X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from QMTA13.emeryville.ca.mail.comcast.net ([76.96.27.243] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3552513 for flyrotary@lancaironline.net; Thu, 19 Mar 2009 09:21:56 -0400 Received-SPF: pass receiver=logan.com; client-ip=76.96.27.243; envelope-from=wschertz@comcast.net Received: from OMTA09.emeryville.ca.mail.comcast.net ([76.96.30.20]) by QMTA13.emeryville.ca.mail.comcast.net with comcast id V1Az1b0040S2fkCAD1MLgg; Thu, 19 Mar 2009 13:21:20 +0000 Received: from WschertzPC ([71.57.77.95]) by OMTA09.emeryville.ca.mail.comcast.net with comcast id V1MK1b00Z23NHuF8V1MLAl; Thu, 19 Mar 2009 13:21:20 +0000 Message-ID: From: "Bill Schertz" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Alternator (Off topic) Date: Thu, 19 Mar 2009 08:21:16 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0039_01C9A86B.AC45EA80" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6001.18000 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6001.18049 This is a multi-part message in MIME format. ------=_NextPart_000_0039_01C9A86B.AC45EA80 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable From a logic standpoint, if you are generating current, you are doing = work -- doing work requires the expenditure of energy. Therefore when = you put a load on the alternator, it must draw power from the engine, = and increase the fuel burn -- or decrease the amount of power available = for other purposes. If you want to test this, take a small electric motor (such as from a = fan) that doesn't have lots of power. hook it up to drive the alternator = with no field current, and then turn the field current on and watch the = speed change. Bill Schertz KIS Cruiser #4045 N343BS ----- Original Message -----=20 From: Ben Baltrusaitis=20 To: Rotary motors in aircraft=20 Sent: Thursday, March 19, 2009 8:08 AM Subject: [FlyRotary] Alternator (Off topic) Since it's quiet: When I was a kid a guy at the parts store demonstrated to my Dad that = when electrical power was needed, a generator put a load on the engine. = After that, my Dad was careful not to run lights, radio, heater fan, or = other non-essentials when he was trying to get good gas mileage. I have continued that tradition, however, I have seen it stated that = electrical draw on an alternator doesn't increase the mechanical load. When low on fuel will it help to turn off electrical components not = needed for flight? Is it true of an alternator; an electrical power demand doesn't cause = an increased mechanical load? Or, does keeping headlights on during the day decrease gas mileage? Thanks! Ben ------=_NextPart_000_0039_01C9A86B.AC45EA80 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
From a logic standpoint, if you are = generating=20 current, you are doing work -- doing work requires the expenditure of = energy.=20 Therefore when you put a load on the alternator, it must draw power from = the=20 engine, and increase the fuel burn -- or decrease the amount of power = available=20 for other purposes.
 
If you want to test this, take a small = electric=20 motor (such as from a fan) that doesn't have lots of power. hook it up = to drive=20 the alternator with no field current, and then turn the field current on = and=20 watch the speed change.
Bill Schertz
KIS Cruiser #4045
N343BS
----- Original Message -----
From:=20 Ben=20 Baltrusaitis
Sent: Thursday, March 19, 2009 = 8:08=20 AM
Subject: [FlyRotary] Alternator = (Off=20 topic)

Since it's=20 quiet:
 
When I was = a kid a guy at=20 the parts store demonstrated to my Dad that when electrical power was = needed,=20 a generator put a load on the engine. After that, my Dad was careful = not to=20 run lights, radio, heater fan, or other non-essentials when he was = trying to=20 get good gas mileage.
 
I have = continued that=20 tradition, however, I have seen it stated that electrical draw on an=20 alternator doesn't increase the mechanical load.
 
When low on = fuel will it=20 help to turn off electrical components not needed for = flight?
 
Is it true = of an=20 alternator; an electrical power demand doesn't cause an increased = mechanical=20 load?
 
Or, does = keeping=20 headlights on during the day decrease gas mileage?
 
Thanks!
Ben
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