Return-Path: Received: from ycc.com ([204.155.150.41]) by ns1.olsusa.com (Post.Office MTA v3.5.3 release 223 ID# 0-64832U3500L350S0V35) with SMTP id com for ; Mon, 8 May 2000 23:14:23 -0400 Received: from YccPrimaryDomain-Message_Server by ycc.com with Novell_GroupWise; Mon, 08 May 2000 22:23:39 -0500 Message-Id: Date: Mon, 08 May 2000 22:23:36 -0500 From: "Bill Gradwohl" To: Subject: Re: More on engines Mime-Version: 1.0 Content-Disposition: inline X-Mailing-List: lancair.list@olsusa.com <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> Fred - it sounds like you've done some homework over the years to come up with that dissertation. Very interesting write up. I don't know if you're theorizing about a possible V8 engine design, or if you're contemplating engines in existence, or soon to be made available. Conspicuous by its absence in your email is any mention of the PSRU's commonly found on engines resembling an auto engine, or should I more succinctly say not resembling a typical aircraft engine. Even engines that have been scratch built for aircraft use that resemble an auto engine in appearance usually have a PSRU to reduce as well as relocate the source of rotation for the prop. The inverted V8 that does not use a PSRU that we're not supposed to mention any longer due to lack of follow up documentation is the only example that I'm aware of that is the exception. A PSRU adds considerable weight, complexity, and overall length to a typical V8 engine. I believe it's accurate to say that PSRU's have been problematic in the past due to their short shafts and high bearing loads during maneuvers, and also due to vibration. I remember reading that very wide rubber belts as well as snowmobile chains have been used to help limit the vibration transmitted between the engine and the PSRU. The PSRU consumes quite a bit of internal volume, and is inconveniently located precisely where one would like to put a radiator. Given the existing cowling, how do you envision cramming a radiator in the engine compartment large enough to cool the engine at altitude? If its outside the engine compartment, then drag would surely be a penalty which would call for a bigger engine and more horsepower to compensate, limiting any fuel savings. If you're theorizing about what might be, then I also wonder why no one has specifically designed a V6 for aircraft use that due to the efficiencies you mentioned could be run at higher horsepower levels to rival the Continentals and Lycomings with increased reliability and more modern systems for fuel injection, spark, etc. That engine could possibly put the radiator under the cowling since its more compact than the V8's even though it likely will also need a PSRU. All the purpose built V8's that I'm aware of are relatively large because they've tried to increase the power output significantly above the typical TSIO 550. A more modest V6, or even a more diminutive V8 might be better competition for the existing aircraft engines, and might allow the radiator and associated plumbing and weight to remain inside the existing cowl envelope. Although Lancair owners in general and IV-P owners specifically want speed, I for one would be perfectly happy with a purpose built V6 or small V8 that matches the speed characteristics of the TSIO 550. That's plenty fast for me if I can get reliability and possibly lower operating costs. Fred, please put your considerable writing talents to use telling us about diesel engines, as I think that's where someone will eventually hit a gold mine. Bill Gradwohl IV-P Builder >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LML website: http://www.olsusa.com/Users/Mkaye/maillist.html Builders' Bookstore: http://www.buildersbooks.com/lancair Please send your photos and drawings to marvkaye@olsusa.com. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>