...a few years back I worked at United Tech , the manufacturer of the Titan III solid rocket boosters. While there, I did conceptual and preliminary design on a number of things, such as an abort motor for capsules and Orbital Space plane (US patent #6629673) and a reusable launch vehicle (US patent #6726154... which I was left off of and not even notified about... yes, that thrilled me to no end). While at the time I could provide you with detaield diagrams of both, only the abort motor was what you might can a "real" project, in that it was designed to a high level of fideleity and was seriously intended to be built. The RLV was much more hand-wavy. And while working there, i drew up a number of other motors and vehicles, some of which were very impressive looking... adn which were not really describable as "projects," more like "quick sketches." ...
