Return-Path: Received: from out002.verizon.net ([206.46.170.141] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 567056 for flyrotary@lancaironline.net; Tue, 14 Dec 2004 09:29:10 -0500 Received-SPF: pass receiver=logan.com; client-ip=206.46.170.141; envelope-from=finn.lassen@verizon.net Received: from verizon.net ([4.12.145.173]) by out002.verizon.net (InterMail vM.5.01.06.06 201-253-122-130-106-20030910) with ESMTP id <20041214142844.ZANB12052.out002.verizon.net@verizon.net> for ; Tue, 14 Dec 2004 08:28:44 -0600 Message-ID: <41BEF899.5090002@verizon.net> Date: Tue, 14 Dec 2004 09:28:41 -0500 From: Finn Lassen User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax; PROMO) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Dynamic balance References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------020709000901030906080906" X-Authentication-Info: Submitted using SMTP AUTH at out002.verizon.net from [4.12.145.173] at Tue, 14 Dec 2004 08:28:44 -0600 This is a multi-part message in MIME format. --------------020709000901030906080906 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Early on I hooked up an accelometer to an oscilloscope. It sure was a mess - very hard to discern any fundamental frequency. My conclusiion was that I needed a prop pickup to trigger the scope and perhaps a notch filter so I would only be looking at the fundamental frequency of the prop. I never did get back and try it. Finn Perry Mick wrote: > > I've used the balancer many times before with no problem on > direct-drive. I think it's getting confused by harmonics or beat > frequencies between the engine and redrive. For a first step it > usually asks for 20-30 grams at a certain radial position, the fender > washer is about right. This is on the prop bolt circle (4.75 inches?), > not out at spinner diameters. It will just be moved around the six > locations temporarily to see if the vibration gets worse or better. > > Perry > > --------------020709000901030906080906 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit Early on I hooked up an accelometer to an oscilloscope. It sure was a mess - very hard to discern any fundamental frequency. My conclusiion was that I needed a prop pickup to trigger the scope and perhaps a notch filter so I would only be looking at the fundamental frequency of the prop. I never did get back and try it.

Finn

Perry Mick wrote:

I've used the balancer many times before with no problem on direct-drive. I think it's getting confused by harmonics or beat frequencies between the engine and redrive. For a first step it usually asks for 20-30 grams at a certain radial position, the fender washer is about right. This is on the prop bolt circle (4.75 inches?), not out at spinner diameters. It will just be moved around the six locations temporarily to see if the vibration gets worse or better.

Perry


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