Return-Path: Received: from wb2-a.mail.utexas.edu ([128.83.126.136] verified) by logan.com (CommuniGate Pro SMTP 4.2b3) with ESMTP-TLS id 3228748 for flyrotary@lancaironline.net; Wed, 12 May 2004 11:14:36 -0400 Received: (qmail 29959 invoked from network); 12 May 2004 15:14:35 -0000 Received: from dhcp-191-101.per.utexas.edu (HELO benefits3.mail.utexas.edu) (146.6.191.101) by wb2.mail.utexas.edu with RC4-SHA encrypted SMTP; 12 May 2004 15:14:35 -0000 Message-Id: <5.1.1.5.2.20040512100739.02b68e58@localhost> X-Sender: msteitle@mail.utexas.edu@localhost X-Mailer: QUALCOMM Windows Eudora Version 5.1.1 Date: Wed, 12 May 2004 10:13:46 -0500 To: "Rotary motors in aircraft" From: Mark Steitle Subject: Re: [FlyRotary] Rusty's 3rd intake - PP variable intake In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Ken, This is directed at the engineer types in the group... What I was thinking is would you actually need two separate runners, or could you add a resonance chamber to the shorter intake so as to fool it into thinking it was longer than it actually was? A butterfly valve could open and close the chamber. I got this idea from studying the intake on my LS1 Chevy pickup. It uses a resonance chamber in the intake between the air filter and the TB. Not sure why, but though this same idea may work here too. Mark S. (back to lurking) At 02:19 AM 5/12/2004 +0000, you wrote: >Rusty, >I just gotta ask - why don't you just copy Tracy's intake and be done with >it??? > >I calculated intake runner length for a PP engine last year but >unfortunately I don't have the results here in sunny Florida (playing >tourist, much to the chagrin of the natives). So these numbers mean >nothing, but I THINK that I calculated that a 16" runner length for 7400 >RPM (2.85 redrive) and 24" for either 5600 or 6000 RPM. The problem we >are all seeing here (and Ed is addressing) is that we need several >distinct lengths to correspond to the differing engine RPM. Since I am >dealing with a PP engine I am sorta on my on but Ed's work has been a >great help because his formulas will allow you to calculate the length for >a given RPM. My thought on the solution to this is a little different >from Ed's infinitely variable length but simpler to build - since a PP >engine only needs 2 runners (1 per rotor) the idea is to have a short >runner (16") for high rpm and a long runner (24") for cruise; a butterfly >valve will be used to switch between the two. I hope that this setup will >not need to be automated - set the butterfly to 'long' for takeoff, climb >and low altitude cruise and 'short' for WFO and high altitude cruise. > >Ken P. > > > >> Homepage: http://www.flyrotary.com/ > >> Archive: http://lancaironline.net/lists/flyrotary/List.html