How to plan a Kerbin-Eve-Kerbin-Kerbin-Jool Transfer

[SpaceDirt]

I have attempted to use the KEKKJ route to get to Laythe before, but I wasn't able to make it without using a lot more fuel than I would like. What kind of transfer window would be optimal for the route, and are there any other things that I would need to know to do this with minimal Delta V?

[Gaarst]

Everything you need is up there.

[Weywot8]

Timing, experimentation and patience/warping - the trade-off for a low dV flight plan is a lot of travel time and potentially decade long waits till transfer windows appear just like IRL.

The flybyfinder doesn't do KK but there is supposed to be a spreadsheet posted in that forum that does. A more definitive answer below:

And for a couple of hundred dV more, someone has done this:

 

[Human Person]

Good question. I usually don't cause it's too tedious to do. A direct transfer takes only about 800 m/s more. 

[PLAD]

The thread Weywot8 links to above is a good one, I made two runs using the same KEKKJ window (starts Earth day 146.1) in it and give a fair number of details in the imgur albums. I also did  KEKKJ run using a different window, one that starts on (Earth time) day 2016.2. Here is the imgur album for that one, note that the last picture shows the details for the run in both Kerbal and Earth time. Note you should skip the start of that one since I used a fairly tricky multi-Mun flyby method to get enough energy to get to Eve, but from there on it is universal. I found a number of KEKKJ windows but I have only run the two shown in the above albums. The day 2016.2 (equals Kerbin Y19 D383.8) one is more forgiving of errors. Let's see if I can show a chart of the others I've found:

 
K            E              K          dbl         K             J           start m/s       
146.1    195.65    296.2    0.424    509.25    821         1068       
318.75    338    430.2    0.46    643.25    1210            1345       
498.5    546.9    639    0.46    852    1062.5                1163       
644.75    679.8    767    0.51    980.05    1292            1151       
855.8    903    1000    0.44    1213.05    1647              1388       
2016.2    2065.6    2165.6    0.445    2378.65    2675    1079    

Times are all Earth days, if you enter these in my LambertHOPM spreadsheet (available in the Flyby Finder thread) it gives you the details. The 'dbl' column is a little code Lambert uses to indicate the details of the K-K leg. So for instance the first row means leave Kerbin orbit on day 146.1, flyby Eve on day 195.65, set it up so you are flung back to Kerbin and fly by it on day 296.2, then fly by Kerbin again on day 509.25 (note this is exactly 2 Kerbin years, or 213.05, days after the first Kerbin flyby) and then arrive at Jool on day 821. Don't sweat the arrival day at Jool, but the time of the Eve periapsis should be within +/- 6 hours of day 195.65, the first two K's can be off by +/-18 hours or so.

When I wrote Flyby Finder KSP only used Earth time (24 hours in a day, 365 days in a year) so most of my work uses that time mode, nowadays the Kerbal system of 6 hour days and 426-day years is generally used. Lambert translates from Earth time to Kerbal time if you need it.

Be careful if you try the windows I've haven't, with some of them the final Kerbin flyby is dangerously low and some luck will be required to be able to make the final K-J leg without a big correction burn.

 

[noobsrtoast]

On 6/19/2017 at 7:16 PM, PLAD said:

The thread Weywot8 links to above is a good one, I made two runs using the same KEKKJ window (starts Earth day 146.1) in it and give a fair number of details in the imgur albums. I also did  KEKKJ run using a different window, one that starts on (Earth time) day 2016.2. Here is the imgur album for that one, note that the last picture shows the details for the run in both Kerbal and Earth time. Note you should skip the start of that one since I used a fairly tricky multi-Mun flyby method to get enough energy to get to Eve, but from there on it is universal. I found a number of KEKKJ windows but I have only run the two shown in the above albums. The day 2016.2 (equals Kerbin Y19 D383.8) one is more forgiving of errors. Let's see if I can show a chart of the others I've found:

 
K            E              K          dbl         K             J           start m/s       
146.1    195.65    296.2    0.424    509.25    821         1068       
318.75    338    430.2    0.46    643.25    1210            1345       
498.5    546.9    639    0.46    852    1062.5                1163       
644.75    679.8    767    0.51    980.05    1292            1151       
855.8    903    1000    0.44    1213.05    1647              1388       
2016.2    2065.6    2165.6    0.445    2378.65    2675    1079    

Times are all Earth days, if you enter these in my LambertHOPM spreadsheet (available in the Flyby Finder thread) it gives you the details. The 'dbl' column is a little code Lambert uses to indicate the details of the K-K leg. So for instance the first row means leave Kerbin orbit on day 146.1, flyby Eve on day 195.65, set it up so you are flung back to Kerbin and fly by it on day 296.2, then fly by Kerbin again on day 509.25 (note this is exactly 2 Kerbin years, or 213.05, days after the first Kerbin flyby) and then arrive at Jool on day 821. Don't sweat the arrival day at Jool, but the time of the Eve periapsis should be within +/- 6 hours of day 195.65, the first two K's can be off by +/-18 hours or so.

When I wrote Flyby Finder KSP only used Earth time (24 hours in a day, 365 days in a year) so most of my work uses that time mode, nowadays the Kerbal system of 6 hour days and 426-day years is generally used. Lambert translates from Earth time to Kerbal time if you need it.

Be careful if you try the windows I've haven't, with some of them the final Kerbin flyby is dangerously low and some luck will be required to be able to make the final K-J leg without a big correction burn.

 

may i please know how you find these windows? what mathematics are required? i really would like to expand on this and find more.