Single-stage-to-orbit — fly to orbit and back on one vehicle, no expended stages — is the white whale of launch. Most who chase it run aground on the physics. US11649070B2, granted to Radian Aerospace on May 16, 2023, claims an "Earth to orbit transportation system" built around that ambition.
The CPC is a launch-system spread: B64G 1/14 (launch vehicles / spacecraft for launching), B64G 1/002, 1/402 (propulsion), 1/64 (stage separation provisions), and B64G 5/00 (ground equipment). The companion grant US11643994B2 ("Rocket propulsion systems and associated methods") fills in the engine side of the architecture.
The mechanism is the system-level integration that SSTO demands. The brutal arithmetic of single-stage flight leaves almost no mass margin, so everything — structure, propulsion, thermal protection, and in Radian's case a horizontal launch assist — has to be co-optimized. The patent claims that integrated transportation system rather than any single component, because in SSTO the architecture is the invention.
For analysts, the value of the record is in what it reveals about Radian's thesis: horizontal takeoff with launch assistance to relieve some of the SSTO mass penalty, paired with a propulsion approach claimed separately. As a private firm, Radian leaves little public trace beyond filings like this; the patents are the clearest available map of its technical bet.
The discipline this desk insists on: an Earth-to-orbit-system claim is broad in title but bounded by its specific embodiments, and — most important — a granted patent is emphatically not a flown spaceplane. SSTO's graveyard is full of well-engineered concepts. Read this as documentation of a serious, ambitious architecture and an early priority date, not as evidence the hardest problem in launch has been solved.