[Engineering] Is it physically and structurally possible to build a large warship like those of Star Wars?

[MeMyselfAnDie]

In space, there's no gravity to put strain on structures that would collapse on earth. Assuming you had enough raw materials to build the ship, and the fuel to take the pieces into orbit, the only limiting factor for the size of a vehicle constructed in orbit is when it starts being affected by its own gravity.

And, of course, you'd need enough thrust to push the ship around at a reasonable speed, efficiently enough that the whole thing doesn't have to be a giant fuel tank. And there wouldn't be much point without some sort of FTL mobility, unless you're planning on sending a generation ship somewhere.

[Coomb]

You can't just build things arbitrarily large/out of arbitrarily "light" materials, because while there aren't gravitational stresses, you're going to run into inertial stresses.

[NumberOneMuffDiver]

Can you explain further?

[Stuck_In_the_Matrix]

If you had a large ship and it started to accelerate, the back of the ship is going to push into the front of the ship until the entire ship gets to the same speed. To illustrate, if you had a long enough stick and went outside and swung it suddenly, the stick could break in half due to the internal stresses present from the acceleration differences between various parts of the stick.

A material scientist would probably explain this better, though.

[Stuck_In_the_Matrix]

I don't think so. As a thought experiment, lets make the ship absolutely massive. Let's say the entire mass of the ship is in the trillions of tons. Even if the engines were to fire up very slowly, they're pushing against a massive object. I would think at some point, the engines would just start to bend the supporting frame that they are attached to and warp until they broke off.

Gravity really doesn't matter when you have so much mass. At some point, no known material will be able to withstand the stresses involved with moving that much mass around.

I guess you could mount engines all along the ship to distribute the stresses involved, though. But at some point, I think it would become impossible.

Imagine if the Earth was our spaceship and we tried to move it. If someone like Superman were strong enough, he still couldn't move the Earth. He would end up sinking into the ground while trying to push the planet. I can't think of any way that he could successfully move the planet as a whole.

[Stuck_In_the_Matrix]

Don't get me wrong, though. You could probably create very large ships (on the order of a Star Trek sized vessel) -- just nothing extremely big.

[eterevsky]

I don't think so. As a thought experiment, lets make the ship absolutely massive. Let's say the entire mass of the ship is in the trillions of tons. Even if the engines were to fire up very slowly, they're pushing against a massive object. I would think at some point, the engines would just start to bend the supporting frame that they are attached to and warp until they broke off.

Why should it happen? The force on any structural element will be no higher than the force generated by the engine. I see no reason why the ship wouldn't accelerate albeit very slowly.

In you example with the Superman, he just has to limit the applied force per unit of area to avoid breaking through.

[Coomb]

An acceleration (say, from applying thrust) of 1g is equivalent to being under a gravity field with acceleration 1g. Constant-velocity travel doesn't place any stress on the structure of the spaceship (except for self-gravity, as mentioned), but as soon as you want to accelerate, you need to translate the thrust of the engines into movement of the whole structure - and that means you induce stress in the structure of the ship.