Going mach 6 at high altitude is not as much of a boost as it seems. Consider that orbital velocity is ~mach 25, and energy = (1/2)mv^2. Launching a space veh

Going mach 6 at high altitude is not as much of a boost as it seems. Consider that orbital velocity is ~mach 25, and energy = (1/2)mv^2. Launching a space vehicle from a carrier moving mach 6 would give you (6^2)/(25^2)= 5.76% of the energy required to reach orbit. You do get some benefit from launching at high altitude, and reducing atmospheric drag, but that does not require a high speed launch. The high speed launch adds significant danger due to aerodynamic issues, along with requiring a massive fuel expenditure, and a much heavier, more complex, and expensive carrier.