Propulsion for low fare transportation to earth orbit

An aircraft system is described that is accelerated to 0.4 km/sec by a runway-length, ground-based launcher and to 1.5 km/sec by only ramjet engines. Operational costs are compared for all earth-to-orbit transportation systems described in the literature. It is concluded that propulsion for low fare transportation to earth orbit will include a ground-based launcher and variable-geometry, ramjet engines that initially produce about 100,000 pounds of thrust and are capable of accelerating at a constant dynamic pressure up to 1.5 km/sec (approximately Mach 5) with no more than a 30 percent loss in thrust.