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: "Charlie England ceengland7@gmail.com" Received: from mail-ot1-f50.google.com ([209.85.210.50] verified) by logan.com (CommuniGate Pro SMTP 6.3.5) with ESMTPS id 154633 for flyrotary@lancaironline.net; Tue, 20 Jul 2021 22:21:33 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.210.50; envelope-from=ceengland7@gmail.com Received: by mail-ot1-f50.google.com with SMTP id a17-20020a9d3e110000b02904ce97efee36so738708otd.7 for ; Tue, 20 Jul 2021 19:21:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language; bh=jeZc7dmIiZCFDtUSLUvAEzOPRMUpsYmqL2wFhUWfhhs=; b=AfP4PR7H207crVOgiCo8xpgLeZlgzruMXhfgNY2m/ivXe9xWr8huf2hSp22q1rnzt+ 80YQcnPoHv5iugTUZffO1DfAQ/HREA9BV086eI+Xc/gPMxNsPbjCp9SfJYh/YoWHA6aj 4BK5sZenLX0eJQvvhVUlZfHiOB5hNwYRppEfLKZCZLAfTLwgbpNAO1EsFsw7VNXtYKxo fwslCtqcEdV/2Pn1IZHXlVMTf5FpILwTD1aEGqh55zuWOIaN1h7ObyHZaYVoHff0rkQc Z+ihptR/yAJK9jhcIqYrFKtTzZYLwNqgc6ZaUGZCIVTioRr5j104AVGLRFveZbYRlGe3 6taQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language; bh=jeZc7dmIiZCFDtUSLUvAEzOPRMUpsYmqL2wFhUWfhhs=; b=HhtZ0XLaeYd/Jk32xJvuwH6wnqkebnPzx77+DVWq1n1WTQjQwuXGDjNg/IXfCI7MYN ZQySoelB4+LD3MWop3s5ZPx2UGHIJUtC+efLJtPgiPDygRs23YvUVypINVnT+49KHPE2 YgtH5Nj0T2qPMy5q721u3BgTAWyn/kLiHQt/w+iRfQ3ekDeQhubQqPO+RFjS4zaH/z1K flyEjj13IS2Sjn5IBVhki1U40eBCC52AB+fVoAKb+O0Sck5HOg5o9JxA1+KOLh9BPzUK rXQiKD8gRayRYMIWgU0tCEf/mW6EH9gj1aPbhpacW7T3kVB9MMv2S+U/FtU202P7TiBP vVLg== X-Gm-Message-State: AOAM532VVjTmpUQyon64sKi3w2Gz5uGT+Dzv7K64kWPKiVORhWwAes1A v4y/HCB9z5L2EAlP7tdZLJJZf/FkE9s= X-Google-Smtp-Source: ABdhPJynRzhwv+/qvpzjbD4q71BA6xau0MJfGmiOviqou/KXw7MJbDD1glXAqZD/Gxm4P0DRZ5bfLQ== X-Received: by 2002:a9d:77c6:: with SMTP id w6mr25457142otl.123.1626834077042; Tue, 20 Jul 2021 19:21:17 -0700 (PDT) Return-Path: Received: from [192.168.1.18] ([172.58.144.98]) by smtp.googlemail.com with ESMTPSA id v26sm4276380oof.30.2021.07.20.19.21.16 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 20 Jul 2021 19:21:16 -0700 (PDT) Subject: Re: [FlyRotary] Re: Fwd: Inlet cooling article To: Rotary motors in aircraft References: Message-ID: Date: Tue, 20 Jul 2021 21:25:14 -0500 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------4A51AB0FBFF37C77BF2C8480" Content-Language: en-US X-Antivirus: Avast (VPS 210720-4, 7/20/2021), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. --------------4A51AB0FBFF37C77BF2C8480 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit 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, > >                    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 – I have seen too many that > do not work – without any degree. > > Neil. > > *From:* Rotary motors in aircraft > *Sent:* Wednesday, July 21, 2021 7:07 AM > *To:* Rotary motors in aircraft > *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* > >  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 > > > > > > Virus-free. www.avast.com > > > -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus --------------4A51AB0FBFF37C77BF2C8480 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit
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,

                   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 – I have seen too many that do not work – 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

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

 

Virus-free. www.avast.com

 


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