I am wondering about the basic design considerations when building a rocket body.
- is it made as a separate hollow cylinder with standalone tanks inserted inside?
- is it made so that the tank walls are the fuselage walls?
It seems to me that some rockets have it like option 1 (e.g. Falcon 9).
The SpaceX's Starship seems to have only single common wall between the fuselage and the tank, i.e. the tank is the fuselage and vice versa.
Is the second option common or it it new to Starship? Or is it the other way around? Or is it somehow different altogether?