We will be operating from Spaceport America in southern New Mexico, USA.
LAUNCH SITE LATITUDE: 33.0o
=<<>>=
ORBITAL INCLINATION = 33.0o
Equation
PAYLOAD = –6.044 x ORBITAL ALTITUDE + 33568
Example
LOW ORBIT = 200 km
PAYLOAD = –6.044 x ORBITAL ALTITUDE + 33568
PAYLOAD = –6.044 x 200 + 33568
PAYLOAD = 32,359 kg
Example
HIGH ORBIT = 1,000 km
PAYLOAD = –6.044 x ORBITAL ALTITUDE + 33568
PAYLOAD = –6.044 x 1000 + 33568
PAYLOAD = 27,524 kg
Example
STANDARD ORBIT = 901 km
PAYLOAD = –6.044 x ORBITAL ALTITUDE + 33568
PAYLOAD = –6.044 x 901 + 33568
PAYLOAD = 28,122 kg
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Our blueprint calls for a 60–degree orbital inclination, requiring the VentureStar RRV to make a 27–degree turn to the south. This turn results in less payload reaching orbit. Therefore, the calculations change as well.
ORBITAL INCLINATION = 60.0o
Equation
PAYLOAD = –5.864 x ORBITAL ALTITUDE + 26286
Example
LOW ORBIT = 200 km
PAYLOAD = –5.864 x ORBITAL ALTITUDE + 26286
PAYLOAD = –5.864 x 200 + 28286
PAYLOAD = 25,113 kg
LOW ORBIT = 200 km
PAYLOAD = –5.864 x ORBITAL ALTITUDE + 26286
PAYLOAD = –5.864 x 200 + 28286
PAYLOAD = 25,113 kg
Example
HIGH ORBIT = 1,000 km
PAYLOAD = –5.864 x ORBITAL ALTITUDE + 26286
PAYLOAD = –5.864 x 1000 + 26286
PAYLOAD = 20,422 kg
HIGH ORBIT = 1,000 km
PAYLOAD = –5.864 x ORBITAL ALTITUDE + 26286
PAYLOAD = –5.864 x 1000 + 26286
PAYLOAD = 20,422 kg
STANDARD ORBIT = 901 km
PAYLOAD = –5.864 x ORBITAL ALTITUDE + 26286
PAYLOAD = –5.864 x 901 + 26286
PAYLOAD = 21,003 kg
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Graph 1 represents the payload capability of the VentureStar operating from Spaceport America. The endpoints range from 200 km to 1,000 km orbital altitude. Standard Orbit from a 33-degree launch site to a 60-degree orbital inclination at an altitude of 901 km yields a payload capability of 21,003 kg.
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| Graph 1: 33 Degree Latitude Launch Site payload capability |
Since we are lifting a lighter load into space, our GLOW has correspondingly changed:
Gross Mass
GROSS MASS = PROPELLANT MASS + EMPTY MASS + STANDARD PAYLOAD MASS
GROSS MASS = 1100206 + 112012 + 21003
GROSS MASS = 1,233,221 kg
Gross Liftoff Weight
GLOW = g0(GROSS MASS)
CEO GLOW = 9.80665(133221)
CEO GLOW = 12,093,766 N
Therefore, the new VentureStar Thrust–to–Weight Ratio is:
NEW THRUST–TO–WEIGHT RATIO = (TOTAL THRUST / GLOW) : 1
NEW THRUST–TO–WEIGHT RATIO = (13419000 / 12093766) : 1
TNEW HRUST–TO–WEIGHT RATIO = 1.10958 : 1
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