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[220.235.119.136]) by smtp.gmail.com with ESMTPSA id l6sm28139796pff.74.2021.07.21.16.16.22 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 21 Jul 2021 16:16:23 -0700 (PDT) Content-Type: multipart/alternative; boundary="Apple-Mail=_856BA9C1-4181-47AA-BFE7-D001B8FDC83E" Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.100.0.2.22\)) Subject: Re: [FlyRotary] Inlet cooling article Date: Thu, 22 Jul 2021 07:16:19 +0800 References: To: Rotary motors in aircraft In-Reply-To: Message-Id: <1A824424-ECD4-4BF2-8E0B-03D9E92409FA@gmail.com> X-Mailer: Apple Mail (2.3654.100.0.2.22) --Apple-Mail=_856BA9C1-4181-47AA-BFE7-D001B8FDC83E Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 This is the first time I've heard of Ed=E2=80=99s workbook! All a bit late for me at this stage, but would be interested in reading = through it as I=E2=80=99ve still git sooooo much to learn. Steve Iz > On 22 Jul 2021, at 4:26 am, Bobby Hughes BHughes@qnsinc.net = wrote: >=20 > It=E2=80=99s all in Ed=E2=80=99s cooling workbook. J > =20 > Bobby > =20 > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net = ]=20 > Sent: Wednesday, July 21, 2021 3:19 PM > To: Rotary motors in aircraft > Subject: [FlyRotary] Re: Fwd: Inlet cooling article > =20 > Yep, as I see it we have at least three factors: > 1) Flow (speed) of coolant through engine optimized for maximum heat = removal. > 2) Flow of coolant through radiator optimized for maximum heat = dissipation. > 3) Flow of air (speed and mass) through radiator optimized for maximum = heat removal. >=20 > 2 should be matched to 1 (hoses, radiator tubes, fins and size). >=20 > 3 should be optimized for minimum needed air mass to remove heat, and = is achieved by optimized inlet duct or diffuser as well as outlet = ducting with flap to minimize to only needed airflow at climb, cruise = and max speeds at any OAT. Again, only the actually needed air flow for = each condition of flight. >=20 > Sounds simple, doesn't it? ;) >=20 > Finn >=20 > On 7/21/2021 1:39 PM, eanderson@carolina.rr.com = wrote: > Just to add my 0.02. Like many other things, cooling is a group of = compromises. This sounds a bit like a shade tree myth that has been = around a long time. > =20 > The myth goes if you run hot water through a radiator 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 remove heat. = That is shown by the fact the slower the flow the greater the water = temperature difference between intake and output of the radiator. And = all of this is absolutely factual. =20 > =20 > The problem is - that is not the complete story. The objective is to = remove heat from the engine, the slower flow will show greater delta T = across the radiator - but, will not remove as much heat from the engine = (the objective) per unit time - which is the true objective. However, = if you increase flow too greatly you are taking more HP to increase the = flow (watch out for cavitation) and therefore creating more heat - = although increased turbulence in the flow may help pick up heat better = and offset that to some degree. =20 > =20 > Additionally, some folks early-on did try to increase their flow and = found increased engine temp rather than less. This "proved" to them = that fast flow was not as good as slower flow. 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 faster rotating pump. But, it did add = to the myth of slow flow cools better. If that were the case, then = taken to the limit - stopped flow should cool best.=F0=9F=98=81 > =20 > Again, like many things in the actual world, best cooling is dependent = on the circumstances and objectives. > =20 > Back to my hole > =20 > Ed > =20 > =20 > =20 > =20 > ------ 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 > =20 > Charlie, > 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. Pass slowly and you will see what the argument is. As = I said the truth is there somewhere and as Lyn so aptly puts it =E2=80=9C= I could well be wrong=E2=80=9D..=20 > Neil. > =20 > From: Rotary motors in aircraft >=20 > Sent: Wednesday, July 21, 2021 12:25 PM > To: Rotary motors in aircraft > > Subject: [FlyRotary] Re: Fwd: Inlet cooling article > =20 > Hi Neil, >=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 = understand it >=20 > Charlie >=20 > On 7/20/2021 5:01 PM, 12348ung@gmail.com = wrote: > Charlie, > Much wisdom out there, you just have to find the = truth! Max cooling is apparently 30 MPH, so Any faster and it does not = pick up heat before going past. Look at big trucks, that grill is not = only for looks, they slow the air to get max cooling. If too slow they = have a quite large fan that kicks in to drag air through at 30 MPH not = 100! > 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. > Neil. > =20 > From: Rotary motors in aircraft = =20 > Sent: Wednesday, July 21, 2021 7:07 AM > To: Rotary motors in aircraft = > Subject: [FlyRotary] Re: Fwd: Inlet cooling article > =20 > On 7/20/2021 3:26 PM, Marc Wiese cardmarc@charter.net = wrote: > Comments? > =20 > Subject: Inlet cooling article >=20 > =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, = but not many of the details. > This: > The plenum 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. >=20 > 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.=20 >=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, which increases *pressure*, which is what actually = makes the air move through the fins. >=20 > But what do I know; I have an Economics degree.... >=20 > Charlie > =20 > = =09 > Virus-free. www.avast.com = > =20 > =20 > =20 >=20 >=20 >=20 > Disclaimer >=20 > The information contained in this communication from the sender is = confidential. It is intended solely for use by the recipient and others = authorized to receive it. If you are not the recipient, you are hereby = notified that any disclosure, copying, distribution or taking action in = relation of the contents of this information is strictly prohibited and = may be unlawful. >=20 > This email has been scanned for viruses and malware, and may have been = automatically archived by Mimecast Ltd, an innovator in Software as a = Service (SaaS) for business. Providing a safer and more useful place for = your human generated data. Specializing in; Security, archiving and = compliance. To find out more Click Here = . >=20 --Apple-Mail=_856BA9C1-4181-47AA-BFE7-D001B8FDC83E Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 This = is the first time I've heard of Ed=E2=80=99s workbook!
All = a bit late for me at this stage, but would be interested in reading = through it as I=E2=80=99ve still git sooooo much to learn.

Steve Iz

On 22 Jul 2021, at 4:26 am, Bobby Hughes BHughes@qnsinc.net = <flyrotary@lancaironline.net> wrote:

It=E2=80=99s all in = Ed=E2=80=99s cooling workbook. J
 
Bobby
 
From: Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] 
Sent: Wednesday, July 21, 2021 = 3:19 PM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Re: Fwd: Inlet = cooling article
 
Yep, as I see it we have at least three factors:
1) Flow (speed) of coolant through engine optimized for = maximum heat removal.
2) Flow of coolant through radiator = optimized for maximum heat dissipation.
3) Flow of air = (speed and mass) through radiator optimized for maximum heat removal.

2 should be matched to 1 (hoses, radiator = tubes, fins and size).

3 should be = optimized for minimum needed air mass to remove heat, and is achieved by = optimized inlet duct or diffuser as well as outlet ducting with flap to = minimize to only needed airflow at climb, cruise and max speeds at any = OAT. Again, only the actually needed air flow for each condition of = flight.

Sounds simple, doesn't it? ;)

Finn

On 7/21/2021 = 1:39 PM, eanderson@carolina.rr.com wrote:
Just to add my 0.02.  Like many = other things, cooling is a group of compromises.  This 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 radiator 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 remove heat.  = That is shown by the fact the slower the flow the greater the water = temperature difference between intake and output of the radiator.  = And all of this is absolutely factual.  
 
The problem = is - that is not the complete story.  The objective is to remove = heat from the engine, the slower flow will show greater delta T across = the radiator - but, will not remove as much heat from the engine (the = objective) per unit time - which is the true objective.  However, = if you increase flow too greatly you are taking more HP to increase the = flow (watch out for cavitation) and therefore creating more heat - = although increased turbulence in the flow may help pick up heat better = and offset that to some degree.  
 
Additionally,= some folks early-on did try to increase their flow and found increased = engine temp rather than less.  This "proved" to them that fast flow = was not as good as slower flow.  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 faster rotating pump.  But, it did add to the = myth of slow flow cools better.  If that were the case,  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 circumstances and = objectives.
 
Back to my hole
 
Ed
 
 
 
 
------ Original Message ------
From: "12348ung@gmail.com" <flyrotary@lancaironline.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: 7/20/2021 11:48:32 PM
Subject: [FlyRotary] Re: Fwd: Inlet cooling = article
 
Charlie,
          &nb= sp;          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.  Pass slowly and you will see what the argument is. =   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.. 
Neil.
 
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
 
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, 12348ung@gmail.com wrote:
Charlie,
          &nb= sp;        Much wisdom out there, you = just have to find the truth!   Max cooling is apparently 30 = MPH, so Any faster and it does not pick up heat before going past.  = Look at big trucks, that grill is not only for looks, they slow the air = to get max cooling.  If too slow they have a quite large fan that = kicks in to drag air through  at 30 MPH not 100!
          &nb= sp;     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.
Neil.
 
From: Rotary 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
 
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, but not many of the = details.
This:
The plenum 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
 

 



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