Finally managed to get the lander down.
I put my peroapsis on my flyby trajectory at about 19km, this provided enough aerobraking to slow me down enough to allow an orbit without expending too much delta V. Here's the trajectory I wound up on:
From here I decided to more or less go for a straight landing. There wasn't any good spots on the day side so I tried to pick a good one on the night side. I thought about circularizing and waiting for the day side to line up with my peroapsis but I just didn't have the patience and didn't want to waste the fuel. The first place I tried to land was a largish island with a huge crater lake on it. Problem was that I would either wind up landing in the lake or land on the side of the mountain right next to it. That particular island is super mountainous (which I couldn't see before hand due to the darkness) so I couldn't really land there. I picked another island without a lake and set my peroapsis at 18.6km, which brought me in for a landing.
Look how fast I was going! And that after I had already slowed down a bit.
I used the last bit of juice in my core stage to kill most of my translational velocity then dumped it. That left me with about 10 seconds to separate the stage, fire up the skipper landing engine, drop my landing gears, get my velocity below 100m/s and deploy the chutes. After the chutes opened, I had maybe another 7 seconds to get my final descent velocity right. It was freaking brutal and the timing had to be precise or I would crash.
I did find one last bug in my lander that hadn't popped up in testing: the landing legs give only a few centimeters of clearance for the engine bell. This wasn't a problem during descent tests on Kerbin where the descent was nice and slow due to the thick atmosphere and the landings there were on nice flat land near the KSC. On Laythe, the problem was that I descended a bit faster than on Kerbin and I landed on the side of a mountain. So when I hit the ground, my landing legs flexed a bit and that, coupled with the inclination of the mountain meant my engine clipped the ground and blew up.
So I can't test this thing to see if it can get back to orbit.
Here's where I landed:
I'm on the edge of a valley, which means I won't be able to set up my final base here. However, the island I'm on is roughly equatorial, which will help me when I started putting the base together. Also, in the direction of the bottom of the 2nd picture, there is a large, flat plain where I can set down my base components. I'll leave this lander as a marker for when I send more stuff in the future.
Here's the launch vehicle. It's so big I can't zoom out all the way in the VAB to show it all to you, but this is pretty much it, the lander is clipped off at the top of the picture. It put over 200tons on an encounter trajectory with Jool. By the time I get to Laythe orbit, I think I still had 110tons, of which 65 was the lander.
I've got a few tweaks planned for this vehicle. I'm going to delete the mainsail on the central stack. As you can see, each side booster has twin mainsails, which gives this rocket a phenomenal T/W right off the pad. The mainsail on the central core is thus unneeded and once I've ditched the last 2 side stages, I turn it off and switch to the NERVA's anyways.
I'm also going to disconnect the fuel lines that run from the last booster stages to the core since I won't need them without the mainsail on that stage.
I'm going to place decouplers on each of the 3 orange tanks on the central stack so I can dump them when they are empty. My current design carried the empty tanks with me all the way out to laythe (and they even wound up crashing onto the surface) and this was just a waste of deltaV. I'll have to move the NERVA's to the top tank in that stack of 3 so they don't get dumped, and I'll have to route fuel lines up the stack so that the bottom tanks get drained first so I can dump them.
Put docking ports and probe cores on the final tank! I wound up getting to Laythe with fuel left over in my central tank. Even with a slight heavier lander, I expect this will remain the case as I'll be dropping off additional empty tank mass in flight with my redesigned launcher. So if I add a probe core and a docking port to the final orange tank on my booster core, I can use it as an ersatz tanker in Laythe orbit. It won't have a ton of fuel to give up, but there's no point in wasting a single drop if I can avoid it. It'll also be nice to build up some infrastructure for my colony at Laythe and the core stage can also double as a communications relay and mapping/observation satellite. I may not end up with enough fuel left to make docking worth it but you never know.
Oh and I'll move the RCS thrusters. I placed them on the CoM of the core/lander stack, but since I'm not docking that stack to anything, having the thrusters there is terrible. Because they're on the CoM, the RCS thrusters can translate my ship easily without tumble, but they have to work very hard to turn it as there is no moment arm for them to act on. That's a serious problem and like I said, I'm not docking the thing on the trip out there so having the RCS thrusters on the CoM does me no good. I'll just have to deal with tumble if I try and use the final orange tank as a refueling station but it shouldn't be a big deal.
I'm going to add more chutes to the lander so I don't have to be a throttle jockey during the last few seconds of descent, I want a nice slow descent. I'm also going to add bigger fuel tanks to the side tanks. Currently, the lander has a T/W of about 1.06, but in Laythe's .8g, I can safely add 20% more mass and keep the same T/W. Also, because I do have to do a deorbit burn and a bit of a burn to slow to below 100m/s, that means I'll have less mass at lift-off from Laythe, which means I can start with more fuel and still have a T/W > 1 at lift-off. I also have to place the side tanks and landing legs lower to give more clearance to the skipper engine bell.
After I verify the refit of the launcher and lander, I'm going to send out 3 of these in a row. That will provide me with crew return options for 12 kerbalnauts. I'll send them all at the same time so that I can avoid spending hours per mission; I can hop from one ship to the next and just spend hours on the total mission as a caravan.
Oh and here's a picture of that little tug I designed:
I'm probably going to send a stack of these to Laythe to assist with docking there in case any landers wind up short on deltaV or RCS fuel.
