X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 23 Sep 2005 22:26:54 -0400 Message-ID: X-Original-Return-Path: Received: from smtpauth01.mail.atl.earthlink.net ([209.86.89.61] verified) by logan.com (CommuniGate Pro SMTP 5.0c2) with ESMTP id 731549 for lml@lancaironline.net; Fri, 23 Sep 2005 22:01:56 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.61; envelope-from=lancair403@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=YT+LBl9paPmfuH/dxaw1hP3tEAniUSHFtjrKZSxw4D9dPYJVVfEjvvw6qce/ZxD6; h=Received:Message-ID:X-Priority:Reply-To:X-Mailer:From:To:Subject:Date:MIME-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; Received: from [4.153.188.129] (helo=earthlink.net) by smtpauth01.mail.atl.earthlink.net with asmtp (Exim 4.34) id 1EIzLj-0000qU-S6 for lml@lancaironline.net; Fri, 23 Sep 2005 22:01:12 -0400 X-Original-Message-ID: <410-2200596242110579@earthlink.net> X-Priority: 3 Reply-To: lancair403@earthlink.net X-Mailer: EarthLink MailBox 2005.1.47.0 (Windows) From: "william rumburg" X-Original-To: "Lancair Mailing List" Subject: Alternator RPM X-Original-Date: Fri, 23 Sep 2005 22:01:10 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_84815C5ABAF209EF376268C8" X-ELNK-Trace: 27715828ce90b1c1624ea3431430cac6239a348a220c260988d379c405c27d448576d0051dad94ae350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 4.153.188.129 ------=_NextPart_84815C5ABAF209EF376268C8 Content-type: text/plain; charset=US-ASCII Alternator rpm = engine rpm X (engine pulley diameter/alternator pulley diameter). My Lycoming has the 7.5" (small) pulley and my alternator has a 2.75" pulley, which I believe to be typical. This results in alternator speeds in the 7,000 rpm range during cruise, which I believe to be excessive. A 4" diameter pulley is available for my alternator, which would reduce it's speed to the 4,000 rpm range and, I believe, produce full-rated output. I spoke with Mark Landoll who told me that alternators typically require a minimum of 1,000 rpm to produce a stable output, but he didn't know what rpm is usually required to produce full-rated output. I believe it to be in the 4,000 rpm range. He did agree that, while alternator bearings seem to hold up well to high speeds, lower speeds would produce less stress and vibration. Is anyone on the LML knowledgeable of the alternator speed typically required to produce full rated output? Bill Rumburg N403WR (Sonic bOOm) ------=_NextPart_84815C5ABAF209EF376268C8 Content-Type: text/html; charset=US-ASCII

Alternator rpm = engine rpm X (engine pulley diameter/alternator pulley diameter).

My Lycoming has the 7.5" (small) pulley and my alternator has a 2.75" pulley, which I believe to be typical. This results in alternator speeds in the 7,000 rpm range during cruise, which I believe to be excessive. A 4" diameter pulley is available for my alternator, which would reduce it's speed to the 4,000 rpm range and, I believe, produce full-rated output.

I spoke with Mark Landoll who told me that alternators typically require a minimum of 1,000 rpm to produce a stable output, but he didn't know what rpm is usually required to produce full-rated output. I believe it to be in the 4,000 rpm range. He did agree that, while alternator bearings seem to hold up well to high speeds, lower speeds would produce less stress and vibration.

Is anyone on the LML knowledgeable of the alternator speed typically required to produce full rated output?

Bill Rumburg

N403WR (Sonic bOOm)

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