Grogs

Good point, thanks. Thanks. I tried searching for something like this, but "long burn" and "multi-orbit" didn't find it. Thanks, cool trick. Playing with this, I guess I answered my first question which is how to get pointed in the right direction initially. I started my maneuver at T-30 days, moved it to the launch window using the "+1 orbit" button repeatedly, then set up the minimum dV direct transfer to Jool. Once I had it, I moved it back to the current orbit using the "-1 orbit" button. Now I can start pointed in the right direction, which will (hopefully) get rid of a lot of the 16% extra dV I had when I tested this before. Playing with all these maneuver nodes has also reminded me of just what a pain setting them up is with the stock controls. I'm going to try and complete the Jool-5 without them just as a matter of pride, but once that's done I'm adding a mod that lets me create/modify them more easily ASAP.

Yeah, I agree that moving to the 500km parking orbit wasn't the most efficient move. I just had extra fuel in my launch stage and moved it up as high as I could. The thing was so top-heavy it would snap-hook into the ground if I tried any sort of normal gravity turn so I included a lot of extra dV and kept it pointing straight up until it had a lot of speed.

It seems pretty clear that the first step is to kick up the apoapsis over a few steps. Then after the penultimate burn arrive back at the periapsis at about the launch window time. The parts that I'm not 100% sure on how to optimize are: 1. Which direction to point initially. I've just been setting a maneuver node that just gets me to Jool's orbit for the least amount of dV. The only problem is that Jool isn't in position for an encounter yet. 20-30 days later when it's time for the final kick, Kerbin has moved around the sun and the apoapsis is no longer aligned in the right direction. I noticed that the final maneuver node was several degrees past the periapsis when I gave it a try. 2. Does it matter whether I just go for it and make the final burn all at once, regardless of how far off periapsis I am? Or should I follow bewing's advice and burn just enough to escape Kerbin's SOI and then correct once I escape? I ran a couple of quick tests and they seem to suggest that just burning it all at Kerbin periapsis is better. I managed a close encounter with Jool for 2174 m/s (16% higher than the minimum value of 1872) with this versus 2534 m/s correcting after Kerbin escape. It seemed like handling the plane change might explain part of the difference. In any case, I know I included a good safety margin on fuel so the "don't overthink it" advice is probably sound. I'll just try to get a transfer that's acceptable for now and try to optimize it later for the absolute minimum if that's what I want.

Thanks, that's a great resource that explains a lot, especially the timing of the last couple of maneuvers. The one thing there that is quite a bit different is that he's launching to Eve. Starting from a 71-km orbit, the transfer is 1038 m/s, and from escaping the Kerbin SOI it only takes a small bit more burn. That lets him break it down into 8 pieces, and the last one that launches to Eve isn't all that much larger than the first seven. In contrast, when going to Jool if I tried to break it into 8 pieces, I would bring my apoapsis to the edge of the Kerbin SOI with #3 and escape with #4. Handling that last big chunk at the end seems like it might? require something different. I'm playing around with some tests to get an idea of how much this matters.

Hi all, I'm working on a Jool-5 mission. I've managed to get my rather large mother ship into orbit and dock all of my landers/tugs. I'm using Nerv engines, which gives me a rather low TWR. Even so, I'm not sure I can even use 100% thrust because I have several ships connected together via docking ports. As a result, a Jool ejection maneuver of ~ 2000 m/s will require at least 18 minutes, and possibly more. I put my mother ship into a 500-km orbit in anticipation of this, but even at this altitude the period is just over an hour. Given that the maneuver will require about 1/3 or more of an orbit, I think I need to split the burn over a couple of orbits, but I'm not sure the best way to go about it. A 500 m/s burn puts me in an orbit with an apoapsis of 4400 km and a period of 5 hours. 700 m/s gets me an Ap of 34000km with a period of over 10 days, and much more than that hits Kerbin escape. Given an orbital transfer window at time X, what's the best way to go about this as far as how to set maneuver nodes, when to start the first burn, etc. BTW, I'm running an unmodded 1.6.1 with MH if it matters. Here's the assembled craft: Thanks, Grogs

They do seem to be minimums or close to it. For example, going from Low Kerbin Orbit to the circular orbit around Jool adds to 4900 m/s using the chart. Looking at Alex Moon's tool, the optimum launch over a period of 10 years is 4887 m/s. For planning I've been adding about a 25% safety margin to these numbers to account for my less than optimum flying ability.

Thanks. If only I could get work to see it that way and provide me with some educational assistance for my playing time.

Hi all, I just picked up the KSP and Making History bundle a couple months ago, and my only complaint about the game so far is that it takes up most of my free time. I grew up as a kid dreaming of Apollo missions, and this is the closest I think I'll ever come to being an astronaut. So far I have managed to land on both of Kerbin's moons and (just barely) Duna. For the last couple of weeks, I've been planning a Jool-5 mission and I hope to start on that soon. Right now I'm running the game unmodded. I have a list of mods that I want to install, but I've decided I'll run through the Jool-5 with the native tools before I start trying out mods. I've picked up quite a few tips from reading the forums and the wiki, and I've decided to join up. Anyway, no specific questions right now, but I'd just like to say thanks to all of you for the helpful advice and support. Thanks, Grogs