SpaceX Starts Testing Its Next-Gen Super Heavy — Booster 18 (V3) Undergoes Pre-Launch Validation

SpaceX has kicked off pre-launch testing for Booster 18, the very first Super Heavy V3 booster, marking a significant milestone in its Starship development roadmap. According to sources, the initial tests will focus on validating the booster's redesigned propellant systems and assessing its structural strength — two fundamental upgrades for this next-generation booster. 

While still early in the test campaign, the choice to begin with propellant system checks suggests that SpaceX is prioritizing fluid dynamics, tank integrity, and pressure behavior under cryogenic conditions. Meanwhile, structural tests — likely involving stress rigs and load simulators — will help engineers confirm that the new design can withstand the extreme forces of launch, stage separation, and reentry. These tests are being carried out at Starbase, where Booster 18 has already been spotted in test-stand setups.

One of the biggest visual and design changes on V3 is its grid fins. Unlike V2, the V3 booster reportedly has only three fins instead of four, arranged in a T-shape, and each roughly 50% larger and structurally stronger.These redesigns are not just for aerodynamic control — they also play a key role during reentry, helping the booster return more precisely and safely, especially when paired with SpaceX's future catching “arms” on the tower.

Another major innovation is the integration of a hot-staging ring directly into the booster structure, instead of having it as a separate component. According to coverage by NASASpaceFlight, this integrated ring will face rigorous load testing, simulating the axial and thermal stresses it will encounter during real flights. This integration not only simplifies the booster architecture but also potentially improves mass efficiency and reliability.

The pre-launch testing of Booster 18 sets the stage for the first full V3 flight, which is expected to launch in a future Block 3 Starship configuration. By successfully validating these propellant and structural upgrades on the ground, SpaceX moves closer to a fully operational V3 booster — a major step toward more powerful, reusable, and cost-effective Starship missions.