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Duna Outpost Mission Architecture Challenge


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Chapter 10 (already?) is finished, I'll post chapter 11 later this evening after I take a break :D

 

rsca2h.jpg

 

SLV 04, mining ops, Kerbin Early Return (with sample) on its way. Things are getting hotter by the minute cause there's an incoming bullet train to catch !

Edited by Kerbolitto
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On 7/9/2018 at 4:24 AM, Death Engineering said:

If a Kerbal is left at the outpost alone (for any reason) for more than 10 days, they suffer 'Over-stressed crew' penalty.

I was wondering about this one, but since Kerbals in Kerbin orbit don't count towards points I'm assuming this is not a problem for mining operations in Kerbin SOI?

Also, made a "little" video of my test flying the miner in Kerbin orbit today, discovered some shortcomings still and will need to rebalance some things (weight balancing is REALLY difficult with this payload). The SLV and PLV (Payload Vehicle) will land back on Kerbin, both have been tested and can be landed. I'm using the PLV to keep the payload together during refueling ops. The PLV uses monoprop engines so as to clearly NOT be able to transfer fuel between PLV and payload, which works on LH2/LOx and uses barely any monoprop  which it is delivered to LKO with and all docks are set to disallow crossfeed, so any transfer would have to be deliberate.

My SLV/PLV is rated for lifting the exact weight of 79.0415 t (which is the perfect weight to allow me a double launch during each window while consuming the exact total maximum allowed mass with a reusable SLV/PLV.

During the video some messages pop-up of Kerbals dieing, that's another test, which I haven't fully assembled yet (using Quicksaves to revert to the correct moment after the test-base has been placed at it's destination near the desert temple).

 

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So, erm, I seem to have hit a snag. I've been on ksp131 for mod compatibility, now I've found out that there's a nasty bug involving asteroids hanging their shape on every load, leading to exploding vessels and/or drills hanging high and dry.

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1 hour ago, Kerbolitto said:

What's the problem with weight balance, design is assymetrical ?

It's very narrowly cut, I'm playing with kilograms of weight on each part to balance stuff out. The miner has JUST enough fuel to bring the tank into Minmus SOI, but not enough to land it on the first go, so I have to land the miner, refuel it and then go back up to bring the tank on the first launch...

I did manage to find another 250kg by changing the solar panel layout and used it to attach a bunch of cameras, antennas and capacitors, I think the result is excellent! That test made me fix a lot of little issues with my system!

 

8 minutes ago, Laie said:

leading to exploding vessels

Oh crap, there goes the asteroid mining plan, or you require a complete redesign in 1.4.5 with updated mods (if available)... I had to rebuild my entire install to move from 1.3.1 to 1.4.5 and it doesn't work smootly unfortunately... Got some texture issues and other mostly visual errors, nothing exploded so far (except for pilot error ofcourse!)

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1 minute ago, hoioh said:

It's very narrowly cut, I'm playing with kilograms of weight on each part to balance stuff out. The miner has JUST enough fuel to bring the tank into Minmus SOI, but not enough to land it on the first go, so I have to land the miner, refuel it and then go back up to bring the tank on the first launch...!)

You might find a way to change your packaging so there's no docking maneuvers in LKO, you may add a bit more fuel by removing all monoprop or just use very little ?

 

12 minutes ago, Laie said:

So, erm, I seem to have hit a snag. I've been on ksp131 for mod compatibility, now I've found out that there's a nasty bug involving asteroids hanging their shape on every load, leading to exploding vessels and/or drills hanging high and dry.

Too bad that would have been awesome ! :/

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4 minutes ago, hoioh said:

It's very narrowly cut, I'm playing with kilograms of weight on each part to balance stuff out.

Don't sweat. You probably have RCS build aid, but if you don't, even KER will display how much torque you get from imbalance. Compare that figure to the strength of your reaction wheels: 5% is barely noticeable, 20% well bearable even without gimbals. With gimbals, you can go totally over the top. Not that I recommend it... but tweaking it on a kilogram level just isn't necessary.

18 minutes ago, hoioh said:

Oh crap, there goes the asteroid mining plan, or you require a complete redesign in 1.4.5 with updated mods

Working on it. I'll still have to redesign my vessels, which will take a while. However, most interesting: Asteroid HSJ-227, Class E (huge), appears to show up right at game start on always the same trajectory, no matter what. So I can salvage my mission plan if nothing else.

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13 minutes ago, Laie said:

Don't sweat. You probably have RCS build aid, but if you don't, even KER will display how much torque you get from imbalance. Compare that figure to the strength of your reaction wheels: 5% is barely noticeable, 20% well bearable even without gimbals. With gimbals, you can go totally over the top. Not that I recommend it... but tweaking it on a kilogram level just isn't necessary.

Different kind of balance, this is not about symmetry as much as it is about the weight of each component. If I add something to the miner I need to reduce the weight of the tank, or the base(s) in order to remain within the limits of the launch vehicle, which is the highly specific 79.0415t weight limit. currently my payload weighs 79.038t so I have 3.5kg to spare :cool:

Edited by hoioh
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10 minutes ago, Laie said:

Don't sweat. You probably have RCS build aid, but if you don't, even KER will display how much torque you get from imbalance. Compare that figure to the strength of your reaction wheels: 5% is barely noticeable, 20% well bearable even without gimbals. With gimbals, you can go totally over the top. Not that I recommend it... but tweaking it on a kilogram level just isn't necessary.

Torque is definitely manageable if you throw enough control at it. i made this SSSTO (single stage seaplane to orbit) monstrosity a while back, and in atmo it had up to 1.5 meganewton-meters of torque. This was managed with a combination of a crapton of reaction wheels and large aerodynamic surfaces. Once the oxidizer burned off and the craft switched to Nervs, the CoM shifted and the torque was a more normal 50-100 kilonewton-meters.

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4 minutes ago, Kerbolitto said:

What if you send 2 or 3 small ISRU instead of one big ? Or only one drill ?

The single big one is SO MUCH MORE effective, it is rediculous! Not going back to half size 1/8th efficiency

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1 minute ago, Kerbolitto said:

What if you send 2 or 3 small ISRU instead of one big ? Or only one drill ?

If time is a factor... usually, mining is limited by drilling rate. You definitely want a skilled engineer on-site, and even then, it usually takes several drills to fully utilize a single converter. Small converters waste most of the ore input, though. Last time I filled up a huge vessel on Minmus, it took 180days on a small converter, 30days on a large one. Everything else being... well, similar.

Incidentally, that's one of the problems solved by asteroids: mining rate is insanely high there, or at least used to be. Last time I tried, a single large drill could have fed several converters, even without engineers. I'm counting on it still being thus.

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6 minutes ago, hoioh said:

The single big one is SO MUCH MORE effective, it is rediculous! Not going back to half size 1/8th efficiency

Well if you're stuck with the weight capacity, you could use a miner which refuel in 2 days rather than 2 hours it's no big deal since first transfer window is 170 days after launch?

4 minutes ago, Laie said:

If time is a factor... usually, mining is limited by drilling rate. You definitely want a skilled engineer on-site, and even then, it usually takes several drills to fully utilize a single converter. Small converters waste most of the ore input, though. Last time I filled up a huge vessel on Minmus, it took 180days on a small converter, 30days on a large one. Everything else being... well, similar.

Don't know, mine has a big convertotron with 2 large drills and it refuels 2 medium mk3 fuselage in less than a day. The small converto that's on the outpost refuels 22.5t. in around 3 days with only 1 big drill.

Point is, you can use 1 or 2 little ISRU on first launch just to get enough fuel to inject to Duna, then use this stuff to mine Ike. For the next injections if you got more weight in orbit, you can plan another big / more efficient ISRU which'll stay near Minmus. (just an idea !)

Edited by Kerbolitto
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Just now, sturmhauke said:

One big problem with the small converter is that it will overheat and shut down. You literally cannot prevent it, at least in the stock version. That means you have to babysit it more.

Don't know, mine works pretty well .. But I did not do any math around it so it might be over engineered :/ I usually always watch what ISRUs are doing, to adjust fuel-cell consumption, so yeah maybe you can't leave it do its thing during one month, I don't know.

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1 hour ago, hoioh said:

It's very narrowly cut, I'm playing with kilograms of weight on each part to balance stuff out. The miner has JUST enough fuel to bring the tank into Minmus SOI, but not enough to land it on the first go, so I have to land the miner, refuel it and then go back up to bring the tank on the first launch...

I did manage to find another 250kg by changing the solar panel layout and used it to attach a bunch of cameras, antennas and capacitors, I think the result is excellent! That test made me fix a lot of little issues with my system!

[...]

A couple of suggestions for saving weight: I'm using 4 small drills rather than 2 large, will that work? And is an engineer strictly necessary? Also, do you need two of those pods? They're only 90kg, you could just move your radial ore container opposite it. Also, it looks like you're using micronodes for your engines. You can trim a bunch of kg by replacing those with surface attached cubic struts. (near future construction will let you switch "cubic family struts" to planes rather than cubes, for a 2kg per strut savings) Finally, are you sure you're minmaxing the radiators enough? Static edge panel radiators have a core heat transfer per kg of 5000, as do the small panels. And all of the near future or atomic age radiators beat stock. Finally, you might want to consider using structural parts for landing gear instead of landing gear, if you can get away with it.

 

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...aaand, just because I happen to think of it at the moment: is there a sufficiently flat site somewhere on Duna, preferably within ten degrees of the equator? I plan to come with winged landers and would rather not cope with 30m Dunes on every approach, nor do I look forward to my base going up and down the hill.

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Just now, Laie said:

...aaand, just because I happen to think of it at the moment: is there a sufficiently flat site somewhere on Duna, preferably within ten degrees of the equator? I plan to come with winged landers and would rather not cope with 30m Dunes on every approach, nor do I look forward to my base going up and down the hill.

Ooh, very Von Braun. Looking forward to seeing how that will work.

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18 minutes ago, Mad Rocket Scientist said:

A couple of suggestions for saving weight: I'm using 4 small drills rather than 2 large, will that work? And is an engineer strictly necessary? Also, do you need two of those pods? They're only 90kg, you could just move your radial ore container opposite it. Also, it looks like you're using micronodes for your engines. You can trim a bunch of kg by replacing those with surface attached cubic struts. (near future construction will let you switch "cubic family struts" to planes rather than cubes, for a 2kg per strut savings) Finally, are you sure you're minmaxing the radiators enough? Static edge panel radiators have a core heat transfer per kg of 5000, as do the small panels. And all of the near future or atomic age radiators beat stock. Finally, you might want to consider using structural parts for landing gear instead of landing gear, if you can get away with it.

 

The drills are scaled a little because the K&K ISRU is a little lighter, they come in at 0.9t each and cleanly max out the ISRU unit's capacity. Since the small drills have the same drill volume per weight, that wouldn't make any difference.

The cubes were a cosmetic choice, but you're right, if I replace those wth cubic struts I could scale up the engines a little bit, which would also make them more efficient because of Oberth-effect.

I slapped on the 2 smaller radiators because the 2 medium ones didn't cut it, simple empyrical test showed me that

Structural instead of gear, need to consider, I've never built that way before

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9 minutes ago, hoioh said:

The drills are scaled a little because the K&K ISRU is a little lighter, they come in at 0.9t each and cleanly max out the ISRU unit's capacity. Since the small drills have the same drill volume per weight, that wouldn't make any difference.

The cubes were a cosmetic choice, but you're right, if I replace those wth cubic struts I could scale up the engines a little bit, which would also make them more efficient because of Oberth-effect.

I slapped on the 2 smaller radiators because the 2 medium ones didn't cut it, simple empyrical test showed me that

Structural instead of gear, need to consider, I've never built that way before

Oh, I didn't realize you were using tweakscale. I ended up deciding against it since it takes so long to copy the relevant info into spreadsheets.

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27 minutes ago, Laie said:

...aaand, just because I happen to think of it at the moment: is there a sufficiently flat site somewhere on Duna, preferably within ten degrees of the equator? I plan to come with winged landers and would rather not cope with 30m Dunes on every approach, nor do I look forward to my base going up and down the hill.

Hard to find .. I've landed a few SSTO on the midland sea if I remember, but even there there's small bumps (20-30m hills) which makes things quite dangerous with low l/d ratio =/

I can try to find the landing flags in one of my sandboxes if you want.

Edited by Kerbolitto
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5 minutes ago, Mad Rocket Scientist said:

Oh, I didn't realize you were using tweakscale. I ended up deciding against it since it takes so long to copy the relevant info into spreadsheets.

I don't know what's relevant to you, but my Excell excells, so to speak. And it's a horrible mess :wink: it works for me though!

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22 minutes ago, Laie said:

...aaand, just because I happen to think of it at the moment: is there a sufficiently flat site somewhere on Duna, preferably within ten degrees of the equator? I plan to come with winged landers and would rather not cope with 30m Dunes on every approach, nor do I look forward to my base going up and down the hill.

There is the Midlands Sea biome which is pretty flat (may be the flattest out there), very low on altimeter and literally covers almost half the Ike-facing side.

 

Speaking of which... asking for samples from 5-6 biomes has implications, especially combined with mobile base condition. Yes, that's where I've been stuck lately... already got 10 biomes and there is 4 more clustered down in the south. Also searching for these

492701f2d819.png

 

On another note, I think I'm satisfied with this design for what my third launch will be

3a87b6be17aa.png

Yup, a pile of everything, but the launcher doesn't mind, especially if it's couple tons lighter than standard payload.

The package includes:

  • a lander for 4 crew with long-term life support. And a sturdy reentry capsule
  • 2 boosters/tankers for it (the delta budget v for quick return from Duna surface turned out a bit too tight, so we'll leave some fuel in orbit - also the tankers might get further use down the line)
  • a literal scrapton (or maybe a few) of spare parts for the first base module - just some little improvements, especially in power department (also some more things will be stripped from the lander that could be used for other purposes)
  • 2 more commsats (under fairings)
  • a transfer stage for the next launch
  • no fuel (there is more than enough time to mine it)
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1 hour ago, hoioh said:

I don't know what's relevant to you, but my Excell excells, so to speak. And it's a horrible mess :wink: it works for me though!

There's a bunch of exponents that define how the stats scale that can only be found in cfg files, along with all the regular stats that have to be copied over. Armed with that info, you can figure out whether a scaled up spark is better than a poodle, or any number of other comparisons. I could probably just do it with a python program though...

And sometimes mod makers make mistakes in balance. I remember for this challenge, I made a lifter with that used a tantares engine that got ridiculously cheap (like less than 100 funds) when scaled down, and tanks that were free except for the cost of fuel. All in all, my rocket could deliver above average payload to LKO for the lowest cost/kg of any of the competing rockets even with markup of nearly 100%.

Of course, the challenge died before anything could fly on my rocket. :( And then the reboot died too.

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