X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.102] (HELO ms-smtp-03-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 5.0c2) with ESMTP id 712010 for flyrotary@lancaironline.net; Mon, 05 Sep 2005 17:12:43 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.102; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-065-188-083-049.carolina.res.rr.com [65.188.83.49]) by ms-smtp-03-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j85LBsY5001235 for ; Mon, 5 Sep 2005 17:11:55 -0400 (EDT) Message-ID: <000a01c5b25e$301e76e0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Another great flying day = another day of troubleshooting Date: Mon, 5 Sep 2005 17:10:05 -0400 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Scanned: Symantec AntiVirus Scan Engine Uncle! You are right, Thomas. Just got off on the wrong track with pressure ratio and kept going. Duh! Ed ----- Original Message ----- From: "rijakits" To: "Rotary motors in aircraft" Sent: Monday, September 05, 2005 5:02 PM Subject: [FlyRotary] Re: Another great flying day = another day of troubleshooting >I GUESS, Dave runs a regular manifold pressure gauge like in any regular > (speak certified) aircraft with piston engines. > IF that is so, you read absolut pressure at whatever place you have the > probe (not necessarily the actual pressure in the manifold...but somewhere > close). > If Dave observes 36" og Hg (Mercury) on the gauge, it means it is roughly > 6" > of Pressure (Hg) above sealevel. > If he sees 26" at 10.000 feet that is exactly what it should be, IF he > didn't increase the charging rate. You loose about 1" Hg per 1000ft climb > (at least that's what I teach my flight students, correct me if I am > wrong!!!). > > Ed I think you got on the wrong track somewhere...... at least with the > manifold pressures...:) > > I think you mic up boost rate (how many times do you compress ambient > pressure) and absolute pressure (ambient pressure + "boosted" pressure) > somewhere. You can get to the same "boosted" pressure value at different > rates at different altitudes) > To mix it up some more we could start to talk about ambient to boosted > ratio > :)), which changes constantly wit haltitude IF you keep the absolute > pressure constant - that's where you run out of Turbo rpm sometime if you > keep climbing and boosting!! :)) > > IF MSD is so great for spark, why is not everyone running it? (as Jim > suggested....) > Lynn, how are the MSD's doing with Radionoise? Do you use any radios in > your > racing? Might there be a problem with Aviation Radios (Com and Nav)? > > Thomas J. > > > ----- Original Message ----- > From: "Jim Sower" > To: "Rotary motors in aircraft" > Sent: Monday, September 05, 2005 2:32 PM > Subject: [FlyRotary] Re: Another great flying day = another day of > troubleshooting > > >> In any event, I read it as 36" of something at SL and 26" at 10k'. >> Don't know how to make more of anything at 10k out of that with the >> exception of pressure ratio which doesn't mean much to us. >> Jim S. >> >> Ed Anderson wrote: >> >> > Could be, but - I don't think so, Jim. >> > >> > Most of the time if you are talking "Hg boost you are talking absolute >> > pressure. If you are talking "psi" boost then you are generally >> > talking differential pressure "gauge" pressure(absolute - ambient = >> > gauge). 66" HG of manifold pressure at sea level = (66-30) = 36 "Hg >> > boost = 36/2 = approx 13 psi boost - that's a lot of boost for our >> > application! Dave would be producing considerably more HP than an NA >> > 13B. Something on the order of more than 260 HP! Hot Dog!! >> > >> > On the other hand, if his pressure was absolute of 36" then 36-30 = >> > 6"hg of boost or approx 3 psi or so. This would give Dave approx >> > 200HP instead of the 260HP or more that a 66" Hg figure would give. >> > >> > But, perhaps Dave is producing 260HP - however, that was not the >> > impression I got. >> > >> > Ed A >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > ----- Original Message ----- From: "Jim Sower" > >> > To: "Rotary motors in aircraft" >> > Sent: Monday, September 05, 2005 1:51 PM >> > Subject: [FlyRotary] Re: Another great flying day = another day of >> > troubleshooting >> > >> > >> >> If you're defining boost as over pressure, his SL pressure was 30" >> >> ambient + 36" boost 0 66" MAP and at 10k' he's got 26" ambient + 26" >> >> boost = 54" MAP >> >> I think he's talking 36" MAP at SL and 26" MAP at 10k. >> >> Either way, MAP at altitude is a LOT less ... Jim S. >> >> >> >> >> >> Ed Anderson wrote: >> >> >> >>> Well, actually it is absolute pressure that the spark plug is >> >>> reacting to. In this example, the absolute pressure in the intake >> >>> is 1.234" HG higher at 10,000 with your 26 " boost than at sea level >> >>> with your 36" of boost.. This would contribute to an increased >> >>> pressure in the combustion chamber when it is compressed over the >> >>> sea level compression pressure. Therefore, the spark plug is facing >> >>> a tougher task at 10,000 than at Sea level (in this example). >> >>> Ed >> >>> >> >>> ----- Original Message ----- >> >>> *From:* David Leonard >> >>> *To:* Rotary motors in aircraft >> >>> >> >>> *Sent:* Monday, September 05, 2005 12:57 PM >> >>> *Subject:* [FlyRotary] Re: Another great flying day = another day >> >>> of troubleshooting >> >>> >> >>> Actually, Dave you had a higher pressure ratio (manifold >> >>> to ambient) at 10,000 feet with 26" boost than at sea >> >>> level with 36". At sea level the pressure ratio would be >> >>> 36/29.92 = 1.20. At 10,000 ft ambient pressure = 20.57 " >> >>> hg , so the pressure ratio would be 26/20.57 = 1.26. >> >>> Not >> >>> much greater, but it was higher by approx.1.23" Hg. (1.20 >> >>> -1.26 = .06 *20.57 = 1.234" Hg). >> >>> >> >>> Ed A >> >>> >> >>> Right. But what does the plug know about the ambient pressure? >> >>> I >> >>> thought that it was just the absolute density of the charge that >> >>> was contributing to SAG. >> >>> >> >>> -- Dave Leonard >> >>> Turbo Rotary RV-6 N4VY >> >>> http://members.aol.com/_ht_a/rotaryroster/index.html >> >>> http://members.aol.com/_ht_a/vp4skydoc/index.html >> >> >> >> >> >> -- >> >> Homepage: http://www.flyrotary.com/ >> >> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >> >> >> > >> > >> > >> > -- >> > Homepage: http://www.flyrotary.com/ >> > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >> > >> > >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >