Originally Posted by
pasta
If they were using a reusable XB-70 derivative to launch a smaller reusable orbiter from the 1990s, I wonder why they replaced it a decade later with the distinctly lower-tech (expendable launcher) X-37B?
Perhaps some of the same reasons that expendables still have a place in transonic and space flight. Remember the Space Shuttle was originally envisioned as a space truck that could be rapidly reused and re-launched cheaply and easily, but as we saw it did not replace expendable boosters, was never cheap, and was replaced by Titan derivatives for heavy payloads. Only now are we seeing some truly reusable launch methods, but even these are only partially reusable, and they work....sometimes.....
IF an Aurora or XB-70 type aircraft was developed as a mother ship for a reusable orbiter, that would have been two very complex airframe systems with exotic materials, fuels, maintenance and security requirements. Not cheap or easy.
Crewed vehicles also have the highest safety requirements.