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...It only takes building 4 Space Solar Power satellites per yearto.....
On Dec 17, 10:24*am, Me wrote:
On Dec 17, 3:06*am, "Androcles" wrote: Three SRBs can lift the vehicle to orbit without the tank No, they can't. *They would burn out at 2 minutes into the flight with the orbiter still in the atmosphere and 1000's mph short of orbital velocity. *The SSME's using propellant from the ET provide most of the velocity. The SSME and ET provide approx 588M pounds sec of total impulse. *One SRB only provide 336M pounds sec of total impulse, not enough. *And the burn is too short Exactly right! A pound of SRB propellant will produce a pound of thrust for 260 seconds. A pound of ET propellant will produce a pound of thrust for 455 seconds. This is an important point captured in the rocket equation; Isp = specific impulse = 260 for SRB, 455 for SSME Vf = Isp * g0 * LN(1/(1-u)) Where Vf = final velocity (9.2 km/sec) Isp = specific impulse g0 = gravity constant = 9.802 m/sec u = propellant fraction needed achieve Vf given Isp |
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