king of nowhere

it's not a matter of left or right, but of passing in front or behind a planet. if you pass behind a planet, you are accelerated, while if you pass in front of a planet you are slowed down. since all the planets rotate in the same direction, it translates to left and right for a multiple gravity assist, you have to be ejected into an orbit with a duration multiple of the target body - a resonant orbit. that is, if you aim for kerbin and you want to take a second passage, you need to eject into an orbit that lasts exactly 2 years, or 3 years. or 2.5 years, in which case you will meet kerbin 5 years later in a 5:2 resonance. to see how long the new orbit would be, put a maneuver node after the planetary encounter, leave it at 0 m/s; when selecting it, you'll be able to see the orbital time in the lower left corner. this is a common misconceptions: a gravity assist will not slow you down compared to the planet. it will change your speed relative to the sun, or you can get one from a moon and change speed relative to its planet. but your speed relative to the celestial body providing the assist is always the same. so you still should enter aligned with the planetary rotation. Even with gravity assists, a full grand tour requires more deltaV than a ship can reasonably have. so you have a few options if you don't want to mine fuel: 1) use lots of drop tanks 2) use ion engines and lots of xenon I'm not aware of any advanced one - the one linked by @Caerfinon is pretty basic and looks like stuff you already know - but, at the cost of looking crass for shipping my own content, I will point out that in my mission reports I do talk extensively of gravity assists with technical details, because I do think a mission report should allow someone else to replicate what you've done. So I'll link a few chapters dealing with lots of gravity assists: https://forum.kerbalspaceprogram.com/index.php?/topic/203233-lucy-in-the-sky-with-deadly-radiations-3-skys-just-got-a-lot-bigger-kerbalism-opm-grand-tour/&do=findComment&comment=4046683 this first one is a mission to moho using lots of conjoined gravity assists into resonant orbits to lower deltaV cost. https://forum.kerbalspaceprogram.com/index.php?/topic/203233-lucy-in-the-sky-with-deadly-radiations-3-skys-just-got-a-lot-bigger-kerbalism-opm-grand-tour/&do=findComment&comment=4055758 this is the next chapter, detailing the return trip from moho to the mun using eve https://forum.kerbalspaceprogram.com/index.php?/topic/203233-lucy-in-the-sky-with-deadly-radiations-3-skys-just-got-a-lot-bigger-kerbalism-opm-grand-tour/&do=findComment&comment=4068922 this chapter deals mostly with dwindling life support resources, but subchapter 19.2 uses a jool+tylo gravity assist to reduce speed and set up an encounter with kerbin, and 19.4 details a way to turn that into a low speed encounter with duna a few years later. https://forum.kerbalspaceprogram.com/index.php?/topic/208134-lucy-in-the-sky-with-deadly-radiations-4-the-real-sky-this-time/&do=findComment&comment=4139639 4.2 details going from phobos to venus using an earth flyby, and 4.6 the reverse trip, still using an earth flyby https://forum.kerbalspaceprogram.com/index.php?/topic/208134-lucy-in-the-sky-with-deadly-radiations-4-the-real-sky-this-time/&do=findComment&comment=4145720 this chapter is the trip to mercury, which entails the same amount of gravity assist as the trip to moho i linked earlier https://forum.kerbalspaceprogram.com/index.php?/topic/208134-lucy-in-the-sky-with-deadly-radiations-4-the-real-sky-this-time/&do=findComment&comment=4166092 and this final chapter is my greatest achievement in gravity assists: reaching Io, the innermost moon of jupiter, with limited fuel. It includes 30 gravity assists. I do believe you can find more informations there than in most guides.

Part 13: Deep Blue Dot Cylinder goes to a Neptune flyby, drops Clamp on Triton, returns to Uranus for refueling. Two more nuclear reactors are broken, putting strain on the long term energy supply of the mission. Triton with Neptune in background 13.1) How the heck do I eject from this place??? 13.2) Free return trajectory is not for free 13.3) On Neptune 13.4) Return to Titania, now with 50% more plane change Bugs compilation updated Broken parts compilation

Just noticed this report, I'll be following it. Not many people use my style of (detailed) reports. And I'm definitely thinking of trying this pack as soon as I finish my current grand tour. However, if I can give one piece of advice, you should put the reports under spoilers. It makes the page a lot easier to navigate.

you need to pass in front of mun, not behind it. it's basic gravity assist theory: if you pass behind a planet, it will accelerate you, while if you pass in front of it, it will slow you down. as for maneuver nodes not showing much in the future, indeed after a few changes of SoI the game stops showing trajectories. the workaround for that is to set up another maneuver node - keep it at 0 m/s, you don't want to actually make a maneuver there - forward into the future. in this case, you could make it in munar orbit. this will persuade the game to show you your planned trajectory a bit longer

braking in low jool orbit is normally a bad idea; not much because of the cost, as you remarked it is very cheap because Oberth (iirc 200 m/s to get captured arriving from kerbin), but because when you go to jool you always move to a moon afterwards, and to go to a moon a low jool insertion is bad. as you know, the more similar your orbit is to that of your target, the lower the intercept deltaV is going to be; and if you have a periapsis skimming jool's atmosphere, that's going to result into an expensive transfer to whatever moon you're aiming at. this is the second reason you're better off using a gravity capture at tylo or laythe; not only you save the insertion deltaV entirely, you also end up in an orbit with a lower insertion deltaV for the moons. I say it's "normally" a bad idea because there are corner cases where you want to do this: namely, when you come to jool with such a high intercept speed that using gravity capture is impossible, and what you gain by oberth effect far offsets the extra cost of injecting into a moon. not something that happens very often, but if for some reason you're using a high energy trajectory, then this is more efficient. another case where this option is best is for gas giants other than jool; On jool you have two big moons perfect for gravity capture, but there are lots of modded planets out there lacking such luxury. In the OPM system, it can be a good strategy to inject into urlum - though direct injection at wal is often preferrable. For Sarnus and Neidon, aerobraking at tekto and nissee respectively are generally the best options, but injection into low orbit of the gas giant is the next best thing if aerobraking is not possible. In RSS, direct injection into low orbit is the best method of capture for uranus and neptune, because none of their moons are big enough for gravity capture or direct injection. with jupiter direct injection into a moon is often convenient, depending on the mission. as for Saturn, if you're performing a grand tour or similar mission and you're not coming from earth, you generally can aerobrake on titan; but if that's not possible, again, injecting into low orbit is often for the best. so, injection into low orbit on a gas giant is actually the most efficient way to get captured in many cases; however, jool is just so conveniently set to give better options that you don't want to do it there. other modded planets, including the real planets we have in our solar systems, don't have such conveniences and justify that injection strategy

to keep the mission within reasonable mass, you can use an helicopterocket. it's still going to require several tens of tons, though. an example of helicopterocket. at 15 km of altitude it jettisons the helicopter part and goes up like a rocket as for reentry, landing on eve tends to require some careful sequence. here i am first dropping the upper heat shields - which I use as aerobrakes and to keep the craft pointed the right way that's because they fall slower than the rocket, so they have time to move away then I activate the parachutes including parabrakes first, because opening the main parachutes too suddenly may destroy it. finally, now that the rocket is falling slower than the thermal shield would on its own, I can drop the lower thermal shield. parachutes are opened at high altitude to give more time to gain distance from the shield.

it works partially. but really, you don't need to stack heat shields. a properly made reentry pod still works. i reentered safely at up to 9 km/s with nothing but a pod and a thermal shield.

alternatively, you could aim for duna and aerobrake there; duna is a lot more forgiving on aerobraking due to its lower gravity, so you may be able to survive. of course, then you need to go from duna to kerbin. fairly cheap if you have some fuel left, but not feasible if you discarded all the ship to keep only the reentry pod. Aiming for eve and using its gravity assist to go to kerbin at a lower speed is also possible

or, you could learn to perform those maneuvers manually. it will be hard at first, but you can be a lot more efficient than mechjeb is, and it will be a lot more fulfilling. besides advertising my own agenda on how this game should be played, I can attest that this game has a mod to fix everything, but the more mods, the more it becomes instable. all those mods add their own issues. In the end I found that it's better to not rely on a mod unless you really have to. Wait, does that still count as advertising my own agenda on how this game should be played? Damnit!

here's an example. the backwards heat shields act as parachutes and prevent the craft from flipping. there is also a giant tail fin (barely visible as it's night and i had yet to learn to increase brightness) to keep the lander steered in the right direction. eve's atmosphere is hard, you really need an aerodinamically stable vessel.

Part 7: A premature end The Jool mission arrived to Jool. It got captured in orbit. However, it was seriously lacking in xenon. I don't have enough to return to Kerbin. Not on a high energy trajectory, at least. If this was one of my main challenges, I'd go back to the drawing board and fix the problem. Just adding 4-5 extra xenon tanks would suffice. Except that would require replaying every other mission too. Lots and lots of slow xenon burns. I lost the passion in this challenge long ago. I picked it up thinking it would take a few weeks. Now I don't have a problem I can immediately fix, and I don't have the dedication to reload all the way back. The worst part is, it wouldn't even be interesting. There is no engineering to be done, no playing with orbits. All I'd have to do is add a bunch more xenon, and then do exactly what I've already done. I've already shown completing a return mission from anywhere in 2 years is possible, I'd only need to follow through. So, I'm giving it up.

Finding myself with a bit of a problem here. I am about to split my mothership in two, and I am transferring the fuel to the part that will need it most; routine operation, but I noticed something different If you can't tell from the image, there are a bunch of fuel tanks with a radial symmetry. I selected all of them simultaneously, then drained the fuel to another target tank Here I noticed that some of the fuel tanks had a lot more fuel left than some others. the tanks are all symmetric. they are all identical. I started with my tanks full after completing isru on the planet below, and they were all at the same level after ascent. yet now that I drained them into the big tank, their individual fuel levels changed. some tanks were drained faster than others. as you can imagine, this is going to be a problem because my fuel mass will no longer by symmetrical. it may lead to asymmetric thrust and the ship spinning - though as long as the difference is small, the reaction wheels and gimbals can compensate. I want to stress once more than I never did anything that could differentiate those fuel tanks. I selected them all simultaneously before giving the transfer order - which was for the larger tank to get fuel inside it. Anyone knows why fuel is behaving like that, and how I can fix the issue without manually readjusting all the tanks?

ah, then it looks like a mechjeb problem of some sort. i'm not familiar with mechjeb, so others can help you better there. as a purist of finding my own trajectories who takes great fun simulating my own ejections, insertions and gravity assists, I would say it's karma punishing you for trying to skip that part and relying on a mod to do your job . but I realize it's unfair and other people have fun in different ways than i do.

the deltaV map is not accurate when it comes to jool. or rather, it technically is, but it assumes that you would capture in a low jool orbit, then circularize, then go from low jool orbit to a moon. which is the worst way you could approach that. there are better ways to approach jool. the best one, in your case, would be to use a tylo gravity assist for capture, around jool, followed by arrival at laythe with other maneuvers; it could reduce intercept speed on laythe to almost 0 if done well, but it's very difficult to pull off; a mediocre execution, where you gravity capture around jool but end up in an imperfect trajectory for laythe, would cost several hundred m/s, which is still less than 1 km/s.. direct insertion around laythe is also another good way, it should cost no more than 400 m/s of intercept speed. what I mean by "direct injection" is that you come to jool from interplanetary, you hit laythe, and you perform the capture burn there. Here's an example from another system, and it also did net a low deltaV for an interplanetary capture the position of capture around the orbit is very important; as you see, I put a thorough care in intercepting the moon by being tangential to its trajectory. this way, the orbital velocity of the moon is subtracted from that of your vessel. You also get to use oberth effect from the moon in addition to oberth effect from the planet. Either way, you can reduce your intercept speed towards laythe to less tha 500 m/s, so you'll be at 3 km/s when entering the atmosphere. then again, if your plane can survive a reentry at 4 km/s (which it apparently can, given your testing on kerbin), then there's no reason to bother finding the perfect intercept, because you'll areobrake all the excess speed away for free anyway. As for periapsis, start with 35 km and see if it works. save the game as soon as you enter laythe's SoI; if the periapsis is too high or too low, you can reload to the beginning on the SoI and change the periapsis with a simple radial burn; as long as the change is only a few km, the burn is cheap. or, if you are sure your plane is extremely resistant, you can even go for a 30 km periapsis, which is guaranteed to capture you.

the thing is, atmospheric density only depends on altitude. the atmosphere of duna, for example, is a lot thinner than that of kerbin; however, being at 50 km altitude on kerbin or at 30 km altitude on duna or at 70 km on eve makes little difference. it only means you have to go lower or higher. and this is why you can feasibly aerocapture no matter your speed, as long as your ship can take the heat. I did aerocapture from 10 km/s on kerbin with a 30 km periapsis, I could have done the same on duna with a 10 km periapsis. there are some minor differences in atmospheric profile, but they are minor; except for laythe. btw, I did not realize laythe is different by reading the charts, but by trying to aerobrake there and basically hitting a wall. you could do that, but as i said, it's got little practical effect. there are only two basic scenarios: - you burn before you slow down - you slow down before you burn up and in the first scenario, a passage in the atmosphere isn't going to help you much, so you may as well disregard it. For example, if you come at kerbin too fast, you probably can set a periapsis around 55 km and survive. but such a periapsis will slow you by 10 m/s or less, so you can't aerocapture with it. A good way to estimate aerobraking is to set a maneuver node at periapsis for 0 km/s. when your ship starts braking in the atmosphere, the game will change the maneuver node accordingly telling you that you have to accelerate to achieve the same trajectory. so the maneuver node will start at 0 and gradually go up, telling you how much you brake in the atmosphere. generally speaking, for any atmosphere there is a sort of boundary line; above it, drag is small and you will make a fast passage and get out of the atmosphere again. below, drag is strong and you will lose hudreds of m/s. of course, the atmosphere changes gradually and so there isn't a well defined line, yet the difference between "you pass with low drag" and "you stop there" is only a few km. for example, on kerbin a 50 km periapsis can be used when returning from mun, and you will get out of the atmosphere having slowed down by a few tens of m/s. A 45 km periapsis will result in hundreds of m/s of braking, but if you're coming from mun it will take you a few passages before you are captured. A 40 km periapsis is generally enough for interplanetary capture. And even the time I came in at 10 km/s from a high energy trajectory, a 30 km/s was enough to stop my pod. Hard. we're talking some 40 g of deceleration. Similarly, i aerocaptured a lot of different ships on duna, but it was always with a periapsis between 22 and 27 km. below that, the atmosphere is so dense that it will stop you abruptly. above, it's not dense enough to make much of an effect. this is why the speed at which you enter atmosphere - and whether your ship can survive it - is the only significant parameter.

that is... there are ways to introduce this error accidentally. do prograde/retrograde flip when changing sphere of influence? this is normal. do they change because you are doing something to your ship? maybe you're controlling it from another position? that can also be normal. there is a command to invert the direction of command in the menu of any probe core and crew pod, though it's not something you can press by accident. also if you do docking, that can flip the ship; the game can get persuaded that the front of the ship is now the docking port you just used, even though that docking port may be pointed backwards. you mentioned having "gas stations" around, so you dock stuff every time, so I guess that's what happened. make sure of where your ship is pointing. you can open the menu of the Mk2 cabin and select "control from here" to reset the control point. if it's not one of those issues, then i have no idea

way too complicated to simulate. you are much better off going by trial and error here, reloading and trying with different periapsis. I can, though, give a lot of pointers you may find useful. Most important thing to consider is that when you arrive at a planet from interplanetary, you then fall towards the planet. so when you enter atmosphere you pick up speed roughly close to the escape velocity of the planet. which is about 1,4 km/s for duna, 2.7 km/s for laythe, 3.2 km/s for kerbin, 4.5 km/s for eve, give or take. you add that to your intercept speed. so, for example, you simulate that you'd need a 600 m/s burn to capture around duna (and stay in a high elliptic orbit)? this means you'll enter duna's atmosphere at roughly 2 km/s. if your ship will survive entering kerbin's atmosphere at that speed, it will survive at duna too, and you'll be able to aerobrake all the way. on the other hand, doing the same on eve means facing a reentry at 5 km/s, which is only feasible with excellent thermal protection. generally speaking, if your ship cannot survive the heat of your reentry, then going for a shallower trajectory is not worth the effort, you can at most save a few tens of m/s on capture. what you can do is rocket brake part of the way before entering atmosphere. for example, your ship can survive reentry at 2 km/s and you're coming to duna with 1 km/s intercept speed (which means hitting atmosphere at 2.4 km/s)? rocket brake for 400 m/s until you're at 2 km/s, then enter atmosphere. you'll get some inefficiencies because you're not burning at periapsis, but you can still get aerocaptured. So the actual drag coefficient of your ship matters nothing. what matters is the maximum speed at which it can survive. which is something you can test on kerbin too. if you can survive reentry at a certain speed, then you can aerocapture all the way and it's just a matter of finding the right periapsis - which is something you can only do by trial and error, basically. calculating it would be too complex normal altitudes for aerocapture are: 40-50 km for kerbin, 20-30 km for duna, 35-45 km for laythe. i never tried aerocapture at eve, but i guess 60-70 km would probably be it. laythe is a bit different from the others because its atmosphere is weird, it gets very dense very fast, to the point that even though it is 20 km shorter than kerbin's, it is more dense at equal altitude for most of the way. while other atospheres start gradually, laythe atmosphere is like kerbin's atmosphere with the top 20 km removed, and it starts very abruptly. so aerobraking there requires some extra heat resistance.

question: Now that I'm done with Wal, I was considering going forward with Polta. However, I discovered that the roll cage of my rover doesn't work anymore as intended, because wheels are a lot more fragile and keep breaking. I considered adding 4-6 struts on the bottom of the rover, to be deployed quickly in an emergency to complete the roll cage on the bottom and protect the wheels. A minor change for a rover that's already very elaborate If I were to do such a change - using alt-f12 to bring the new rover in place and pretending it's always been like that - would it be legitimate? Or do I have to launch anew and repeat all the trip to Polta?

Part 12: Outward to the lopsided planet A'Twin moves outward to Uranus, sends a lander to the moons and refuels there. Refueling on Titania, admiring a passage of Ariel and Umbriel over Uranus 12.1) Make sure you fill up your nitrogen stock before leaving Saturn 12.2) En route to where? 12.3) Moons of a midsummer night 12.4) SSllooww... rreeffuueelliinngg... oonn... TTiittaanniiaa... Bugs compilation updated

ok, I guess it makes sense. So, I already told you about oberth effect and why you want to make those burns in the planetary orbit. As for how to make the maneuver, I suggest a simple way that's relatively accurate. First, go to alexmoon.github.io/ksp. it's a very useful tool. So you want to go from kerbin to jool, tell the tool just that. In this case, it will tell you that the best time to start is in year 2:258, but you get a good transfer window also around 1:200. This will let you know the transfer windows. Then you scroll down, there are a bunch of additional informations. most of them I myself don't know how to use, because they don't have an easy ksp reference. but one you can use, the ejection deltaV. In this case it says 1987 m/s, so you know you should spend some 2 km/s to get there. you'll likely spend a bit more because you're not perfect, but try to stay within 10% of that. So now it's the transfer window, time to plan your maneuver. take your ship in kerbin orbit, and plot a prograde maneuver for 2 km/s. Any direction is good, you'll fix it later. So now your planned trajectory will exit kerbin and go in solar orbit, where it will produce an apoapsis (or periapsis if you're leaving on the wrong side. Highlight the apoapsis. You want to push apoapsis up as high as possible. So move your maneuver around kerbin's orbit, you'll see apoapsis increase, until you hit some point where you get maximum apoapsis and then it decreases. you found the optimal position for your ejection burn. Since this is the transfer window, chances are by now you'll also be seeing a close approach, because this is jool. now you can make small corrections to turn that into an encounter. for other, smaller planets you're unlikely to yet be seeing a close approach. In this case I suggest you also plot a second maneuver, on the planar nodes- they are marked as AN or DN, ascending or descending node, meaning that your ship is passing through the plane of the target orbit going up or down. if you maneuver on the descending node, make a burn upward (purple triangle). if you maneuvr on the ascending node, make a burn downward (purple triangle with lines coming out of it). once you match the target inclination, you'll see a close approach. again, you'll need small corrections, but they will be small.

FInally finished my Wal equatorial circumnavigation, that I started 8 moths ago. I mostly let it drop for several months, until picking it up seriously again in september. I wanted to make the best mountain-climbing rover and test it on the most difficult terrain I knew, and nothing beats the equatorial mountain ring of Wal. Ok, kerbin has steeper mountains, but it's kind of a different environment. And I already climbed devil's tower (big mountains with near vertical cliffs and flat top to the west of ksc) on wheel power alone, but I wouldn't want to do that for a grand tour. anyway, mountains, mountains and even more mountains. This circumnavigation was more challenging, but less interesting than the one on Slate. Less variety

Part 8: going home The circumnavigation is not complete without returning to Kerbin.

Part 7: full circumnavigation After 8 months and 2800 km, Leaping Mantis makes it back to its sky crane

Part 6: moar mountaineering! It's all this mission is about, after all I made it to halfway!

ah, that's it. you are not making use of oberth effect. Oberth effect means that making a prograde burn close to a planet is cheaper. making such a burn in solar orbit is a lot more expensive. you spent 2800 m/s to go from kerbin orbit to jool in solar orbit. that's already a lot more than it should be. from low kerbin orbit, you can spend 2000 m/s and reach jool. it's much cheaper, even though you have to spend 900 m/s just to get out of kerbin's gravity. from minmus you are already almost out of it, and you can spend less than 1300 m/s; the best way is from minmus to fall down on kerbin and make the ejection burn close to it, as shown in this picture 160 m/s to go from minmus to low kerbin orbit, then it's only 1150 m/s to jool. and the same applies to jool, except you are potentially losing eve more there. I already showed you a pic where you could have returned from pol with 1 km/s, because jool is very big and has a lot of oberth effect. making the burn around bop would also add a tiny bit of oberth from the moon. by getting out of jool, then lowering periapsis in solar orbit, you spent a fortune leaving the gas giant and you also lost your oberth effect. frankly, i am surprised that you got to the point where you can make a spaceplane that can ssto from kerbin with enough fuel left to reach minmus (while carrying a lot of payload in the form of heavy passenger cabin and mining equipment) but you don't know about oberth effect and efficient interplanetary transfers. it's like finding a civilization that has discovered electricity but never invented the wheel.