[Spaceships] I'm closing on nothing, and 4 other confusions.

[mlangsdorf]

Originally Posted by weevis

I’M GOING SO FAST I HAVE TO TAKE EVASIVE ACTION

All I was thinking is: If I am moving and in a room with a chair, I have other options besides moving away from it or toward it. And: If I am moving away from it I have other options besides jinking from left to right eratically as though to dodge incoming lasers. In 3-D space the same is true but I have even more directions to move.

Okay, let's try a mental model that is fairly inaccurate but closer to what might be happening in Spaceships: two jet aircraft high over an ocean. They're flying due north on parallel courses at 600 mph, with 10 miles separation, and are basically nose to nose with each other on the east-west axis. One of them then kicks in the afterburners, accelerating to 1500 mph. It has a couple of options here:
1. Turn to west west, moving horizontally towards the other aircraft.
2. stay on course, moving horizontally away from the other aircraft.
3. Turn to the east, moving horizontally away from the other aircraft.
4. Perform a loop or similar maneuver, using some of that extra change in position (ie, speed) to change it's vertical position without changing its horizontal position relative to the other aircraft.

Option 1 is a closing maneuver. Option 2 is effectively an evasive maneuver (making it harder to hit). Option 3 is effectively an evasive maneuver (making it harder to hit). Option 4 is obviously an evasive maneuver (it's doing aerobatics).

If the aircraft didn't want to be forced to take either an evasive maneuver or closing maneuver, it shouldn't have accelerated up to 1500 mph. If it had only accelerated to 700 mph, it could have Held Course and stayed roughly in the same relative position to the other aircraft.

Movement in Spaceships is abstract and relative to the other vehicles in the combat. Relative to some fixed object (say the Sun), all the ships involved in a combat could be moving really fast, say 1000 mps, but as long as they're not moving that fast relative to each other it doesn't matter.

Spaceships aren't "fast", they're "quick accelerators." This is important, because any spacecraft can get to any relative velocity to a distant fixed object, given enough time and reaction mass. In a combat between a solar sailor that accelerates at 0.0001gs and got to 1000 mps velocity relative to to the sun over a couple of weeks, and a super reactionless drive starcraft that accelerates at 100gs and got to 1000 mps velocity relative to the Sun over a couple of minutes, they're both moving at 1000 mps velocity relative to the Sun. And relative to each other, they're both moving at about 0 mps. If the starcraft decides to turn on that super reactionless drive to max ouput, it's going to change its velocity relative to the solar sailor somehow: either closing quickly, opening the distance quickly, or making astrobatic maneuvers to keep the same relative distance.

So if your super TL11^ spaceship wants to stay in the vicinity of an asteroid to use it as cover - well, remember, the asteroid is moving pretty fast relative to the sun already. But the important velocity is your ship's velocity relative to the asteroid. If you want to stay near the asteroid, you don't use all that awesome acceleration by performing a Controlled Drift or Hold Course maneuver. And if you decide to use all that awesome acceleration, then you need to go somewhere: closer to it or away from it or in a loop, and two of those options are evasive.