Jool-5 Mission Report

[NecroBones]

Jool-5 Mission

Completed 2014-06-20, version 0.23.5

So I finally completed the Jool-5 mission, with some bonus landings! The ship consisted of a large drive-section, plus docked landers and a tug. I had two mission landers, one for Tylo, and one for everything else. Plus the "return lander" for landing back on Kerbin with both dudes.

Mods used were all computational and informational aids, and visual/audio enhancements. The only "parts" mod used was KAS, for the struts:

Mods: Toolbar, Environmental Visual Enhancements, Chatterer, Engineer, KAS, MechJeb, Targetron, KAC, and Alternate Resource Panel.

For most of the mission, MechJeb was only useful for information, and creating some of the maneuvers. It couldn't execute them with a wobbly ship, without shaking me apart, so I did almost all of the burns manually, until I was back in Kerbin's SOI. Also, I didn't use MJ for landings or take-offs, since that's the fun part!

The standard mission profile was to use put the ship into a stable, high orbit around each moon, and then use the tug to take the lander to a lower orbit to do the descent. This meant two rendezvous/dockings after each moon. In some cases, the tug did the actual de-orbit burn, and then released the lander, and re-circularized itself. With nuclear engines, this made for a little more fuel efficiency in the long run.

The mission was also "Apollo style" in that one of the guys stayed with the main ship, while the other did the excursions.

Mission description, in order:

* 2 launches to get the ship halves together. This doesn't include re-launches (launched the drive section three times, due to finding problems after orbit), or a separate launch to bring up a box of KAS struts after seeing how wobbly the docking ports were.

* Escape burn from Kerbin, in two passes. Had to run the KR-2L boosters at 1/3 throttle to avoid folding the ship in half. I should have used something smaller and more efficient.

* First stop, Tylo, to get rid of the heaviest lander. This was a special-purpose lander, with over 6km/s dV. I screwed up my descent, and forgot to stage off the first set of tanks until the second stage was nearly depleted. I also made a very cautious descent, not a suicide burn. So I landed with only 2 km/s, instead of the 3 I planned on. Ooops! I managed to almost re-orbit (20km x -6km (yes, negative 6), or somewhere around there), and ran out of fuel about 60m/s short of circularizing. So I finished that burn with RCS, and had the tug come down and get me. After recovering science/crew, the remaining piece of the lander was discarded.

* Next, Laythe! The general-purpose lander needed to hit Laythe as its first stop, so that I could use the RAPIER engines and discard them. I had to try the landing a couple of times, since my first attempts were too steep, and I couldn't lose the speed before hitting the mountains. I was trying very hard to hit that island! I changed my descent angle, then landed easily. The lift-off was even easier. The 4 RAPIERs were plenty to get me up through most of the lower atmosphere. Once they switched modes, I let them use their own remaining fuel, then discarded them, and only THEN did I start the rocket engines. I had quite a lot of fuel left over when I met back up with the tug.

* Vall was the logical next choice, since it was close-by, and in a similar orbital plane. Landed, took off, very standard mission without any real surprises.

* Then we shot all the way out to the outer moon, Pol. This made good sense at the time, since its orbital inclination is between the other moons I already did, and the last remaining one, Bop. Also, inclination changes are cheaper at the outer orbits. This ended up being a neat landing, because I just happened to be in a good position to land right next to a probe-ship that I crash-landed there a LONG time ago. That probe-ship was one of my first attempts at a "Jool-5 probe", as it had detachable probes. I was new enough to the game at the time that I had no idea what the dV requirements would really be like, plus the probes were unbalanced and useless. So it was neat to be able to inspect the wreckage.

* Last stop for Jool, Bop! I had previously landed near the dead Kraken, so when I got here, I had a nice flag marker to follow, and landed there again. Otherwise, very easy mission.

* On to the bonus phases! Now that the drive-section was almost depleted, but still had some dV to spare, and I realized the tug could also be used as a replacement set of engines, I decided to hit a few more stops on the way. Mainly, Dres. I had only been there once before. I got there with my last stage of the engine section, and then dropped those last engines and used the tug to finish the departure burn.

* Arriving back at Kerbin, I aerobraked into an eccentric orbit, and then set course for Mun! Landed there, no problems. This was the first time I didn't bother to refuel the lander after docking back to the ship.

* Then Minmus! I ended up landing less than 3km away from my first ever manned landing on anything other than Kerbin. That was nifty.

* Once finished with Kerbin's moons, I came back to Kerbin and re-entered the atmosphere. After the nice re-entry effects subsided, I ditched the tug and moon-lander, and parachuted the return-lander to the surface. The science collected was only about 1900 points, because I didn't bring instruments with me, and it was limited to EVA reports and soil samples. Plus, I had visited almost all of those locations before, so even though were spotty in terms of science awarded. I only kept the reports/samples that actually awarded science, and discarded those that didn't.

Lessons Learned:

* Struts! OMG struts. For a ship strung together with docking ports, KAS struts are fantastic. I knew this, of course, but I haven't flown a ship this massive, docked together in orbit, since before 0.23.5. I thought the docking ports would be a little stiffer, but I was wrong. I reinstalled KAS specifically for this mission. I used them to fix the docking interface between the engine section and the main-stack of the ship, plus used them to stabilize the lander to the tug after each landing. The KAS struts aren't a fix-all, though. They're limited to a shorter length than stock struts, and they take time to put in place on EVA. I got good at strutting my lander after each mission, through repetition, but it's tedium that I could do without. The mission would have still worked without the KAS struts, but all of my maneuvers would have been a little harder since the ship would have been more floppy.

* KR-2L engines are too powerful for something this flimsy. I've used them for orbital transfers before, but only in single-launch, single-destination ships only. For my Kerbin escape, I wanted something beefy to keep the burn-time manageable while the ship was still heavy and fully fueled. Next time, I'll do something different (with different engines, or use a puller-design).

* Pusher engines suck for "space trains". Since everything was docked together, it's like trying to push a chain on the floor. I should have put a ring of engines at the front, and docked everything else behind it.

* Extra docking ports are always a good thing. Sometimes you need to temporarily stow a lander or something, while re-organizing, or using combinations of things you didn't plan on. For instance, I originally didn't expect to hit Tylo first, so I had to move the other lander out of the way during the Tylo mission. The tug was the only size-adapter in the main stack, which left with the Tylo lander, so the general-lander sat on the side of the engines during that time.

* Be flexible! Mission parameters can change on the fly. I didn't expect to use the tug for nearly every moon, but it was useful for that. In the field, I realized I could do de-orbit burns with it. I realized also I could move my "box of struts" around and the "tug spacer" was about the same size, so the ship was always balanced if I docked those in the right places. I also didn't choose the moon order until I was there and could play with the maneuver nodes. Plus, I extended the mission with bonus landings after realizing the tug would make a great final engine stage (except for all the thrust exhaust going right past the lifeboat).

* Don't forget the action groups! I had set them up for my solar panels, but completely spaced-out (heh) on making them for engine groups on the landers and the tug. I had to flip engines on and off manually (I don't have a mod installed to edit action groups in flight). Next time, I'll use more action groups!

Pictures:

Be forewarned. This album below has 321 images in it. I took pictures everywhere. I may try to make a second gallery with just the highlights.

View the thumbnails: http://imgur.com/a/nS4em/all

Gallery:

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Edited June 24, 2014 by NecroBones