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Author Topic: Formula on my manual. how do I do the operation  (Read 4990 times)

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jgrillo2002

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20 March 2003, 01:37:20
HI Dan. I found a formual on the New manual. Launch Azimuth = arcsin (cos
(desired_orbital_inclination) / cos (launch_ latitude)). how do I do the Operation. tell me what cos
& sin operate as altitude or heading, etc.:help::wonder::wonder::wonder:

Zack


« Last Edit: 20 March 2003, 02:57:46 by jgrillo2002 »

Offline DanSteph

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Reply #1 - 20 March 2003, 02:08:59
I quote gbregman that replied the same question some day before:

You have to use the equatorial reference point for ISS's inclination, because you're using the
equatorial reference point for both launch azimuth and launch latitude. It's around 51.x, which, if
you'll notice deviates about 23' from your given inclination of 74.51'. This is due to the 23.x' axial
tilt of the earth to ecliptic. To convert your value (which is ecliptic reference) to earth-equatorial
reference, just subtract 23.x' (sorry, can't remember the exact value). Then the equation should
work fine.


for Iss departure from KCS (launch on ascent node)
----------------------------------


74.51°(iss inclinaison in degree)
23.26° (equatorial inclinaison (constant in degree))
desired_orbital_inclination=51.25°  (iss - equatorial)
launch_ latitude=28.34N


So:
Launch Azimuth = arcsin (cos(51.25) / cos (28.34))

Launch Azimuth= 0.789638401776836957

as the result is in radian you must convert it in degree with 180/Pi

so:
Launch Azimuth = arcsin (cos(51.25) / cos (28.34))*180/Pi

Launch Azimuth=45.24°

Dan

« Last Edit: 20 March 2003, 02:57:46 by DanSteph »

jgrillo2002

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Reply #2 - 20 March 2003, 02:57:46
Thank you. I got 40.74 as my launch azimuth.

Cheers :friend::friend::friend::friend::top:
Zack

« Last Edit: 20 March 2003, 02:57:46 by jgrillo2002 »