Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Thu, 23 Dec 2004 19:04:29 -0500 Message-ID: X-Original-Return-Path: Received: from imo-d06.mx.aol.com ([205.188.157.38] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 578586 for lml@lancaironline.net; Thu, 23 Dec 2004 18:36:34 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.157.38; envelope-from=REHBINC@aol.com Received: from REHBINC@aol.com by imo-d06.mx.aol.com (mail_out_v37_r3.8.) id q.c1.4e5c62cd (4418) for ; Thu, 23 Dec 2004 18:36:04 -0500 (EST) From: REHBINC@aol.com X-Original-Message-ID: X-Original-Date: Thu, 23 Dec 2004 18:36:03 EST Subject: Re: [LML] Re: Electrical ignition and airspeed X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1103844963" X-Mailer: 9.0 for Windows sub 5116 -------------------------------1103844963 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 12/23/2004 5:28:56 PM Eastern Standard Time, Sky2high@aol.com writes: Probably the best way to determine what power to use for the non varying friction is to drive an exemplar engine with an electric motor and measure the electric power it draws. Anyone have an engine laying around they want to experiment with? Set it up with WOP and whatever rpm you what to know the answer for. Is that with or without the plugs in? How much non-friction power does compression take? Do you disconnect the accessories? Scott, You would want the engine in as close to flight configuration as possible. Plugs in, magneto on but attached to a spark gap outside the engine, full oil, and all driven accessories and vacuum pump with loads connected. Ideally it should be at operating temperature the fuel should be on too, but this would not be so good for the engine. The alternator field could be disconnected as its output could be easily determined on the plane you actually fly. Otherwise you would want to power up all electrical accessories used in flight. This would get you very close to the 0-power losses at whatever RPM you conducted the test. The only problem I see is that the working fluid would be much too dense. I don't think this error would be very big but if you wanted to eliminate it you could perform the test in a hypobaric chamber or feed the engine some gas with ground level thermodynamic properties equivalent to those of air at 1-3 inHg or what ever density you expect the 0-power MAP to be. How accurate do you want to be? The compression loss depends on the effective valve timing and the cylinder heat transfer rate. This test would account for it, what ever value it might have. Rob -------------------------------1103844963 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 12/23/2004 5:28:56 PM Eastern Standard Time, Sky2hig= h@aol.com writes:

Probably the best way to determine what power to use for the non varyin= g friction is to drive an exemplar engine with an electric motor and measure= the electric power it draws. Anyone have an engine laying around they want=20= to experiment with? Set it up with WOP and whatever rpm you what to know the= answer for.

Is that with or without the plugs in? = How much non-friction power does compression take? Do you disconnect=20= the accessories?

Scott,

You would want the engine in as close to flight configuration as possib= le. Plugs in, magneto on but attached to a spark gap outside the engine, ful= l oil, and all driven accessories and vacuum pump with loads connected.= Ideally it should be at operating temperature the fuel should be on too, bu= t this would not be so good for the engine. The alternator field could be di= sconnected as its output could be easily determined on the plane you actuall= y fly. Otherwise you would want to power up all electrical accessories used=20= in flight.

This would get you very close to the 0-power losses at whatever RPM you= conducted the test. The only problem I see is that the working fluid would=20= be much too dense. I don't think this error would be very big but if you wan= ted to eliminate it you could perform the test in a hypobaric chamber o= r feed the engine some gas with ground level thermodynamic propert= ies equivalent to those of air at 1-3 inHg or what ever density yo= u expect the 0-power MAP to be. How accurate do you want to be?

The compression loss depends on the effective valve timing and the cyli= nder heat transfer rate. This test would account for it, what ever value it=20= might have.

Rob

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