a bit like=20  magic.  There are so many factors that can be interacting = that its=20 tough to get a handle on it even with data collection and = analysis.
 
But, your results shows the 1st order=20 effects.
 
Sufficient intake area (which you = have)
Sufficient core area (which you = have)
sufficient exit area (which you now = have).
 
Easy said, sometimes hard to figure out = though. =20
 
Good work, Dennis
 
Ed
 
 
----- Original Message -----
From:=20 Dennis Haverlah
Sent: Saturday, September 29, = 2007 9:20=20 AM
Subject: [FlyRotary] Re: RV-7A=20 Cooling

Ed had asked the following:

I still = believe you=20 need to divide you plenum vertically - have you tried that, I know you = tried=20 several things, but I don't recall whether you tried that = approach. =20 Perhaps as you suggested having more exit opening would help as well = as your=20 cowl pressure seemed a bit high near your core=20 exits.

Ed

You asked if I had divided my inlet = plenum to=20 divert more of the water cooling air into the oil cooler.  The = attached=20 picture shows a 1/8 inch thick foam board with a thin layer of glass = cloth=20 covering it.  I installed the diverter and flew several = times.  No=20 measurable improvement was noted.  It probably helped some but I = needed=20 quite a bit more!  The picture also shows some white vanes I = installed on=20 the rear half of the oil cooler - left side in plenum.  I had = thought=20 that the air flow was having to make too big a direction change at the = radiator face.  The vanes did not improve cooling of the oil=20 significantly either.  Bobby H. brought over a spare radiator and = we=20 tested it on our improvised wind-tunnel at 90 deg. to the air stream = and 30=20 deg to the air stream.  The duct leading to the radiator was = shaped so=20 that the radiator surface area receiving the air flow was kept the = same in=20 both tests.  Using a very sensitive velocity measuring device = Bobby=20 provided we found that the exit velocity was 28.7 mph at 90 deg - in = this test=20 the air went straight through the radiator fins.  With the = radiator at 30=20 deg. to the air stream the air had to turn 60 deg to go through the=20 radiator.  The air speed behind the radiator at 30 deg was 28.0=20 mph.  This test proved my suspicion that the radiator fins were = causing=20 turbulent flow at the surface of the radiator was WRONG!  This = was=20 Good News to me because it meant my oil/water cooling = system=20 probably could be made to cool without major redesign.

I have = made 3=20 flights recently with static pressure, dynamic pressure and = temperature probes=20 under the cowl.  After reviewing the data, I made a change to the = cowl=20 outlet area and flew again.  The cooling was GREAT.  My = oil/water=20 cooling system will work.  I'll post pictures and results = soon. =20 I need to do some more flight tests to determine if I will need any = sort of=20 cowl flap or not.   My water was much cooler and the oil = stayed=20 below 210 deg. F. while climbing at 25 in MP. to 6500 ft.  Also=20 additional tests may show that I can blank off some of the water = radiator=20 surface to force more air into the oil cooler.  Only testing will = tell!

Some time ago I modified the James cowl by cutting the = upper=20 inlet hole just below the spinner.  This opening provides = combustion air=20 to the engine.  A fiberglass plate was installed to separate this = combustion air inlet from the oil/water plenum.  This increased = my=20 manifold pressure in cruise significantly.
Ed Anderson wrote:=20
 

Ed

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