X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 26 Sep 2005 23:19:52 -0400 Message-ID: X-Original-Return-Path: Received: from smtpauth07.mail.atl.earthlink.net ([209.86.89.67] verified) by logan.com (CommuniGate Pro SMTP 5.0c2) with ESMTP id 734178 for lml@lancaironline.net; Mon, 26 Sep 2005 20:55:12 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.67; envelope-from=lancair403@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=ZOeWzCMB7zIzPtRlmACVljTH57o9uqDt873MpBYCiPl2h77+rZPfVsYg2Ojbq+m3; 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 [4.153.190.29] (helo=earthlink.net) by smtpauth07.mail.atl.earthlink.net with asmtp (Exim 4.34) id 1EK3jn-0006l5-1j for lml@lancaironline.net; Mon, 26 Sep 2005 20:54:28 -0400 X-Original-Message-ID: <410-22005922705423171@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: RE: Alternator RPM X-Original-Date: Mon, 26 Sep 2005 20:54:23 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_84815C5ABAF209EF376268C8" X-ELNK-Trace: 27715828ce90b1c1624ea3431430cac6239a348a220c260993bee4c5a2859b32c13d00f922635f68a2d4e88014a4647c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 4.153.190.29 ------=_NextPart_84815C5ABAF209EF376268C8 Content-type: text/plain; charset=US-ASCII Is anyone on the LML knowledgeable of the alternator speed typically required to produce full rated output? Try this question on the Matronics sponsored Aeroelectric Mail List. See www.matronics.com to sign up. Mark- I did as you suggested and sent my question of alternator speed vs. output to the Aeroelectric Mail List and received the following response from Bob Nuckols: (my estimate that 4,000 rpm would produce full-rated current wasn't far off....) Here's a typical output current curve for an automotive alternator. The population of mfgrs and part numbers will "wiggle" a bit from this curve but it's probably plus or minus 10 percent for the whole lot. http://www.aeroelectric.com/Pictures/80A_OutCurve.gif It depends on what you want . . . and what the tradeoffs are. If you'd like to have good output at ramp idle and taxi speeds (most folk really like the low speed capability in both cars and airplanes), then leave the pulley small. If you're worried about bearing and brush life, know that B&C has been selling the L40/L60 series machines for about 15 years with thousands of units in service. The first wearout in B&C history arrived back in Newton about a year ago . . . needed brushes . . . after 2200 hours in service. These alternators run nicely at over 10,000 rpm in cruise with no evidence of having "over stressed" anything due to the high speeds. If it were my airplane, I'd leave the small pulley on . . . especially if your ring gear pulley is smaller than most . . . you've already taken a hit on pre-flight output capability. Bob . . . ------=_NextPart_84815C5ABAF209EF376268C8 Content-Type: text/html; charset=US-ASCII
Is anyone on the LML knowledgeable of the alternator speed typically required to produce full rated output?
 
Try this question on the Matronics sponsored Aeroelectric Mail List. See www.matronics.com to sign up.
 
Mark-
 
I did as you suggested and sent my question of alternator speed vs. output to the Aeroelectric Mail List and received the following response from Bob Nuckols: (my estimate that 4,000 rpm would produce full-rated current wasn't far off....)
 
Here's a typical output current curve for an
automotive alternator. The population of
mfgrs and part numbers will "wiggle" a bit
from this curve but it's probably plus or minus
10 percent for the whole lot.
 
 
It depends on what you want . . . and what the tradeoffs
are. If you'd like to have good output at ramp idle and
taxi speeds (most folk really like the low speed
capability in both cars and airplanes), then leave the
pulley small. If you're worried about bearing and brush
life, know that B&C has been selling the L40/L60 series
machines for about 15 years with thousands of units in
service. The first wearout in B&C history arrived back
in Newton about a year ago . . . needed brushes . . .
after 2200 hours in service. These alternators run nicely
at over 10,000 rpm in cruise with no evidence of having
"over stressed" anything due to the high speeds.
 
If it were my airplane, I'd leave the small pulley
on . . . especially if your ring gear pulley is smaller
than most . . . you've already taken a hit on pre-flight
output capability.
 
Bob . . .
 
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