X-CGP-ClamAV-Result: CLEAN X-VirusScanner: Niversoft's CGPClamav Helper v1.23.0 (ClamAV engine v0.103.0) X-Junk-Score: 0 [] X-KAS-Score: 0 [] From: "Ernest Christley echristley@att.net" Received: from sonic311-19.consmr.mail.bf2.yahoo.com ([74.6.131.193] verified) by logan.com (CommuniGate Pro SMTP 6.3.5) with ESMTPS id 155706 for flyrotary@lancaironline.net; Wed, 21 Jul 2021 11:54:22 -0400 Received-SPF: none receiver=logan.com; client-ip=74.6.131.193; envelope-from=echristley@att.net DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=att.net; s=s1024; t=1626882845; bh=iBQi3h16PSImzicbeB1fiFv/HM8otCRoVv+56fyTVjo=; h=Date:From:To:In-Reply-To:References:Subject:From:Subject:Reply-To; b=P/pAkJNmFnKImIsNZyYFSJamhmzH2giQW4Yf4mEoZcOztcaB/sB5GENJ/amxGygQc4GPVt1KNQ1NtZN8Wupg8QJSeMzzC4u55SPZClKLGpaYk2y1k7Y8tSUoB56JIWqisp4x/Gl20reEUtME8Wi5uo3f0V2RutDJl16bnIUb24Y= X-SONIC-DKIM-SIGN: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1626882845; bh=H/J1ws/wzOsbzarQDJTebsdNtuRISa4/VpFHgOExWKc=; h=X-Sonic-MF:Date:From:To:Subject:From:Subject; b=ForyQAkwjsmdWXjixF7jRs5bPxbvjG5OQdkP1/kxKFc8DPK3B9R8XX9AbtcX9v/LDpYIf2gqFdlXasIlAO3Tfa9imFHoEdogP6EAe8xu6Cd6KNbZQ42rOtjSoI2gxM7CDM+v+qRGOAJTNUyfNV212bPYvZt2b96LEOHverRtdyteo7mUah5/dYsEHoUKpXjMwoO2+jxXD90GgGSegpHnNdJB0gRiF3nvH1ex8TeHq2V0/dOfmCPxBcmrmLk+Ah4Se6JJY0K+d7J7XII97jXrEE3Q4nVDC48XYezMJI/1FuO8Kla6BzjkIOAn0oay3FDj32MsY2nL+emfUH2ZeDd52g== X-YMail-OSG: 4qPDrXYVM1nSzz3RFW6to9_Ocullf61ovhY2KaxNdrYUDIFecHEbvNUENc83aZo yg04m6K7XD1DMRl9H.qwUN2XL6kzlaPeNheLuFyKj7pqASMweNdebkX8XpRjyTFcFB.9vLeGqdMe cz0ulckRuyh077tzFXHtUbpoyJrBvaR8xui1bQsBa.9_9PPM5unXFn.cWPmbU6yvnYgDOiu3lxon .NqgVnqskpQVCVd._FeMy_kVwLZsJ3FYti5HeFizu9.Bssw9XgshjEuRf_8xx0esl.6PXQCKLyXF PfVUzCppzipSvMSms49WEqGZ7OyWf2fiAAyfMJc7wHNy7l8_5wzAIJ7ALBmEzqcaM5JljPn_HNL3 7Z386bNLCWdxFIOoD_ncHBYGJWQcKuAUhm4.23_3W9IhH9I9qJfbR2SKSsIE8BFaXgd661dgLtNw hUWtvgd37Fcy6lcaYFnJTGVOQ8.N.9QDMcDr.NZrWcUAozKwHLzIGBtflL.eJwn_3YxmpqdDgVP5 ZxzxoZN7Z2l5hsKkNhGm9YD7ZbVVi72eW9ot7XYrOE19JZsxTX98cK77t0O6eWk6X8.7abwKOpAQ h.9mtahygUkI0_LtGRZTn.3TDvzx3R5iz_u8btpmFN0.6ABmRAds15yDvolYrzPfxDSpML8YySv3 2Z7R5BMDAb9LpqrADfo_irJaYupEW9dcyqtYeTD82rpPJZzSH.8w_h1Pczm_jXSsvBlJd2QMdpmq xP3J9WU9XAazRiWfxVeEZZDrTeCv5LTg.vgMTNLq9g5hDKc_KGRZPxu8XYtpRzFxGZtmnvTPoIks gjbBAtrvzeLoB5ZdgK2PmSYY_Sj5FTwQW5oJsqFZh.uW8FMBa26ddEPvDvxqBPdU8vLr76grt6s4 INbBXPF0Ui6RTiCtESfi.1mwVHjl66.F9tIN1gjiogMDxSr0gi1Y.YHtGoF21nWakxUdmKssQ2GY lnfusYftD0LzA6Uaw0PwHjOkL4RTv1x.iiCr5UCooV2qZme..a9KaBD6LRdpC5_Lpz5_S_ROSKNE KlsDND9XU79mb3TKBcgjPT.nLD5Rt1vaTPBJ.8P9M5ElrxgRwl_1pVPAU3SigwSi1FsQryY4kRML RFzeaRJZw4EyqngmMDylNzM.dM3AOixg0sgjZd3ugXUzHoV_TtD5ijhMxRYAVjG0YPRthU1y_G1E q4Pl4A1d_OLKtCmCdsQW_YMcdQKjiPOzuFBRrKQSumOGOQNI.wu9qDDBaK0IczmS8bs6F6Yf50QL jYrbudFxz03RRispMLh9r08i9ztyj0ZY5bFqnlsHBo25zdIhgML7VxNjpBXW2QFnLBQfp5KsqyA7 lcJgbZQIALgYTp8B2pMZ5WfwKWhO5FjFqL8PtjmVW16vOIa7MvJtRKtl7WW7RhqxHpdz7B1FECmb trm.ddJTkPD.XIW3KDBc7FXmbFfEN6g6Ut8_0rH3YMyRPkftBhIc5egySqmaej54SaYy6t6RlAw3 V4bEHZbAQM8ODAvXw.DG._p32XVRVenI9wsumtiKLVmFKlEE8oQAvgSx1o8OdyHtANqH4IbhmXiV a.5aSYR9rS.UUHEMxH9X2TxyXDyPdHgbDRwDC4PK8wZKmvphTqW4kYqX2quPtAgDkykgc1tzYfEd SKFD52hXc.TKAe_QImN6kITQXz2si7IZb63l9gUNfjHTMpnohoVoc1MBBY0Q9_TFRt9PV2.4aLdn GosPRc3tNBVEqbpiBmzQl8mZrjJwtmqdggXLZ9JffaL9fgrbgtFns4Ut_1vafjorjRqtT4bIV1BQ cNa4b7_p2c42E3JuTIzf8_CgwSca1r4.qKFZU.WPhyfAKtVUXRb.ZmvC984nrVbU.ziMR_ip2RtI Gxf3TSQl8FiyEF9vkDCkLdUX1xGKnBZN.EZODd.nt7xGesLyHUe8sOAlYjIodv_7p5923iZPwZJG XLgpLHBxXfGGb56omIG2dLa8uF.rQIdHzceulqxqk65FiEiuYbFu7JxtyBR0HVMdAas1w3cmhYpv D_Q6KNV5TzXgeC5P8pLNCH5FWyaQYzjkpZKURJOlXdQjoGyHnDPpVnKjMacDjL844Qi.UAqYJEvk cqrWRfQ.oG4SP4ywIG2v37Zn21LKTz0vnPfHxMfxqpZdgYq_rEq3hh6DxFKr8jpUp0cjbhebzS6u p4zbLx0K12ViLatdnx4cTGRBfvsyP8.fQsMyR3WAl_NmOyetmh_2ePxkx8KHG8xaVv4Bg1I9Dznb FPIfL7mSHtGh0QtZOFeGaJVFHk0jIjKixt.Je5DwsgO9WnKlpGN_B4s2wJLb57cWTN_mcWpSzn.q NrClAmNqNvqxWAN4SlNiK4ObCxrMhavGSxVE2ZNfw9vQJhlWZlDjPK47IFYSXnwsZ4wtYP6X0HgQ T5Vek2mvbO1QCs4jH0qrTxa1huFAvXOoxcTKUf..6d_8- X-Sonic-MF: Received: from sonic.gate.mail.ne1.yahoo.com by sonic311.consmr.mail.bf2.yahoo.com with HTTP; Wed, 21 Jul 2021 15:54:05 +0000 Date: Wed, 21 Jul 2021 15:54:00 +0000 (UTC) To: "Marc Wiese cardmarc@charter.net" Message-ID: <2070085567.836863.1626882840564@mail.yahoo.com> In-Reply-To: References: Subject: Re: [FlyRotary] Re: Inlet cooling article MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_836862_1845646033.1626882840558" X-Mailer: WebService/1.1.18469 YMailNorrin Content-Length: 35888 ------=_Part_836862_1845646033.1626882840558 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable I'm just a computer programmer, not an aerodynamicist, but I think the who= le converting speed to pressure thing is a red-herring that causes more con= fusion than it solves. What you're after is flow through the entire heat exchanger.=C2=A0 Building= big plenums so that the you can stop the air and then accelerate it is one= way to get there, but where else in aviation do we attempt to stop the air= so that we can start it again? The first radiators just hung out in the airstream and had terrible perform= ance.=C2=A0 The problem was that they created so much turbulence that air w= ent around them instead of through, and some parts of the radiator didn't g= et used at all.=C2=A0 As airplanes got faster, that turbulence would occur = even between fins, obstructing the flow, and making some parts of the radia= tor unused.=C2=A0 The point that K&W was making, at least by my reading, wa= s that the air needed to be slowed to be smooth through the WHOLE heat exch= anger. The ducting I have on top of my Corvair engine doesn't look like any others= I've seen. Bascially, all I have is a sheet of aluminum that taper down as= it goes back. I do not have a "plenum" of any sort, and I do not try to sl= ow the air down.=C2=A0 I just make sure that it smoothly spreads out and mo= ves through all the cylinders.=C2=A0 When first flying, I was concerned abo= ut the CHTs being too low. . . that the cooling might be TOO good, because= =C2=A0they stay below 250*F. I guess my message is that you're not looking for "pressure recovery".=C2= =A0 That is just one means to reach the end, which is to make sure that ALL= of the radiator is radiating. I could very well be completely off base. On Wednesday, July 21, 2021, 11:30:45 AM EDT, Marc Wiese cardmarc@chart= er.net wrote: =20 =20 As I recall the K&N curves, the duct/plenum is supposed to decrease the sp= eed approaching the radiator (or fins), thusly increasing the pressure, whi= ch does the cooling. Not speed, pressure differential. After the fins, the = deal is to regain the speed and have an adequate size smooth hot air exit.= =C2=A0So a couple of inches of H2O pressure drop across the fins? The P51 arrangement seems to be about the best? Or wing root LE like the Hu= rricane/Mosquito?M Sent from my iPhone On Jul 21, 2021, at 10:12 AM, Finn Lassen finn.lassen@verizon.net wrote: =EF=BB=BF Seems what we're missing is a curve that's the product of these c= urves. =20 In other words some kind of bell or parabolic curve with top where you hav= e max cooling/drag. =20 Obviously you can push fluid (and air) through a radiator at a furious rat= e, but the drag will go up. =20 So for both fluid and air rates there must be an optimum spot. =20 Finn =20 On 7/21/2021 8:42 AM, Stephen Izett stephen.izett@gmail.com wrote: =20 This graph from Mocal might be helpful. It's for their oil coolers but the= trends may be transferable to water exchangers. The solid line is Pressure Drop. The two dotted lines tell the story of tw= o different oil flow rates/tube.=20 =20 =20 | m/sec | 5 | 10 | 15 | 20 | 25 | | kmh | 18 | 36 | 54 | 72 | 90 | | mph | 11.2 | 22.4 | 33.6 | 44.8 | 55.9 | =20 Increasing the air flow 5 fold from 11 to 56 mph only increases the heat = transfer: 2 fold with an oil flow of 0.02 L/sec/ tube and 2.3 fold by doubl= ing the oil flow rate per tube to 0.04 L/sec/tube While pressure drop incre= ased 13 fold.=20 So, diminishing returns from increasing airflow or fluid flow.=20 Steve Izett=20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 On 21 Jul 2021, at 2:48 pm, 12348ung@gmail.com wrote:=20 Charlie, =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 No, no reference,= just what I have read and also talking to Rad manufacturers such as BWR in= Brisbane.=C2=A0 You can check it out by passing your hand through a naked = flame.=C2=A0 Quickly and there is no heat transfer.=C2=A0 Pass slowly and y= ou will see what the argument is. =C2=A0=C2=A0As I said the truth is there = somewhere and as Lyn so aptly puts it=C2=A0 =E2=80=9CI could well be wrong= =E2=80=9D..=C2=A0=C2=A0 Neil. =C2=A0 From:=C2=A0Rotary motors in aircraf= t =C2=A0 Sent:=C2=A0Wednesday, July 21, 2021 12:25 PM To:=C2=A0Rotary motors in aircraft Subject:=C2=A0[FlyRotary] Re: Fwd: Inlet cooling article =C2=A0 Hi Nei= l, =20 Do you have a reference for that? Slowing a medium down so it has time to = absorb the heat seems to conflict with physics as I've been led to understa= nd it. =20 Charlie =20 On 7/20/2021 5:01 PM,=C2=A012348ung@gmail.com=C2=A0wrote: =20 Charlie, =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Much wisdom out there, you ju= st have to find the truth!=C2=A0=C2=A0 Max cooling is apparently 30 MPH, so= Any faster and it does not pick up heat before going past.=C2=A0 Look at b= ig trucks, that grill is not only for looks, they slow the air to get max c= ooling.=C2=A0 If too slow they have a quite large fan that kicks in to drag= air through =C2=A0at 30 MPH not 100! =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 As you say, what do = I know =E2=80=93 I have seen too many that do not work =E2=80=93 without an= y degree. Neil. =C2=A0 From:=C2=A0Rotary motors in aircraft=C2=A0=C2=A0 Sent:=C2=A0Wednesday, July 21, 2021 7:07 AM To:=C2=A0Rotary motors in aircraft=C2=A0 Subject:=C2=A0[FlyRotary] Re: Fwd: Inlet cooling article =C2=A0 On 7/20= /2021 3:26 PM, Marc Wiese=C2=A0cardmarc@charter.net=C2=A0wrote: =20 Comments? =C2=A0 =20 =20 Subject:=C2=A0Inlet cooling article =20 =20 =20 =EF=BB=BF=C2=A0https://www.kitplanes.com/down-to-earth-40/ Sent from my iPhone =20 =20 I remember the Laboda article about enlarging their cooling inlets, but no= t many of the details. This: The plenum receives air through two circular air intake ducts behind the p= ropeller and squeezes it, Bernoulli-style, so that the air accelerates acro= ss the cylinders and between their fins, carrying the heat back, down and o= ut an outflow "gate" at the back and bottom of the engine area, forward of = the firewall. =20 Is contrary to everything I've ever read about cooling efficiently. Faster= relative flow will always have higher drag, all else being equal. Accelera= ting the air even faster than freestream just sounds crazy. My understandin= g is that there's a balancing act between having the room in an a/c to 'rec= over' (increase) differential pressure across the heat exchanger (engine fi= ns, in this case), and causing too much drag from the air going through the= fins too fast (there's aerodynamic drag in the heat exchanger, just like o= ver the a/c itself). It's surprising to me that James made the plenum the w= ay he did. The rest sounds like putting bandaids on stuff. The next-to-last= image, of the final inlet, shows what appears to be a *much* smaller plenu= m inlet than the cowl ring in front of it, and a rather sharp edged lip whe= re the plenum starts. It looks like the air would accelerate until it hits = that sharp lip, and immediately go turbulent, which will kill any pressure = recovery and actually slow flow into the cylinder fins.=C2=A0 =20 Most Lyc plenums I've seen (even the ones James made for the 4 cyl engines= ) have significant volume above the cylinders with smoothly expanding ducts= feeding the plenum. That allows the air to slow in an organized fashion, w= hich increases *pressure*, which is what actually makes the air move throug= h the fins. =20 But what do I know; I have an Economics degree.... =20 Charlie =C2=A0=20 | | Virus-free.=C2=A0www.avast.com | =20 =20 =20 =20 =20 =20 =20 =20 ------=_Part_836862_1845646033.1626882840558 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
I'm just a computer programm= er, not an aerodynamicist, but I think the whole converting speed to pressu= re thing is a red-herring that causes more confusion than it solves.
<= div dir=3D"ltr" data-setdir=3D"false">
What you're after is flow through the entire heat exchanger.&nb= sp; Building big plenums so that the you can stop the air and then accelera= te it is one way to get there, but where else in aviation do we attempt to = stop the air so that we can start it again?

The first rad= iators just hung out in the airstream and had terrible performance.  T= he problem was that they created so much turbulence that air went around th= em instead of through, and some parts of the radiator didn't get used at al= l.  As airplanes got faster, that turbulence would occur even between = fins, obstructing the flow, and making some parts of the radiator unused.&n= bsp; The point that K&W was making, at least by my reading, was that th= e air needed to be slowed to be smooth through the WHOLE heat exchanger.

The ducting I have on top of my Corvair engine doesn't look= like any others I've seen. Bascially, all I have is a sheet of aluminum th= at taper down as it goes back. I do not have a "plenum" of any sort, and I = do not try to slow the air down.  I just make sure that it smoothly sp= reads out and moves through all the cylinders.  When first flying, I w= as concerned about the CHTs being too low. . . that the cooling might be TO= O good, because they stay below 250*F.

I guess my me= ssage is that you're not looking for "pressure recovery".  That is jus= t one means to reach the end, which is to make sure that ALL of the radiato= r is radiating.

I could very well be completely off base.=

=20
=20
On Wednesday, July 21, 2021, 11:30:45 AM EDT, Marc Wies= e cardmarc@charter.net <flyrotary@lancaironline.net> wrote:


As I recall the K&N= curves, the duct/plenum is supposed to decrease the speed approaching the = radiator (or fins), thusly increasing the pressure, which does the cooling.= Not speed, pressure differential. After the fins, the deal is to regain th= e speed and have an adequate size smooth hot air exit. 
So a coupl= e of inches of H2O pressure drop across the fins?
The P51 arrangeme= nt seems to be about the best? Or wing root LE like the Hurricane/Mosquito?=
M

Sent from my iPhone

On Jul 21, 2021, at 10:12 AM, Finn Lassen= finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:

=
=EF=BB=BF =20 =20 =20 =20
Seems what we're missing is= a curve that's the product of these curves.

In other words some kind of bell or parabolic curve with top where you have max cooling/drag.

Obviously you can push fluid (and air) through a radiator at a furious rate, but the drag will go up.

So for both fluid and air rates there must be an optimum spot.

Finn

On 7/21/2021 8:42 AM, Stephen Izett ste= phen.izett@gmail.com wrote:
=20 This graph from Mocal might be helpful. It's for their oil coolers but the trends may be transferable to water exchangers.
The solid line is Pressure Drop.
The two dotted lines tell the story of t= wo different oil flow rates/tube.

<Screen Shot 2021-07-21 at 7.58.= 40 pm.png>

=20
m/sec 5 10 15 20 25
kmh 18 36 54 72 90
mph 11.2 22.4 33.6 44.8 55.9

Increasing the air flow 5 fold from 11 t= o 56 mph only increases the heat transfer:
2 fold with an oil flow of 0.02 L/sec/ t= ube and 2.3 fold by doubling the oil flow rate per tube to 0.04 L/sec/tube
While pressure drop increased 13 fold.

So, diminishing returns from increasing = airflow or fluid flow.

Steve Izett















On 21 Jul 2021, at 2:48 pm, 12348ung@g= mail.com <flyrotary@lancaironline.net> wrote:

=20
Charlie,
=20
          &nbs= p;          No, no reference, just what I have read and also talking to Rad manufacturers such as BWR in Brisbane.  You can check it out by passing your hand through a naked flame.  Quickly and there is no heat transfer.&nbs= p; Pass slowly and you will see what the argument is.  &nb= sp;As I said the truth is there somewhere and as Lyn so aptly puts it  =E2=80=9CI could well be wrong=E2= =80=9D..  
=20
Neil.
=20
 
=20
From:=  Rotary motors in aircraft <flyrotary@lancaironline.net> 
Sent: Wednesday, July 21, 2021 12:25 PM
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: Fwd: Inlet cooling article
=20
 
=20
Hi Neil,

Do you have a reference for that? Slowing a medium down so it has time to absorb the heat seems to conflict with physics as I've been led to understand it.

Charlie

On 7/20/2021 5:01 PM, 1= 2348ung@gmail.com&nb= sp;wrote:
=20
Charlie,
=20
          &nbs= p;        Much wisdom out there, you just have to find the truth!   M= ax cooling is apparently 30 MPH, so Any faster and it does not pick up heat before going past.  Look a= t big trucks, that grill is not only for looks, they slow the air to get max cooling.  If too slow th= ey have a quite large fan that kicks in to drag air through  at 30 MPH not 100!
=20
          &nbs= p;     As you say, what do I know =E2=80=93 I have seen too many that do not work = =E2=80=93 without any degree.
=20
Neil.
=20
 
=20
Fro= m: Rotar= y motors in aircraft <flyrotary@lancaironline.net> 
Sent: Wednesday, July 21, 2021 7:07 AM
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: Fwd: Inlet cooling article
=20
 
=20
On 7/20/2021 3:26 PM, Marc Wiese cardmarc@charter.net wrote:
=20
Comments?
=20
 
=20

Subject: Inlet cooling article

=20

=EF=BB=BF https://www.kitplanes.com/down-to-earth-40/

=20
Sent from my iPhone
=20
I remember the Laboda article about enlarging their cooling inlets, but not many of the details.
This:
The plen= um receives air through two circular air intake ducts behind the propeller and squeezes it, Bernoulli-style, so that the air accelerates across the cylinders and between their fins, carrying the heat back, down and out an outflow "gate" at the back and bottom of the engine area, forward of the firewall.

Is contrary to everything I've ever read about cooling efficiently. Faster relative flow will always have higher drag, all else being equal. Accelerating the air even faster than freestream just sounds crazy. My understanding is that there's a balancing act between having the room in an a/c to 'recover' (increase) differential pressure across the heat exchanger (engine fins, in this case), and causing too much drag from the air going through the fins too fast (there's aerodynamic drag in the heat exchanger, just like over the a/c itself). It's surprising to me that James made the plenum the way he did. The rest sounds like putting bandaids on stuff. The next-to-last image, of the final inlet, shows what appears to be a *much* smaller plenum inlet than the cowl ring in front of it, and a rather sharp edged lip where the plenum starts. It looks like the air would accelerate until it hits that sharp lip, and immediately go turbulent, which will kill any pressure recovery and actually slow flow into the cylinder fins. 

Most Lyc plenums I've seen (even the ones James made for the 4 cyl engines) have significant volume above the cylinders with smoothly expanding ducts feeding the plenum. That allows the air to slow in an organized fashion, which increases *pressure*, which is what actually makes the air move through the fins.

But what do I know; I have an Economics degree....

Charlie
=20
 
=20
=20
Virus-free. www.avast.com


=20
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