X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2463844 for flyrotary@lancaironline.net; Fri, 09 Nov 2007 15:03:46 -0500 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([24.74.103.61]) by cdptpa-omta02.mail.rr.com with SMTP id <20071109200308.XYRJ26419.cdptpa-omta02.mail.rr.com@edward2> for ; Fri, 9 Nov 2007 20:03:08 +0000 Message-ID: <000401c8230b$4be57340$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: knowledge of Heat Transfer was Total,duct, Ambient or Velocity???? Date: Fri, 9 Nov 2007 15:01:19 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C822E1.62BBF410" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C822E1.62BBF410 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable One thing for certain. When I look back on my first attempts at cooling = my 13B back a decade ago - it is certainly humbling to realize how very = ignorant I was of even the most fundamental concepts of heat transfer. = I mean back then it was - get a big radiator and funnel air to it - I = mean how hard could it be?? Well, you can certainly cool that way, but = the drag and weight may be much higher than if you went at the design = with a bit more knowledge - Know what I mean?{:>) Ed ----- Original Message -----=20 From: H & J Johnson=20 To: Rotary motors in aircraft=20 Sent: Friday, November 09, 2007 2:03 PM Subject: [FlyRotary] Re: Total,duct, Ambient or Velocity???? It would.. there are those out there who are already there to some extent.. all systems have to have a 'first run' at some point :-) Throwing some computer validation into the mix always adds another level of 'fun' to the process.=20 I'm finishing a job right now that had somewhere around 5000 parts in it, it's all modeled via 3D design and it's been fitting = together amazingly well.. there have been VERY few parts that needed to be touched up to fit.. it's great to see parts coming from all over North America that come to the shop and bolt on w/ the first try.. I'm hoping to be able to do this w/ a larger portion of my=20 project .. when I get that far along :-) Anyway, it's not to say that computers haven't been a HUGE help in the way things are designed today.. but they still aren't completly and entirely absolute for the entire project.. I'm not sure we'll ever get there in my day.. and I'm not to 'well aged' yet.. :-) Jarrett > Yes, Jarrett, it would be very interesting to design a cooling=20 > system using CFD, fabricate, install and test it to see the=20 > results. =20 >=20 > Ed=20 > ----- Original Message -----=20 > From: H & J Johnson=20 > To: Rotary motors in aircraft=20 > Sent: Friday, November 09, 2007 11:40 AM=20 > Subject: [FlyRotary] Re: Total,duct, Ambient or Velocity????=20 >=20 >=20 >=20 >=20 >=20 > > But, semantics aside, yes, I agree, lower exit pressure is=20 > what=20 > > you are after and that does not always equate to larger exit=20 > duct=20 > > area. In fact, if the air heated by the core flows through a=20 > > nozzle it might even produce thrust and lower exit pressure=20 > using=20 > > a smaller exit. But, in general, I still believe that in most=20 > of=20 > > our cases, we are short of the level of duct design that would=20 > > reliably permit that. What we need is someone to invest in=20 > one of=20 > > those $$$$ Computer Fluid Flow software programs and see what=20 > they=20 > > would reveal.=20 > >=20 > > Ed=20 > >=20 > >=20 > > Ed,=20 > >=20 > > I have to disagree with the big $$$ CFD idea. Until I see=20 > proper=20 > > exit ducts and every effort made to do things right inlet=20 > > wise....CFD is a waste of time. I have yet to see an=20 > installation=20 > > at the level of refinement where CFD would start to make=20 > sense.=20 > > You can get to 90% of optimum by following a few simple=20 > guidelines=20 > > and some fairly simple math.=20 > >=20 > > 1.) do a heat balance at the cruise condition to figure out=20 > how=20 > > much air you need to ingest.=20 > >=20 > > 2.) Size your inlet appropriately.=20 > >=20 > > 3.) Provide a real exit duct.=20 > >=20 > > 4.) Use a cowl flap.=20 > >=20 > > 5.) Do some testing with oil and tufts to make improvements.=20 > >=20 > > A properly done CFD will only get you another 5% beyond these=20 > > simple steps that are within reach of mere mortals. In fact if=20 > the=20 > > guy/gal doing the CFD work is not intimately familiar with the=20 > > situation and what sort of assumptions to make/conditions to=20 > > assign it is very likely that the results will be less=20 > successful=20 > > that the empirical method.=20 > >=20 > > In other words CFD=3Ddecimal dust.=20 > >=20 > >=20 > > Monty=20 >=20 >=20 > Well.. I haven't spent $$$ on it but SolidWorks now comes w/ a=20 > version of=20 >=20 > CosmosFloWorks in the package in 2008.. I've got the software=20 > so I may give it=20 >=20 > a whirl.. I was waiting to test it before I commented but..=20 > since people are talking=20 >=20 > directly about it.. :-)=20 >=20 >=20 >=20 > Jarrett=20 >=20 >=20 > --=20 >=20 > Homepage: http://www.flyrotary.com/=20 >=20 > Archive and UnSub: =20 > http://mail.lancaironline.net:81/lists/flyrotary/List.html -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_0001_01C822E1.62BBF410 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
One thing for certain.  When I look back on = my first=20 attempts at cooling my 13B back a decade ago - it is certainly humbling = to=20 realize how very ignorant I was of even the most fundamental concepts of = heat=20 transfer.  I mean back then it was - get a big radiator and = funnel air=20 to it - I mean how hard could it be??  Well, you can certainly cool = that=20 way, but the drag and weight may be much higher than if you went at the = design=20 with a bit more knowledge - Know what I mean?{:>)
 
Ed
----- Original Message -----
From:=20 H & J=20 Johnson
Sent: Friday, November 09, 2007 = 2:03=20 PM
Subject: [FlyRotary] Re: = Total,duct,=20 Ambient or Velocity????

It would.. there are those out there who are already there to = some

extent.. all systems have to have a 'first run' at some point = :-)

Throwing some computer validation into the mix always adds

another level of 'fun' to the process.

I'm  finishing a job right now that had somewhere around = 5000

parts in it, it's all modeled via 3D design and it's been fitting=20 together

amazingly well..  there have been VERY few parts that needed = to

be touched up to fit.. it's great to see parts coming from all = over

North America that come to the shop and bolt on w/ the first = try..

I'm hoping to be able to do this w/ a larger portion of my

project .. when I get that far along :-)

Anyway, it's not to say that computers haven't been a HUGE help

in the way things are designed today.. but they still aren't = completly

and entirely absolute for the entire project.. I'm not sure = we'll

ever get there in my day.. and I'm not to 'well aged' yet.. :-)

 

Jarrett

 

> Yes, Jarrett,  it would be very  interesting to = design a=20 cooling
> system using CFD, fabricate, install and test it to = see the=20
> results. 
>
> Ed
>  ----- = Original=20 Message -----
>  From: H & J Johnson
>  = To: Rotary=20 motors in aircraft
>  Sent: Friday, November 09, 2007 = 11:40 AM=20
>  Subject: [FlyRotary] Re: Total,duct, Ambient or = Velocity????=20
>
>
>
>
>
>  > But,=20 semantics aside, yes, I agree, lower exit pressure is
> what=20
>  > you are after and that does not always equate to = larger=20 exit
> duct
>  > area.  In fact, if the air = heated=20 by the core flows through a
>  > nozzle it might even = produce=20 thrust and lower exit pressure
> using
>  > a = smaller=20 exit.  But, in general, I still believe that in most
> of=20
>  > our cases, we are short of the level of duct = design that=20 would
>  > reliably permit that.  What we need is = someone=20 to invest in
> one of
>  > those $$$$ Computer = Fluid=20 Flow software programs and see what
> they
>  > = would=20 reveal.
>  >
>  > Ed
>  > =
>  >
>  > Ed,
>  > =
> =20 > I have to disagree with the big $$$ CFD idea. Until I see =
> proper=20
>  > exit ducts and every effort made to do things = right inlet=20
>  > wise....CFD is a waste of time. I have yet to see = an=20
> installation
>  > at the level of refinement = where CFD=20 would start to make
> sense.
>  > You can get to = 90% of=20 optimum by following a few simple
> guidelines
>  = > and=20 some fairly simple math.
>  >
>  > 1.) = do a heat=20 balance at the cruise condition to figure out
> how =
>  >=20 much air you need to ingest.
>  >
>  > = 2.) Size=20 your inlet appropriately.
>  >
>  > 3.) = Provide=20 a real exit duct.
>  >
>  > 4.) Use a = cowl flap.=20
>  >
>  > 5.) Do some testing with oil = and tufts=20 to make improvements.
>  >
>  > A = properly done=20 CFD will only get you another 5% beyond these
>  > = simple steps=20 that are within reach of mere mortals. In fact if
> the =
> =20 > guy/gal doing the CFD work is not intimately familiar with the=20
>  > situation and what sort of assumptions to = make/conditions=20 to
>  > assign it is very likely that the results will = be less=20
> successful
>  > that the empirical method.=20
>  >
>  > In other words CFD=3Ddecimal = dust.=20
>  >
>  >
>  > Monty =
>=20
>
>  Well.. I haven't spent $$$ on it but = SolidWorks now=20 comes w/ a
> version of
>
>  CosmosFloWorks = in the=20 package in 2008..  I've got the software
> so I may give = it=20
>
>  a whirl.. I was waiting to test it before I = commented=20 but..
> since people are talking
>
>  = directly about=20 it..  :-)
>
>
>
>  Jarrett =
>=20
>
> --
>
> Homepage: =20 http://www.flyrotary.com/
>
> Archive and = UnSub:  =20
> = http://mail.lancaironline.net:81/lists/flyrotary/List.html

--

Homepage:  http://www.flyrotary.com/

Archive and UnSub:   =
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