Return-Path: Received: from pop3.olsusa.com ([63.150.212.2] verified) by logan.com (CommuniGate Pro SMTP 3.5.6) with ESMTP id 1121401 for rob@logan.com; Sun, 24 Feb 2002 18:57:24 -0500 Received: from smtp014.mail.yahoo.com ([216.136.173.58]) by pop3.olsusa.com (Post.Office MTA v3.5.3 release 223 ID# 0-71866U8000L800S0V35) with SMTP id com for ; Sun, 24 Feb 2002 14:59:12 -0500 Received: from djmolny (AUTH LOGIN) at 12-252-152-30.client.attbi.com (HELO c1360498b) (djmolny@12.252.152.30) by smtp.mail.vip.sc5.yahoo.com with SMTP; 24 Feb 2002 20:01:46 -0000 Reply-To: Reply-To: lancair.list@olsusa.com From: "DJ Molny" To: Subject: RE: LIV-P Prop/Engine Combos related to early fatigue? Date: Sun, 24 Feb 2002 13:01:22 -0700 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Importance: Normal In-Reply-To: <002101c1bc6b$e490c520$0201a8c0@net.Bellsouth.net> X-Mailing-List: lancair.list@olsusa.com <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> Douglas - Not a direct answer to your question, but... Aerobatic performers and weekend enthusiasts like myself tend to favor composite props mainly because they induce far less torsional loads on the crankshaft during gyroscopic maneuvers. For instance, a Pitts with a metal prop doing a snap rolls has to withstand 55,000 in-lb at the crank! Yowch. Having flown a Pitts S-2B with both 2-blade metal Hartzell and 3-blade composite MT, I will say that the flywheel effect is markedly less with the MT. And I felt that the engine ran smoother with the MT, because those blades (thin glass covering over wood core) absorb vibration quite well. I also flew a 3-blade Hartzell composite (Kevlar!) and found the vibration level to be somewhere between the metal Hartzell and the glass/wood MT. And yes, aerobatic engines have lower TBO's. I think that's due to a combination of frequent and rapid power changes, generally high power settings, torsional loads, and momentary oil starvation during maneuvers. Vibration is typically the least of our worries. :-) Regards, DJ Molny Extra 300/L, N133DF Lancair someday, maybe >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LML website: http://members.olsusa.com/mkaye/maillist.html LML Builders' Bookstore: http://www.buildersbooks.com/lancair Please remember that purchases from the Builders' Bookstore assist with the management of the LML. Please send your photos and drawings to marvkaye@olsusa.com. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>