School bus : a "Level up" mission design

[Warzouz]

I was reading about experience and planning a mission from my next career game. I find the experience very grindy. So I would like to build a one shot mission to train Kerbal up to level 5. The mission is designed to be done mid-game with limited resources and skills

Here is the mission plan

• Orbit Kerbin (2)
• Orbit Kerbol (6)
• Orbit Jool (9)
• Fly by Tylo (8)
• Fly by Laythe (8)
• Flyby Vall (8)
• Orbit Bop (12)
• Orbit Pol (12)
• Return to Kerbin

That should give 65xp, it's level 5 !

I chose no to plant flag or land to save time and fuel. Landing would allow to do one less flyby, but those are easy to get in Jool system.

 

Assuming no refuel, what dV would you pack for such a mission ?

Constraints :

• Departing from LKO (I find easier to design a mission that way)
• Not too technical gravity assist at Laythe/Tylo (but that's a good way to do fly-by

2 options for return:

• Option 1 = non reusable vehicle : the ship can aerobrake / aerocapture then land on Kerbin
• Option 2 = reusable vehicle : the ship has to dock at LKO (so do a proper interplanetary travel back and not a quick and dirty intercept)

 

What would be your flight plan ?

I would say try to do a gravity assist at Tylo so I could be on an elliptic orbit that could cross Vall and Laythe at a reasonable cost

Then go to Bop and Pol

Finally, from Pol dive to Jool and burn to escape SOI at Pe

[Snark]

Here's my two cents:

First-- I assume you're doing this just for the heck (challenge) of it rather than practical reasons?  I only mention it because simply launching a mission that peeks outside Kerbin's SoI and returns will get you to level 3, and there's really not much practical benefit to going all the way to 5.  So I'll assume that that's not a factor, and the simple answer of "skip the whole mission and do an SoI peek" is off the table.

You mention that adding a landing would skip the need for a flyby.  In that case, I'd suggest that it's worth landing on Pol.  Pol is so tiny, and its escape velocity so low, that if you're already in orbit around it, you might as well land.  Would take just a couple of minutes and minimal fuel.  I assume you're going to be sending a mission with a whole lot of kerbals on it so that you can train 'em all in one whack.  In that case, it's fine not to plant flags (when you've got a dozen or more kerbals, it's an incredible pain to take them all out one by one to plant flags and get back in again; IMHO the "plant flag for XP" mechanic is a silly one, landing should be sufficient), but simply landing and taking off again is quick and easy.

More to the point:  it's faster, easier, and takes less of your time than setting up an additional inter-moon transfer.  For example, if you can skip  Bop (which is another oddball orbit that takes some fiddling to get an intercept with), so that you just do flybys of the three inner (circular, coplanar) moons, your life gets a lot easier.

One of the handy things about those inner moons is that they are 1. packed close together, and 2. lugging large SoIs around with them.  This means it's very easy to set up flyby encounters with them.  All you need to do is make a very elliptical orbit whose Pe is down close to Jool (below Laythe), and whose Ap is quite high, and you can get flybys practically for free.

So here's the minimal-dV, minimal-elbow-grease flight plan that I would suggest:

1. Arrive from Kerbin.
2. Use a reverse gravity assist from Tylo or Laythe to capture to capture to a highly eccentric equatorial orbit of Jool with a very low Pe and a high Pe that's up around Pol.
   • This takes care of one of your flybys.
   • It expends minimal dV, since, first, "highly eccentric with low Pe and high Ap" is the cheapest-dV orbit to capture to, and, second, the gravity assist is helping.
3. Spend some time looping around Jool to get flybys of Vall and whichever one of Tylo-or-Laythe wasn't the one you used in the gravity assist.
   • Your orbit crosses all of them, so you can get this for practically zero dV if you're willing to just watch and wait.
   • That said, you can hurry it along a bit by doing tiny-dV burns when you're way out at Ap.  This can both speed up the process, and help avoid getting flybys that are too close and end up disturbing your orbit too much.
4. Once you have all your flybys, set up an encounter with Pol.  If you do this when you're out at Jool apoapsis, it shouldn't take a lot of dV.
5. Arrive at Pol, capture to orbit.
6. Land.
7. Take off, dive to Jool, slingshot home.

I would also add that you could top off your journey with a Mun flyby, for minimal effort and almost no dV expenditure.  Given that you're coming home all the way from Jool, it'll take a year or two to get back.  For a journey that long, only a very tiny tweak at the start can change the date of your Kerbin arrival by several days.  So you can use a little nudge at the start of your homeward trip to delay or advance your Kerbin arrival by a day or two, so that the Mun gets in the way and you brush its SoI on the way in to Kerbin.  Practically free, and it buys you a few extra XP.  Not many, but hey, why not? 

Edited January 5, 2016 by Snark

[Streetwind]

There isn't really an easy answer to this, because your dV expenditure will depend strongly on your trajectories inside the Jool system, and the alignment of the moons at the time you arrive (and the way that alignment develops as you check off your various objectives). Even someone who has already done this exact mission will not be able to tell you a figure you can replicate exactly.

However, you can use a dV map to place rough constraints on your dV needed. For example, a Jool mission starting from LKO and returning directly to Kerbin (Mun assist, aerobraking) without major propulsive factors requires at least 3250 m/s to get to Jool, barely capture, and then head back under the most optimal of conditions. A more realistic assessment might name 3750 m/s for doing this, which includes a plane change and some other less-than-ideal starting conditions. Since you're not sounding overly confident, make it a flat 4000 m/s for safety. Unfortunately this is split between the trip there and the trip back, so you cannot comfortably sequester it in a dedicated stage. Staging at least once during the mission is still the way to go, though, since - if I understand your plan correctly - you don't have the LV-N available to you.

Then you need to maneuver around the Jool system itself. This is the almost impossible to plan part. You can for example try to add up the dV cost of intercepting each of Jool's moons and returning to your highly elliptcal Jool orbit in between, but that's not how you fly around the Jool system. Especially not if you're after a series of flybys. For starters, you can get at least one flyby of the inner moons completely free of charge - either because you're using Tylo or Laythe as a dV saver for capturing at Jool, or because you made sure that the elliptical orbit you captured into eventually leads to an encounter automatically. If you are not doing one of these two approaches, you're doing it wrong Though I recommend the former option.

Because Laythe, Tylo and Vall are in roughly the same plane, you should be able to get all three of them with minimal propulsive effort - perhaps they can just gravity kick you from one to the other. You'd be surprised how little effort that takes, if you get the initial trajectory right. Make sure Vall is not last in the series, so you can use one of the other two, heavier moons for your plane change towards Bop. Since Bop requires a much larger plane change than Pol, you should use the gravity assist for Bop. Since Bop is not a flyby target, but rather an orbit target, getting to Pol will be different from the rest of your maneuvers; it'll feel exactly like making an interplanetary transfer, except the center body is Jool, not the sun. Unfortunately the dV maps don't usually help with inter-satellite transfers.

So I'd recommend the following flight plan:
Kerbin ejection & Jool transfer -> Laythe gravity assist into Jool capture, flinging you towards -> Vall flyby, flinging you towards -> Tylo flyby, flinging you towards -> transfer to Bop orbit -> wait for Pol transfer window -> transfer to Pol orbit -> wait for Kerbin transfer window -> transfer to Tylo or Laythe flyby, flinging you towards -> Jool ejection & Kerbin transfer.

Remember that your flybys don't have to happen on the first orbit - looping around Jool several times between each encounter is perfectly fine. You'll have plenty of time before your return window opens. Use the maneuver node orbit-forward feature to check for, and plan, future encounters.

For maneuvering around the Jool system like this, I would - pure gut feeling - budget around 2000 m/s. It's really hard to say. So much depends on variables and getting the trajectories right, and I've personally never done a Bop -> Pol transfer. Alexmoon's calculator gives some windows with as little as 235 m/s for this, but most windows are also around 400-500 instead, and a lot of out-of-window ransfers range around 1000 - that's how much variance there is just for this one element. How much you ultimately end up paying depends on which kind of, and how many, Bop -> Pol windows you get before your Kerbin return window draws near and forces you to transfer.

 

TL;DR: Two-stage expendable vehicle, ~3000 m/s in each stage should do it with a high likelyhood. And those numbers are easily achievable with poodles/terriers. Even if you add another 500 to each for safety margin (and you can use any excess fuel to avoid/mitigate the risky aerocapture at Kerbin).

 

Edited January 5, 2016 by Streetwind

[steuben]

mid-game ... so level 6 fully researched? with one or two level 7s?

how many kerbals? though if you can get one on that tour you can get 16 for a minimal mass increment.

If my math is right it would be roughly 13 to 15 kps delta-v, correct?

Edited January 5, 2016 by steuben

[Warzouz]

12 minutes ago, steuben said:

mid-game ... so level 6 fully researched? with one or two level 7s?

how many kerbals? though if you can get one on that tour you can get 16 for a minimal mass increment.

If my math is right it would be roughly 13 to 15 kps delta-v, correct?

For tech level, I don't have a precise idea. What I call "mid-game" is when you nearly unlock all the tech tree. When you are at that level, you have only a few kerbals up to level 3, most of them will be level 2.

13 to 15 km/s ??? I suppose you include the launch to LKO. I find that very high.

Going to Jool is nearly 2200m/s. Coming back would cost 1000/1200 for a aero-capture at Kerbin or 2200m/s if circularizing at LKO for docking without aero capture (including a worst case scenario about plane change)  - from an eliptic Jool orbit.

But I've a harder time to calculate what I need to do 3 fly-by (Laythe, Vall and Tylo) and 2 orbiting (Bop/Pol). I suppose this shouldn't be too expensive. Reasonable gravity assist should help on decelerating. Maybe some aerobrake at Laythe could help (I plan to add a big heat shield upfront)

I think this can be done with less than 5000m/s (not counting launch to LKO) in option 1. 1800m/s should be enough to get 3 flyby and orbiting Bop and Pol (cheap moons).

Finally for the size/stages/structure of the ship, that doesn't matter too much. I'm pretty sure I will use a MK3 passenger ans some adapters. The ship will be crude, it's not an exploration ship.

 

 

[Warzouz]

50 minutes ago, Streetwind said:

There isn't really an easy answer to this, because your dV expenditure will depend strongly on your trajectories inside the Jool system, and the alignment of the moons at the time you arrive (and the way that alignment develops as you check off your various objectives). Even someone who has already done this exact mission will not be able to tell you a figure you can replicate exactly.

However, you can use a dV map to place rough constraints on your dV needed. For example, a Jool mission starting from LKO and returning directly to Kerbin (Mun assist, aerobraking) without major propulsive factors requires at least 3250 m/s to get to Jool, barely capture, and then head back under the most optimal of conditions. A more realistic assessment might name 3750 m/s for doing this, which includes a plane change and some other less-than-ideal starting conditions. Since you're not sounding overly confident, make it a flat 4000 m/s for safety. Unfortunately this is split between the trip there and the trip back, so you cannot comfortably sequester it in a dedicated stage. Staging at least once during the mission is still the way to go, though, since - if I understand your plan correctly - you don't have the LV-N available to you.

Then you need to maneuver around the Jool system itself. This is the almost impossible to plan part. You can for example try to add up the dV cost of intercepting each of Jool's moons and returning to your highly elliptcal Jool orbit in between, but that's not how you fly around the Jool system. Especially not if you're after a series of flybys. For starters, you can get at least one flyby of the inner moons completely free of charge - either because you're using Tylo or Laythe as a dV saver for capturing at Jool, or because you made sure that the elliptical orbit you captured into eventually leads to an encounter automatically. If you are not doing one of these two approaches, you're doing it wrong Though I recommend the former option.

Because Laythe, Tylo and Vall are in roughly the same plane, you should be able to get all three of them with minimal propulsive effort - perhaps they can just gravity kick you from one to the other. You'd be surprised how little effort that takes, if you get the initial trajectory right. Make sure Vall is not last in the series, so you can use one of the other two, heavier moons for your plane change towards Bop. Since Bop requires a much larger plane change than Pol, you should use the gravity assist for Bop. Since Bop is not a flyby target, but rather an orbit target, getting to Pol will be different from the rest of your maneuvers; it'll feel exactly like making an interplanetary transfer, except the center body is Jool, not the sun. Unfortunately the dV maps don't usually help with inter-satellite transfers.

So I'd recommend the following flight plan:
Kerbin ejection & Jool transfer -> Laythe gravity assist into Jool capture, flinging you towards -> Vall flyby, flinging you towards -> Tylo flyby, flinging you towards -> transfer to Bop orbit -> wait for Pol transfer window -> transfer to Pol orbit -> wait for Kerbin transfer window -> transfer to Tylo or Laythe flyby, flinging you towards -> Jool ejection & Kerbin transfer.

Remember that your flybys don't have to happen on the first orbit - looping around Jool several times between each encounter is perfectly fine. You'll have plenty of time before your return window opens. Use the maneuver node orbit-forward feature to check for, and plan, future encounters.

For maneuvering around the Jool system like this, I would - pure gut feeling - budget around 2000 m/s. It's really hard to say. So much depends on variables and getting the trajectories right, and I've personally never done a Bop -> Pol transfer. Alexmoon's calculator gives some windows with as little as 235 m/s for this, but most windows are also around 400-500 instead, and a lot of out-of-window ransfers range around 1000 - that's how much variance there is just for this one element. How much you ultimately end up paying depends on which kind of, and how many, Bop -> Pol windows you get before your Kerbin return window draws near and forces you to transfer.

 

TL;DR: Two-stage expendable vehicle, ~3000 m/s in each stage should do it with a high likelyhood. And those numbers are easily achievable with poodles/terriers. Even if you add another 500 to each for safety margin (and you can use any excess fuel to avoid/mitigate the risky aerocapture at Kerbin).

 

I agree with you but the dV map is only valid for transfers from Kerbin (even, I'm not sure about "to Kerbin"). There was a dV map for Jool system, which was quite hard to understand. The classic dV map is a non-sense when you go from Laythe to Vall, you don't get to a hyper elliptic orbit from Jool LO to Jool nearly escape Ap.

My first quick an dirty design is 5800m/s with 2 LVN for a total of 45 tons (wet). It carries 16 kerbals, has a large heatshield and 1 ton of undefined stuff (energy, chutes, airbrakes,). This is for a direct to land ship (option 1). For a circularizing option, I would remove the heatshield and cutes, but add a docking ring and RCS fuel and packs. I should alos add the plane change transfer cost and the kerbin circularizing (total 1200m/s)

I'm not sure about the frontal heatshield. I chose the biggest one with a fuelled adapter. I hope this can handle the ship reentry as high speed (of course I would burn all the fuel left before entering atmosphere).

[steuben]

I do have some aggressive dv numbers in there, and don't include aerobraking. 

950 from LKO to Kerbin SOI
1250 to Jool SOI
160 to Jool Orbit
400 to Tylo SOI
1100 to Tylo Orbit
400 to Tylo SOI
930 to Laythe SOI
1070 to Laythe Orbit
930 to Laythe SOI
620 to Vall SOI
910 to Vall Orbit
620 to Vall SOI
2660 to Bop SOI
900 to Bop orbit
220 to Bop SOI
760 to Pol SOI
820 to Pol Orbit
160 to Pol SOI
160 to Jool SOI
1250 to Kerbin SOI
950 to LKO
total 16860 m/s

The numbers are pulled from the subway map,  http://wiki.kerbalspaceprogram.com/wiki/Cheat_sheet

Given you are only doing flybys of Tylo, Laythe and Vall you can shave about 2.5 to 3 km/s off those numbers. Patience and some good orbit planning, like Streetwind mentioned, can shave off a lot of the plane changes so maybe another 2 km/s.

 

 

[Streetwind]

14 minutes ago, steuben said:

I do have some aggressive dv numbers in there, and don't include aerobraking. 

950 from LKO to Kerbin SOI
1250 to Jool SOI
160 to Jool Orbit
400 to Tylo SOI
1100 to Tylo Orbit
400 to Tylo SOI
930 to Laythe SOI
1070 to Laythe Orbit
930 to Laythe SOI
620 to Vall SOI
910 to Vall Orbit
620 to Vall SOI
2660 to Bop SOI
900 to Bop orbit
220 to Bop SOI
760 to Pol SOI
820 to Pol Orbit
160 to Pol SOI
160 to Jool SOI
1250 to Kerbin SOI
950 to LKO
total 16860 m/s

The numbers are pulled from the subway map,  http://wiki.kerbalspaceprogram.com/wiki/Cheat_sheet

Given you are only doing flybys of Tylo, Laythe and Vall you can shave about 2.5 to 3 km/s off those numbers. Patience and some good orbit planning, like Streetwind mentioned, can shave off a lot of the plane changes so maybe another 2 km/s.

 

 

You're misreading that dV map, I'm afraid.

To get credit for orbiting a body, you don't need to circularize 10km over the surface, which is what the dV map numbers are for. You only need to capture into a highly eccentric orbit. The map gives those figures for planets, but not for moons.

Then there's the fact that you're adding steps to orbit bodies that Warzouz only wants flybys of.

Additionally, you're backtracking after each of your encounters - you include dV to re-establish the highly eccentric Jool orbit after you have encountered each moon. If you think about it for a moment, there's no way anyone would fly that way, right? At minimum you would choose a direct hohmann transfer from moon to moon. After all, to go from Kerbin to Duna you don't establish an eccentric solar orbit first, only to lower it back down again after you get a Duna encounter!

And then finally, you assume that absolutely every step is done propulsively, without any gravity asissts... which are a dime a dozen around Jool (and in fact, probably unavoidable even if you wanted to).

That's why your figures are so much higher than you'd realistically need.

 

Edited January 5, 2016 by Streetwind

[Warzouz]

39 minutes ago, steuben said:

I do have some aggressive dv numbers in there, and don't include aerobraking. 

950 from LKO to Kerbin SOI
...
950 to LKO
total 16860 m/s

The numbers are pulled from the subway map,  http://wiki.kerbalspaceprogram.com/wiki/Cheat_sheet

Given you are only doing flybys of Tylo, Laythe and Vall you can shave about 2.5 to 3 km/s off those numbers. Patience and some good orbit planning, like Streetwind mentioned, can shave off a lot of the plane changes so maybe another 2 km/s.

This are wrong numbers. This dV map is meant to be used from Kerbin TO ONE target body only. You don't need that much to go from Bop to Pol. When you're on a Bop orbit you don't set your PE to 210km and your AP to near escape, then do plane change and go to Pol. You do a interplanetary transfert. But you need to use another dV Map (I have on my computer at home but I can't find on the forum

EDIT : Google is my friend. The Jool dV Map with a example from Laythe to Pol

 

For example to go from Laythe to Pol with

• Jool dV map : 1350m/s
• Alexmoon tool : 1220m/s
• Kerbol map : 5200m/s (what you're using)

Other example to go from Bop to Pol

• Jool dV map : 220m/s (doesn't count plane change)
• Alexmoon tool : 430m/s (but I found a 230 by waiting longer)
• Kerbol map : 1800m/s (what you're using)

 

 

Edited January 5, 2016 by Warzouz

[Warzouz]

Snark, I checked if I could avoid Bop (I hate this moon...) and land on Pol instead, but the whole trip would give 59XP instead of 65 (62 with the mun fly-by). I would miss level 5. A Mun flyby would only give 3 points. Maybe a Vall landing could be possible, but that would cost a lot. I also studied a refuel at Vall (in my current game, I've a station there), but when I'll try that (in 1.1), I wouldn't have space station there yet.

I think, I'll go for a 6500m/s ship.

And BTW, it's true, it's for the challenge and a bit of RP

[Snark]

1 hour ago, Warzouz said:

Snark, I checked if I could avoid Bop (I hate this moon...) and land on Pol instead, but the whole trip would give 59XP instead of 65 (62 with the mun fly-by). I would miss level 5. A Mun flyby would only give 3 points. Maybe a Vall landing could be possible, but that would cost a lot.

So near and yet so far.... bummer!  Yeah, landing on Vall's a big deal, especially compared with a flyby which is totally free.

Maybe a follow-up mission to swing past Minmus, so you don't have to go to Bop?

Anyway, whatever you decide, good luck with the field trip!

[StarManta]

Just want to add that the "School Bus" name for this mission is absolutely perfect...

[fourfa]

School Bus Challenge: minimum dV expended to reach 65 XP

[Warzouz]

I started a mission. The ship is 6470m/s. I'll keep a log of the burns I do.

 

So far I got a Tylo + Vall encounter for 1.2m/s

[Snark]

21 minutes ago, Warzouz said:

I started a mission. The ship is 6470m/s. I'll keep a log of the burns I do.

 

So far I got a Tylo + Vall encounter for 1.2m/s

Sounds like the kind of situation where multi-orbit advance planning could come in handy. 

 

[Warzouz]

Advancement detail

• Escape burn 1925m/s (from 200km - 10 min)
• Jool plane change 210m/s (DN was very near Kerbin) but I got a Tylo encounter
• Tuning in Kerbol SOI : 1.2m/s (got a vall encounter)
• Tuning before Vall : 3.7m/s (got a Laythe encounter)
• Tuning before Laythe : 9.1m/s (got a very far DN with Bop)
• Bop plane change : 250m/s (Ap is on Bop Dn, cool)
• Random node tweaking 200m/s : Bop encounter ...
• Avoid crashing into Bop = 12m/s
• Circularizing at Bop = 80m/s
• Escape + partial plane change = 247m/s (a very dirty interplanetary transfer...)
• Final plane change 50m/s with Pol
• Random node tweaking 40m/s : Pol encounter
• Circularizing at Pol = 65m/s
• Dirty escape from Pol/Jool and partial plane change with Kerbin : 1280m/s (I missed the window and don't want to wait)
• Final plane change and Kerbin encounter = 150m/s

When entering Kerbin SOI, I've 1650m/s left,

EDIT : I mess my encounter with Kerbin. I was too eager to finish that experiment and arrived at Kerbin at 6500m/s... I should have waited for a proper and less expensive return.

In the end, I Got the School bus in dV = 4800m/s

Edited January 6, 2016 by Warzouz

[Warzouz]

On 5/1/2016 at 7:00 PM, Snark said:

So near and yet so far.... bummer!  Yeah, landing on Vall's a big deal, especially compared with a flyby which is totally free.

Maybe a follow-up mission to swing past Minmus, so you don't have to go to Bop?

Anyway, whatever you decide, good luck with the field trip!

After rechecking, I forgot I could graze the laythe upper atmoshpere.

Question : does grazing atmosphere count as FLIGHT ? or does the ship has to be on suborbital ?

If it counts, that would lead us to

• Current option : 65xp
• Removing Bop orbit and flyby : -12xp
• Adding a Laythe flight bonus : +4xp
• Landing at Pol bonus : +6.4xp
• Total = 63.4xp (aaaarrrgh, 0.6 missing!)

I could add a Mun Flyby for 2 points, but that may not be too easy to get and further more, I may not be able to aerobrake at Kerbin, so I should pack more fuel.

Or : aerocapture at kerbin until Ap is on Mun orbit wait for an encounter.

[RexKramer]

On January 5, 2016 at 3:54 AM, Warzouz said:

Here is the mission plan

• Orbit Kerbin (2)
• Orbit Kerbol (6)
• Orbit Jool (9)
• Fly by Tylo (8)
• Fly by Laythe (8)
• Flyby Vall (8)
• Orbit Bop (12)
• Orbit Pol (12)
• Return to Kerbin

That should give 65xp, it's level 5 !

Warzouz, that's a great idea, which I plan on borrowing!  I usually have a mining/refueling operation set up at Bop or Pol, so that will make my adventure easier to do.

[juanml82]

This is a great idea. Too bad by the time the first transfer windows to Jool opens in a career game I don't usually have that many astronauts.

Anyway, what I'd do is to skip Bop, but send level 1 or 2 kerbonauts by having them orbit Mun and Minmus (if they weren't rescued there, that's it) before hand.

Or maybe there is the chance to do something like Jool-Duna-Kerbin or Jool-Eve-Kerbin, although making it to Kerbin after a flyby in either body should be tricky and fuel expensive. Or can you skip Bop but orbit all three major moons? How much fuel is that? Laythe has an atmosphere, so there is the option to aerobreak

Edited February 15, 2016 by juanml82

[LiveHereNow]

On January 5, 2016 at 3:22 PM, Warzouz said:

I started a mission. The ship is 6470m/s. I'll keep a log of the burns I do.

 

So far I got a Tylo + Vall encounter for 1.2m/s

Can you post pictures of the craft?  I'm curious what you're using for a "bus" and want to get some ideas.  I really like this idea and am thinking of doing something similar.

[Snark]

14 hours ago, Warzouz said:

Question : does grazing atmosphere count as FLIGHT ? or does the ship has to be on suborbital ?

Grazing atmosphere doesn't count as flight if you are on an escape trajectory.

You don't have to be suborbital.  Orbital is fine, i.e. an orbit where the Pe happens to dip into atmosphere.  But you can't just go flying past and touch atmosphere-- they did that by design, specifically to prevent the exact thing that you had in mind.

[Warzouz]

12 hours ago, LiveHereNow said:

Can you post pictures of the craft?  I'm curious what you're using for a "bus" and want to get some ideas.  I really like this idea and am thinking of doing something similar.

No I don't have but I still have the ship. It was q quick and dirty ship, just to test the navigation. I used a MK3 passenger module some fuel tank, a large heat shield at the front and LVN engines at the back with coolers. There wasn't any command pods but a probe core and some reactions wheels and solar panels (sufficient as my vehicle wasn't power hungry)

As it was a test run, I hyperedited it to LKO. The ship has really nothing special. Just a dV, engines and passenger capacity.

[Warzouz]

8 hours ago, Snark said:

Grazing atmosphere doesn't count as flight if you are on an escape trajectory.

You don't have to be suborbital.  Orbital is fine, i.e. an orbit where the Pe happens to dip into atmosphere.  But you can't just go flying past and touch atmosphere-- they did that by design, specifically to prevent the exact thing that you had in mind.

Sad, so I'm not 0.6xp short but 4.6 short (59.6xp). Orbiting Mun and Minmus are 5xp, that'll do it, but it's a bit complex to do it in only one mission (which was the original concept.

On the other hand, what @juanml82 says makes sense : at the start of the game, you don't have 16 kerbals, and as you may have the technology to go to Jool, you may have several which kerbal already did Mun and Minmus. So the first trip to Jool may not need to go to Bop after all but land at Pol.

[cerberusti]

On 1/5/2016 at 3:15 PM, StarManta said:

Just want to add that the "School Bus" name for this mission is absolutely perfect...

I named mine "JoolBus", and had landings on minmus, bop, pol, and laythe (my JoolBus is a spaceplane).  

It has an ISRU, but I usually do not need to refuel given that it has nukes and the entire trip usually only uses 4 - 7k vaccum dv (out of a bit over 9k in lko).  You pretty much just need to get there, gravity assists make almost everything cheap if you set it up right (a maneuver node editor is highly recommended).

Edited February 19, 2016 by cerberusti

[RexKramer]

I had been using a ferry which could transport 8 Kerbals, and had 7800dv.  I ditched the two Hitchhiker pods for a single MK3 cargo compartment which holds 16 Kerbals.  Dv dropped to 7500, which is still more than enough to get to Jool and back, especially with a fuel operation at Bop.

The ship is only 38 parts, I'm trying hard to keep my part counts as low as possible.  Electric is a single large battery and two RTGs (only need one, the second is for 'just in case').  There's a single RCS tank.  Two large docking ports and a single medium docking port.

I added a single 200kW radiator to help keep the 4 LV-Ns cool.  Eventually heat still becomes a problem, but it takes a very long time.  I also added a single antenna, again a 'just in case' item.

The first couple of photos are docking with a SSTO to transfer Kerbals to/from the surface of Kerbin.  With all the RCS ports I used, it's very easy to dock.  I didn't even put any RCS on the spaceplane, the heavy ferry takes care of all the docking work no problem.

Works great, thanks again Warzouz for the idea.  As long as I'm sending a ship to Jool, might as well take as many Kerbals as possible.

My flight plan has generally been:  Start from Minmus orbit with full fuel, then drop to a Kerbin PE of ~300km for the burn to Jool.  With the initial low thrust to weight ratio, a Kerbin PE of less than 250km isn't really efficient because it takes too long to complete the burn.  About 300km PE gives me enough time to complete the burn to Jool.  After dropping from Minmus, it takes next to nothing to escape Kerbin, so almost your entire burn is raising your Kerbol AP out towards Jool.

My first trip hit flybys of Laythe, Tylo, and Vall, followed by a stop at Bop for refueling, and finally a landing at Pol before departing for home.  However, Bop is a pain because it's off kilter from the rest of the moons.  So my second trip had flybys of Laythe, Tylo and Vall, then I went out to Pol (landing) before going to Bop for a refuel.  Worked much better, and I was able to use Tylo to get my orbit straightened back out before departing for Kerbin.

I have two of these things going now, and am about to launch a third one because I don't like waiting for a ship to get back from Jool.  The spaceplane isn't very efficient, but it is easy to get to orbit, and only costs about 6K funds in fuel to get 16 Kerbals to and from orbit.  

[Warzouz]

BTW, I redid the mission and spent 4650m/s. My ship had 5200m/s (from LKO) and I ditched my engines with 550m/s left in it. Play time : 3 hours.

Gravity assist beauty :