The header tank is bulged out at the top and the bottom.What may be the reason for this?Can't simple cylinder tanks be used instead?
Elon Musk also posted the image of Starship fuel header tank.
Space Exploration Stack Exchange is a question and answer site for spacecraft operators, scientists, engineers, and enthusiasts. It only takes a minute to sign up.
Sign up to join this communityThe header tank is bulged out at the top and the bottom.What may be the reason for this?Can't simple cylinder tanks be used instead?
Elon Musk also posted the image of Starship fuel header tank.
A simple cylinder with flat circular sheets at both ends is less stable and would be heavier than a cylinder with hemispherical or elliptical ends.
A sphere has the best ratio of volume to surface and also of mass to volume. Material stress caused by internal pressure is homogenusly distributed over the surface.
If a sphere's diameter is too big for the rocket, a (short) cylinder with hemispheres at both ends is the second best optimal form. But for the cylindrical part stress in axial direction is only half of that in tangential (circumference) direction.
See Wikipedia and the Kesselformel, only the german version has the essential formulas for axial and tangential tension.