Alternity RPG "gravity induction engines"

[someone_else]

In short, no. If you're in the exact centre of the Earth you're more likely to be weightless, due to the mass surrounding you pulling you equally in all directions.

That is a very particular situation. I was talking of ships at 600 km from the Earth center. And of a mass centered in a point in space (i.e. no bulk), as Newton's gravity equation say. I don't know relativity equations on gravity, but you don't look to know them either, so Newton gravity remains the best we have.

The danger is that tiny errors add up.

By the inverse square law there must be a distance where the gravity pull becomes so weak to be insignificant. Insignificant= the Sun dies of old age before the planets deviate its orbit by a significant amount.
No ship will be allowed to use its grav-engines in the "planet's safety zone", and it will be enforced with big guns.
Any tiny deviation caused by an engine can be spotted, and then corrected by another engine.

Perhaps they're very small, short-lived ones . Absurdly small ones would have a similarly small event horizon and so on.

the point is not the event horizon, the point is that the hull will be ripped by tidal effects, gravity from such tiny black holes pulls in all directions through all the ship's frame. Not to mention the tidal effects on the crew. If the black holes don't pull all the ship, the acceleration is pathetic, and I'd rather use a ion engine. Gravity must be nearly unidirectional and nearly constant through the ship, otherwise there will be differences in acceleration (or in the direction of acceleration) between the decks, and thus deadly tidal effects.

Let's assume a change in direction:

Nope, you dampen acceleration, not speed. When you fall down, you only get hurt when you hit the ground. (i.e. when the speed you have is instantly decelerated to 0 by the impact with the ground that has a quite big inertia, so does not move)
If you find no ground (i.e. you are not instantly decelerated) you are in free fall, just like the things orbiting earth (and the pink humans in them).
We are sitting on a planet that orbits the Sun, but the Sun is not fixed, it moves at about 200 km/s in its own orbit around the galaxy core (according to wikipedia article on the sun, and many others).
But EVERYTHING is moving in that direction at the same speed, we tiny pink creatures, the Earth, and the big mighty Sun.
Space shuttle does not need inertial dampeners to do its work, because it is the only thing accelerating, and it is already moving at those speeds due to being launched from Earth (that is already at those speeds).

In your example, when I accelerate towards West, my ship mantains the same speed of 1km/s towards North.
If I accelerate west for some time, until I get at 1Km/s West, then my ship is travelling 1 Km/s West and 1Km/s North. If I want to slow down the North speed I need to accelerate towards South. Otherwise that speed will remain the same forever. And this applies to any kind of real space vessel, rockets, space shuttles, probes, whatever.

What I was trying to say though, is that the gravity should affect everything onboard the ship at the same time, so while it accelerates the ship's frame, it accelerates the crew and cargo at the same time. Noone will feel pushed nor be crushed by walls, because both them and the walls will accelerate at the same time in the same direction. So will not even feel moving.

[Teleros]

That is a very particular situation. I was talking of ships at 600 km from the Earth center. And of a mass centered in a point in space (i.e. no bulk), as Newton's gravity equation say.

Sorry, you made it sound rather like if you were within a massive object.

Any tiny deviation caused by an engine can be spotted, and then corrected by another engine.

Not directly related to this topic, but expect other uses of the computers used for this then.

Nope, you dampen acceleration, not speed. When you fall down, you only get hurt when you hit the ground. (i.e. when the speed you have is instantly decelerated to 0 by the impact with the ground that has a quite big inertia, so does not move)
If you find no ground (i.e. you are not instantly decelerated) you are in free fall, just like the things orbiting earth (and the pink humans in them).

It depends on just how fast you accelerate or decelerate. Going from 100m/s to 0m/s in a fraction of a second due to a fall WILL hurt, doing so over a couple of minutes won't. If you're travelling in one direction and suddenly get accelerated hard in another, you'll notice it believe me, whatever happens to cause the effect. Making slow turns should help minimise this though.

Space shuttle does not need inertial dampeners to do its work, because it is the only thing accelerating, and it is already moving at those speeds due to being launched from Earth (that is already at those speeds).

That's because when space shuttles launch they only accelerate at no more than about 3g's tops (according to Wiki, mainly to avoid harming the (strapped down, padded) astronauts aboard. If it was able to accelerate at, say, 100g's, then it would need to be either uncrewed or fitted with some sort of inertial dampener to avoid killing the crew. Of course, we have no idea how to even begin to make an inertial dampener...

Noone will feel pushed nor be crushed by walls, because both them and the walls will accelerate at the same time in the same direction. So will not even feel moving.

Yeah fair enough, assuming the ship isn't ridiculously large I doubt the "lag" will be much of an issue either.