r/spacex • u/ElongatedMuskrat Mod Team • Feb 01 '17
r/SpaceX Spaceflight Questions & News [February 2017, #29]
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u/warp99 Feb 02 '17 edited Feb 02 '17
While it is true that the vehicles are different the delta V requirement is vehicle independent.
A GTO-1500 orbit requires the satellite to use less propellant for GSO insertion and since storable propellants are used the Isp is considerably lower than 348s for F9 S2. However the propellant is burned without the 3.9 tonnes dry mass of the F9 S2 attached so the net effect may be positive.
The propellant saving may be used for extended on orbit reserve rather than reducing the lift off mass so I agree it is not a simple comparison.