Traveling with Alcubierre Drive Mod

[Artienia]

So in a nutshell, I tried a test run going from kerbin to eve, and when reached even had 10k m/s, and i obviously can't correct that

So, There must be a calculation that made it be 10k, so how can we reduce it? There must be some 'formula' to do (Like planet velocity / Destination * 3 + Vessel speed) So what is it?
Thanks

[Zhetaan]

@Artienia:

It's all vector addition.  What you experienced is the fact that the Alcubierre drive doesn't work like an engine:  what it does is move the space around your vessel, not move the vessel through space.  It's difficult to grasp intuitively what that means (and fictions such as Star Trek don't make it any easier), but the result is that whatever your velocity when you start the drive, you keep it when you shut the drive off.  Thus, when you leave Kerbin for Eve, you arrive at Eve with the same velocity that you had at Kerbin--and since Kerbin is moving at a different speed and probably a different direction, that all adds up to a potentially gigantic difference.

There's a trick to using the Alcubierre drive:  you need to separate the velocity into speed and direction components and correct each of them individually, and only then go to your destination.  Practically, this means that you need to make use of the nearest deep gravity well, which is the sun's.

To go from Kerbin to Eve, you first need to take note of Eve's direction relative to Kerbin, and make your direction match.  That requires you to warp down to low solar orbit and coast around the sun until your direction and Eve's direction are parallel.  The closer to the sun you get, the less time it will take.

Second, you need to find Eve's solar orbital speed, and you need to make your vessel's solar orbital speed match.  Eve is closer to the sun than Kerbin, so it will be moving faster.  This means that you, having matched direction with Eve already, need to warp to a somewhat high solar orbit on a trajectory that falls directly into the sun.  In other words, you want to be 90 degrees behind Eve and falling directly into the sun.  As you fall, you will gain speed.  Somewhat high is not well defined, but the idea is that you want to be far enough away that you can gain a lot of speed, but not so high that it takes five years to accomplish.  If you cannot gain enough speed on one fall, then warp back out to a somewhat high altitude and fall again.  When your speed and direction are equal to Eve's, then you can warp to Eve and arrive with near-zero relative velocity.

To return from Kerbin, it's the same process:  correct your direction so that it is parallel to Kerbin's, and then warp to a point that is both very low to the sun and such that your path points directly away from it.  Lose speed as you climb higher until it matches Kerbin's speed (warping back down as necessary to complete this step quickly), and warp to Kerbin with near-zero relative velocity.

Depending on the velocity difference, it may be better to correct speed first and direction second:  if it takes so much time to correct speed that the direction changes, then do that.  Or you may find it best to split both steps into several phases and incrementally arrive at the correct velocity.  You can also time your journey so that you only go when Kerbin and Eve are in conjunction--meaning that they already point in the same direction, which saves you a step.  However, you'll still need to warp to a point ninety degrees behind and fall towards the sun to build speed.

Edited August 22, 2018 by Zhetaan

[Artienia]

6 minutes ago, Zhetaan said:

@Artienia:

It's all vector addition.  What you experienced is the fact that the Alcubierre drive doesn't work like an engine:  what it does is move the space around your vessel, not move the vessel through space.  It's difficult to grasp intuitively what that means (and fictions such as Star Trek don't make it any easier), but the result is that whatever your velocity when you start the drive, you keep it when you shut the drive off.  Thus, when you leave Kerbin for Eve, you arrive at Eve with the same velocity that you had at Kerbin--and since Kerbin is moving at a different speed and probably a different direction, that all adds up to a potentially gigantic difference.

There's a trick to using the Alcubierre drive:  you need to separate the velocity into speed and direction components and correct each of them individually, and only then go to your destination.  Practically, this means that you need to make use of the nearest deep gravity well, which is the sun's.

To go from Kerbin to Eve, you first need to take note of Eve's direction relative to Kerbin, and make your direction match.  That requires you to warp down to low solar orbit and coast around the sun until your direction and Eve's direction are parallel.  The closer to the sun you get, the less time it will take.

Second, you need to find Eve's solar orbital speed, and you need to make your vessel's solar orbital speed match.  Eve is closer to the sun than Kerbin, so it will be moving faster.  This means that you, having matched direction with Eve already, need to warp to a somewhat high solar orbit on a trajectory that falls directly into the sun.  In other words, you want to be 90 degrees behind Eve and falling directly into the sun.  As you fall, you will gain speed.  Somewhat high is not well defined, but the idea is that you want to be far enough away that you can gain a lot of speed, but not so high that it takes five years to accomplish.  If you cannot gain enough speed on one fall, then warp back out to a somewhat high altitude and fall again.  When your speed and direction are equal to Eve's, then you can warp to Eve and arrive with near-zero relative velocity.

To return from Kerbin, it's the same process:  correct your direction so that it is parallel to Kerbin's, and then warp to a point that is both very low to the sun and such that your path points directly away from it.  Lose speed as you climb higher until it matches Kerbin's speed (warping back down as necessary to complete this step quickly), and warp to Kerbin with near-zero relative velocity.

Depending on the velocity difference, it may be better to correct speed first and direction second:  if it takes so much time to correct speed that the direction changes, then do that.  Or you may find it best to split both steps into several phases and incrementally arrive at the correct velocity.

So should i warp into solar Orbit from kerbin, Fall, and when i reach Eve's Orbital speed, warp to eve?

[Zhetaan]

1 minute ago, Artienia said:

So should i warp into solar Orbit from kerbin, Fall, and when i reach Eve's Orbital speed, warp to eve?

That's half of it.  You also, as a separate step, need to warp to a place where you can swing around the sun until your direction is the same as Eve's.  In other words, you need to find a solar orbit where you can (relatively quickly) go around the sun until you are exactly between the sun and Eve.  I can't tell you what this orbit is, because it will change as Eve's position relative to Kerbin changes.  However, to save time, it should be one that's inside Moho's orbit, if possible.

I think the most straightforward way to do this is to start from Kerbin and warp straight towards the sun until you are inside Moho's orbit.  If your orbit on exiting warp goes too close to the sun, then warp back out closer to Kerbin until you're comfortable with your solar periapsis.  The key here is to be in a close orbit (not so close that you burn up), and to use that close orbit to change your direction until you are moving parallel to Eve, which occurs when you are on the line connecting Eve to the centre of the sun.  You want a close orbit because close orbits are fast orbits:  nothing prevents you from doing this out at Eeloo's orbit, but of course the point of warp drive is to save time.

[Artienia]

4 minutes ago, Zhetaan said:

That's half of it.  You also, as a separate step, need to warp to a place where you can swing around the sun until your direction is the same as Eve's.  In other words, you need to find a solar orbit where you can (relatively quickly) go around the sun until you are exactly between the sun and Eve.  I can't tell you what this orbit is, because it will change as Eve's position relative to Kerbin changes.  However, to save time, it should be one that's inside Moho's orbit, if possible.

I think the most straightforward way to do this is to start from Kerbin and warp straight towards the sun until you are inside Moho's orbit.  If your orbit on exiting warp goes too close to the sun, then warp back out closer to Kerbin until you're comfortable with your solar periapsis.  The key here is to be in a close orbit (not so close that you burn up), and to use that close orbit to change your direction until you are moving parallel to Eve, which occurs when you are on the line connecting Eve to the centre of the sun.  You want a close orbit because close orbits are fast orbits:  nothing prevents you from doing this out at Eeloo's orbit, but of course the point of warp drive is to save time.

Tried this and got 16k orbital vel

https://imgur.com/laOFNwU

[Zhetaan]

40 minutes ago, Artienia said:

Tried this and got 16k orbital vel

If you're having trouble, you can also make lots of short jumps around your destination until you slow down enough to make orbit; just understand that Eve, though a heavy planet, simply isn't in the same league as the sun.

Also, try this and this to get a more visual understanding of what I'm trying to tell you.

Edited August 22, 2018 by Zhetaan