Re: Launches - directional
Wed, 27 Mar 1996 10:30:28 -0500

     From reading the initial responses to the message below, I think 
     there has been some misunderstanding.  The question was whether some 
     launches would be going in the direction of the west coast of 
     Florida.  As I read the question, the requirement is that the launch 
     pass over the west coast of Florida, not that the launch be toward 
     the west.
     The most efficient way to launch a payload into orbit is to launch it 
     due east from the launch pad.  This takes maximum advantage of the 
     Earth's own linear rotational speed at the surface of the earth to 
     achieve orbital velocity.  (1,037 mph at sea level at the equator, 0 
     mph at the poles)  A launch due east from any of the existing launch 
     sites, with no other major directional changes, results in an orbital 
     inclination that is equal to the latitude of the launch site.  
     Kennedy Space Center is at 28.5 deg North so a launch due east from 
     there will result in an an orbital inclination of 28.5 deg.  A launch 
     from Vandenberg AFB in California is not permitted due to safety 
     The basic equation to compute orbital inclination based on the launch 
     site location and the azimuth of the launch is:
     cos (inclination) = cos (latitude) x sin (launch azimuth)
     To avoid launching over populated areas, the minimum launch azimuth 
     from Cape Kennedy is 35 deg and the maximum is 120 deg.  The resulting 
     orbit inclinations (approximate) are 57 deg and 39 deg, respectively.  
     Note that the minimum orbital inclination is equal to the latitude of 
     the launch site.
     A commercially owned launch site has been constructed on the east 
     coast of Texas.  A rocket launched from their could pass over the west 
     coast of Florida during its launch phase but the rocket would be at a 
     high altitude by then.
     It is possible that a launch from Russia, Japan, China or India could 
     pass over the west coast of Florida on the first revolution but the 
     payload would already be in at least low earth orbit by then and not 
     in the launch phase.
     The bottom line is that there is very little chance that a "launch" 
     would pass over the west coast of Florida.
     Jeff Barker
______________________________ Reply Separator _________________________________
Subject: Launches - directional
Author: at SMTPGATE 
Date:    3/26/96 8:23 PM
>Message was resent -- Original recipients were: 
I am very interested in getting a schedule of the upcoming launches for the 
next year that might be going in the direction of the gulf (west) coast of 
Florida (imparticular over the Sarasota area) and what possible times they 
might be observed in that area.  If you could send me that information, I 
would very much appreciate it.  Thank you.