What part of a rocket actually supports its tremendous weight as it sits on the pad?

Question

I would intuit that a thin-walled rocket nozzle is not strong enough to do the job.

Like Gray answered, I would have thought the gantry tower did the job, but that gets pulled away prior to launch. I would think a thin-walled nozzle can't do the job, but that's just an intution.

Answer 1

It's the rear end of the rocket. If it could not support the static weight of the rocket, how would it be able to push with a greater force during acceleration of 2G and more?

Actually the rear end of the rocket is bolted to the launch pad and those bolts are cut by pyrotechnics at the moment of lift-off. The tower does not hold the rocked in the seconds before lift-off.

Answer 2

The base of the rocket, called the thrust structure, has the job of taking all that thrust generated by the rocket engines and spreading it out to push the mass of the rocket above. Tat also means it is strong enough to hold up the entire weight of the rocket while it is on the pad. The base is clamped to the pad by hold-down arms which are released, usually by a small explosive mechanism, just at the moment of launch.

For a Saturn V launch you can see the four hold-down arms around the base of the rocket. They are arranged 90 degrees apart and clamp into special brackets around the base of the rocket. They hold the rocket in place, and they even hold it down while the engines are building up to full thrust, before releasing the rocket as the count reaches zero.

The tower alongside the rocket provides the various fuel lines and electrical connections to the rocket stages prior to launch. The rocket must be fuelled on the pad, especially if it uses cryogenic propellants like liquid hydrogen and liquid oxygen, but the upper stages are a little inaccessable. The tower is there to provide a support for fuel lines so they can be connected to parts of the rocket many feet above the ground. It has no structural function whatsoever in terms of holding the rocket up. If you look at some launch angles of the Saturn V you'll see that in fact the connections to the rocket are very flexible and totally inadequate for any kind of support.

Answer 3

The rocket is actually held in place by the gantry tower and supports that holds the ship upright. When the rocket takes off these supports fall away allowing it to clear the tower.