X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ms-smtp-01.southeast.rr.com ([24.25.9.100] verified) by logan.com (CommuniGate Pro SMTP 5.1.9) with ESMTP id 2078865 for flyrotary@lancaironline.net; Fri, 01 Jun 2007 13:20:25 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.100; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-103-061.carolina.res.rr.com [24.74.103.61]) by ms-smtp-01.southeast.rr.com (8.13.6/8.13.6) with SMTP id l51HJiA9012568 for ; Fri, 1 Jun 2007 13:19:44 -0400 (EDT) Message-ID: <000e01c7a471$145d7f80$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Intake CFM air flow Date: Fri, 1 Jun 2007 13:19:57 -0400 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3028 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 X-Virus-Scanned: Symantec AntiVirus Scan Engine I agree, Hans. But, 99% of us are not using PP and since I'm not certain how much over a good PP can be, its hard to quantify - other than guess. But I would said (just a SWAG) that 125% Ve would probably be the upper limit and it might in reality be closer to 110-115% for the type PP we would use. Does anybody have any data/references that might give us a clue? Ed ----- Original Message ----- From: "Hans Conser" To: "Rotary motors in aircraft" Sent: Friday, June 01, 2007 10:11 AM Subject: [FlyRotary] Re: Intake CFM air flow > Don't forget the VE on PP engine can be over 100%! > > On 6/1/07, Ed Anderson wrote: >> Remember that the 13B is supposedly an 80 CID engine. In reality it acts >> like a 160 CID 4 cylinder 4 stroke or a 80 CID 2 stoke power-wise. Now >> this >> is assuming a 100% Ve for induction efficiency, any restrictions and your >> air flow is, of course, less. >> >> So for a 160 CID 4 cylinder air flow CFM = CID*RPM/(2*1728) = 160 *6000 >> /(2*1728) = 277.77 CFM >> >> Now if you can turn 7500 rpm (say with a Renesis and the 2.85 gear box) >> you >> would have >> >> Air Flow = 160 *7500 * (2*1728) = 347 CFM and if in an automobile and >> winding to 9000 rpm you would get >> >> Air Flow = 160 * 9000 * (2 *1728) = 416 CFM but still short of an >> all-out >> V8 - sorry! If you want more airflow then forced induction or nitrous >> oxide injection is the only way I know got get that kind power. With >> nitrous oxide of course you don't need to increase the airflow because >> the >> nitrous oxide gas is providing the extra oxygen needed during the >> combustion >> process.. >> >> Concerning air velocity through your throttle body >> >> For a 3" dia TB flowing 278 CFM here is what I get using my Excel >> Spreadsheet. >> >> Your TB area is pi*(dia/2)^2 = 7.068 sq inch = 7.068/144 = .049087 sq ft >> >> Flow rate = Velocity * Area = (ft/min)*(ft^2) = (ft^3/min), so solving >> for >> velocity = Flow Rate/Area >> >> Velocity = flow rate (ft^3/min)/Area (ft^2) = >> 277(ft^3/min)/(.049087(ft^2)) >> = 5663.369 ft/min velocity through TB >> >> Converting to feet/sec = 5663.369(ft/min)/60(sec/min) = 94.389 ft/sec >> converting that to MPH = 94.389(ft/sec)*3600(sec/hour) /5280(ft/mile) = >> 64.35 Miles/hour MPH for air velocity through your TB at 6000 rpm. I >> could >> have screwed up the math along the way, but that's what I get. >> >> So I get 64.35 mph air velocity through your 3 " TB - a rather stiff >> breeze >> {:>). So its important to minimize pressure drops and drag in your >> inlet - >> but, keep in mind its just one part of the total 3 component system - >> induction/engine/exhaust - that determines your through put. You can >> have >> the best inlet money and theory can buy, but if you engine and/or >> exhaust >> can not support that flow, then you won't get it. >> >> >> >> Ed >> >> >> >> ----- Original Message ----- >> From: "Bill Bradburry" >> To: "Rotary motors in aircraft" >> Sent: Friday, June 01, 2007 8:16 AM >> Subject: [FlyRotary] Intake CFM air flow >> >> >> > Thanks Bob and Ed. >> > >> > I would appreciate the pictures, Bob. >> > >> > Ed, I expected a much higher flow. I thought that it would be in the >> > neighborhood of 600-800 CFM! I guess I have been spending too much >> > time >> > reading the carburetor adds for V8s.... >> > I think that the 278 CFM would translate to an air velocity of about >> > 48.25 >> > MPH going through my 3 inch throttle body. That seems like a gentle >> > breeze! Maybe I am spending too much time trying to remove >> > restrictions >> > to the air flow in the inlet?? :<) >> > >> > Bill B >> > >> > >> > >> > Subject: >> > Re: [FlyRotary] Intake CFM air flow >> > From: >> > Bob White >> > Date: >> > Thu, 31 May 2007 18:48:02 -0600 >> > >> > Hi Bill, >> > >> > I built a can around it out of aluminum. The can clamped on at the >> > same place as the filter and it was about 6" dia or maybe a little >> > larger. I then made a fiberglass air inlet that sealed to the can with >> > a strip of red silicon engine baffle. I was hoping to generate some >> > ram air pressure, but didn't get a chance to measure it to see how good >> > it worked. I'll take some pictures next time I get to the airport. >> > >> > Bob W. >> > >> > >> >> Subject: >> >> Re: [FlyRotary] Intake CFM air flow >> >> From: >> >> "Ed Anderson" >> >> Date: >> >> Thu, 31 May 2007 19:22:24 -0400 >> >> >> >> >> >> Bill, at 6000 rpm the airflow is 277 CFM assuming 100% Ve. Here is a >> >> formula >> >> for calculating airflow for the rotary. >> >> >> >> Air Flow (CFM) = (40 cubic inches per face)*2(number rotors) * 3(faces >> >> per rotor)*rpm of rotors(= E shaft rpm/3) /1728 (conversion to CF) = >> >> 40*2*3 *(6000/3)/1728 = 240*2000/1728 = 277.77 CFM >> >> >> >> Or simplifying Air Flow (CFM) = 80*RPM/1728 = 277.77 CFM air flow at >> >> 6000 >> >> rpm for a 2 rotor. >> >> >> >> Ed >> > >> > -- >> > Homepage: http://www.flyrotary.com/ >> > Archive and UnSub: >> > 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 >> > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html