X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao06.cox.net ([68.230.241.33] verified) by logan.com (CommuniGate Pro SMTP 5.0c2) with ESMTP id 719217 for flyrotary@lancaironline.net; Mon, 12 Sep 2005 12:18:51 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.33; envelope-from=ALVentures@cox.net Received: from BigAl ([68.7.14.39]) by fed1rmmtao06.cox.net (InterMail vM.6.01.05.02 201-2131-123-102-20050715) with ESMTP id <20050912161806.DEXB2438.fed1rmmtao06.cox.net@BigAl> for ; Mon, 12 Sep 2005 12:18:06 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Optimal GPM water pump flow. Date: Mon, 12 Sep 2005 09:18:16 -0700 Message-ID: <000001c5b7b5$94f20620$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C5B77A.E8932E20" 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_0001_01C5B77A.E8932E20 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable =20 Al. What I am after is trying to determine what the minimum required flow = is for the horsepower generated. More than anything else, I do not want to = be BELOW that amount, and consider it a minimum. Understandably, trying to place twice or nearly 3 times the flow through the same circuit will = result in higher pressures and perhaps some pump cavitation. I will deal with = that as I have to.. more than anything else I want to make sure I am not = starting off with a DEFICIT of water flow ability. =20 I don=92t know what water pump you have (stock), but as a general = comment, I would say that the stock pump would provide adequate flow rate. The = main issues with cooling are usually with other aspects, and generally = related to the =91air-side=92 =96 heat exchanger sizing, scoop and duct design, = pressure drop, etc. =20 I am considering 2 smaller radiators, and originally I intended to plumb them in series to get the best cumulative Delta-T across them, but if I = have "pressure" problems due to the pump's flow, I may go to a parralel arrangement=20 =20 Cumulative coolant side delta-T (determined by the flow rate) is, by = itself, not the issue; but rather average radiator temp. The higher that is = (for a given flow rate), the more effective the heat transfer to the air. = Parallel flow will give you a higher average rad temp. =20 Designing heat rejection is always a tradeoff of cooling capacity and = drag, and if you don=92t have air flow control you have to design for takeoff = and climb, and have excess capacity for cruise. For the Velocity SE, = 180-200 hp is plenty for takeoff, even if you have more available. So on the = warmest days you may throttle back shortly after the wheels are off. About 65 = sq. in. =91effective=92 scoop intake area (for coolant) should give you = adequate airflow on a hot day. Figuring a radiator core thickness of about 2 = =BD=94, and a core face area of about 250 - 275 sq. in. should do it. =20 With a pusher, there is always another aspect, cooling on the ground. = This may require auxiliary fan(s); however, I have found that with the = cooling air exiting the cowl, the negative pressure created by the prop at taxi = rpm is sufficient to allow running 15-20 minutes at low power with air temp = of about 80F, or lower. Your results may vary. =20 Just one man=92s analysis for similar power (NA 20B), John and Steve = also have data for their Cozys. =20 Al -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ ------=_NextPart_000_0001_01C5B77A.E8932E20 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

 

Al.
   What I am after is trying to determine what the minimum = required flow is for the horsepower generated.  More than anything else, I = do not want to be BELOW that amount, and consider it a minimum. Understandably, = trying to place twice or nearly 3 times the flow through the same circuit will = result in higher pressures and perhaps some pump cavitation. I will deal with = that as I have to.. more than anything else I want to make sure I am not = starting off with a DEFICIT of water flow ability.

 

I don’t =
know what water pump you have (stock), but as a general comment, I would =
say that the stock pump would provide adequate flow rate. =A0The main =
issues with cooling are usually with other aspects, and generally =
related to the ‘air-side’ – heat exchanger sizing, =
scoop and duct design, pressure drop, etc.

 

I am considering 2 smaller radiators, and =
originally I intended to plumb them in series to get the best cumulative =
Delta-T across them, but if I have "pressure" problems due to =
the pump's flow, I may go to a parralel arrangement =

 
= 
Cumulative coolant side delta-T (determined by the flow =
rate) is, by itself, not the issue; but rather average radiator temp. =
=A0The higher that is (for a given flow rate), the more effective the =
heat transfer to the air. Parallel flow will give you a higher average =
rad temp.
 
Designing heat =
rejection is always a tradeoff of cooling capacity and drag, and if you =
don’t have air flow control you have to design for takeoff and =
climb, and have excess capacity for cruise. =A0For the Velocity SE, =
180-200 hp is plenty for takeoff, even if you have more available. =A0So =
on the warmest days you may throttle back shortly after the wheels are =
off. =A0About 65 sq. in. ‘effective’ scoop intake area (for =
coolant) should give you adequate airflow on a hot day.=A0 Figuring a =
radiator core thickness of about 2 =BD”, and a core face area of =
about 250 - 275 sq. in. should do it.
 
With a pusher, =
there is always another aspect, cooling on the ground.=A0 This may =
require auxiliary fan(s); however, I have found that with the cooling =
air exiting the cowl, the negative pressure created by the prop at taxi =
rpm is sufficient to allow running 15-20 minutes at low power with air =
temp of about 80F, or lower.=A0 Your results may =
vary.
 
Just one =
man’s analysis for similar power (NA 20B), John and Steve also =
have data for their Cozys.
 
Al

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