X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 30 [X] Return-Path: Received: from ms-smtp-03.southeast.rr.com ([24.25.9.102] verified) by logan.com (CommuniGate Pro SMTP 5.1.9) with ESMTP id 2070277 for flyrotary@lancaironline.net; Sun, 27 May 2007 17:07:00 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.102; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-103-061.carolina.res.rr.com [24.74.103.61]) by ms-smtp-03.southeast.rr.com (8.13.6/8.13.6) with SMTP id l4RL6BZf023125 for ; Sun, 27 May 2007 17:06:11 -0400 (EDT) Message-ID: <002101c7a0a2$dc349c50$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] James Cowl - RV-7a - Renesis - Cooling Date: Sun, 27 May 2007 17:06:13 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001E_01C7A081.54D8FB00" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3028 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_001E_01C7A081.54D8FB00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Dennis, Sorry to hear you experiment did not work as hoped for. Unfortunately, = I don't have any information on size of turning vanes. 1st your = radiator core and oil cooler core are plenty large enough for 160 HP - = that's the good news, so it would appear to be strictly a matter of air = flow.=20 As you discovered, what would appear to make logical sense by putting = the turning vane in for diverting air to your engine intake - did not = turn out as expected. It frequently happens that way. It took me 5 = different attempt to finally get my oil temps where they should be. I = even ended up with a 5" dia duct at one point which made it flyable = (bearly), but it wasn't until I moved my oil cooler up under the nose = that the problem was licked. I would first recommend you remove the diverter you put in - unless it = clearly showed a marked improvement in engine performance. You may not = be helping either - on the other hand if your engine performance did = indeed show a meaningful improvement then that would mean more power and = more heat to get rid of - the two go hand in hand. But. unless you = picked a couple hundred rpm static, I would remove it - for the moment = at least. I have a small opening (10x2") that serves for my oil cooler and my = engine inlet. I made no effort to put a vane to divert flow to the = engine for two reasons.=20 First, if your duct is doing the job it will be slowing down the air = and converting is kinetic energy it into pressure - that should provide = plenty of air for your engine - it does for mine with a smaller volume = duct. =20 Second (and probably most importantly) , you are very likely creating a = major air flow separation/disturbance/eddie with your flow separator = particularly in a climb attitude. This will have a major adverse impact = on your cooling and is likely the principle reason your cooling = deteriorated - airflow separation. If you have K&W turn to page 279. There you will see several = configurations of cores and ducts coming into them at various angles = from straight on (figure A) to an almost 20 deg angle (figure D). If = you took figure B and reversed the inlet and outlet, it would appear = that would be close to your configuration. You should be able to get adequate cooling with you radiator at the = angle it is without turning vanes. The only turning vanes related to = cooling I can recall seeing in K&W are those fabricated as part of the = core (see figure 12.8) but there may be some mention of using turning = vanes up stream else where - I do not recall. =20 I could not tell what type of profile your duct follows from the inlet = opening to your core. But, if it looks anything like figure 12-10 in = K&W then you do need to correct the shape as that shape or any similar = to it creates air flow separation =3D cooling killer. In fact the paragraph under it tells you what the objective is - you = need to keep your duct walls nearly parallel (perhaps slightly = converging) until just before your core and then flare (like a trumpet) = the duct to meet the core. My total inlet area is 52 square inches - my outlet is quite a bit = bigger (does not mean its better - just bigger). So I agree, your 50 = inches should provide enough air. =20 My believe is that you are getting flow turbulence which is compromising = your cooling core capability to reject heat. Keep working at it, I would remove the divider as I believe it is = hurting cooling much more than it is helping engine power. I would = strive to get a smooth duct from the inlet (without any jogs or sharp = edges) to the core. You would naturally have to blend the round intake = area to the rectangular core area and keep the cross section as constant = as you can and approx the size of your inlet until within six -nine or = so inches of the core and then rapidly flare it to a bell/trumpet shape. = That would help keep the boundary layer flow high until you are ready = to flare the duct to get your pressure recovery. That's about all I can think to suggest at this time. You'll get there, = it will just take a bit of messing with it. With few exceptions, cooling = always seems to be the biggest challenge. We pretty much have a tractor = configuration that we have proven works - which is the one similar to = what I, Bill Eslick, Tracy and others fly with using the standard cowl = openings, but, I believe that you are going to be one of the first on = this list that works out what is needed using the James Cowl. You'll = get it whipped, disappointing as it is to find your installation is not = "perfect", it will not take you long to whip it into shape. Best Regards and good luck Ed ----- Original Message -----=20 From: "Dennis Haverlah" To: "Rotary motors in aircraft" Sent: Sunday, May 27, 2007 2:11 PM Subject: [FlyRotary] James Cowl - RV-7a - Renesis - Cooling >I had very marginal cooling on my first and second flight - RV 7A, = James=20 > cowl, Griffin Scirocco aluminum double pass water radiator with a = Mazda=20 > 1989? RX-7 oil cooler. Water radiator fin size - 22LX13WX2.5T inches. = > Oil - 19LX4.5WX 2T inches. The radiators are mounted side-by-side=20 > under the engine and are at about 25 - 30 degree to the inlet air = flow.=20 > (The air must turn 60-65 deg to flow through the radiators) See = photos=20 > 1 and 2. After my first 2 flights, I constructed a divider/duct to=20 > provide a duct for the engine combustion air to make the sharp turn 90 = > deg. up after the inlet to get to the filter. The bottom of this duct = > was also supposed to provide a duct wall for the air going to the=20 > radiators. See photo 3. Two flights demonstrated this really hurt -=20 > not helped - my cooling. Now I can barely take off and fly the = pattern=20 > before getting up to 210 - 215 on oil and water. The divider duct = took=20 > out about 8-10 sq. in. of inlet area but removed the engine combustion = > air requirement form the remaining inlet air going in the larger = inlet. >=20 > My inlet is about 50 sq. in. and the outlet is about 67 sq. in. This=20 > cowl was used successfully on the Power Sport a/c so I believe the = inlet=20 > and outlet are at least big enough for 160 + hp. When I first posted=20 > pictures of the radiator installation someone suggested I may need=20 > turning vanes to improve flow to the radiators. I am now ready to try = > the turning vanes below the radiators. >=20 > Does anyone have info. I can use to design the turning vanes? The K&W = > document on page 273 mentions guide vanes but does not go into detail. = =20 > I am thinking of 2 inch wide vanes long enough to go from the left to=20 > right side of the radiators and spaced 4 inches apart with the top of = > the vanes about 3/4 inch below the radiator fins. > Comments or -- Any other ideas?=20 >=20 > Dennis H. >=20 >=20 >=20 > -------------------------------------------------------------------------= ------- > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html > ------=_NextPart_000_001E_01C7A081.54D8FB00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Dennis,
 
Sorry to hear you experiment did not work as = hoped=20 for.  Unfortunately, I don't have any information on size of = turning=20 vanes.   1st your radiator core and oil cooler core are plenty = large=20 enough for 160 HP - that's the good news, so it would appear to be = strictly a=20 matter of air flow.
 
As you discovered, what would appear to make = logical sense=20 by putting the turning vane in for diverting air to your engine intake - = did not=20 turn out as expected.  It frequently happens that way.  It = took me 5=20 different attempt to finally get my oil temps where they should = be.  I even=20 ended up with a 5" dia duct at one point which made it flyable (bearly), = but it=20 wasn't until I moved my oil cooler up under the nose that the problem = was=20 licked.
 
I would first recommend you remove the diverter = you put in=20 - unless it clearly showed a marked improvement in engine = performance.  You=20 may not be helping either  - on the other hand if your engine = performance=20 did indeed show a meaningful improvement then that would mean more power = and=20 more heat to get rid of - the two go hand in hand. But. unless you = picked a=20 couple hundred rpm static, I would remove it - for the moment at=20 least.
 
I have a small opening (10x2") that serves for = my oil=20 cooler and my engine inlet.  I made no effort to put a vane to = divert flow=20 to the engine for two reasons. 
 
 First, if your duct is doing the job it = will be=20 slowing down the air and converting is kinetic energy  it into = pressure -=20 that should provide plenty of air for your engine - it does for mine = with a=20 smaller volume duct. 
 
Second (and probably most importantly) , you are = very=20 likely creating a major air flow separation/disturbance/eddie with your = flow=20 separator particularly in a climb attitude.  This will have a major = adverse=20 impact on your cooling and is likely the principle reason your cooling=20 deteriorated - airflow separation.
 
If you have K&W turn to page  = 279.  There=20 you will see several configurations of cores and ducts coming into them = at=20 various angles from straight on (figure A) to an almost 20 deg angle = (figure=20 D).  If you took figure B and reversed the inlet and outlet, it = would=20 appear that would be close to your configuration.
 
You should be able to get adequate cooling with = you=20 radiator at the angle it is without turning vanes.  The only = turning vanes=20 related to cooling I can recall seeing in K&W are those fabricated = as part=20 of the core (see figure 12.8) but there may be some mention of=20 using turning vanes up stream else where - I do not = recall. =20
 
I could not tell what type of profile your duct = follows=20 from the inlet opening to your core.  But, if it looks anything = like figure=20 12-10 in K&W then you do need to correct the shape as   = that shape=20 or any similar to it creates air flow separation =3D cooling = killer.
 
In fact the paragraph under it tells you = what the=20 objective is - you need to keep your duct walls nearly parallel (perhaps = slightly converging) until just before your core and then flare (like a = trumpet)=20 the duct to meet the core.
 
My total inlet area is 52 square inches - my = outlet is=20 quite a bit bigger (does not mean its better - just bigger). So I agree, = your 50=20 inches should provide enough air. 
 
My believe is that you are getting flow = turbulence which=20 is compromising your cooling core capability to reject = heat.
 
Keep working at it, I would remove the divider = as I=20 believe it is hurting cooling much more than it is helping engine = power.  I=20 would strive to get a smooth duct from the inlet (without any jogs or = sharp=20 edges) to the core.  You would naturally have to blend the round = intake=20 area to the rectangular core area and keep the cross section as constant = as you=20 can and approx the size of your inlet until within six=20 -nine or so inches of the core and then rapidly flare it to a=20 bell/trumpet shape.  That would help keep the boundary layer flow = high=20 until you are ready to flare the duct to get your pressure=20 recovery.
 
That's about all I can think to suggest at this=20 time.  You'll get there, it will just take a bit of messing with = it. With=20 few exceptions, cooling always seems to be the biggest challenge.  = We=20 pretty much have a tractor configuration that we have proven works - = which is=20 the one similar to what I, Bill Eslick, Tracy and others fly with using = the=20 standard cowl openings, but, I believe that you are going to be one of = the first=20 on this list that works out what is needed using the James Cowl.  = You'll=20 get it whipped, disappointing as it is to find your installation is not=20 "perfect", it will not take you long to whip it into shape.
 
Best Regards and good luck
 
Ed
 
 
 
----- Original Message -----
From: "Dennis Haverlah" <clouduster@austin.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, May 27, 2007 2:11 PM
Subject: [FlyRotary] James Cowl - RV-7a - = Renesis -=20 Cooling

>I had = very marginal=20 cooling on my first and second flight - RV 7A, James
> cowl, = Griffin=20 Scirocco aluminum double pass water radiator with a Mazda
> 1989? = RX-7=20 oil cooler.  Water radiator fin size - 22LX13WX2.5T inches. =
> Oil -=20 19LX4.5WX 2T  inches.  The radiators are mounted side-by-side =
>=20 under the engine and are at about 25 - 30 degree to the inlet air flow. =
>=20 (The air must turn 60-65 deg to flow through the radiators)   = See=20 photos
> 1 and 2.  After my first 2 flights, I constructed a = divider/duct to
> provide a duct for the engine combustion air to = make=20 the sharp turn 90
> deg. up after the inlet to get to the = filter. =20 The bottom of this duct
> was also supposed to provide a duct = wall for=20 the air going to the
> radiators.  See photo 3.  Two = flights=20 demonstrated this really hurt -
> not helped  - my = cooling. =20 Now I can barely take off and fly the pattern
> before getting up = to 210=20 - 215 on oil and water.  The divider duct took
> out about = 8-10 sq.=20 in. of inlet area but removed the engine combustion
> air = requirement=20 form the remaining inlet air going in the larger inlet.
>
> = My=20 inlet is about 50 sq. in. and the outlet is about 67 sq. in.  This =
>=20 cowl was used successfully on the Power Sport a/c so I believe the inlet =
> and outlet are at least big enough for 160 + hp.  When I = first=20 posted
> pictures of the radiator installation someone suggested = I may=20 need
> turning vanes to improve flow to the radiators.  I am = now=20 ready to try
> the turning vanes below the radiators.
> =
>=20 Does anyone have info. I can use to design the turning vanes?  The = K&W=20
> document on page 273 mentions guide vanes but does not go into=20 detail. 
> I am thinking of 2 inch wide vanes long enough to = go from=20 the left to
> right side of the radiators and spaced 4 inches = apart =20 with the top of
> the vanes about 3/4 inch below the = radiator =20 fins.
> Comments or -- Any other ideas?
>
> Dennis=20 H.
>
>
>
>

> --
> Homepage:  http://www.flyrotary.com/
> Archive=20 and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html
> ------=_NextPart_000_001E_01C7A081.54D8FB00--