Return-Path: Received: from r1.name2host.com ([64.35.113.48] verified) by logan.com (CommuniGate Pro SMTP 4.2b1) with SMTP id 3152061 for flyrotary@lancaironline.net; Thu, 08 Apr 2004 02:42:22 -0400 Received: (qmail 56168 invoked from network); 8 Apr 2004 06:42:20 -0000 Received: from adsl-216-101-149-124.dsl.snfc21.pacbell.net (HELO rapunzel) (fly@bewersdorff.com@216.101.149.124) by r1.name2host.com with SMTP; 8 Apr 2004 06:42:20 -0000 From: "Marko Bewersdorff" To: "Rotary motors in aircraft" Subject: RE: [FlyRotary] HP and turbos / altitude Date: Wed, 7 Apr 2004 23:39:00 -0700 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 assuming that you tune the prop for the desired altitude and the rpms stay up at the rated level: you loose roughly 1/30 of the maximum power per 1000 feet of altitude. or more precisely at 10,000' there is a pressure of about 0.7 atmospheres (0.696 bar) -> so you can achieve roundabout 0.7 times your max sea level hp. Pull out any old airplane handbook and check the power chart, some charts allow rated power of 75% up to e.g. 5000 feet, because the old Lycomings and Continentals are not designed to withstand 100% power for more than a few minutes. So if you want to limit maximum manifold pressure (as to not overload your con-rods ;-)) to lets say 27" then you can go to about 4000 to 5000 feet before you run fully open on the throttle and only when you're going higher than that will you see a power reduction of 1/30 max hp per 1000' If you listen to the old Rutan reasoning you can keep 75% power to even higher levels by simply revving the engine higher. With a rotary there is a lot of leeway. Marko > -----Original Message----- > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On > Behalf Of Chad Robinson > Sent: Wednesday, April 07, 2004 4:38 PM > To: Rotary motors in aircraft > Subject: [FlyRotary] HP and turbos / altitude > > > What kind of losses can I expect in horsepower based on altitude? > I'd be doing > most of my flying around airports that are between 100-1000 MSL > so I don't > exactly need a turbo to help get off the ground. However, since > this is a Cozy > and it climbs quickly, it wouldn't be unusual to cruise between > 8000-10000'. > I'm debating whether a turbo would be beneficial, and if so how much. > > Regards, > Chad > > >> Homepage: http://www.flyrotary.com/ > >> Archive: http://lancaironline.net/lists/flyrotary/List.html >