X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao101.cox.net ([68.230.241.45] verified) by logan.com (CommuniGate Pro SMTP 5.3.1) with ESMTP id 4095807 for flyrotary@lancaironline.net; Mon, 25 Jan 2010 19:51:33 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.45; envelope-from=alventures@cox.net Received: from fed1rmimpo02.cox.net ([70.169.32.72]) by fed1rmmtao101.cox.net (InterMail vM.8.00.01.00 201-2244-105-20090324) with ESMTP id <20100126005058.IDYK4995.fed1rmmtao101.cox.net@fed1rmimpo02.cox.net> for ; Mon, 25 Jan 2010 19:50:58 -0500 Received: from BigAl ([72.192.128.205]) by fed1rmimpo02.cox.net with bizsmtp id a0qQ1d00c4S1t5C040qbfr; Mon, 25 Jan 2010 19:50:35 -0500 X-VR-Score: -100.00 X-Authority-Analysis: v=1.1 cv=zS9SgV63hfBKgCfMNmcWTXDxxMKGbBeTgNVRdCpsi3s= c=1 sm=1 a=WbNVUdcZcaUA:10 a=Vegc0WxVmH5BHtpNDyThtA==:17 a=Ia-xEzejAAAA:8 a=ayC55rCoAAAA:8 a=arxwEM4EAAAA:8 a=QdXCYpuVAAAA:8 a=7g1VtSJxAAAA:8 a=ekHE3smAAAAA:20 a=UretUmmEAAAA:8 a=nUuTZ29dAAAA:8 a=g62sVVjSzBYsDcWlHWcA:9 a=ztvuRGU5MY17O5QtNWwA:7 a=ba5Y3ZMI2I1Ckhg_3_QSJaGak6IA:4 a=5zrLeAV0Z70A:10 a=1vhyWl4Y8LcA:10 a=EzXvWhQp4_cA:10 a=LFN7zHaLrMlMR4oo:21 a=7EKyfye4f6stRWi-:21 a=HAX1qVzvXOrTxD2y8LsA:9 a=9GjKEYsefEmh_NhCxEkA:7 a=iIPtcec5SW04SL8KAisEbk7C8CsA:4 a=XVctLqh5gpHwoeMC:21 a=raKu9AuftQTTzpQi:21 a=Vegc0WxVmH5BHtpNDyThtA==:117 X-CM-Score: 0.00 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Wedge/Oblique Duct Date: Mon, 25 Jan 2010 16:52:17 -0800 Message-ID: <920DDCF472AC40578482091CC7A3C038@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000F_01CA9DDE.C6DA0D40" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6856 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 In-Reply-To: Importance: Normal Thread-Index: AcqeD1wUSqqhTmHyTjyBwiBa+5+8IwACIycg This is a multi-part message in MIME format. ------=_NextPart_000_000F_01CA9DDE.C6DA0D40 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable George; =20 I haven't been following this thread, and stepping in here may reflect = that; but I don't really understand your question. The size of the inlet = opening is determined by the amount of heat you need to reject, best taken as corresponding to something close to the climb power. That; with the = density and specific heat of air, gives you the cfm required. When you know = that, and the approximate climb speed of your application, you can calculate = the required inlet opening.=20 =20 Having done all those calcs, I (or ED, I'm sure) could scale those = numbers for you fairly readily to your power level and speed. =20 Other things follow from there; including the face area of the rad. Optimally, you'd like to have a way of adjusting inlet and exit areas = for absolute minimum drag; but that's very complicated. If you can do one = of those, adjust the exit area. If both are fixed and you want least drag, = you can size the inlet for something closer to cruise speed, and add the complexity of the spray-bar idea for added cooling during high power regimes. =20 =20 It's good to have some sort of control over the amount of cooling to maintain engine temps within some reasonable range. If the cooling = system is sized for climb on a hot day, a thermostat is a way to maintain temps = for other regimes. There is the rare possibility of a thermostat sticking closed, but that is something that hopefully would be noted before = takeoff. =20 Not that I advocate this approach, but I have a setup that doesn't = require any pilot intervention and serves quite well. I have 2 coolant = radiators, one which can handle the cooling for normal cruise (both coolant and = some of the oil heat), and one (connected in parallel) that can handle maybe = 30-40% more (in the wing root with presumably a fairly low drag inlet/outlet. = The second has an in-line thermostat, so only comes into service during high-power operation, or very hot days. I have an oil/air cooler that handles normal cruise power, and small oil/water exchanger (in parallel) that keeps the oil temps at a safe level for high power by transferring = heat to the coolant. Yeah; the plumbing is a little more complicated, but I = like the way it works. =20 (Sorry, it seems what starts out to be a simple answer always turn into = more complicated discussions). =20 Al G =20 =20 =20 -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George Lendich Sent: Monday, January 25, 2010 2:31 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Wedge/Oblique Duct =20 Ed, I have been thinking about this, if I use A1V1=3DA2V2 to solve for the = inlet opening size, how do I know if the speed of air through the duct is = correct i.e. 10% for cruise and 30% for climb. =20 Also If I use the Cessna 171 speed of approx 100 K for cruise =3D 10 K = through core, 70 knot climb and approx 20 K through core. Do I then use the = climb speed to calculate inlet air openings and attach an adjustable louver = exit OR I suppose I could do as Tracy does and calculate for cruise and = attach a spray bar. =20 I'm still a little confused on the best approach. George ( down under) BTW it's Australia Day today - arrival of the first fleet. =20 George, For the bell shaped duct, what I have read in K & W it appears = they say the inlet area should be between 0.25 - 0.40 of the core area. The = more slowing of the air velocity that needs to be done by the diffuser before = the core that is needed appears to call for lower area ratio values of Ai/Ab (area inlet/area core). In the example plotted of an streamline duct in = K&W the chart shows the area ratio was 0.40. Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm =20 _____ =20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George Lendich Sent: Wednesday, January 20, 2010 6:16 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Wedge/Oblique Duct =20 Ed, If Ai is .33 Ab and .44 Ab for the wedge ducts, what's it for the bell shaped duct - is there any similar drawing? George ( down under) ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Wednesday, January 20, 2010 3:39 AM Subject: [FlyRotary] Wedge/Oblique Duct =20 =20 George, here are two figures from K&W - one could be described as a = "Wedge" figure 12-6 and the other one a "streamline" wedge figure 12-12. =20 Always dangerous for me to try to interpret what K&W are really saying, = but from what I get from these two figures, it would appear that the "streamline" wedge permits you to use a smaller inlet (Ai =3D 0.30 Ab) = for the same performance (same losses) that you get with a larger opening Ai =3D = 0.44 Ab for the pure Wedge. But, that is just my take on it. =20 The slight bump (where the 64 deg angle is annotated) of the Streamline wedge may be to increase the boundary layer velocity to delay separation = of the boundary layer in that far corner where duct meets core. =20 =20 Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm =20 =20 __________ Information from ESET NOD32 Antivirus, version of virus = signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com _____ =20 -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html __________ Information from ESET NOD32 Antivirus, version of virus = signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ------=_NextPart_000_000F_01CA9DDE.C6DA0D40 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

George;

 

I haven’t been following = this thread, and stepping in here may reflect that; but I don’t really = understand your question.  The size of the inlet opening is determined by the = amount of heat you need to reject, best taken as corresponding to something = close to the climb power.  That; with the density and specific heat of air, = gives you the cfm required.  When you know that, and the approximate = climb speed of your application, you can calculate the required inlet opening. =

 

Having done all those calcs, I = (or ED, I’m sure) could scale those numbers for you fairly readily to your power = level and speed.

 

Other things follow from there; including the face area of the rad. Optimally, you’d like to have = a way of adjusting inlet and exit areas for absolute minimum drag; but = that’s very complicated.  If you can do one of those, adjust the exit = area. If both are fixed and you want least drag, you can size the inlet for = something closer to cruise speed, and add the complexity of the spray-bar idea for = added cooling during high power regimes. 

 

It’s good to have some sort = of control over the amount of cooling to maintain engine temps within some reasonable range.  If the cooling system is sized for climb on a = hot day, a thermostat is a way to maintain temps for other regimes. There is the = rare possibility of a thermostat sticking closed, but that is something that hopefully = would be noted before takeoff.

 

Not that I advocate this = approach, but I have a setup that doesn’t require any pilot intervention and = serves quite well.  I have 2 coolant radiators, one which can handle the cooling = for normal cruise (both coolant and some of the oil heat), and one (connected in = parallel) that can handle maybe 30-40% more (in the wing root with presumably a = fairly low drag inlet/outlet. The second has an in-line thermostat, so only = comes into service during high-power operation, or very hot days.  I have an = oil/air cooler that handles normal cruise power, and small oil/water exchanger = (in parallel) that keeps the oil temps at a safe level for high power by transferring heat to the coolant. Yeah; the plumbing is a little more complicated, but I like the way it works.

 

(Sorry, it seems what starts out = to be a simple answer always turn into more complicated = discussions).

 

Al G

 

 

 

-----Original = Message-----
From: Rotary motors in = aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George Lendich
Sent: Monday, January 25, = 2010 2:31 PM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Re: Wedge/Oblique Duct

 

 Ed,

I have been thinking about = this, if I use A1V1=3DA2V2 to solve for the inlet opening size, how do I know if = the speed of air through the duct is correct i.e. 10% for cruise and 30% for = climb.

 

Also If I use the Cessna = 171 speed of approx 100 K for cruise =3D 10 K through core, 70 knot climb and = approx 20 K through core. Do I then use the climb speed to calculate inlet air = openings and attach an adjustable louver exit OR I suppose I could do as Tracy = does and calculate for cruise and attach a spray bar.

 

I'm still a little confused = on the best approach.

George ( down = under)

BTW it's Australia Day = today - arrival of the first fleet.

 

=

George, For the = bell shaped duct, what I have read in K & W it appears they  say the = inlet area should be between 0.25 – 0.40 of the core area.  The = more slowing of the air velocity that needs to be done by the diffuser before = the core that is needed appears to call for lower area ratio values of Ai/Ab = (area inlet/area core).  In the example plotted of an streamline duct in = K&W the chart shows the area ratio was 0.40.

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George Lendich
Sent: Wednesday, January = 20, 2010 6:16 PM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Re: Wedge/Oblique Duct

 

Ed,

If Ai is .33 Ab and .44 Ab = for the wedge ducts, what's it for the bell shaped duct - is there any =  similar drawing?

George ( down = under)

----- Original Message = -----

From: Ed Anderson

Sent: Wednesday, January 20, 2010 3:39 AM

Subject: [FlyRotary] Wedge/Oblique Duct

 

 

George, here are two = figures from K&W – one could be described as a “Wedge” figure = 12-6 and the other one a “streamline” wedge figure = 12-12.

 

Always  dangerous for = me to try to interpret what K&W are really saying, but from what I get from = these two figures, it would appear that the “streamline” wedge permits = you to use a smaller inlet (Ai =3D 0.30 Ab) for the same performance (same = losses) that you get with a larger opening Ai =3D 0.44 Ab for the pure Wedge.  = But, that is just my take on it.

 

The slight bump (where the = 64 deg angle is annotated) of the Streamline wedge may be to increase the = boundary layer velocity to delay separation of the boundary layer  in that = far corner where duct meets core. 

 

Ed

Ed = Anderson

Rv-6A N494BW Rotary = Powered

Matthews, = NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html<= /p>

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.r= otaryaviation.com/Rotorhead%20Truth.htm

 



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Homepage:  http://www.flyrotary.com/
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