My first Mün landing

[hjalfi]

Is, as you can see, totally 100% successful.

Hally there is looking quietly pleased. Or possibly concerned. It's hard to tell. As the consummate professional that she is, of course, she sees this as an opportunity rather than a problem. In particular, she notes that despite the ascent engine being some way off, she still has an RCS tank and thrusters. Some adept piloting later...

And she's safely in Münar orbit. With a periapsis of 4500 metres, she gets a stunning view of the 4000m high mountains go by below.

Meanwhile, back home on Kerbin, a major R&D effort is underway. It's time for a rescue mission! And so her fellow kerbonaut Matvis Kerman flies to the rescue...

...in a custom built and totally untested vehicle, the Behemoth 5D R-series. And it's totally not a quick hack of the L-series lander with the legs stuck on top.

A very fiddly few hours of exquisitely careful piloting later and they rendezvous, scarily close to the Mün.

There's only one problem. The grapple on the top of the R-series doesn't work.

Continued...

Edited June 24, 2021 by hjalfi

[hjalfi]

There's only one thing for it. Matvis decides to push Hally home.

Balancing the L-series on the top of the grapple is hard, but Matvis thinks of Jeb and it's easy. Well, not easy. Still hard. But he does it. They ascend out of Mün orbit into a transfer orbit to Kerbin.

Once at Kerbin apoapsis it's time to do the rendevous all over again. This time it's even harder, as the dark L-series capsule is almost invisible against the blackness of space. Who painted them black, anyway? Matvis swears he will find the kerbal responsible and punch them.

(The view through the forward camera. That's not the moon, it's the bottom of Hally's capsule. Matvis looking imperturbable, as usual.)

They boost again, slowing the L-series capsule into a descent trajectory to Kerbin.

Success! Hally is going home.

Continued...

Edited June 24, 2021 by hjalfi

[hjalfi]

Hally watches Kerbin approach.

Splashdown!

...and while waiting pickup, she watches the dawn she was afraid she might never see again.

Now it's Matvis' turn. The faithful R-series, job done, begins to break up in the upper atmosphere.

Matvis, quietly pleased, poses with his capsule. By sheer chance he lands a mere 90km from Hally's capsule. He thinks he'll go and visit: hell, Jeb walks that far every morning before breakfast.

Edited June 24, 2021 by hjalfi

[hjalfi]

Okay, now that's done (it took about four days RL), a few questions:

The grapple didn't work. When the legs closed, the capsule would jitter for a few moments and then something would explode and it would go flying. (I absolutely spammed the quicksave doing this.) I've seen people build grapples on Youtube; what am I doing wrong?

The alternative rescue mission was to send a capsule and EVA Hally over to it. Unfortunately all the capsules are full. Is there any better way to get a spare seat on a capsule than to EVA on the launchpad and push a kerbal off?

Fine scale rendezvous is hellishly hard, not least because I had no idea which way up the vehicle was, and so didn't know which thrust axis did what... the forward hull cam really helped: I spent ages aligning it to match the nav ball. Unfortunately the R-series shook like a collie every time I used the RCS, and the SAS didn't do a great job keeping it steady. It would tend to swing back and forth. Any suggestions on how to improve handling in space? Is it just a matter of more SAS units and more thruster blocks?

And if you look at that last picture of the R-series grapple, something very odd is going on...

[Vanamonde]

A great and gripping story, and well-told.

I can't help you with the grapple because I don't use mods. But as for making room in a capsule, you can EVA the guy and "end flight" him. The effect is the same, but you don't have a simulated death on your conscience.

As I understand it, th devs realize the SAS tends to result in oscillations, but it's not a priority to fix right now. More of the modules won't help, unfortunately. When I was having similar trouble, smart people advised me to use ASAS instead of the basic model, and it still happens but isn't as severe. The ejectable fuel tanks you have are not a bad idea in themselves, but their mass is all at one end of the ship. That means that when you turn, that mass has momentum that tries to keep the ship turning, which makes steering sloppy, which the SAS than fails to entirely control. Try moving them up so that they're closer to the middle of the ship. They will still have momentum there, of course, but it will be a bit more controllable. The ship will still try to keep rotating, but it won't wallow off on odd angles as much. Anyway, just some suggestions. Try them or not as you see fit.

[hjalfi]

The grapple is all stock parts --- just the lightweight landing legs arranged in a circle. And, facepalm about the tanks. As the R-series started life as a lander I wanted the CoG low, which is of course totally not what you want for orbital manoeuvring. (In fact, on reentry the R-series had 1/3 full in the external tanks and the internal tank was untouched. Still, better fuel you have but don't need that fuel you need but don't have, eh?)

[pebble_garden]

That was an epic rescue, all the more so because of the unanticipated difficulties. Well done!

RCS placement is really tricky, you want their average influence to bracket your ship's center of mass. Otherwise any RCS use will impart unwanted rotations, as you discovered.

I did a couple of grapple-mission videos using only stock parts, and found that using more legs (I used six) helped distribute the load better. They're still brittle, though. The game wasn't really built for this kind of detailed collision physics - not yet, anyway. So I made the 'closed' configuration match the target's diameter fairly closely. Pinching too hard will snap those suckers right off.

[Ascimator]

My first Mun landing left nothing but the pod. During the second landing the rocket bounced a little and fell on its side. After getting it back up using the landing struts and ASAS I felt like a cheater, so I tried launching back home. Was just a little bit too low on fuel, unfortunately.

[hjalfi]

Bielliptic transfer orbits FTW!

It also occurred to me that one feasible way to get Hally home would have been to have her get out and push --- EVA jetpacks refuel in the command pod, IIRC, so you get unlimited dV that way. But it would be very long and very tedious and it's unquestionably cheating.