Return-Path: Received: from smtp4.netdoor.com ([208.137.128.158] verified) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2927917 for flyrotary@lancaironline.net; Sun, 11 Jan 2004 13:20:17 -0500 Received: from netdoor.com (port156.jxn.netdoor.com [208.137.132.156]) by smtp4.netdoor.com (8.12.10/8.12.1) with ESMTP id i0BIKDIs007853 for ; Sun, 11 Jan 2004 12:20:14 -0600 (CST) Message-ID: <400193D8.4080205@netdoor.com> Date: Sun, 11 Jan 2004 12:20:08 -0600 From: Charlie & Tupper England Reply-To: cengland@netdoor.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Radiator ducting References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: 0.1 X-Scanned-By: MIMEDefang 2.31 (www . roaringpenguin . com / mimedefang) If they were Commanchees, remember that size was probably for 250/260hp engines; also the duct shape can't be optimized to an air cooled a/c engine like it can be to a radiator. Charlie john wrote: > Finn; I measured the inlets on the Lopresti, pipers at Oshkosh and > the inlets were 5 1/4". JohnD > > ----- Original Message ----- > From: Finn Lassen > To: Rotary motors in aircraft > Sent: Saturday, January 10, 2004 6:58 PM > Subject: [FlyRotary] Re: Radiator ducting > > Thanks Ed. > > I guess it might be a good idea to go around with a measuring tape > and look at planes with Sam James, Lu Presti and other round > inlets cowls. But I guess 4.5 to 5" diameter is reasonable. > > I just measured my right radiator location. As you know, it is > slanted fore/aft. One side (closest to prop hub) is 6" from prop > edge, and the outboard edge is 13.5" from the prop edge. Coming > from a 5" diameter inlet, what should the ducting look like? Bell > or trumpet shaped? Or just direct lines from each point on the > radiator circumference to nearest point on the inlet circle? > > Where do I find some 5" diameter tubing that will stretch to 12" > diameter (or 9" x 10" square)? > > Finn > > Ed Anderson wrote: > >>Finn, >> >> I would not go below about 18 square inches initially. I did reduce one >>of my duct openings to around 9-10 square inches, but left the other one at >>24 square inches. Cooling is still fine (increased coolant temp by 5F), but >>I suspect the 24 Square inche one is carrying more of the load. K&W >>indicates that if your inlet opening is below a certain critical ratio then >>the losses go way up. Using the 95 square inches of the cores I calculated >>that 18 square inches was a good minimum. If you duct shape and outlet are >>close to optimum you could go smaller, but then things have got to be just >>right. I know that 24 square inches per core works great, and my total >>coolant inlet are is now at 33 square inches and still cooled on 90F day. I >>would pay particular attention to the lower lip of your inlet making certain >>it has a sort of airfoil curve to it so that air will find an easy path when >>the nose is up relative to the airstream (like during your climb). >> >>Don't have a clue as to whether the "round" inlets are better, some folks >>believe so. Van sort of poop pooed the idea at one dinner. >> >> >>Ed Anderson >> >> >> >> >>>> Homepage: http://www.flyrotary.com/ >>>> Archive: http://lancaironline.net/lists/flyrotary/List.html >>>> >>>> >> >> >> >>