Return-Path: Received: from relay02.roc.ny.frontiernet.net ([66.133.182.165] verified) by logan.com (CommuniGate Pro SMTP 4.3c2) with ESMTP id 758217 for flyrotary@lancaironline.net; Thu, 24 Feb 2005 18:43:43 -0500 Received-SPF: pass receiver=logan.com; client-ip=66.133.182.165; envelope-from=canarder@frontiernet.net Received: from filter04.roc.ny.frontiernet.net (filter04.roc.ny.frontiernet.net [66.133.183.71]) by relay02.roc.ny.frontiernet.net (Postfix) with ESMTP id 706883701F6 for ; Thu, 24 Feb 2005 23:42:56 +0000 (UTC) Received: from relay02.roc.ny.frontiernet.net ([66.133.182.165]) by filter04.roc.ny.frontiernet.net (filter04.roc.ny.frontiernet.net [66.133.183.71]) (amavisd-new, port 10024) with LMTP id 17314-09-59 for ; Thu, 24 Feb 2005 23:42:55 +0000 (UTC) Received: from [127.0.0.1] (67-137-89-39.dsl2.cok.tn.frontiernet.net [67.137.89.39]) by relay02.roc.ny.frontiernet.net (Postfix) with ESMTP id C9C7A370240 for ; Thu, 24 Feb 2005 23:42:54 +0000 (UTC) Message-ID: <421E6681.1080305@frontiernet.net> Date: Thu, 24 Feb 2005 17:42:57 -0600 From: Jim Sower User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040514 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] PM Alternators Disadvantages References: In-Reply-To: Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit X-Antivirus: avast! (VPS 0508-2, 02/23/2005), Outbound message X-Antivirus-Status: Clean X-Virus-Scanned: by amavisd-new-20040701 (2.0) at filter04.roc.ny.frontiernet.net <... switched reluctance integrated starter/alternator ...>
What might that be? How might one work? I've flown turbines with starter/generators, and they were an abomination.
I've no idea what a starter/alternator would look like or how big/heavy it would be ... Jim S.

Fred Osborn wrote:

Sorry, I forgot to change the subject when I sent this before so most guys just passed
it by. FWIW.

>Richard Sohn wrote:

>We should not overlook the disadvantage of PM alternators. At higher operating speed,
>the not used output will have to be dissipated. This is the main reason why automotive
>alternators are regulated by the excitation system.

Another disadvantage of PM devices is the hystersis losses in the stator laminations.
At 6000 rpm continuous you could end up with a very warm stator. Actually, the ultimate
answer to all this will probably be a switched reluctance integrated starter/alternator.
Used with an EWP - no belts at all.

Fred Osborn

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