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# Goat Engineering Inc. needs you!

Go to solution Solved by mabdi36,

## Question

So, first: I know it is kind of selfish this thread, so I think that when you answer my question I will delete this, second: I wrote this here as I guess it fits well with "questions and gameplay" I guess. So, here there is what is happening: I need someone to calculate an absurd amount of Delta-V. And with absurd I mean a grand tour (actually not really "grand") of the kerbol system: a flyby of Dres, Moho, Kerbin, maybe Eeloo, and maybe maybe maybe a Moho lander. All in one. Without mining. I know, it is crazy, but what I just need the Delta-V, the craft I'll do it. Well, if you ask the reason I can tell you that is a long story. Well I hope someone answers... Oh yeah: I only have one month. Yep, I won't make it probably.

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• Solution
Just now, Goaty1208 said:

Well, so I will send three probes.

This is the thing. We can use math to find out how much it would take to travel all these distances. To flyby Moho, and approach at its apoapsis (which is possible due to its argument of perigee), we can use a delta v map to find an intercept with moho takes 1690 m/s from LKO. If you wait for a long, LONG, LONG, LONG, LONG amount of time in game, you MAY be able to get an intercept with Kerbin again without another drop of fuel. Then, if we assume that Moho and Dres are on the same plane (which they are not) and that you will hit Dres' trajectory at periapsis (you probably won't), we can use vis viva to find that that takes 1806 m/s in an absolutely perfect world. Using the same assumptions as last time, we find that an Oberth to Eeloo takes 1444 m/s.

It is needless to say that this arrangement is impossible due to the way the planets are laid out in the game.
Adding the numbers gives 4940m/s. Even though that may sound relatively small, basically ALL of these planets are on different planes, so much say that it is easily safe to say that you may need a 80% margin for orbital maneuvers, boosting it up to 8500m/s. Another cost you will have to pay dearly for is time. You are going to waste so much time, both real time and game time to go to a few different planets, that it is LITERALLY easier to build a completely new rocket.

The d/v may sound like chicken scraps; afterall, that is how much is needed for a duna mission. Remember, though that you need a separate lifter stage to get your Duna rocket into orbit. And without mods, it is even harder.

It is up to you, to make the decision now.

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So, as @jimmymcgoochie and @mabdi36 already wrote: sending separate probes to the planets is the easiest approach.

But if you use gravity assists wisely, then you can do a flyby of all planets with very little dV, as demonstrated by Scott Manley in this video here: Visiting All Kerbal Planets Using Gravity Assists

Another approach would be to build a craft that can get to and land on the farthest planet/moon and then use the minging/ISRU equipment to refuel. You'll still have to plan your journey to get from refueling place to refueling place so it is harder than just sending separate probes, but still easier than figuring out the gravity assists.

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There are some mods that might help you - Where Can I Go, Slingshotter, Astrogator, Transfer Window Planner, MechJeb to name a few. Transfers vary wildly in their delta-V requirements depending on where the planets are and most transfers take a lot longer than a month (or did you mean a real time month not ~30 game days?).

Or use a warp drive mod to warp yourself there, or the cheats to ping your vessel across the solar system at will.

Why do you want to fly by Eeloo, Moho and Dres in one go without refuelling? I would send separate probes to each.

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12 minutes ago, jimmymcgoochie said:

There are some mods that might help you - Where Can I Go, Slingshotter, Astrogator, Transfer Window Planner, MechJeb to name a few. Transfers vary wildly in their delta-V requirements depending on where the planets are and most transfers take a lot longer than a month (or did you mean a real time month not ~30 game days?).

1 I can't use mods as I play on enhanced edition

2 I mean real time.

3 beacuse I need a lot of xbox achievements

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Just now, Goaty1208 said:

1 I can't use mods as I play on enhanced edition

2 I mean real time.

3 beacuse I need a lot of xbox achievements

Exactly. Getting number 3 is absurdly easier if you just send seperate probes, but that is only my two cents.

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3 minutes ago, mabdi36 said:

Exactly. Getting number 3 is absurdly easier if you just send seperate probes, but that is only my two cents.

Well, so I will send three probes.

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So, I decided to go with at least three probes... the Eeloo 1is on it's way. Thanks for the help.

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you can use a single probe if you use gravity slingshots well, like the voyager missions. the voyager missions took advantage of a special alignment of the planets that only happens every century or so. since you can speed up time in the game, you can afford to wait the right moment, and if you want to do something cool, it would be a nice thing to do (in fact, i'm surprised this isn't an achievement on its own). but if you just care for visiting planets, go for different rockets.

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34 minutes ago, king of nowhere said:

you can use a single probe if you use gravity slingshots well, like the voyager missions. the voyager missions took advantage of a special alignment of the planets that only happens every century or so. since you can speed up time in the game, you can afford to wait the right moment, and if you want to do something cool, it would be a nice thing to do (in fact, i'm surprised this isn't an achievement on its own). but if you just care for visiting planets, go for different rockets.

Well, if only 8 years with time warp is a lot, I can't imagine how on Earth... ehrm on Kerbin  how long that could be. Second: me + gravity assist: xbox thrown down the window.

39 minutes ago, king of nowhere said:

(in fact, i'm surprised this isn't an achievement on its own)

me too, because it is such an achievement...

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well, making a gravity assist is not difficult if you don't need to line things up too accurately.

If you want to try, you can use a simple one on mun to escape kerbin gravity. Normally you need about 1000 m/s of delta-v from a low orbit, but you can instead made a burn for about 850 m/s, and direct it to pass close to Mun, and behind it. this will send you on a trajectory away from kerbin. If you do it when Mun is pointing towards the sun, you will lose orbital speed compared to the sun, and will save fuel for visiting the inner planets. If you do it when Mun is away from the sun, you will gain speed, and you can visit the outer planets. I could lower my periapsis enough to intersect Eve with this simple manuever.

now, the actually difficult part is lining things up. If I had wanted to reach my periapsis on Eve's orbit right at the time when Eve is passing there, that would have been much harder (i'll just park on a higher orbit and wait eve to reach me). And if you want to come out from your gravity assist lined up with a planet so you can get a gravity assist from it and reach exactly another planet... well, that's why we have rocket scientists. even with some course correction manuevers, it still requires the planets to be roughly in certain positions.

but performing a basic gravity assist is very simple indeed. try it for a "i am a rocket scientist" feel

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