From the D-3 He Levitated Dipole Rocket to a p-11B Adaptation: Original Design, Proposed Modification, and Comparison

Advanced space propulsion is constrained by the rocket equation: crewed solar-system transit needs ultra-high exhaust velocity alongside a low dry-mass fraction. Fusion propulsion can meet those criteria, but only if plasma physics, shielding, and in-flight maintenance are solved together. This paper is organized for a systems reader who wants a ship-level mass picture and a submarine-engineering-officer view of startup and electric plant, then the fuel-specific reactor details. The Introduction states the thesis. Common ship architecture gives a fuel-agnostic mass inventory and a generic schematic (reactor bay left as a hole). Chapter 1 is the historical Deuterium–Helium-3 (D–³He) Levitated Dipole Rocket (LDR), including deuterium-state definitions, NBI startup, battery sizing, and a D–³He-specific mass fill-in. Chapter 2 adapts the same bus to proton–boron-11 (p–¹¹B) with CHARM / TAE-FRC grafts, a parallel ops primer, and a p–¹¹B-specific mass fill-in. Chapter 3 compares feasibility, cost/mass, ownership, and an adapted Plant Odds Score (POS★)—a weighted diligence score from the companion p–¹¹B survey, not a propulsion acronym. We conclude that the LDR topology can be retained for both fuels, while p–¹¹B requires kinetics and ash retuning against the Rider / Bremsstrahlung limit. On shielding: the thick neutron moderator of the D–³He LDR can be largely removed for p–¹¹B; a thinner high-Z X-ray shadow remains; galactic cosmic-ray habitat mass is unchanged. D–³He remains the nearer-term physics path; p–¹¹B is the cleaner long-term mass and fuel-logistics bet—if those modules close. As of mid-2026, neither rocket thesis has a commercial or dedicated government owner: the only commercial LDC firm (OpenStar) targets terrestrial DT electricity.