X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from web83915.mail.sp1.yahoo.com ([69.147.92.125] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with SMTP id 3554724 for flyrotary@lancaironline.net; Sat, 21 Mar 2009 09:15:05 -0400 Received-SPF: none receiver=logan.com; client-ip=69.147.92.125; envelope-from=delta11xd@att.net Received: (qmail 48224 invoked by uid 60001); 21 Mar 2009 13:14:28 -0000 Message-ID: <803379.46011.qm@web83915.mail.sp1.yahoo.com> X-YMail-OSG: xybN1esVM1kV0CB0VBJPJi9jVLUUPkeGr5SLfivhDPybTXBsrdUUzfC4qSqSvgVi_Np51Ps8cLVt8eFkHjlgqs.4m53kOa8JUP54GPNLQOMQ7F1O0clu4TCAIN8JX3IQH3.DZu57WYRfNPwvzX.BoYBxrREfbNVsipVjnLp4ZM4kxYkSKBQaql6KQZ6wh_36aNGyN15QcYmETnojZTrLNtrLF56x.V_MuFtS91jrzm70XyTfmL7TpZM9Hit17c8fNgzJ Received: from [76.243.126.69] by web83915.mail.sp1.yahoo.com via HTTP; Sat, 21 Mar 2009 06:14:28 PDT X-Mailer: YahooMailWebService/0.7.289.1 Date: Sat, 21 Mar 2009 06:14:28 -0700 (PDT) From: James Maher Reply-To: delta11xd@att.net Subject: Re: [FlyRotary] Re: Alternator (Off topic) To: Rotary motors in aircraft In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-602595304-1237641268=:46011" --0-602595304-1237641268=:46011 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable George, I'm sorry to disagree with you but you are quite mistaken in your belief ab= out the alternator function. The alternator output is mostly a function of load because of the voltage r= egulator, whose function is to keep the voltage constant with changes in load and RPM= . It performs this function by varying the field current in the alternator. If fact this is one of the many advantages of the alternator over a generat= or. The alternator's voltage output is also more or less constant regardless of= engine RPM, also due to the regulator's function. You said "The alternator charges the battery - which in turn runs the acces= sories". This is not exactly true. If the battery voltage is below that of the alter= nator output then yes the alternator will function to charge the battery, however if the= battery is fully charged then the alternator will not be charging the batt= ery but will provide the necessary power to drive any other loads connected= to the system. So reducing the electrical load on the system will indeed reduce the mechan= ical load on the engine thereby using less overall energy. Hope this clarifies your misconception. Don't feel bad, many people do not fully understand even the most simple of= electrical devices and the alternator/regulator charging system is fairly = complex. Jim --- On Sat, 3/21/09, George Lendich wrote: From: George Lendich Subject: [FlyRotary] Re: Alternator (Off topic) To: "Rotary motors in aircraft" Date: Saturday, March 21, 2009, 5:07 AM =A0 =A0Jim, To my way of thinking, the alternator is running with the engine RPM so the= power generated is relative to the RPM. This can't be changed unless you d= isconnect the alternator. =A0 The alternator charges the battery - which in turn runs the accessories. =A0 So no savings can be made unless you disconnect the alternator. =A0 So turning off things does little - it only saves the battery charge which = is being recharged whether you like it or not. Unless you put a clutch on the alternator. =A0 So no savings of HP or fuel. =A0 In some cases, systems like to have a continuous drain on the battery, like= the Harleys. That's why they run around with their lights on - so they don= 't overheat the battery.=A0 The chaps who=A0select 'lights=A0on' rather tha= n the hard wired factory systems, always have battery problems.=A0 George ( down under) =A0 It doesn't matter what is generating the electricity, a generator, alternat= or or battery it takes at least 1 HP to make 746 watts of electricity. That is the conversion factor under ideal conditions with an efficiency of = 1. Of course in the real world there are losses that reduce the amount of elec= tricity or increase the horsepower necessary. Alternators are probably more efficient than generators but then there are = losses in the rectifier and regulator circuits. The laws of physics dictate that there is no free lunch. Energy can neither be created or destroyed, only converted from one form to= another=20 (mechanical,electrical,chemical etc.), and always with losses in the conver= sion process. So turning off electrical devices will reduce the load on the engine by wha= tever amount they draw plus what ever losses are required in the conversion= . Jim --- On Thu, 3/19/09, Ben Baltrusaitis wrote: From: Ben Baltrusaitis Subject: [FlyRotary] Alternator (Off topic) To: "Rotary motors in aircraft" Date: Thursday, March 19, 2009, 9:08 AM Since it's quiet: =A0 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 th= at, my Dad was careful not to run lights, radio, heater fan, or other non-e= ssentials when he was trying to get good gas mileage. =A0 I have continued that tradition, however, I have seen it stated that electr= ical draw on an alternator doesn't increase the mechanical load. =A0 When low on fuel will it help to turn off electrical components not needed = for flight? =A0 Is it true of an alternator; an electrical power demand doesn't cause an in= creased mechanical load? =A0 Or, does keeping headlights on during the day decrease gas mileage? =A0 Thanks! Ben --0-602595304-1237641268=:46011 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
George,
I'm sorry to disagree with you but you are quite mistaken in your beli= ef about the
alternator function.
The alternator output is mostly a function of load because of the volt= age regulator,
whose function is to keep the voltage constant with changes in load an= d RPM.
It performs this function by varying the field current in the alternat= or.
If fact this is one of the many advantages of the alternator over a ge= nerator.
The alternator's voltage output is also more or less constant regardle= ss of engine RPM, also due to the regulator's function.
You said "The alternator charges the battery - which in turn runs the = accessories".
This is not exactly true. If the battery voltage is below that of the = alternator output
then yes the alternator will function to charge the battery, however i= f the battery is fully charged then the alternator will not be charging the= battery but will provide the necessary power to drive any other loads conn= ected to the system.
So reducing the electrical load on the system will indeed reduce the m= echanical load on
the engine thereby using less overall energy.
Hope this clarifies your misconception.
Don't feel bad, many people do not fully understand even the most simp= le of electrical devices and the alternator/regulator charging system is fa= irly complex.
Jim

--- On Sat, 3/21/09, George Lendich <= lendich@optusnet.com.au> wrote:
From: George Lendich <lendich@optusnet.com.au><= BR>Subject: [FlyRotary] Re: Alternator (Off topic)
To: "Rotary motors in= aircraft" <flyrotary@lancaironline.net>
Date: Saturday, March 21,= 2009, 5:07 AM

 
 Jim,
To my way of thinking, the alternator is ru= nning with the engine RPM so the power generated is relative to the RPM. Th= is can't be changed unless you disconnect the alternator.
 
The alternator charges the battery - which = in turn runs the accessories.
 
So no savings can be made unless you discon= nect the alternator.
 
So turning off things does little - it only= saves the battery charge which is being recharged whether you like it or n= ot.
Unless you put a clutch on the alternator.<= /DIV>
 
So no savings of HP or fuel.
 
In some cases, systems like to have a conti= nuous drain on the battery, like the Harleys. That's why they run around wi= th their lights on - so they don't overheat the battery.  The chaps wh= o select 'lights on' rather than the hard wired factory systems, = always have battery problems. 
George ( down under)
 
It doesn't matter what is generating the electricity, a generator, alt= ernator or battery it takes at least 1 HP to make 746 watts of electricity.=
That is the conversion factor under ideal conditions with an efficienc= y of 1.
Of course in the real world there are losses that reduce the amount of= electricity or increase the horsepower necessary.
Alternators are probably more efficient than generators but then there= are losses in the rectifier and regulator circuits.
The laws of physics dictate that there is no free lunch.
Energy can neither be created or destroyed, only converted from one fo= rm to another
(mechanical,electrical,chemical etc.), and always with losses in the c= onversion process.
So turning off electrical devices will reduce the load on the engine b= y whatever amount they draw plus what ever losses are required in the conve= rsion.
Jim

--- On Thu, 3/19/09, Ben Baltrusaitis &l= t;expressben@verizon.net> wrote:
From: Ben Baltrusaitis <expressben@verizon.net>=
Subject: [FlyRotary] Alternator (Off topic)
To: "Rotary motors in ai= rcraft" <flyrotary@lancaironline.net>
Date: Thursday, March 19, 20= 09, 9:08 AM

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 c= areful not to run lights, radio, heater fan, or other non-essentials when h= e 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 mechanic= al load?
 
Or, does keeping= headlights on during the day decrease gas mileage?
 
Thanks!
Ben
=
--0-602595304-1237641268=:46011--