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The ARM megathread

KvickFlygarn87

By KvickFlygarn87
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Rakaydos

Rakaydos

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Hmm... can a science lab reset a canister that had it's science stored in a command pod?

If so, it seems like the best "science stack" would be a Lab with Antenna, a 3 man pod, and a material science bay. Every biome, you check the science, process it in the lab, transmit and reset, re-expose, take the leftover science into the command pod, and reset again. And take an EVA report while you're collecting the science.

It's massive and has to come home, but it will generate about 10% more science than a 100% science return, and might even be more mass efficent if you have the deltav and science for, say, a grand jool tour.

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TranquilTempest

TranquilTempest

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What do you think of this?

I've noticed a lot of streamers leaving SAS on when they are trying to push a large asteroid around with a big engine, only to have the astroid spin out of control despite it starting out with their rocket aligned with the center of mass.

While SAS tries to keep the ship pointed toward in the same direction, the flexibility of the joint between the ship and the asteroid will cause the force from the main engines to torque the asteroid in the opposite direction of the control input, dragging the ship along with it. The stronger the control input, the more the joint flexes, and the more severely the asteroid spins out of control.

tl;dr: If the asteroid and thrust is large enough, SAS is harmful and pitch and yaw inputs get inverted by the flexibility of the joint.

What's a way to solve this problem? After attaching, disable gimbaling/rcs/reaction wheels on the ship doing the pushing, and attach a second ship with a bunch of reaction wheels or RCS to provide enough attitude control to overcome the small initial inaccuracy. Obviously you should still try to point your pusher rocket as close to the center of mass as you can.

There are certainly more ways to solve the problem, perhaps designing a more rigid method of attaching to the asteroid, but that would require experimentation and I don't yet have the asteroid mission update.

source: http://www.reddit.com/r/KerbalSpaceProgram/comments/21efaz/psa_asteroids_and_attitude_control/
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Rakaydos

Rakaydos

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Posted (edited)

You can probably manage that in a single launch, with a set of docked "wheelman" probes- Claw, Probecore, call it 3 reaction wheels (12 overall, with 4x symetry- should hopefully be enough for an E class asteroid), enough RTGs to power them and RCS to maneuver into position attached to the sides, and a docking port to attack to the "main" craft during the trip out.

Edited by Rakaydos
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Kasuha

Kasuha

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That's definitely true.

Well, since the joint appears to be flexible, I guess pulling would be the right answer. You'll just need to disable engine gimbal (because docking with asteroid at the ship bottom will move them ahead of CoM) but you can still rely on Torque and SAS.

And you need to either use angled engines or keep sufficient distance from the asteroid (about three long I-beams)

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Sandworm

Sandworm

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So you are going direct you engine exhaust towards the asteroid you are towing? I hope it doesn't melt.

I think the answer is to dock multiple ships (3) then use thrust limits to balance them in line with the com. Remember also that as you burn fuel you will change the com, mandating regular corrections.

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KvickFlygarn87

KvickFlygarn87

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So you are going direct you engine exhaust towards the asteroid you are towing? I hope it doesn't melt.

I think the answer is to dock multiple ships (3) then use thrust limits to balance them in line with the com. Remember also that as you burn fuel you will change the com, mandating regular corrections.

Two ships + TAC fuel balancer is enough. Besides, doesn't need corrections.

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Wayfare

Wayfare

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Well, since the joint appears to be flexible, I guess pulling would be the right answer. You'll just need to disable engine gimbal (because docking with asteroid at the ship bottom will move them ahead of CoM) but you can still rely on Torque and SAS.

And you need to either use angled engines or keep sufficient distance from the asteroid (about three long I-beams)

My thoughts exactly. And putting the claw on the end of a boom like that has the added advantage of more leverage for your puller probe's RCS and/or reaction wheels for attitude control.

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Cmdr. Arn1e

Cmdr. Arn1e

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Reading these latest posts is giving me the idea for a plan... might try it out quick in stock 0.23 to see if it will work when the patch is released! fun times ahead ^.^

oh, and nearly forgot the obligatory "is it here yet? how about now? refresh again... how about now?" hehe... :sticktongue:

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Deathsoul097

Deathsoul097

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I must've missed that, but that would be good. However, even within the NASA parts there is inconsistency. The 3.75m thrusters have yellow/orange plumes and the 2.5m clusters have pale blue/purple plumes. I'm going to have to look into modding those, it seems...

Well, not all engines in real life have the same exhausts, and the LFO boosters are based on the F-1B powered Pyrios Boosters, which would have a different exhaust to the core stage, as they use a different fuel. I really don't think it matters though, as it was good enough for NASA.

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MKI

MKI

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I am checking every now and then, but don't the devs release an animation before the patches? Till we see the animation the patch isn't going to get released :'(

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Bomoo

Bomoo

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Well, not all engines in real life have the same exhausts, and the LFO boosters are based on the F-1B powered Pyrios Boosters, which would have a different exhaust to the core stage, as they use a different fuel. I really don't think it matters though, as it was good enough for NASA.

Something to put on my business cards, then: "Pickier than NASA"

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RuBisCO

RuBisCO

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Posted (edited)

Well real-ish fuels have not been implemented for KSP, but if an engine is burning Kerosene and LOX its flame should be brilliant yellow from all the white hot glowing carbon. If the engines are burning LH2 and LO2 it should be clear blue. Perhaps this is a prelude to that.

I remember the old asteriod mods, I would grabed small asteriod with KAS hooks, adjusted position with robotic arms at the end of each hook and moved the little buggers around. This Claw sounds like its going to make it way too easy. I might just want to see if I could do what I did before again with my own KAS+robotic parts ad hoc solution.

Edited by RuBisCO
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Nikolai

Nikolai

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Stupid questions no one may know the answers to:

* Do asteroids in the coming ARM pack have an initial spin rate? If so, can they have more than one axis of rotation, and different rates around different axes?

* Is there a way to force the software to recalculate burn time at a maneuver node when the indicator can't figure it out?

* Do near-Kerbin asteroids continually spawn and disappear, or is it just a handful at the beginning and that's it?

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Nikolai

Nikolai

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It's best to wait till the pack is released or there's another dev blog before asking stuff like this to be honest, no one can really answer these except the devs themselves.

D'okay. Just wondering if someone with better observational skills than mine might have seen something displayed that hints at answers. If no one has answers yet, that's no big deal; I'll find out when I get to play with it.

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Kasuha

Kasuha

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* Do asteroids in the coming ARM pack have an initial spin rate? If so, can they have more than one axis of rotation, and different rates around different axes?

No, they behave exactly like any other ships, i.e. they enter physics mode with zero rotation.

* Is there a way to force the software to recalculate burn time at a maneuver node when the indicator can't figure it out?

Not sure what you mean but if you activate your engines for a moment, it will adjust the burn time estimate accordingly. In any case, it's always only an estimate.

* Do near-Kerbin asteroids continually spawn and disappear, or is it just a handful at the beginning and that's it?

They constantly appear and if you don't start tracking them they will disappear again. Therefore number of untracked asteroids never exceeds certain value. Number of tracked asteroids can be as big as your PC can handle.

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Rune

Rune

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That's definitely true.

Well, since the joint appears to be flexible, I guess pulling would be the right answer. You'll just need to disable engine gimbal (because docking with asteroid at the ship bottom will move them ahead of CoM) but you can still rely on Torque and SAS.

And you need to either use angled engines or keep sufficient distance from the asteroid (about three long I-beams)

Or you could rely on torque sources, even with a bit of flexing you should get over the point where the connection reaches its flexibility limit and starts transferring angular momentum the right way. Or you could use independent RCS probes scattered across the surface evenly. Or you could build a tall tower with ion engines pointing radially outwards and fancy action group triggering if you are after extreme efficiency. Or install KAS and play with tethers to secure your ship. Or resurrect multi-docking techniques for use with the claw. Or build stock tethers using the natural flexibility of parts (that's an interesting idea, I wonder if it is actually possible). Or...

And someone, somewhere, will figure out some other way involving a hilarious game glitch in no time, I'm sure.

Rune. That's why I love this game, it's got more possibilities than Lego! (and increasing)

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Cmdr. Arn1e

Cmdr. Arn1e

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And someone, somewhere, will figure out some other way involving a hilarious game glitch in no time, I'm sure.

Now taking bets on how long before someone tries to attach a K-drive... or multiple K-drives... to an asteroid recovery ship >.<

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