X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from smtp1.av-mx.com ([137.118.16.57] verified) by logan.com (CommuniGate Pro SMTP 5.2.3) with ESMTP id 2952176 for flyrotary@lancaironline.net; Tue, 03 Jun 2008 19:39:46 -0400 Received-SPF: pass receiver=logan.com; client-ip=137.118.16.57; envelope-from=res12@fairpoint.net Received: from main (dflo-67-158-146-148.gtcom.net [67.158.146.148]) (Authenticated sender: res12@fairpoint.net) by smtp1.av-mx.com (Postfix) with ESMTP id 5B63329065A for ; Tue, 3 Jun 2008 19:39:08 -0400 (EDT) Message-ID: <003b01c8c5d3$080c3c10$0202a8c0@main> From: "Richard Sohn" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] combined starter alternator Date: Tue, 3 Jun 2008 18:39:12 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0038_01C8C5A9.1E559810" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 This is a multi-part message in MIME format. ------=_NextPart_000_0038_01C8C5A9.1E559810 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I do not have the direct answer to your question, it would be too long, = however, the first two cars I owned had a starter-generator set up. The = first one was a 700cc DKW model 1938 and the other one was a 1949 DKW, = sort of a post war successor. Both were two cylinder two strokes. It had = an outside armature on the crank shaft with a set of brushes on a disc = type commutation. Once the engine was running, it worked as a generator = through a separate exciter winding in the stator, controlled through the = voltage regulator. The windings on the armature were used as starter and = generator.=20 There was frequently a problem with cranking, because it was loosing = torque with the slightest voltage drop in the system. I do not believe that such a system could be built competing, at least = weight wise, with a gear reduction starter motor. As a mater of = principle, a high torque electric motor is always heavier than a high = speed motor producing the same torque through gear reduction. And, of = course, at the same hp. FWIW. Richard Sohn N2071U ----- Original Message -----=20 From: George Lendich=20 To: Rotary motors in aircraft=20 Sent: Tuesday, June 03, 2008 5:28 PM Subject: [FlyRotary] combined starter alternator Directed to the electronic wiz types. This is not a development issue but an educational issue as I would = like to understand the issues associated with developing a starter = alternator. Personally I believe a combined starter, alternator, flywheel, damper, = timing wheel and pick up would be a great advantage (we live to dream). Some systems use the combined starter alternator attached to the gear = box shaft just, between the motor and the gearbox fluid damper. =20 I believe from talking to Bill Jepson that getting sufficient power = from the current winding used is problematic but that there had been = major improvements in this field. Also reading a little on the Internet = ( if I understand it correctly) an alternator is AC ( alternating = current) and a generator is DC. As Batteries are DC and starters are DC, = we would need to use a DC generator winding in the starter generator = (someone tell if I'm wrong here). Of course nothing is as simple as this, so I'm keen to understand the = issues associated - from anyone out there in the electronics world!? George (down under). -------------------------------------------------------------------------= ----- No virus found in this incoming message. Checked by AVG.=20 Version: 8.0.100 / Virus Database: 269.24.6/1481 - Release Date: = 6/3/2008 7:31 PM ------=_NextPart_000_0038_01C8C5A9.1E559810 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I do not have the direct answer to your = question,=20 it would be too long, however, the first two cars I owned had a=20 starter-generator set up. The first one was a 700cc DKW model 1938 and = the other=20 one was a 1949 DKW, sort of a post war successor. Both were two cylinder = two=20 strokes. It had an outside armature on the crank shaft with a set of = brushes on=20 a disc type commutation. Once the engine was running, it worked as a = generator=20 through a separate exciter winding in the stator, controlled through the = voltage=20 regulator. The windings on the armature were used as starter and = generator.=20
There was frequently a problem with = cranking,=20 because it was loosing torque with the slightest voltage drop = in the=20 system.
I do not believe that such a system = could be built=20 competing, at least weight wise, with a gear reduction starter motor. As = a mater=20 of principle, a high torque electric motor is always heavier than a high = speed=20 motor producing the same torque through gear reduction. And, of course, = at the=20 same hp.
 
FWIW.
 
Richard Sohn
N2071U
----- Original Message -----
From:=20 George=20 Lendich
Sent: Tuesday, June 03, 2008 = 5:28=20 PM
Subject: [FlyRotary] combined = starter=20 alternator

Directed to the electronic wiz=20 types.
 
This is not a development issue but = an=20 educational issue as I = would like to=20 understand the issues associated with developing a starter=20 alternator.
 
Personally I believe a combined = starter,=20 alternator, flywheel, damper, timing wheel and pick up would be a = great=20 advantage (we live to dream).
Some systems use the combined starter = alternator=20 attached to the gear box shaft just, between the motor and the gearbox = fluid=20 damper. 
 
I believe from talking to Bill Jepson = that=20 getting sufficient power from the current winding used is = problematic but=20 that there had been major improvements in this field. Also reading a = little on=20 the Internet ( if I understand it correctly) an alternator is AC ( = alternating=20 current) and a generator is DC. As Batteries are DC and starters are = DC, we=20 would need to use a DC generator winding in the starter generator = (someone=20 tell if I'm wrong here).
 
Of course nothing is as simple as = this, so I'm=20 keen to understand the issues associated - from anyone out there in = the=20 electronics world!?
George (down under).


No virus found in this incoming message.
Checked by AVG. =
Version: 8.0.100 / Virus Database: 269.24.6/1481 - Release Date: = 6/3/2008=20 7:31 PM
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