Return-Path: Received: from fed1rmmtao02.cox.net ([68.230.241.37] verified) by logan.com (CommuniGate Pro SMTP 4.3c3) with ESMTP id 813766 for flyrotary@lancaironline.net; Mon, 21 Mar 2005 11:01:53 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.37; envelope-from=ALVentures@cox.net Received: from BigAl ([68.7.14.39]) by fed1rmmtao02.cox.net (InterMail vM.6.01.04.00 201-2131-118-20041027) with ESMTP id <20050321160051.OMTD4787.fed1rmmtao02.cox.net@BigAl> for ; Mon, 21 Mar 2005 11:00:51 -0500 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: BMW and EWP Date: Mon, 21 Mar 2005 08:00:56 -0800 Message-ID: <000a01c52e2f$2ce198d0$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000B_01C52DEC.1EBE58D0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_000B_01C52DEC.1EBE58D0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Al, =20 Could you say a few words about how you determined what the optimum flow requirements for aircraft use shoud be. If it's in the archives, just a pointer to the message(s) would be enough =20 Bob W. =20 Trying to put me on the spot, eh:-). =20 I don=92t know how to respond; it would take much more time than I have = right now. Much of the information has been covered, but to pull it together = from the archives would be very tough as it has been scattered through here = and ACRE over the last 4 years. =20 In general, the design is driven primarily by factors outside the = engine. The design of the cooling jacket and the engine internals is what it is; Mazda has done that, and we can=92t change it. All we know is we = don=92t want the coolant to boil in there, and we know that there are potential hot spots, particularly around the plugs that can be the limiting factor. = We also know that heat load is much higher on the plug side of the engine = than on the other, which can lead to some thermal expansion issues if the temperature drop across the engine gets too high; how high is to high, I don=92t know. =20 Designing for an aircraft has some different priorities than for a car, mostly related to drag, weight and configuration. I first looked at radiator design to get an idea of configuration for minimum cooling drag = and weight. These factors are coupled with configuration issues. I also had = to pick a design point, which I chose as 200 hp climb from sea level on a = 90F day. This is for my Velocity with a 20B. =20 A few years back Fred Moreno posted results of a whole series charts = from detailed software analysis on rad performance. I studied those and = whatever other reference seemed worthwhile. From that I determined approximate = best core thickness (2 to 2 =BD=94), and temp drop across the radiators (20 = to 30F). Obviously there are judgments and tradeoffs involved- your results may = vary. =20 I also studied the airflow side, looking at fin spacing, air side = pressure drop etc., to determine roughly what core configuration and airflow = velocity through the core made most sense. Putting this stuff together with the coolant flow needed for 20-30F drop allowed design of the custom = radiators. Then there was design of scoops to get the needed pressure recovery and = air velocity. =20 The builders of the rads also provided data on the flow and heat = transfer characteristics. When I had the rads and scoops I did flow tests to = measure and confirm pressure drops. Similar design and analysis and testing for = the oil cooler. =20 =20 The dyno tests should me that the flow was lower than needed for 20F = drop, but adequate to get 30F; without a thermostat. With a thermostat (in = open condition) the flow was considerably lower. =20 Overkill? Maybe. I did it because I could; and I wanted to maximize the probability of going flying and having adequate (or better) cooling. = Did I get it right? You design and you test. Some of the things I can=92t = test until I fly; so it remains to be seen. I just know from my years of engineering analysis in industry that it can be a very powerful tool and save a lot of trial and error. =20 =20 Al ------=_NextPart_000_000B_01C52DEC.1EBE58D0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Hi Al,

 

Could you say a few words about how you determined what the optimum = flow

requirements for aircraft use shoud be.=A0 If it's in the archives, = just

a pointer to the message(s) would be enough

 

Bob W.

 

Trying to put me on the spot, ehJ.

 <= /font>

I don’t = know how to respond; it would take much more time than I have right now.=A0 Much = of the information has been covered, but to pull it together from the archives = would be very tough as it has been scattered through here and = ACRE over the last 4 years.

 <= /font>

In general, = the design is driven primarily by factors outside the engine. =A0The design of the = cooling jacket and the engine internals is what it is; Mazda has done that, and we = can’t change it.=A0 All we know is we don’t want the coolant to boil in = there, and we know that there are potential hot spots, particularly around the = plugs that can be the limiting factor.=A0 We also know that heat load is much = higher on the plug side of the engine than on the other, which can lead to some = thermal expansion issues if the temperature drop across the engine gets too = high; how high is to high, I don’t know.

 <= /font>

Designing for = an aircraft has some different priorities than for a car, mostly related to = drag, weight and configuration.=A0 I first looked at radiator design to get an = idea of configuration for minimum cooling drag and weight. These factors are = coupled with configuration issues.=A0 I also had to pick a design point, which I = chose as 200 hp climb from sea level on a 90F day.=A0 This is for my Velocity = with a 20B.

 <= /font>

A few years = back Fred Moreno posted results of a whole series charts from detailed software = analysis on rad performance. =A0I studied those and whatever other reference = seemed worthwhile.=A0 From that I determined approximate best core thickness (2 = to 2 =BD”), and temp drop across the radiators (20 to 30F).=A0 Obviously there are = judgments and tradeoffs involved- your results may vary.

 <= /font>

I also = studied the airflow side, looking at fin spacing, air side pressure drop etc., to = determine roughly what core configuration and airflow velocity through the core = made most sense.=A0 Putting this stuff together with the coolant flow needed for = 20-30F drop allowed design of the custom radiators.=A0 Then there was design of = scoops to get the needed pressure recovery and air velocity.

 <= /font>

The builders = of the rads also provided data on the flow and heat transfer characteristics. = =A0When I had the rads and scoops I did flow tests to measure and confirm pressure = drops. =A0Similar design and analysis and testing for the oil cooler.=A0 =

 <= /font>

The dyno = tests should me that the flow was lower than needed for 20F drop, but adequate to get = 30F; without a thermostat. =A0With a thermostat (in open condition) the flow = was considerably lower.

 <= /font>

Overkill? = Maybe.=A0 I did it because I could; and I wanted to maximize the probability of = going flying and having adequate (or better) cooling.=A0 Did I get it right? = You design and you test.=A0 Some of the things I can’t test until I fly; so = it remains to be seen.=A0 I just know from my years of engineering analysis in = industry that it can be a very powerful tool and save a lot of trial and error.=A0 =

 <= /font>

Al

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