Help with plotting interplanetary trajectories

[Brainlord Mesomorph]

When it came to interplanetary flight, my first instinct was to plot a spoon out maneuver around the back side of the Mun, while the Mun was on the opposite side of Kerbin from the sun (a full Moon).

Done right, this give you free escape velocity out of the Kerbin gravity well into solar orbit at Kerbin distance slightly prograde of Kerbin for the cost of an 800 m/s burn. (to go to the inner solar system, I would go retrograde to Kerbin)

From there, I would plot a transfer orbit, letting the ships float in solar orbit for sometimes 3/4 year. (Good thing Kerbals don’t need air.)

Now I look things up here, and I find launch window calculators, and you guys actually plotting direct Kerbin LKO to Jool transfer orbits. This sounds like a good idea, but with my interplanetary ships (12,000 units of fuel, 2,3 or 4 nuclear engines) a 4 km/s burn would take an hour plus, and I’ll make two orbits of Kerbin in that time. Or actually, not make them, because halfway through the first orbit I am actually burning retrograde, the orbit becomes unstable and I fall out of the sky. (not enough thrust, just like not making orbit, accept from orbit).

For a while, I was thinking about a “departure orbit †at about 1000 km. But now I’m thinking that my original idea might have been better. And instead of massing my fleet in orbit of Kerbin, I should assemble it in solar orbit. prograde of Kerbin, in the weeks just ahead of my launch window.

I’d like to discuss this.

Opinions, comments, questions?

Edited October 21, 2014 by Brainlord Mesomorph

[Aethon]

Ok. We could use some screenshots of your ship.

I'll make some assumptions. Your ship is too damn big. Break it down into 3 or more missions. There are very few reasons to use more than 2 LV-Ns on a craft.

Read the instructions for this and follow them to help you plan windows.: http://alexmoon.github.io/ksp/

The Mun provides very little Oberth effect. Therefore it is almost always best to burn IP directly from LKO.

[Yasmy]

The most fuel efficient way would be to assemble in LKO and do your transfer burn in stages, like the Mars Orbiter Mission (Mangalyaan). Burn for a few minutes each time you reach the correct side of Kerbin, then shut down the engines, complete most of an orbit, and continue elongating your orbit.

Of course, fuel efficiency may not be your priority. If it was, you might not build such monstrous vehicles which take hours to accelerate.

Assembling in high Kerbin orbit or in interplanetary space is always a delta-v loss, but if that doesn't concern you, then go for it.

Another option is to send a fleet of individual rockets.

The beauty of KSP is that you get to try every method. You get to decide what "best" means on a mission-by-mission basis.

You've left such an open ended mission design question for us. What are your concerns? What do you want to do? What sounds fun to you?

[Brainlord Mesomorph]

Ok. We could use some screenshots of your ship.

I'll make some assumptions. Your ship is too damn big. Break it down into 3 or more missions. There are very few reasons to use more than 2 LV-Ns on a craft.

Read the instructions for this and follow them to help you plan windows.: http://alexmoon.github.io/ksp/

The Mun provides very little Oberth effect. Therefore it is almost always best to burn IP directly from LKO.

I got very tired of all of my ships arriving where they were going without enough fuel to get back. So I'm going big.

You want to screen shots and mission parameters, OK.

This is an “Interplanetary Service Module: Model 4 /Nuclear†with extra fuel, carrying a 30 ton “Gamma 1B†lander with extra fuel. It is designated “Moho Rescue One†(seriously, in this game of more than half the ships we make are rescue ships) it supposed to go to Moho to rescue Bob Kerman, who flew a similar ship there, with half as much fuel, and is now out of gas.

It weighs 150 tons, carries 12,000 units of fuel, and gets about 1 m/s per unit of fuel. That gets better as it drops empty tanks. If that’s slightly overkill for the mission that’s good, because that will establish that the ISM4/n is the perfect vehicle for carrying payloads like 50 tons of science to Jool and still having enough fuel for Ops and a return flight. Which are the parameters my upcoming Joolian Exploratory Fleet.

But upon further consideration I’ve decided to (cue the Frank Sinatra music) to do it my way.

I might only be saving 100 m/s with the Oberth maneuver, but there’s no downside to it. And lobbing all the ships into solar orbit gives me much more time to plot their interplanetary burns, to space them hours apart, and to make sure nothing overlaps. (in terms of dispatching a fleet). Not to mention, a 150 ton spaceship flying at 2 kilometers per second less than a kilometer over the surface of the Mun is very exciting!

BTW: I decided I have to totally blog the Joolian Exploratory Fleet, step-by-step live. Which forum should I post that in?

[sedativechunk]

#1: Used a good tool for trajectory planning. First off you need a good tool for interplanetary travel. Personally I like this tool more for plotting trajectories than the alexmoon one:

http://ksp.olex.biz/

The above link will show you where the planets need to be in alignment for doing a successful burn. The customizable "parking orbit" is where you ship currently is in orbit around Kerbin (or whatever planet you are leaving). So if you are in a 80km orbit (80,000 meters) above the surface, you would change that number to 80km. I would recommend avoiding that other site unless you care about exact numbers and the math, otherwise you will confuse yourself. All you have to know is where the planets roughly need to be to do your engine burns.

#2): Start somewhere easy. First and foremost, if you are planning your first interplanetary mission, I recommend you send a probe first and not a kerbal or you will likely lose them. And I recommend your first destination be Duna as it is probably the easiest planet to get to.

3): Understand the basics. When you want to go to a planet that is farther away from the sun (Kerbol), then you want to while at sunset. What does this mean? See the map on the olex.biz site I linked to above? If you set your target to Duna, you will notice that, in your orbit around Kerbin, it tells you to burn about 30 degrees on the bottom right of the orbit. To understand this, look at your orbital map from a top down view. Kerbin, just like everything else, has an orbit with an apoapsis and periapsis. Line up your orbital map exactly as it appears on olex and you can see how Kerbin is moving towards it apopasis. Your ship, even though you are in kerbin traveling at around 2,300~m/s, is still in Kerbin's sphere of influence, and you are actually traveling at Kerbin's velocity around Kerbol.

You want to add velocity into this Kerbin orbit you are in so that your orbit becomes bigger than the one around Kerbin. It's so easy to understand but hard to explain on a forum! Just try to follow exactly how that site shows you where to burn engines.

3) Approach the target closely. Just encounter a planet isn't good enough. If you are going to Duna but you will be 21 million km away from the target, then you will probably not be able to get into a proper orbit. Also, you may come in too fast. To fix this...

1) Get the engine burn right from Kerbin. If you are going to Duna or any planet for that matter, you want your periapsis where your encounter is to be almost in a vertical line with where your apoapsis is at Kerbin. If you encounter Duna too fast in a curved orbit where you aren't meeting at the other side of your orbit, then you will probably be coming in horrendously fast to get into orbit.

2) Get close enough. Once you break free of Kerbin, try to fine turn your orbit along the way. Ideally you should do this when you are past the halway market to your target. You will see a "closest approach" on your encounter. Add a maneuver node and play with it to try to get your orbit as close as possible, within at least 50,000 meters.

4). Build the right ship. Most interplanetary ships are very slow with nuclear engines. They have a high ISP but they lack the thrust that other rockets do. There are a few workarounds to this. Personally on my ship, it makes it harder to launch, but I attach four massive fuel tanks with mainsail engines. These are basically to help me push my rides out of Kerbin's sphere of influence. Once you break free from Kerbin, usually it's pretty easy to line up your target and make orbit. Whatever you do, build your ships as disposable as possible. Use several smaller fuel tanks with fuel lines and eject them once they run out of fuel. For your return trip, ideally you only need one nuclear engine and a fuel tank to come home without all the cargo and other junk you brought to the planet.

I hope this helps!

[Laie]

with my interplanetary ships [...] a 4 km/s burn would take an hour plus,

First off, hardly any destination requires more than 2000-2500m/s on the transfer burn (if you wait for a good launch window, that is). Using launch windows and doing direct transfer burns will also save a lot of dV compared to your approach. On your ship, you coul dprobably starp on twice as many LV-Ns and still have more fuel left in your tank by the time your arrive.

Second: your lander hast the worst engines in the entire game. You could save a lot of weight by using about any other engine.

For a while, I was thinking about a “departure orbit †at about 1000 km. But now I’m thinking that my original idea might have been better. And instead of massing my fleet in orbit of Kerbin, I should assemble it in solar orbit. prograde of Kerbin, in the weeks just ahead of my launch window.

In principle, you could just keep thrusting prograde until you reach escape velocity. It then becomes a question of when to start your burn so that you fly off in the right direction. The Long Burn Calculator may help, but it assumes that you do the plane change in Kerbin SOI.

At any rate, do not start from a 1000km parking orbit. Raise the apoapsis if you must, but keep the periapsis down low. Use the "plus one orbit" thingy on your maneuver node to plan a transfer some days in the future. Then raise your apoapsis, but keep the periapsis at wherever you determined your node needs to be be -- or in case of a low-TWR ship, perhaps a *few* degrees earlier. Add a few m/s on every orbit, beware that you won't encounter the Mun, and make the last burn so that you'll arrive at periapsis in at the pre-determined time. Plan the final maneouver at periapsis. That way, you needn't worry about falling back into Kerbin during your burn.

To that end, it's not necessary to raise apoapsis all the way (where an orbit can take 40 days). An apoapsis well inside Munar SOI still is 80% of Kerbin escape. If the final 200m/s are still a problem, you ship is definitely underpowered.

A really high apoapsis can still be convenient, though. It's many benefit is that it allows for cheap plane changes: on the order of 15m/s for getting from equatorial to polar. But I only recommend this if you have some tool that helps you plan maneuvers that are many orbits in the future -- trying to do this in stock would drive me mad.

[Yasmy]

If you want to save 100 m/s by using the Mun to assist in escaping Kerbin, that's cool and all. It's fun. But it's not a delta-v saving strategy, because if you escape Kerbin, wait for a window, then burn to Jool or Moho, you will spend approximately 1500-1700 m/s more delta-v than burning directly from LKO.

Roughly, without plane changes, to +/- 200 m/s:

Kerbin -> Interplanetary + Interplanetary -> Jool ~= 1000 + 2700 m/s

Kerbin -> Jool ~= 2000 m/s

If you don't care about the extra delta-v, no worries. Do whichever floats your fleet. If you do care, don't park in interplanetary space.

[Brainlord Mesomorph]

If you want to save 100 m/s by using the Mun to assist in escaping Kerbin, that's cool and all. It's fun. But it's not a delta-v saving strategy, because if you escape Kerbin, wait for a window, then burn to Jool or Moho, you will spend approximately 1500-1700 m/s more delta-v than burning directly from LKO.

Roughly, without plane changes, to +/- 200 m/s:

Kerbin -> Interplanetary + Interplanetary -> Jool ~= 1000 + 2700 m/s

Kerbin -> Jool ~= 2000 m/s

If you don't care about the extra delta-v, no worries. Do whichever floats your fleet. If you do care, don't park in interplanetary space.

OK, my bad.

I had gone to this web page, http://alexmoon.github.io/ksp/ to calculate my launch window and I misread the webpage. At the bottom there is a figure for total delta V, but that of course includes the orbital insertion burn when you get there. That’s why I was thinking that I needed a 4 km/s burn, Its actually two 2 km/s burns.

Secondly, it’s taken me a lot of armchair physics to realize that you *are* getting a gravity assist from Kerbin when you launch from Kerbin orbit. If you were flying straight away from the planet (Star Trek style) that wouldn’t be the case, but we’re not, we’re doing a prograde burn around the planet, so yes the gravity of the planet is helping.

And I’m glad I started this conversation, now it looks like I will need a “departure orbit†but that will be a highly eccentric orbit achieved by a series of perigee burns. The question becomes which direction it should be eccentric in, and I think I have an answer for that.

First I should plot a direct transfer orbit from LKO to Moho (or later Jool) even though I won’t be able to do that in one burn. That should be the point for my repetitive perigee burns, right? (that should make the eccentric in the right direction)

Than after I’ve achieved the eccentric orbit re-plot the transfer orbit, which should start just about at perigee, right?

[mhoram]

Secondly, it’s taken me a lot of armchair physics to realize that you *are* getting a gravity assist from Kerbin when you launch from Kerbin orbit. If you were flying straight away from the planet (Star Trek style) that wouldn’t be the case, but we’re not, we’re doing a prograde burn around the planet, so yes the gravity of the planet is helping.

Actually using a gravity assist by Kerbin requires two steps:

- enter Kerbins SOI

- exit Kerbins SOI

in the method you describe you only leave Kerbins SOI, so this is not a gravity assist in the usual meaning.

However since you make your departure burn in Low Kerbin Orbit, you utilize the gravity of Kerbin and this is called the Oberth effect.

First I should plot a direct transfer orbit from LKO to Moho (or later Jool) even though I won’t be able to do that in one burn. That should be the point for my repetitive perigee burns, right? (that should make the eccentric in the right direction)

Than after I’ve achieved the eccentric orbit re-plot the transfer orbit, which should start just about at perigee, right?

If you intend to achieve a highly elliptical orbit around Kerbin (Periapsis near SOI border), you will need around 50 Kerbin-days (if I recall it correctly) to travel from Periapsis to Periapsis.

Since in this time the planets move considerably, I recommend to make the repetitive Periapsis-Burns before the plotted direct transfer orbit from LKO to Moho or Jool.

Edited September 26, 2015 by mhoram
typo

[Brainlord Mesomorph]

OK, OK, OK…. I think I get this now.

To recap: it’s not a 4000 m/s burn it’s a 2000m/s burn. But the problem remains that my ship is big and slow and it takes half an hour to execute the burn and by ship is well off course by the time the burn is complete.

In the real world, NASA would execute a series of perigee burns lengthening the orbit in exactly the right direction until a final escape burn. But I don’t have a team of Kerbals with slide rules to figure that out for me.

Another way of looking at the problem would be to say that the KSP navigation system is flawed. (please no flame, I mean no disrespect, I love this game!) But their system assumes that you have speed “A†until you reach the node and then have speed “B†immediately after. It makes no allowance for the length of the burn. Indeed that’s part of the game, guessing when to begin and end the burn. (I would assume NASA’s nav system tells you when to begin and end your burn)

But what if you were to break the burn up into several pieces? Or to say that another way; plot one burn across several nodes. Here’s what I mean:

I wait until my launch window, I plot one burn from LKO to Moho (or Jool) it’s a 2000m/s burn. But then I *reduce it* to 1000 m/s. That’s a 15 minute burn. Whatever orbit that is doesn't matter. I can start the burn at 7 minutes before the node, end 8 minutes after the node. And then 15 minutes after the first burn and I have plotted a second burn to Moho, this should only be 1000 m/s burn (right?), and would start immediately after the first ends. It’s basically the same thing, but the track in the NAV System is much closer to what the ship is capable of. Which should keep me from falling backwards into Kerbin orbit.

Or maybe its four 500 m/s burns plotted 8 minutes apart. It’s all really the same thing, but it lets me plot a course the ship can actually achieve. Because that’s really the problem, the Nav System is writing checks that the engines can’t cash. I assume guys using Xenon have the same problem.

Does this make any sense?!

Edited October 20, 2014 by Brainlord Mesomorph

[michaelhester07]

I've kept a simpler idea of transfers. It worked for me out to Jool once and Dres, Duna several times and back down to Eve and Moho once. It may not be perfect but here's what I do.

1. Transfer Window: I estimate a transfer window by where the planets are on a "clock", like an old face clock (funny I have to describe it like that ). The transfer window I use is 6:18 to 6:27 on that clock, where kerbin is the hour hand and the target planet is the minute hand. For Eve this also remains true.

2. Ejection direction: From LKO I setup a burn to eject my ship in prograde kerbin orbit when going out, and retrograde kerbin orbit when going in.

3. Try to plot a direct transfer: I plot a transfer burn to get close to the target planet if not dead on (seeing a SOI change on it). If I can get that I'll do the burn.

4. Early transfer corrections: More often than not what looked like a direct transfer changes when I leave kerbin's SOI. A small burn early corrects the intercept.

5. Later transfer corrections: I use kerbal alarm clock to track the transfers so I can do other things in the 66-190 days it takes to transfer. This means I add a late transfer node and make sure that the transfer is still on target, usually 20% of an orbit out from target. Part 4 and 5 burns usually don't take more than 300 d/v since the initial ejection burn setup most of the transfer.

6. Capture burn: When I get into SOI of target I do a capture burn at periapsis until orbit is achieved... unless I don't like the orbit i'll get, then 6b

6b: Orbit correction burn: If the orbit I get when I enter is one I don't want (like a polar orbit around eve) then as soon as possible I'll do an orbit correction burn. Burning toward blue or purple nodes will change the direction I'll get around the planet for a cheap d/v cost.

My latest interplanetary cruiser has an 8000 delta/v capacity with a 2k lander. Since flag contracts I rarely plan for return flight as it is more lucrative to leave the guy on the rock to plant flags whenever they come up.

[mhoram]

OK, OK, OK…. I think I get this now.

To recap: it’s not a 4000 m/s burn it’s a 2000m/s burn. But the problem remains that my ship is big and slow and it takes half an hour to execute the burn and by ship is well off course by the time the burn is complete.

2000m/s in 30 minutes is no fun. I believe that you can circumvent most of your problems by adding more nuclear engines.

[michaelhester07]

Hold the Alt key and you can speed up a NERVA burn with physics warp. Be careful that your ship is well strutted before you go above 2x.

[Brainlord Mesomorph]

Hold the Alt key and you can speed up a NERVA burn with physics warp. Be careful that your ship is well strutted before you go above 2x.

What?

and that sounds like a cheat.

2000m/s in 30 minutes is no fun. I believe that you can circumvent most of your problems by adding more nuclear engines.

She's already in orbit.

and those things are expensive and expensive to loft (I'm in career mode)

I have another design with fewer engines.

And what about my idea of one burn across more than one node? I really think that solves the problem.

Edited October 20, 2014 by Brainlord Mesomorph

[kzauner]

Or maybe its four 500 m/s burns plotted 8 minutes apart. It’s all really the same thing, but it lets me plot a course the ship can actually achieve. Because that’s really the problem, the Nav System is writing checks that the engines can’t cash. I assume guys using Xenon have the same problem.

Does this make any sense?!

Yes. But you can use the transfer-window-planer anyway - especially when it comes to jool, as the window is wide. Take The planers data an plot a course as suggested. Remember that. Now try to get a mün assist that gives you about the same trajectory. One could also calculate that, but I'm a lazy guy. If you fiddle with the nodes a few minutes, you will get an encounter. Takes a little bit of experience, to see when mün will be in about the right position...

[Yasmy]

What?

and that sounds like a cheat.

Physics warp is no more of a cheat than normal warp. Instead of hitting , or . to increase/decrease warp, hit Alt-, or Alt-. to increase physics warp.

During physics warp, the full physics simulation is run, but at a larger time step. To within the accuracy of the physics engine, the results should be the same as at normal speed. But if you have a large, clunky ship, Bad Things can happen, such as Rapid Unplanned Disassembly.

[Kryxal]

6. Capture burn: When I get into SOI of target I do a capture burn at periapsis until orbit is achieved... unless I don't like the orbit i'll get, then 6b

6b: Orbit correction burn: If the orbit I get when I enter is one I don't want (like a polar orbit around eve) then as soon as possible I'll do an orbit correction burn. Burning toward blue or purple nodes will change the direction I'll get around the planet for a cheap d/v cost.

Getting an orbit that crosses the equator at periapsis is generally easy if you set it up early, and a good place for that tends to be about 90 degrees before planetary encounter ... the normal/anti-normal adjustments have a larger effect there. After that, you can just capture into an eccentric orbit, plane-change at apoapsis (more or less), and circularize once you get back to periapsis.

[technion]

One of the difficulties is that every guide ever tells you "USE THE LV-N FOR INTERPLANETARY". But rules are meant to be broken.

Given that Moho requires an exorbitant amount of dv, my winning combination is:

- A return module, with one grey tank and 2 x radial lv-n

- The insertion stage. Under that, one large orange with 2 x LV-N. You can run all four at once to manage the insertion. It doesn't matter if this burn takes eight minutes or whatever, it's the ejection that needs to be precise.

- The transfer stage. 2-4 (depending on payload) radially mounted orange tanks. Asparagus staged with the insertion stage, powered by skippers. I can usually push the whole thing onto a moho intercept with 2-3 minute burn.

The problem with following the "LV-N only" rule is that, while you may shrink your transfer stage two large greys or something, you create a 30 minute ejection burn and you'll actually spent more dv trying to deal with the inaccuracies it causes, not to mention falling asleep doing that ejection.

[Brainlord Mesomorph]

Physics warp is no more of a cheat than normal warp. Instead of hitting , or . to increase/decrease warp, hit Alt-, or Alt-. to increase physics warp.

During physics warp, the full physics simulation is run, but at a larger time step. To within the accuracy of the physics engine, the results should be the same as at normal speed. But if you have a large, clunky ship, Bad Things can happen, such as Rapid Unplanned Disassembly.

But that won't solve the problem that 10 minutes in to the burn the ship is pointing (and moving) in the wrong direction.

it will just do that in five minutes.

[Laie]

Ship's already in space? Well, you made your ship, now fly with it. Or load a savegame and build another vessel. You may also consider sending up another orange tank + docking port + four LV-Ns -- looking at your vessel, I suspect that this would not even hurt delta-V.

First I should plot a direct transfer orbit from LKO to Moho (or later Jool) even though I won’t be able to do that in one burn. That should be the point for my repetitive perigee burns, right? (that should make the eccentric in the right direction)

In principle, yes. But keep in mind that your perigee burns and the orbits between them will take some time: you want your periapsis where it needs to be at the time you come around for the last burn. If you're content with raising your apoapsis by a "mere" 700-800m/s, the whole procedure will take about three or four days. In that case you can determine the periapsis just as you said, a four-day error hardly matters compared to everything else. However, if you want to go all the way to ~1000m/s, the last orbit will take like 40 days to complete.

But what if you were to break the burn up into several pieces? Or to say that another way; plot one burn across several nodes.

Like this? That is a possibility, but leaves you with the problem of how to place a series of nodes -- not easy to do in the stock game. I strongly recommend you get some sort of Maneuver Node Editor before even trying. There's one included in Mechjeb, and at least one standalone mod. Even with a node editor, plotting three to five nodes easily can take up a whole hour of shifting things around before it looks about halfways right. If you're using kOS, I could give you my "manynodes" script that takes an existing node and splits it into an arbitrary number of smaller ones. That's what I used for the picture above.

[Brainlord Mesomorph]

Like this? That is a possibility, but leaves you with the problem of how to place a series of nodes -- not easy to do in the stock game. I strongly recommend you get some sort of Maneuver Node Editor before even trying. There's one included in Mechjeb, and at least one standalone mod. Even with a node editor, plotting three to five nodes easily can take up a whole hour of shifting things around before it looks about halfways right. If you're using kOS, I could give you my "manynodes" script that takes an existing node and splits it into an arbitrary number of smaller ones. That's what I used for the picture above.

EXACTLY!

and I think I have a method for doing it in the stock game! (The trick being that you only need to know the current node and the next node at any given moment, and you have PLENTY of time during one burn to calculate the node after that.)

I have some experiments to run in sandbox mode. (God, I love this game!)

I may have found a few feet on untrodden snow here, I may get to write my own tutorial "Mastering the Long Burn"

I'll get back to you guys in a couple of days.

THANKS!

(kOS exists? I thought that was just a joke on a screen in the new cockpit)

Edited October 21, 2014 by Brainlord Mesomorph

[KerikBalm]

I had gone to this web page, http://alexmoon.github.io/ksp/ to calculate my launch window and I misread the webpage. At the bottom there is a figure for total delta V, but that of course includes the orbital insertion burn when you get there. That’s why I was thinking that I needed a 4 km/s burn, Its actually two 2 km/s burns.

No, it is 1x 2km/s burn if you do it all in one go.

The ~4km/sec numbers you are seeing are to get to jool, and then capture into a low jool orbit, without aerobraking at all (ie, pure rocket thrust).

~2km/sec gets you to Jool

then you aerobrake, then you do a 2nd tiny burn to raise PE.

[Brainlord Mesomorph]

No, it is 1x 2km/s burn if you do it all in one go.

The ~4km/sec numbers you are seeing are to get to jool, and then capture into a low jool orbit, without aerobraking at all (ie, pure rocket thrust).

~2km/sec gets you to Jool

then you aerobrake, then you do a 2nd tiny burn to raise PE.

Current mission is Moho (no atmosphere) but you're right about Jool.

[Laie]

and I think I have a method for doing it in the stock game! (The trick being that you only need to know the current node and the next node at any given moment, and you have PLENTY of time during one burn to calculate the node after that.)

???

Tell me more, like, how do you know when to start without plotting ALL the nodes?

(kOS exists? I thought that was just a joke on a screen in the new cockpit)

http://forum.kerbalspaceprogram.com/threads/68089-0-25-kOS-Scriptable-Autopilot-System-v0-14-2-2014-10-08

Have a look. From what you write, I guess you'd like it.

[metaphor]

I would first plot a trajectory straight to Jool, then burn at that maneuver node/periapsis multiple times to raise your apoapsis up to just inside the Mun's orbit. That should make it only about a 1200 m/s burn left to get to Jool. You can do that at the next periapsis. Don't start too early or you will enter the atmosphere. But just keep burning after you pass periapsis, even if it takes a while, until your solar apoapsis is at Jool's orbit. Then you can do course corrections to get a Jool encounter after leaving Kerbin's SOI.