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After numerous complaints from construction workers at the Kerbal Space Centre, the Kerbal Construction Union has successfully campaigned for a total ban on Oxidiser created on Kerbin. Despite the R&D Department's best efforts to convince the strikers that their recent breathing difficulties were simply due to a bad case of "The Sniffles," the workers believe that the abundant use of oxidizer in ascent stages has caused a lower oxygen concentration in Kerbin's atmosphere. Without the ability to create oxidizer using Kerbin's oxygen, the KSP has turned to a new source: Laythe.

Your challenge:

Design a craft capable of landing on Laythe, mining, and returning to Kerbin without using Oxidizer. Any other engine or form of propulsion (excluding Kraken drives) are permitted. Due to Jeb's short attention span, the mission must be completed in one launch in ten years or less. This challenge must be accomplished in a stock game, though Making History and mods that do not affect gameplay (Scatterer, TextureReplacer) are permitted.

Scoring:

You will gain points for every ore tank you fill with ore mined from Laythe. These tanks must be empty on launch, filled on Laythe, and returned to Kerbin to be scored.

+1 point for each radial tank.

+4 points for each small tank.

+20 points for each large tank.

 

Bonuses

+25 for not using NERVs.

+25 for not using SRBs.

+25 for not using parachutes.

 

Weight Categories (on launch):

Ultralight - 25 tons or less

Lightweight - 50 tons or less

Midweight - 100 tons or less

Heavyweight - 200 tons or less

Ultraheavy - 500 tons or less

Behemoth - Over 500 tons

Edited by Nozza

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I like it!

Are there any rules limiting behemoths? Otherwise it just ends up being "biggest vehicle wins".

What about multiple launches?

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44 minutes ago, sevenperforce said:

Are there any rules limiting behemoths? Otherwise it just ends up being "biggest vehicle wins".

I like this idea - how about a series of weight classes? Entries would be ranked within the same class.

Weight would be counted as mass on launchpad/runway. For multiple launches just sum the weights.

(For fairness I'd suggest no launching empty and ISRU refuelling on Kerbin's surface.)

 

Was thinking something like:

10 tons or less Flyweight
25 tons or less Bantamweight
50 tons or less Featherweight
75 tons or less Lightweight
100 tons or less Welterweight
150 tons or less Middleweight
250 tons or less Cruiserweight
500 tons or less Heavyweight
1000 tons or less Super Heavyweight

 

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I, too, like the idea. A good backstory has value!

As for scoring, challenges have a tendency to turn out over-the-top entries no matter what. Right now it's "biggest vessel wins",  if you scale it according to cost or launch mass you'll get low-TWR gravity assistery. Given the premise, "biggest vessel" doesn't seem to be all that wrong but I agree that it's ultimately boring.

If you want to cut down on gravity assists, I'd suggest to demand a fixed turn-around time like "vessel has to make the whole trip in six years or less".

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Implemented a system for different weights, plus some bonuses and a six year time limit.

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20 hours ago, Nozza said:

Implemented a system for different weights, plus some bonuses and a six year time limit.

This challenge is coming together nicely...could I suggest a little more time allowed, say 10 years?

6 years is pretty tight, even with direct Hohmann transfers and doesn't leave much wiggle room to derp around the Jool system.

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3 hours ago, ManEatingApe said:

This challenge is coming together nicely...could I suggest a little more time allowed, say 10 years?

6 years is pretty tight, even with direct Hohmann transfers and doesn't leave much wiggle room to derp around the Jool system.

Yeah fair enough.

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I just came back from a Jool-5 after 6 years, 18 days on the Kerbal calendar. That includes waiting for, and sitting through, transfers from Tylo to Bop to Pol and ultimately back home again. I admit to not thinking about it very much, like checking if I had an especially nice launch window or something.

Of course, the whole of time limits  idea is based on the premise that this should be repeatable missions, not once-in-a-lifetime events depending on unique planetary alignments. After toying around with alexmoon's planner a bit, I still think that 6 years are fine for a straightforward there-and-back flight. It might demand 100-150m/s more than the cheapest possible transfer on any given launch window, but it's entirely doable.

However, we're not merely going there and back. Mining alone takes time, possibly even a few months.

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I'm in the middle of craft design and notice that there's a point I'd like to have sorted out... will ISRU be okay? I mean, of course I'll have to mine for ore on Laythe, but can I bring a converter and make fuel for the return trip? If so, can I make (and use) oxidizer as well?

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55 minutes ago, Laie said:

I'm in the middle of craft design and notice that there's a point I'd like to have sorted out... will ISRU be okay? I mean, of course I'll have to mine for ore on Laythe, but can I bring a converter and make fuel for the return trip? If so, can I make (and use) oxidizer as well?

 You can, but only on Laythe, and it obviously won't count towards the final score. You won't be able to use the oxidizer engines before refueling too, keep in mind.

Edited by Nozza

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Ok, so I'm being a pest. I can't help it. I love the premise of this challenge, but don't think the scoring system is really up to it.

But, let me start with what I have. SSTOs capable of going to Laythe and back with ISRU aren't particularly hard. It's just a question of scaling it up a little to carry substantial payload:

screenshot38.jpg

The above vessel can take off from Kerbin and proceed to Laythe. I haven't tested the return trip yet. However: being able to SSTO without oxidizer, this one has what I consider to be excessive TWR in the nuclear department. At least for interplanetary purposes. It could, at least in principle, move much more than one cargo bay full of payload between the destinations:

screenshot39.jpg

No docking ports yet, but you get the idea. It's supposed to aerobrake on either end of the trip, the ore tanks will be protected from the worst heat by the wings. Outrigger tanks remain in space, the vessel shuttles five times on either end of the trip.

But once you take it so far, one has to wonder why the plane is supposed to go there and back again. After all, all you need to do is move some ore, which is easy:

screenshot37.jpg

This can shuttle between Kerbin and Laythe; you could probably join at least seven and start several bundles per launch window. It then becomes a question of how many you can fill on any given year. I also wonder how it's supposed to put into any weight class.

By the way, have you ever heard of Laythe Capitalism?

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Question:  is it allowable to launch from Kerbin with some Ore onboard, and then refine it into LF/Ox once out of the atmosphere?

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On 6/8/2018 at 8:17 AM, Laie said:

This can shuttle between Kerbin and Laythe; you could probably join at least seven and start several bundles per launch window. It then becomes a question of how many you can fill on any given year. I also wonder how it's supposed to put into any weight class.

By the way, have you ever heard of Laythe Capitalism?

Not really sure of what you mean, but keep in mind everything needs to be done in 1 launch. Never heard of Laythe Capitalism either, I only joined this forum like a week ago.

22 hours ago, zolotiyeruki said:

Question:  is it allowable to launch from Kerbin with some Ore onboard, and then refine it into LF/Ox once out of the atmosphere?

Nope. The tanks must be empty on launch.

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LaytheLanded.jpg

So, for what it's worth, here is an excellent savegame for this challenge (and presumably others as well): 12% ore density on Laythe, at least on the spot where I'm landed above, also on the small island to the east. On top of that, concentration is 14% on the runway, which makes for easy testing of refinery designs. Savegame is fast-forwarded to the launch window in Year 3.

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I'm totally into this challenge, and I have an awesome idea. Can we use Tweakscale? How about Ubio Welding? I can't get the ship I'm making to work due to the part count. I need bigger tanks and have to stack so many that it crashes the game.

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On 6/8/2018 at 7:19 PM, Nozza said:

Not really sure of what you mean, but keep in mind everything needs to be done in 1 launch. Never heard of Laythe Capitalism either, I only joined this forum like a week ago.

I think what he means is "must the craft stay in one piece the whole time?"  You could design a large craft that goes from Kerbin to Low Laythe Orbit, and then you have a smaller craft that shuttles between that and the surface, ferrying ore up.  That way, you really don't need to worry about your TWR when lifting ore into orbit, because you can ferry a smaller amount of ore many times.

Taken to the extreme, you could have a craft made up of four parts:  A kerbin ascent stage, a Kerbin-to-Laythe ore barge (lots of ore tanks plus an efficient engine and fuel), a Laythe SSTO for ferrying ore up to the ore barge, and an ISRU/drilling module that sits on Laythe.  The first stage stays in LKO, the second part stays in LLO, the third refuels on Laythe each trip, and the fourth just sits on Laythe and mines and refines.

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17 hours ago, doggonemess said:

I'm totally into this challenge, and I have an awesome idea. Can we use Tweakscale? How about Ubio Welding? I can't get the ship I'm making to work due to the part count. I need bigger tanks and have to stack so many that it crashes the game.

Well, that's an outgrowth of "biggest vessel wins"...

13 hours ago, zolotiyeruki said:

Taken to the extreme, you could have a craft made up of four parts:  A kerbin ascent stage, a Kerbin-to-Laythe ore barge [...]

Yup, though that's no longer a "vessel" but a system. It's what reminded me of the Laythe Capitalism challenge which was fun to do but a PITA to score.

--

I've meanwhile done this with a single vessel, a large plane similar to what I posted above. The most difficult part, by far, was takeoff on Laythe under a full load. Even after carefully picking as level a track as I could find, I had to get off the ground at ~80m/s or it would break up -- no runway, see?

I probably shouldn't complain, 80m/s is quite a ludicrous speed for going cross-country...

For testing purposes: if your vessel can break the sound barrier on Kerbin with a full ore load, it can make space on Laythe (fuel permitting, of course).

A direct Laythe->Kerbin Transfer cost me about 1100m/s. However, I had to use my engines for a 500m/s slowdown on Kerbin approach in order to survive the aerobraking.

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40 minutes ago, Laie said:

Well, that's an outgrowth of "biggest vessel wins"...

In general, this would be true. But size isn't my goal - it's a limitation of the parts I'm using that the tanks aren't big enough and I need more than my PC can handle.

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3 hours ago, Laie said:

Yup, though that's no longer a "vessel" but a system. It's what reminded me of the Laythe Capitalism challenge which was fun to do but a PITA to score.

Right. So I think the rules need to be clarified a bit.  I mean, what about an SSTO with a large, detachable ore tank that sits in LLO?

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Maybe it's a little late to change the scoring system, but might it make more sense to make it some function of

(launch weight) / (return ore quantity)

rather than having different weight classes?

I think structural integrity would self-limit the sizes, since it's stock only.

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I had an absolute blast with this challenge. Never really delved too deeply into the mining and ISRU aspects of KSP before, so this was a nice excuse to give these a try.

Learned some new things:

  • Don't forget your parachute radiators.
  • Finding good concentrations of ore takes time and effort.
  • Small ore tanks do not like 4km aero-braking.

Without further ado, here's a sub 25 ton spaceplane entry.

6ipam0O.png

Mining and refuelling on Laythe at 5% efficiency took over a year. 3 PB-NUKs provided constant reliable power. An engineer could have sped this up, but the high power requirements of running at 125% pushed the mass of the craft up too much.

2bbQuJy.png

Seconding @Laie's experience, take off with full ore tanks was sloooow. My technique consisted of driving off the edge of a cliff and desperately trying not to hit the ground.

e8AIt5t.png

Once in LLO, I found I had miscalculated horribly and only had 1,150 m/s dV left. Enough for a Kerbin transfer but not enough to brake successfully. Normally a sequence of gravity assists could whittle the orbit down but the challenge time limit prevented that.

A suitably Kerbal workaround was to convert 1/3 of our precious ore to fuel while in orbit, gaining another 400 m/s dV.

fqyTyKT.png

A Tylo gravity assist flung Jeb to Kerbin for the bargain basement price of 670 m/s.

7wWe1Vi.png

Re-entry was too brisk to capture on the first pass, but diving as low as possible into the atmosphere gave a handy Oberth bonus.

lrJkjIW.png

That slowed the craft down enough that a small 40 m/s adjustment gave a 1:1 resonant orbit with Kerbin and an aero-capture was (just) about possible on the 2nd pass.

i1DeTOl.png

4 small tanks of ore delivered to Kerbin in 9 years, 100 days.

VJuyVr7.png

 

Full album link with more details.

 

@Nozza Nice work on your first challenge - it's both tricky and thoroughly enjoyable :)

The time limit adds a nice pressure. You have to mine quickly enough to get back in time and also bring enough dV to return to Kerbin without the aid of multiple gravity assists.

Edited by ManEatingApe

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That's a neat design! I like the gap in the center stack (and how you follow up with an intake -- for drag reduction I presume?). But, in all honesty, I wonder if it's really worthwhile: personally I'm under the impression that a service or cargo bay is mass well spent.

On 6/17/2018 at 9:04 PM, ManEatingApe said:

My technique consisted of driving off the edge of a cliff and desperately trying not to hit the ground.

Yup, same here :)

Edited by Laie

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1 hour ago, Laie said:

That's a neat design! I like the gap in the center stack (and how you follow up with an intake -- for drag reduction I presume?). But, in all honesty, I wonder if it's really worthwhile: personally I'm under the impression that a service or cargo bay is mass well spent.

Thanks, the gap is the middle is mostly for fun :)

1 hour ago, Laie said:

That's a nice looking craft, hope you're going to submit an entry with it!

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