Preparation for a Duna Kethane Mission

[PTNLemay]

I'll quickly admit that this was directly inspired by Scott Manley's kethane series. Ever since I've seen it I've wanted to build a mobile kethane mining base of my own. I'm doing this in career mode, so I'm quite limited in terms of available parts. I'm sure I may be doing lots of mistakes, so please feel free to offer me up some pointers. (Click the images to get full sized versions.)

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These were my first attempt at the train's basic cars, I couldn't figure out how else to put the remote command module in the center, so I built the car around it. Ended up being too heavy and too fragile.

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On this one I put the module on one end and just put a copy of it on the other end, makes for a sturdier design. I was testing to see if I could lift the thing back up into orbit, but I think it wouldn't have enough thrust to lift a fully loaded car.

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This is a close-up of my current wheel design. I had to use OKTO modules because I don't have any struts that will connect at 90 degrees like that yet. I'm using Editor Extensions and sub-assemblies to keep the wheel mechanism consistent across multiple different cars and vehicles, that way I should be able to connect everything.

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Proof of concept for my cars snapping together. It's a bit tricky because the cars seem to sag when they're heavier, which makes the connection point height uneven. Also you can see my troubles with symmetry...

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Another test to prove the concept. The rocket is very finicky, the part where it connects to the wheels feels fragile and it wants to flip over every time I break or turn (even with a half-empty rocket). But... it connected! Which is exciting.

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Another angle showing off the wheel design (and my latest "flying car"), I'm worried it's too narrow, and that's why the tall components like the rocket want to flip over. But I'm not sure how I can widen the stance and keep it nicely symmetrical. As I said earlier, any advice will be greatly appreciated.

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Here's a line up of my lifters, the right most being my best bet so far. It actually managed to get into a 90km sub-orbital trajectory from Kerbin's surface. So it might just be able to be useful at Duna... Plus thanks to it's low center of mass it's quite stable, even though it's using the narrow wheels.

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This is the home module, where the crew would stay. Added lights to make it feel more homely. Everything connects quite nicely using the new wheel system which has just 5 parts.

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Still to go are kethane converter cars, habitation cars, and a nice big interplanetary vehicle to get it all over there. I'm also starting to think I'll have to make all of the cars "flyers" to some degree, if only to help them land safely on Duna. I'm not sure parachutes are going to cut it in the thin atmosphere.

By the way, is there a clean way to do line breaks on the forum? I don't want to have to add those hyphens if I can avoid it.

Edited January 31, 2014 by PTNLemay

[Brotoro]

You can edit the name of your own thread. Edit the first post and click the Go Advanced button, and then the title is accessible.

Edited January 19, 2014 by Brotoro

[PTNLemay]

Ah... silly me. Thanks.

[Kieve]

Hm... suggestions...

• Build your rover in the SPH, not the VAB. It makes the whole horizontal symmetry thing vastly easier. Best advice is to start with one key component you can remove (say, a probe core at the front), build off of that, and when you have a completed vehicle, detach everything from the core part and save it in the sub-assembly tab. That way, you can load up the completed design in the VAB for actual rocket launch, when it's ready to go.
  
• Creative use of probe cores, but probably not the wisest. They don't suck much electricity, but be wary of where you're sending them - planetary day/night cycles can leave you high and dry when there's no sun for solar power, and electric wheels can be more of a drain than you'd expect if you do a lot of driving around.
  
• Suggestion for widening the stance: aircraft fuselage. I had the same issue with the Centipede initially, and it took a while to figure out a good solution. It still had a tendency to barrel-roll at speeds above 15m/s on the Mun, but I put that down more to the low gravity and KSP's physics. I don't suggest an identical wheel setup, since that was way overkill and sucked batteries dry thanks to all the wheel motors, but using the aircraft fuselage as a side-pylon might be a good way to widen (and lower) the stance on your kethane cars so they're less prone to toppling.
  
• You can use HR tags in brackets for a horizontal rule. Like so:
  

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Hope you find some of that helpful!

[PTNLemay]

Build your rover in the SPH, not the VAB. It makes the whole horizontal symmetry thing vastly easier.

Mmmhmm, I just noticed that Editor Extensions actually has an option to switch the symmetry mechanism from VAB-style to SPH-style, regardless of what building I'm in. That should help with the side-to-side symmetry at least, though I don't think it will work on front-to-back. For that one I'll still have to nudge the positions manually.

Creative use of probe cores, but probably not the wisest.

Yeah, but like I said I'm short on science points. I know there's an octagonal girder that would do the job admirably, but it's too far up the tech tree for me right now. I'll just have to strap a lot of solar panels on my cars, be careful and hope for the best.

Suggestion for widening the stance: aircraft fuselage. I had the same issue with the Centipede initially, and it took a while to figure out a good solution.

It does look really cool... lol. Unfortunately the fuselage piece is pretty heavy, also it kind of looks like you had to resort to parts clipping. It's not a very big deal, I suppose... but if I can avoid it I will. I've heard that loading bugs can be made worse when parts are clipped (though I've never tested this to prove it). Also thanks to the functioning symmetry I was able to widen the stance using simple girders. The only risk is if this paper-mache jumble I'm getting will handle heavy loads or not.

You can use HR tags in brackets for a horizontal rule. Like so:

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Cool beans. Thanks a lot for all of the advice. It DOES help greatly.

[Kieve]

Mmmhmm, I just noticed that Editor Extensions actually has an option to switch the symmetry mechanism from VAB-style to SPH-style, regardless of what building I'm in.

What's the command for doing so? I know the mode switch is there, supposedly, but could never figure it out myself, nor locate it in the documentation.

Yeah, but like I said I'm short on science points. I know there's an octagonal girder that would do the job admirably, but it's too far up the tech tree for me right now. I'll just have to strap a lot of solar panels on my cars, be careful and hope for the best.

I'd sooner advocate using another girder piece, or just attaching the axle girders to the base of the other one directly. I see you've got at least the lightweight strut unlocked already, that should reinforce it enough to be sturdy. I know the tech-tree woes well enough, went through plenty of that with my own career mode (before harvesting 5,000-some science out of the Mun biomes). Ultimately it's your craft of course, just trying to recommend alternatives.

It does look really cool... lol. Unfortunately the fuselage piece is pretty heavy, also it kind of looks like you had to resort to parts clipping. It's not a very big deal, I suppose... but if I can avoid it I will. I've heard that loading bugs can be made worse when parts are clipped (though I've never tested this to prove it).

This may sound unnecessarily defensive (if so, I apologize), but I certainly wouldn't say had to resort to it, as if doing so was out of desperation. I simply rotated the fuselage inward to lower the profile a bit, for aesthetic reasons - didn't need it sticking all the way out to the side like a seaplane pontoon.

Points to consider also:

• 2x Fuselage, mounted mid-section on either side of car
  
• Total Weight: 0.8t
  
• Total Drag: 0.4
  
• Impact Tolerance: 70m/s

• Current Girder Assembly with probe cores
  
• Total Weight: 1.45t
  
• Total Drag: 2
  
• Impact Tolerance: 80m/s girder, 12m/s probe core

Drag only really matters for liftoff and Duna entry, but the weight-savings speaks for itself I think. Moreover you won't have the same issues with electricity drain, a lower part-count, fewer struts needed to stabilize it, and while the lower-profile clipping isn't necessary, I haven't once had any issues with it Kraken-wise.

You might also consider just attaching a pair of girders to the kethane tank itself and using shift+Q/E to rotate them out horizontally from the bottom (+struts as needed to ensure proper stability).

[PTNLemay]

What's the command for doing so? I know the mode switch is there, supposedly, but could never figure it out myself, nor locate it in the documentation.

Sorry it took so long to reply, I didn't want to post again until I had some updates regarding the Duna mission. Progress has been slow on that front... I'll probably go to the Mun first to practice my technique, it's a lot easier to reach even though there's not much science left to gather there.

It's the tab key, that's what switches the modes.

[PTNLemay]

Pardon the double-post, but I seem to be missing something incredibly obvious, though I can't for the life of me figure out what it is.

The contraption has power, it has a converter unit (2 of them in fact), it has a fuel tank with room to spare, I've even connected said tank to the converter unit in case it needs a connection to do it's thing. There's even kethane ready to be converted and yet... nothing's happening. I tested it before and I was working, I'm not sure what it is I'm doing wrong this time around.

http://i.imgur.com/t30YrWL.png Link shows the full pic, you need the full 1080p version to see the little details (like the windows I put up to show everything should be working).

[Captain Sierra]

The fuel lines are backwards.

SOmething about KSP not supporting stuff means the way it works is by CONSUMING a NEGATIVE ammount of the resource its 'producing'. Counterintuitively, the fuel lines need to run from the fuel tank to the converter.