• publiusr

    Not many pressure fed guys left…

  • Jacob Samorodin

    If a rocket’s first-stage burns out at an altitude over 50 km, at speeds over 2.0 km/sec, with inclination of the booster no more than 30 degrees from horizontal at staging, a pressure-fed second stage with a burn time of more than 3 minutes, will be able to orbit good-sized payloads.

  • duheagle

    There’s Vector too.