This document describes a proposed horizontal in-line launch staging (HILLS) system. HILLS involves joining two delta wing aircraft nose to tail to operate as a single reusable vehicle, with the first stage powering both until separation to deliver the second stage and payloads to orbit. Combined with other technologies, HILLS could allow affordable reusable launch services with lessons from the Concorde and lifting bodies providing economy, safety, low vibration and low g-forces. The company is developing prototypes like the SKIP airframe to demonstrate technologies for eventual orbital vehicles.