The past and current designs of rocket launchers have diameters up to 8-10 meters (Saturn-5, N-1, SLS, BFR), up to 13-14 meters for max cross-section dimension for Space Shuttle and Energia-Buran (launcher+orbiter).
I am curious:
Theoretically, for aerodynamic reasons - can a rocket launcher have a diameter of 30 meters and more? Will there be any insurmountable difficulties with air flow or something else? A rocket is supposed to launch from sea level in Earth's atmosphere.
I know two projects of launchers with diameter over 20 meters:
Sea Dragon (diameter 23 meters)
UR-900 (diameter 28 meters)
Both were never close to implementation, and I don't know how mature these projects were in aerodynamics.