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Path: utzoo!kcarroll
From: kcarroll@utzoo.UUCP (Kieran A. Carroll)
Newsgroups: net.space
Subject: Plane Change in Transfer Orbit
Message-ID: <5302@utzoo.UUCP>
Date: Wed, 20-Mar-85 12:45:18 EST
Article-I.D.: utzoo.5302
Posted: Wed Mar 20 12:45:18 1985
Date-Received: Wed, 20-Mar-85 12:45:18 EST
References: <1091@mordor.UUCP>, <310@petrus.UUCP>, <5300@utzoo.UUCP>
Organization: U of Toronto Zoology
Lines: 21

*
   A couple of people have claimed that, when transferring from
low-earth orbit to geosynchronous orbit, it is generally advantageous to
perform any plane-change maneouvres required entirely at apogee,
and none at all at the perigee of the transfer orbit.  Well,
"I am sorry, but that turns out not to be the case..."
   If you calculate the amount of delta-v required for a LEO-to-
geosynch transfer, as a function of the amount of plane change performed
at LEO, you will find in some cases that a slight savings of delta-v
can be had by performing a small amount of plane-change at the
perigee (and most of the plane-change at the apogee) of the transfer
orbit.  I recently calculated exactly this function, while taking an
orbital dynamics course.  LEO was inclined 28.5 degrees to the equator,
and was 300 km high.  If 2.2 degrees of plane change were done in
LEO, at the time of the perigee burn, about 0.6% of the total
delta-v could be saved.  As the professor giving the course pointed
out, this saving may be small, but it's exploited quite frequently
by people launching satellites.
-- 
     Kieran A. Carroll @ U of Toronto Aerospace Institute
     {allegra,ihnp4,linus,decvax}!utzoo!kcarroll