Specific transfer window

[JacobTheFoxx]

Hi, so I have a craft that I want to take to Laythe, but I don't have enough Δ/v to get there direct, so I want to know what the transfer window dates are for the Kerbin -Eve - Kerbin - Kerbin - Jool transfer window. Three dates for it would be appreciated if possible. If there is any website/program that can find these transfers for me that'd also be great!

Thanks,
Jacob.

[4x4cheesecake]

2 hours ago, JacobTheFoxx said:

If there is any website/program that can find these transfers for me that'd also be great!

I guess you're looking for a tool like FlybyFinder or KSPTOT. Multiple flybys are complicated and so are these tools, you should definitly read a bit through the threads. 

I've done a few runs of FlybyFinder and the earliest transfer window I've found begins in Y4 D90:

Spoiler

Start Planet: Kerbin
Orbit Departure Time:
   29527200 seconds UT
   1368 days UT
   Y4   D90   H0
Start Orbit Inclination: -1,3 degrees
Start Boost from that incl.: 1400 m/s
Start Equatorial Z velocity: -85 m/s
Start Equat. Prograde velocity: 1399 m/s
Start Boost from Equat. Orbit: 1401 m/s
V Infinity Leaving Start Planet: 1813 m/s

1st Encounter Planet: Eve
Time from Start to 1st Encounter: 200 days 0 hours
Vinf in: 3790 m/s
Brake to Orbit?: 2686 m/s
1st Encounter Periapsis:
   1568 days UT
   Y4   D290   H0
   112 km altitude

2nd Encounter Planet: Kerbin
Time from 1st to 2nd Encounter: 866 days 0,2 hours
Vinf in: 5218 m/s
Brake to Orbit?: 3856 m/s
2nd Encounter Periapsis:
   2434,04 days UT
   Y6   D304   H0,2
   182 km altitude

3rd Encounter Planet: Jool
Time from 2nd to 3rd Encounter: 776 days 0,7 hours
Vinf in: 2861 m/s
Brake to Orbit?: 3104 m/s
3rd Encounter Periapsis:
   3210,16 days UT
   Y8   D228   H0,9

Total delta V expended: 4505 m/s
Total Travel Time: 1842 days
Total Travel Time: 4,3 years

dV required for this transfer is ~1400m/s but you will definitly need a bit more to do some corrections on your way since it is pretty much impossible to perfectly hit the right angle/burn time to set up multiple flybys in a single burn.
But you should also look at the 'Breaking dv' of ~3100m/s. This is the dV which would be required to break into an orbit around Jool. Well, usually another gravity assist of Tylo and/or Laythe will capture you around Jool as well, but 3100m/s is pretty high anyway.

If you don't already got a mod to edit maneuver nodes, I would highly recommend to get one, for example precise maneuver or precise node. These mods allow you to do some fine adjustments to your maneuver nodes and even more important: to edit the dV values for each direction.

[JacobTheFoxx]

Thank you!

[Rayder]

8 hours ago, 4x4cheesecake said:

...you will definitly need a bit more to do some corrections on your way...

Agreed. Hitting the right windows is already difficult as it is. I can also recommend Precise Manoeuvre. Adjusting nodes really early is almost impossible to do by hand. The adjustments are just way too big.

9 hours ago, 4x4cheesecake said:

usually another gravity assist of Tylo and/or Laythe will capture you around Jool

Dropping down from Tylo would be a good idea - no atmosphere means you can get nice and close. You could even try to line it up with Laythe direct then aerocapture - means insertion into Laythe could be almost free.