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 5.2c2) with ESMTP id 2472709 for flyrotary@lancaironline.net; Wed, 14 Nov 2007 20:38:13 -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-omta01.mail.rr.com with SMTP id <20071115013736.ROHY6760.cdptpa-omta01.mail.rr.com@edward2> for ; Thu, 15 Nov 2007 01:37:36 +0000 Message-ID: <001f01c82728$69d48690$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Thick vs. Thin...ED is trying to scramble your brain like an egg Date: Wed, 14 Nov 2007 20:39:50 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001C_01C826FE.80AD7860" 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_001C_01C826FE.80AD7860 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hey, Hey! Monty After all I've done for you, you go and let the cat out of the bag {:>). = However, I do agree (and I notice that frequently -so do the authors = of those old NACA reports) that practical installation constraints = often do override theoretical considerations. Gee, now I guess I am going to have to revive the dreaded DIE II = (dynamic Intake effect) topic {:>) Sounds like more tooth work than I would want. Hope you're over the = worst Ed ----- Original Message -----=20 From: M Roberts=20 To: Rotary motors in aircraft=20 Sent: Wednesday, November 14, 2007 7:43 PM Subject: [FlyRotary] Thick vs. Thin...ED is trying to scramble your = brain like an egg RESIST! It's a sinister plot to keep us all from working on actual airplanes! = There are too many people completing rotary powered airplanes. Ed is = trying to side track us!! Really tried to remain silent, but all those drugs the dentist used = have lowered my resistance...... I've had more thermo and fluid dynamics than I wanted, and have had to = apply it in the real world. You guys are on a great big snipe hunt. The = only way to fairly compare this is take a core that is say 4 units = thick. spread that exact core out so it is only 1 unit thick. Now run = the numbers both ways sizing the inlets, diffusers, and nozzles and core = area, for the same heat rejection rate and hot side mass flow....All = assuming same efficiencies for diffuser and nozzle (not necessarily = valid, but do it anyway). No rigging the efficiencies or saying this = core is better than that one etc. You can't just assume a cold side = DeltaT. You have to calculate it. Both must be a cross-flow exchanger = etc, etc, etc. You will need a heat transfer book, and a thermo 1 and 2 = text. Before you do this you might want to have a little light = background reading in calculus 1, 2, and 3 and probably fluid dynamics, = You will get real familiar with a lot of funny non dimensional numbers = named after dead German guys. On second thought just go get a mechanical = engineering degree because you will already be so deep in this junk by = then.=20 Then if you avoid any math errors you will find out the magic = theoretical advantage one radiator might have over the other.=20 We are flying too slow and reject too little heat to use the black = magic voodoo Meredith effect....so just put that out of your mind if = that is in any way steering your thinking on this matter. If this sort of thing floats your boat you can spend hours and hours = with spread sheets and equations. and in the end........ sailboat = fuel....turd polishing....snipe hunt. Trade studies for both designs for given airframe and mission are all = that matter....and in the end testing. Packaging/weight/structural constraints will trump some minor = theoretical heat transfer advantage every time.=20 I guess you can argue with the pocket protector set in heat transfer = lab after it's all said and done...but it sure won't get you any dates = (or at least not ones you'd want ;-). All the while you toil, earthbound, in vain, Ed will be flying = overhead with a loud buzzing sound overlain with evil, maniacal, = laughter. Monty ------=_NextPart_000_001C_01C826FE.80AD7860 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hey, Hey! Monty
 
After all I've done for you, you go and let the = cat out of=20 the bag {:>).  However, I do agree (and I notice that = frequently =20 -so do the authors of those old  NACA reports) that practical = installation=20 constraints often do override theoretical considerations.
 
Gee, now I guess I am going to have to revive = the dreaded=20  DIE II  (dynamic Intake effect) topic {:>)
 
Sounds like more tooth work than I would = want.  Hope=20 you're over the worst
 
Ed
----- Original Message -----
From:=20 M=20 Roberts
Sent: Wednesday, November 14, = 2007 7:43=20 PM
Subject: [FlyRotary] Thick vs. = Thin...ED=20 is trying to scramble your brain like an egg

RESIST!
 
It's a sinister plot to keep us all = from working=20 on actual airplanes! There are too many people completing rotary = powered=20 airplanes. Ed is trying to side track us!!
 
Really tried to remain silent, but = all those=20 drugs the dentist used have lowered my resistance......
 
I've had more thermo and fluid = dynamics than=20 I wanted, and have had to apply it in the real world. You guys are on = a great=20 big snipe hunt. The only way to fairly compare this is take a core = that is say=20 4 units thick. spread that exact core out so it is only 1 unit = thick. Now=20 run the numbers both ways sizing the inlets, diffusers, and nozzles = and core=20 area, for the same heat rejection rate and hot side mass=20 flow....All assuming same efficiencies for diffuser and nozzle = (not=20 necessarily valid, but do it anyway). No rigging the efficiencies or = saying=20 this core is better than that one etc. You can't just assume a cold = side=20 DeltaT. You have to calculate it. Both must be a cross-flow exchanger = etc,=20 etc, etc. You will need a heat transfer book, and a thermo 1 and 2 = text.=20 Before you do this you might want to have a little = light background=20 reading in calculus 1, 2, and 3 and probably fluid = dynamics, You=20 will get real familiar with a lot of funny non=20 dimensional numbers named after dead German guys. On = second=20 thought just go get a mechanical engineering degree because you = will=20 already be so deep in this junk by then.
 
Then if you avoid any math = errors you will=20 find out the magic theoretical advantage one radiator might have = over the=20 other.
 
We are flying too slow and reject too = little heat=20 to use the black magic voodoo Meredith effect....so just put = that=20 out of your mind if that is in any way steering your thinking on this=20 matter.
 
If this sort of thing floats your = boat you can=20 spend hours and hours with spread sheets and equations. and in the = end........=20 sailboat fuel....turd polishing....snipe = hunt.
 
Trade studies for both designs for = given airframe=20 and mission are all that matter....and in the end = testing.
 
Packaging/weight/structural  constraints will = trump some=20 minor theoretical heat transfer advantage every = time. 
 
I guess you can argue with the pocket = protector=20 set in heat transfer lab after it's all said and done...but = it sure=20 won't get you any dates (or at least not ones you'd want = ;-).
 
All the while you toil, earthbound, = in vain, Ed=20 will be flying overhead with a loud buzzing sound overlain = with=20 evil, maniacal, laughter.
 
Monty
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