Return-Path: Received: from mail.rdc3.on.home.com ([24.2.9.68]) by truman.olsusa.com (Post.Office MTA v3.5.1 release 219 ID# 0-52269U2500L250S0V35) with ESMTP id com for ; Mon, 20 Dec 1999 18:41:40 -0500 Received: from cr754193a ([24.112.21.90]) by mail.rdc3.on.home.com (InterMail v4.01.01.02 201-229-111-106) with SMTP id <19991220234421.ICTN7552.mail.rdc3.on.home.com@cr754193a> for ; Mon, 20 Dec 1999 15:44:21 -0800 Reply-To: From: "Neil K" To: Subject: RE: Props...Fixed/Variable Pitch...Pros/Cons Date: Mon, 20 Dec 1999 18:47:26 -0500 Message-ID: Importance: Normal In-Reply-To: <0.470e370f.258bc573@aol.com> X-Mailing-List: lancair.list@olsusa.com Mime-Version: 1.0 <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> Hank, I have the first version of the IVO Magnum (3 blade) which is suppose to have an adjustable pitch from 30" to 90", on my L-235. First let me say the prop is quite well made and the factory support has been pretty good. I runs very smooth as well and looks pretty good. Unfortunately, it doesn't work very well on high speed aircraft. I found that take off and climb performance was great but cruise was anemic at best no matter what pitch setting I selected. T-O and climb was better as the pitch was reduced but that wasn't an issue at max pitch settings. What was really confusing was the engine was loaded (high MF pressures) at high cruise power setting but the speed wasn't there. I found I pretty much clapped out at 190mph. A good friend of mine tried the prop on his long-eze with the same results. It took me a while to figure out what was wrong but with a propeller protractor and the angle vs. pitch formula it became pretty clear. The inner portion of the blade does not twist when pitch is added and it's normal pitch is too shallow regardless of pitch setting. Here are the numbers I measured. At the maximum pitch setting; Station Blade Pitch Speed @ Speed @ in inches Angle in inches 2700 2400 3" 6" 9" 30 32 83 74 12" 30.5 44 113 100 15" 36 68 175 155 18" 35 79 202 179 21" 29.5 74 190 169 24" 27.5 78 200 178 27" 25.7 81 208 185 30" 24.5 85 219 195 At 30" diameter and less the blades are working against forward motion. You might also notice that I was not able to measure 90" of pitch anywhere along the blade. Neil >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LML website: http://www.olsusa.com/Users/Mkaye/maillist.html Builders' Bookstore: http://www.buildersbooks.com/lancair >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>