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Transfer Windows without timewarp


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Hi. First of all, i am no hardcore - pure stock - no mechjeb player. And I am not a mathematician, nor a astronomer. My gameplay right now is that of an epic journey in my space program, and the enhanced problems following my decision to use deadly reentry, tac ls and far and trying to work mostly with reusable launch systems, recovering whatever possible.

But right now i find myself most of the time with possibilities, ideas and goals for visits to the planets, but rarely fitting launch windows. And i do not timewarp very often more than 3-6 days, since alarm clock has already a lot of missions that i should handle. My old ways of playing ksp with only one mission at a time and timewarping like crazy are long gone :)

So... say i want to fly to moho or eve, but there is no optimal transfer window. Ok, use non optimal, maybe more expensive transfer windows with the information that alarm clock, mechjeb, protractor and the online calculator are offering, right?

But here everything goes wrong for me. When i try to find possible manouevers i rarely find something that is a bit more expensive - mostly the transfers are extreme in every way. And often when trying to burn one of these manoevernodes with a nuclear engine and lots of time and dv to spare it doesnt hit the target at all.

Mechjeb and protractor rarely get a hit either outside of the optimal launch windows. Surely nothing to rely on. And the very impressing online tools show some tempting options and windows, but give no hint how to use this information to my advantage. And yes, i tried to follow one of the rare guides from 2013, but found it really complicated and not very good explained. Most of the available guides rely heavily on timewarping one single mission anyway.

So... I learned so much in ksp, how can i manage to at least find reliable, non optimal transfers, so that i can concentrate on building vessels capable of handling the extra dv? Is there an easy, step by step explanation that also makes use of the available mods like alarm clock, protractor, ker, mechjeb & co?

How do you handle these situations?

Edited by smart013
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http://alexmoon.github.io/ksp/ shows you ideal transfer options at any given point in time. Just click on the dV transfer-plot according to your desired launch time and see the data on the right. :)

It also makes clear, that missing the ideal transfer to Moho will rapidly increase dV requirements. So its no suprise you cant find worse but still acceptable transfers to there. Eve is a little easier though...

Edited by TrooperCooper
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Yes, i now this tool, and its great. But i still have to understand how to transfer these informations into a precise usable manoever node. I know you should be capable to do this with mechjeb manoever node editor, but at this point everybody seems to think that placing and edititing this node is self explanatory and needs not any explanation. It isnt selfexplanatory for me, thats the problem :)

Edited by smart013
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Non optimal transfers:

Just keep a probe in LKO. When you want to burn to, say, Duna, and it's not an optimal transfer window, just create a node, and keep tweaking it until you get an encounter. Now you know how much dV you need to get there. So you go back into the VAB, and build a ship with 4500dV + whatever dV the maneuver node had + whatever dV you need to do whatever it is when you get there.

When done, delete the node on your probe, and repeat the process the next time you want to go somewhere.

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Yes, i now this tool, and its great. But i still have to understand how to transfer these informations into a precise usable manoever node. I know you should be capable to do this with mechjeb manoever node editor, but at this point everybody seems to think that placing and edititing this node is self explanatory and needs not any explanation. It isnt selfexplanatory for me, thats the problem :)

The complementary tool to do that is the precise node mod. See here. When you have that mod installed, that little editor window comes up everytime you create a maneuver node. You can then edit the node according to the data from alexmoon. Could be that mechjeb can do the same thing, but I have never tried that mod, so I dunno.

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The complementary tool to do that is the precise node mod. See here. When you have that mod installed, that little editor window comes up everytime you create a maneuver node. You can then edit the node according to the data from alexmoon. Could be that mechjeb can do the same thing, but I have never tried that mod, so I dunno.

MechJeb won't calculate a transfer to a planet unless you're already in the SOI of Kerbol. It's fairly decent at flying the maneuver node created by other means. I've had issues from LKO though using low thrust ships--the initial ejection burn from LKO took so long that the trajectory wasn't right by the end and the deltaV requirements to complete the maneuver skyrocketed.

Edited by DavidInAuburn
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Rendezvous without transfer windows:

Step 1, set the thing you want to rendezvous with as a target.

Step 2, get into an orbit that crosses your target's orbit going in roughly the same direction. This means your periapsis needs to be below your target's orbit, your apoapsis needs to be above your target's orbit.

Step 3, your orbits cross in 2 dimensions, make them cross in 3 dimensions by matching planes, or by pushing the AN or DN to one of the two points where your orbit crosses your target's orbit.

Step 4, your orbits cross in 3 dimensions at one point, wait until that point and burn prograde or retrograde until you get back around to this point of your orbit at the same time your target does. Burning prograde will mean the target has more time to catch up with you on the subsequent orbit. use a zero ∆v maneuver node to see further into the future, if necessary.

For a FAST rendezvous without a transfer window, you plan step 4 into step 2. Sometimes this is expensive, as if you're going from Kerbin to Moho, it may require kicking your apoapsis way above Kerbin's orbit.

Edited by TranquilTempest
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