Grand tour launch windows

[UH60guy]

First off, I am aware of the Interactive illustrated interplanetary guide and calculator for KSP and the Launch Window Planner.

Both are awesome tools and I use them heavily.

What I am looking for is to see if anyone knows of the next logical step in these... basically how can I find a launch window planner for a multi-planet probe? Failing that, is there a good equation to use to get the optimal day of the transfer and flight time?

For example, it could be applied in a Duna/Jool/Eloo probe thusly (simplified here, though I'm sure you'd need a little fudge room for non-optimal transfers):

(planets abbreviated by first letter)

This is a grand tour launch date IF

KD burn date + KD flight time = DJ burn date AND DJ burn date + DJ flight time = JE burn date

Such a launch window would greatly save on DV requirements, as you wouldn't need to circularize at the planets en route, and just use gravity assistance and correction maneuvers to go on to the next one.

Edited January 10, 2014 by UH60guy

[quantumpion]

What we need is a program adapted for KSP, like this: http://epubl.ltu.se/1653-0187/2009/062/LTU-PB-EX-09062-SE.pdf

Now that would be awesome!

[tavert]

Closest thing to what you're asking is http://forum.kerbalspaceprogram.com/threads/36476-WIN-KSP-Trajectory-Optimization-Tool-v0-11-Now-with-Mission-Control-Center%21 - it has some capabilities for gravity assists, up to what's feasible in a reasonable amount of computation without professional research tools.

[quantumpion]

Oooh neato I didn't know about that tool. Thanks!

[Sauron]

Closest thing to what you're asking is http://forum.kerbalspaceprogram.com/threads/36476-WIN-KSP-Trajectory-Optimization-Tool-v0-11-Now-with-Mission-Control-Center%21 - it has some capabilities for gravity assists, up to what's feasible in a reasonable amount of computation without professional research tools.

Whoah! Awesome. I may have to return to the stock solar system to test that out

[Redjoker]

Sorry to burst your bubble, but I believe a Grand Tour usually requires a landing on each body.

[Captain Sierra]

Sorry to burst your bubble, but I believe a Grand Tour usually requires a landing on each body.

He's running Grand Tour Lite. That only necessitates a flyby low enough to do biome-sensitive science, though most people circularize anyways since doing a gravity assist flyby is a hard thing to do. Getting that deep in the gravity well can really bend your trajectory. If you bend it too much, you could end up needing more dV than if you were to do aerocapture (possible on all kerbol-orbiting bodies except Dres, Moho, and Eeloo) and another ejection burn. That said, you'd need to circularize high to keep your ejection burns reasonable if this is an ion probe we are talking about.

[UH60guy]

Right, that's the meaning of "grand tour" I was going for- as used in the real-life Voyager probes where they called it a "grand tour of the outer solar system." I recognize it's come to mean something different in the KSP lexicon, where it does imply a landing on each and every body. My goal is a cheap probe to blast off and get readings in space "high above" multiple planets and to simulate a photo run like Voyager did, using minimal fuel or course changes to accomplish.

In this case it's a personal challenge of orbital dynamics rather than a challenge of designing landers and recovery for each body. Thanks for the tips with the website, I'll have to tinker around quite a bit, and I'll be sure to post something if I can find a once-in-a-lifetime launch window like they did for Voyager.

[TheGeoninja]

Don't think that KSP has any super launch windows were the planets all have close launch windows. If you do this then you are going to have to do multiple burns in between planets.