Return-Path: Sender: (Marvin Kaye) To: lml Date: Mon, 29 Jul 2002 22:37:20 -0400 Message-ID: X-Original-Return-Path: Received: from fire.phys.cmu.edu ([128.2.26.129] verified) by logan.com (CommuniGate Pro SMTP 4.0b5) with ESMTP id 1652146 for lml@lancaironline.net; Mon, 29 Jul 2002 22:28:05 -0400 Received: from localhost (jbp@localhost) by fire.phys.cmu.edu (8.11.6/8.11.6) with ESMTP id g6U2S6h06493 for ; Mon, 29 Jul 2002 22:28:06 -0400 X-Original-Date: Mon, 29 Jul 2002 22:28:05 -0400 (EDT) From: Jeffery Peterson X-Original-To: lancair mail list Subject: turbine butterfly valve X-Original-Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII lml: I saw the ATP turbo-prop engine at Oshkosk. Impressive. 200 HP or 300HP (same compact size) and weighs just 200 lbs. Neat electronic fuel injection system. I asked about fuel economy, pariticularly at low power settings and got this answer: A turbine must spin fast , and once it is spinning fast it always pumps plenty of air volume through. Then you have to add some fuel to all that air to keep the fire going. Cant let the mixture get too lean or you get no flame at all. So there is a minimum fuel flow, which is largest at low altitudes, So here is my question... Can you put a butterfly valve in the intake? Then if you need endurance (say to hold in IFR) you choke off airflow, the turbine sucks a vacuum and the automatic injection system will turn down the fuel flow. -Jeff Peterson LNC2 N273CK ps the 200 HP ATP engine supposedly idles at low altitudes at 7 GPH.