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: " eanderson@carolina.rr.com" Received: from [47.43.26.140] (HELO p-impout009.msg.pkvw.co.charter.net) by logan.com (CommuniGate Pro SMTP 6.3.5) with ESMTPS id 155929 for flyrotary@lancaironline.net; Wed, 21 Jul 2021 13:40:14 -0400 Received-SPF: pass receiver=logan.com; client-ip=47.43.26.140; envelope-from=eanderson@carolina.rr.com Received: from [127.0.0.1] ([66.26.212.217]) by cmsmtp with ESMTP id 6GCKmUHexzdY16GCLmrMWb; Wed, 21 Jul 2021 17:39:57 +0000 X-Authority-Analysis: v=2.4 cv=BP52EHcG c=1 sm=1 tr=0 ts=60f85bed a=WcvdwKkRgKsaRaJ9Bx4DbQ==:117 a=WcvdwKkRgKsaRaJ9Bx4DbQ==:17 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=hOpmn2quAAAA:8 a=eKhGbfrDAAAA:8 a=_6GpL_ENAAAA:8 a=SPXtpyHSbjbkczHtPAoA:9 a=QEXdDO2ut3YA:10 a=4PR2P7QzAAAA:8 a=AbL9jiiomMwQRfcEsBcA:9 a=gE1ZxK1exTZ1rMsn:21 a=frz4AuCg-hUA:10 a=_W_S_7VecoQA:10 a=Urk15JJjZg1Xo0ryW_k8:22 a=GyA-uvUxXSCciAkwuKQO:22 a=UDUmxsVa2tvOjJGaeGiU:22 a=4dqwQCo7Po2mVW515mGf:22 To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Fwd: Inlet cooling article Date: Wed, 21 Jul 2021 17:39:57 +0000 Message-Id: In-Reply-To: References: Reply-To: eanderson@carolina.rr.com User-Agent: eM_Client/8.2.1509.0 Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="------=_MBF5590B21-04BE-4CDF-8A8B-477D16CFE57C" X-CMAE-Envelope: MS4xfMzuB/pkwQv9GAiELkGn2g5EwI8bbOsXB6sriRZ7qRXsejE4bjQBS9D79qTQm9aYh8pJvMm3Yrb4jgD6LpaLweUFQ8zZhzcnKYrkJU92GmtMk/FhGzHu MLblbWEPeI0P2rxUS7xCiHBSqyHjloZXLD551yKpCYMaHw/C3pSRSXAF79i/pFuf0tGAsdZfcbgdW4mKn81aeuevilnFoPaKW3k= --------=_MBF5590B21-04BE-4CDF-8A8B-477D16CFE57C Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Just to add my 0.02. Like many other things, cooling is a group of=20 compromises. This sounds a bit like a shade tree myth that has been=20 around a long time. The myth goes if you run hot water through a radiator and measure input=20 and output temperatures (of the water), the slower the water flows=20 through the radiator and more time the cooling air has to remove heat. =20 That is shown by the fact the slower the flow the greater the water=20 temperature difference between intake and output of the radiator. And=20 all of this is absolutely factual. The problem is - that is not the complete story. The objective is to=20 remove heat from the engine, the slower flow will show greater delta T=20 across the radiator - but, will not remove as much heat from the engine=20 (the objective) per unit time - which is the true objective. However,=20 if you increase flow too greatly you are taking more HP to increase the=20 flow (watch out for cavitation) and therefore creating more heat -=20 although increased turbulence in the flow may help pick up heat better=20 and offset that to some degree. Additionally, some folks early-on did try to increase their flow and=20 found increased engine temp rather than less. This "proved" to them=20 that fast flow was not as good as slower flow. Only later was it=20 realized that the attempt to increase flow was by increasing water pump=20 rotation speed which resulted in caviatation and actually resulted in=20 less coolant being pumped by the faster rotating pump. But, it did add=20 to the myth of slow flow cools better. If that were the case, then=20 taken to the limit - stopped flow should cool best.=F0=9F=98=81 Again, like many things in the actual world, best cooling is dependent=20 on the circumstances and objectives. Back to my hole Ed ------ Original Message ------ From: "12348ung@gmail.com" To: "Rotary motors in aircraft" Sent: 7/20/2021 11:48:32 PM Subject: [FlyRotary] Re: Fwd: Inlet cooling article >Charlie, > > No, no reference, just what I have read and also=20 >talking to Rad manufacturers such as BWR in Brisbane. You can check it=20 >out by passing your hand through a naked flame. Quickly and there is=20 >no heat transfer. Pass slowly and you will see what the argument is. =20 >As I said the truth is there somewhere and as Lyn so aptly puts it =E2=80= =9CI=20 >could well be wrong=E2=80=9D.. > >Neil. > > > >From: Rotary motors in aircraft >Sent: Wednesday, July 21, 2021 12:25 PM >To: Rotary motors in aircraft >Subject: [FlyRotary] Re: Fwd: Inlet cooling article > > > >Hi Neil, > >Do you have a reference for that? Slowing a medium down so it has time=20 >to absorb the heat seems to conflict with physics as I've been led to=20 >understand it. > >Charlie > >On 7/20/2021 5:01 PM, 12348ung@gmail.com wrote: > >>Charlie, >> >> Much wisdom out there, you just have to find the=20 >>truth! Max cooling is apparently 30 MPH, so Any faster and it does=20 >>not pick up heat before going past. Look at big trucks, that grill is=20 >>not only for looks, they slow the air to get max cooling. If too slow=20 >>they have a quite large fan that kicks in to drag air through at 30=20 >>MPH not 100! >> >> As you say, what do I know =E2=80=93 I have seen too man= y that=20 >>do not work =E2=80=93 without any degree. >> >>Neil. >> >> >> >>From: Rotary motors in aircraft =20 >> >>Sent: Wednesday, July 21, 2021 7:07 AM >>To: Rotary motors in aircraft =20 >> >>Subject: [FlyRotary] Re: Fwd: Inlet cooling article >> >> >> >>On 7/20/2021 3:26 PM, Marc Wiese cardmarc@charter.net wrote: >> >>>Comments? >>> >>> >>> >>>>Subject:Inlet cooling article >>>> >>>>=EF=BB=BF https://www.kitplanes.com/down-to-earth-40/ >>>> >>>>Sent from my iPhone >>>> >>I remember the Laboda article about enlarging their cooling inlets,=20 >>but not many of the details. >>This: >>The plenum receives air through two circular air intake ducts behind=20 >>the propeller and squeezes it, Bernoulli-style, so that the air=20 >>accelerates across the cylinders and between their fins, carrying the=20 >>heat back, down and out an outflow "gate" at the back and bottom of=20 >>the engine area, forward of the firewall. >> >>Is contrary to everything I've ever read about cooling efficiently.=20 >>Faster relative flow will always have higher drag, all else being=20 >>equal. Accelerating the air even faster than freestream just sounds=20 >>crazy. My understanding is that there's a balancing act between having=20 >>the room in an a/c to 'recover' (increase) differential pressure=20 >>across the heat exchanger (engine fins, in this case), and causing too=20 >>much drag from the air going through the fins too fast (there's=20 >>aerodynamic drag in the heat exchanger, just like over the a/c=20 >>itself). It's surprising to me that James made the plenum the way he=20 >>did. The rest sounds like putting bandaids on stuff. The next-to-last=20 >>image, of the final inlet, shows what appears to be a *much* smaller=20 >>plenum inlet than the cowl ring in front of it, and a rather sharp=20 >>edged lip where the plenum starts. It looks like the air would=20 >>accelerate until it hits that sharp lip, and immediately go turbulent,=20 >>which will kill any pressure recovery and actually slow flow into the=20 >>cylinder fins. >> >>Most Lyc plenums I've seen (even the ones James made for the 4 cyl=20 >>engines) have significant volume above the cylinders with smoothly=20 >>expanding ducts feeding the plenum. That allows the air to slow in an=20 >>organized fashion, which increases *pressure*, which is what actually=20 >>makes the air move through the fins. >> >>But what do I know; I have an Economics degree.... >> >>Charlie >> >> >> >> >> >>Virus-free. www.avast.com=20 >> >> >> >> > > --------=_MBF5590B21-04BE-4CDF-8A8B-477D16CFE57C Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable =
Just to add my 0.02.= =C2=A0 Like many other things, cooling is a group of compromises.=C2=A0 Thi= s sounds a bit like a shade tree myth that has been around a long time.

The myth goes if you run hot water through a radiat= or and measure input and output temperatures (of the water), the slower the = water flows through the radiator and more time the cooling air has to remo= ve heat.=C2=A0 That is shown by the fact the slower the flow the greater th= e water temperature difference between intake and output of the radiator.= =C2=A0 And all of this is absolutely factual.=C2=A0=C2=A0

<= /div>
The problem is - that is not the complete story.=C2=A0 The object= ive is to remove heat from the engine, the slower flow will show greater de= lta T across the radiator - but, will not remove as much heat from the engi= ne (the objective) per unit time - which is the true objective.=C2=A0 Howev= er, if you increase flow too greatly you are taking more HP to increase the = flow (watch out for cavitation) and therefore creating more heat - althoug= h increased turbulence in the flow may help pick up heat better and offset= that to some degree.=C2=A0=C2=A0

Additionally, s= ome folks early-on did try to increase their flow and found increased engin= e temp rather than less.=C2=A0 This "proved" to them that fast flow was not = as good as slower flow.=C2=A0 Only later was it realized that the attempt= to increase flow was by increasing water pump rotation speed which resulted = in caviatation and actually resulted in less coolant being pumped by the f= aster rotating pump.=C2=A0 But, it did add to the myth of slow flow cools b= etter.=C2=A0 If that were the case,=C2=A0 then taken to the limit - stopped = flow should cool best.=F0=9F=98=81

Again, like= many things in the actual world, best cooling is dependent on the circumsta= nces and objectives.

Back to my hole
<= br />
Ed




------ Original Message ------
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: 7/20/2021 11:48:32 PM
Subject: [FlyRotary] Re: Fwd: Inlet cooling article

Cha= rlie,

=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 refe= rence, 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 you 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

Neil.

=C2=A0

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

=C2=A0

Hi Neil,

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

Charlie

On 7/20/2021 5:01 PM, 12348ung@gmail.com wrote:

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 just have to find the trut= h!=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 big trucks, that grill is = not only for looks, they slow the air to get max cooling.=C2=A0 If too slo= w 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 any degree.<= /span>

Neil.

=C2=A0

From: Rotary motors in aircra= ft <flyrotary@lancaironli= ne.net>
Sent: Wednesday, July 21, 2021 7:07 AM
= To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRota= ry] Re: Fwd: Inlet cooling article

=C2=A0

On 7/20/2021 3:26 PM, Marc Wiese cardmarc@charter.net wrote:

Comments?<= /p>

=C2=A0=

<= p class=3D"MsoNormal" style=3D"margin-bottom:12.0pt">Subject: Inl= et cooling article

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

Se= nt from my iPhone

I remember the Laboda article about= enlarging their cooling inlets, but not many of the details.
This:The plenum receives air through two circular air intake ducts beh= ind the propeller and squeezes it, Bernoulli-style, so that the air acceler= ates across the cylinders and between their fins, carrying the heat back, d= own and out an outflow "gate" at the back and bottom of the engine area, fo= rward of the firewall.

Is contrary to everything I've eve= r read about cooling efficiently. Faster relative flow will always have hig= her drag, all else being equal. Accelerating the air even faster than frees= tream just sounds crazy. My understanding is that there's a balancing act b= etween having the room in an a/c to 'recover' (increase) differential press= ure 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 surprisin= g to me that James made the plenum the way he did. The rest sounds like put= ting bandaids on stuff. The next-to-last image, of the final inlet, shows w= hat 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 int= o the cylinder fins.

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

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

Charlie=

=C2=A0

<= td width=3D"470" style=3D"width:352.5pt;border:none;padding:9.0pt .75pt .75= pt .75pt">

Virus-free. www.avast.com

=C2=A0

=C2=A0 --------=_MBF5590B21-04BE-4CDF-8A8B-477D16CFE57C--

<= span style=3D"text-decoration:none">