Heavy lander goes to Laythe!

[technion]

Hey guys,

Welcome to my first mission report. I'd appreciate any feedback, although I'm aware of several improvements that have become quite obvious as the mission progressed.

Following a success at Duna, I set my sights on Laythe. My first Laythe mission was failure in two ways, both with the transport being fuel limited, and the lander being inadequate for a return trip. This time, things were much better planned and destined to be different.

The hero of the mission is this heavy transporter.

The transporter appears to be, for whatever reason, incredibly fragile. I tried a copy in which I added over 200 struts, without improving anything at all and ended up reverting. The result is a lifter that can't throttle up beyond 50% in its early stages, without imploding on itself.

Although common wisdom argues SRBs should be spend in the early stages, it's about the 6KM mark that the lack of early thrust becomes an issue. Note the low speed even with four of them going.

The rocket stages itself to the nuclear engines just a little bit too early, resulting in a nail biting circularisation where the periapsis eventually forms right in right of you and you hit it at about 60KM. You don't mind aerobraking a bit here though, because the Apopsis is 200KM+.

The result however, is quite worthwhile, with a capacity for 10,080 Liquid fuel units and less than 700 spent.

Sandwich'ed between a senior docking clamp and three LV-N engines, we were looking good to go.

[technion]

Our lander meanwhile, has had a significant revamp for version 2.0. The first edition was unable to make orbit, so this new version features extra fuel, and two additional stages. Here we see our Kerbal testing the ladder system on kerbin.

The complete launcher.

The lander, now in orbit.

I really hate docking. When people show me space stations with seven docks I cringe. It took a long time to pull this off, especially with such bulky units.

That big tank on the end isn't actually a part of the lander - it's just there to provide fuel for the docking process, and to top up the traveller. Remember it was 700 units down? We have that much to spare.

Dumping that tank!

Be sure to kill the aerospikes.

Edited November 15, 2013 by technion

[technion]

You've probably noticed - we haven't added any Kerbals yet. This command pod serves a few purposes. Primarily, it delivers our kerbals to the system. It's also - the return unit. Finally, we have two ion powered probes and some additional fuel coming along for the ride.

Getting this into orbit is a breath of fresh air after the last two launches.

One final dock to put the entire mothership together.

[technion]

The final result is well put together and quite capable - if I do say so myself.

I exited Kerbin using six? separate, three minute kicks. I took a lot to get this moving and I wanted to be as efficient as possible with it.

Shortly into the mission, we can empty out the fuel tanks that came with the command pod (they were half empty by docking time anyway).

The major 2.0 upgrade in the command pod: separatrons on this stage!

Go go!

It took a long ass burn to get here.. over 40 minutes to intersect the orbit with Laythe in fact. And I couldn't physics warp whatsoever without having the rocket shatter.

A view as Jool approaches.

Aerobraking at Jool! wow that was scary...

Time to launch those probes and let them do their own thing.

Can you believe how finely we cut it on the fuel? This is where we were at once we got a Laythe intercept.

It's just the return pod and the Lander now, hovering over Laythe...

[technion]

Aerobraking into Laythe orbit.

Screenshot missing: transfer a kerbal to the lander.

I really didn't want to waste any of the lander's fuel deorbiting to an appropriate landing site. Touching down only to find I'd spent too much to get back would be crushing, and with Laythe being mostly water, simply arranging a deorbit wouldn't do the job. So I performed a bit of a hack: I turned the whole rocket around and had the command module burn the nuclear engine retrograde until I like the target. Then, we separated, and the command module resestablished its orbit.

You can see the lander - which we towed this whole way - was just shy of 70T.

Heading down in a ball of fire!

Creative mixing of parachute types allowed for enough early braking that the sudden jolt when the lower atmosphere ones kicked in never hurt anything.

Touchdown!

Celebration!

Back into orbit.

The final stage. A full orbit was established before we got here, so we had an LV-909 and full tank to deal with docking.

Who cares about good intercepts when you can make a 500m spacewalk to get back to the command module?

Everyone safe and sound, most of a full tank.

Nearly 250T left Kerbin's orbit, and here we see less than 30T embark on a return trip.

[technion]

Not a difficult intercept to make...

Coming in..

Touchdown!

[-RanZ-]

great report!

[Geschosskopf]

Egad! A triumph of Kerbal engineering that shall be enshrined forever in the annals of Stupendous Creations

[Brotoro]

Congratulations on getting there and back. I thought your aerobraking at Jool was interesting...it looks like only the front of the ship is on fire.

[wasmic]

Wow, cool. However, I think you overengineered the lander a bit - I'm not sure the SRB's were needed, you could have used smaller liquid fuelled boosters. SRB's have very low I_sp

[technion]

Thanks for the feedback guys! I know there's a few things I'll improve for v3. The command module hauled a lot of monopropellant and didn't use any of it once it left Kerbin - I should have put small tanks on top of those fuel boosters that we ejected early. There were a few parts on the final stage that could have dropped earlier without an issue.

I'm not sure the SRB's were needed, you could have used smaller liquid fuelled boosters.

I went back and forth on this several times. The v1 edition definitely had thrust issues at low atmosphere, the aerospike component was mostly dry before we hit the gravity turn. I did weigh up the SRB vs a small tank and T30 - never did come to a good conclusion about which was better for this scenario. My frustration with exceedingly long burns carrying this weight the whole way there was outweighed by the mind numbing failure of the previous mission not returning to orbit. I do know there was a mistake though - the lander was tested extensively to be water landing capable. Since adding in those SRBs, it isn't (without flipping over), and I only found out once I landed. Landing struts may not weigh much but I sure had a lot of them.