Underwater adventures / Kethane Mining

[Bishop149]

Relevent Mods to this this thread:

KAS

Kethane

All other parts = stock.

So I discovered quite by accident upon playing around with boats that I could make things sink in a controlled manner, mostly by attaching KAS's anchors to things, which got me thinking. . . there's A LOT of inaccessible Kethane on Kerbin. I mean look at it all!

Time to start attempts to exploit this resource!

Basic design principles:

- Anchors make things sink

- Most parts are pretty damn buoyant, the more you have the more of anchors will be required to make it sink, very large multipart divers might be impractically heavy!

- Relatively non buoyant parts seemed to be the various very small girder parts, building solely out of these however is difficult. . . they have a tendency to become very wobbly and fly apart.

- Anchors can been quite picky about clipping . . . trying to cram too many in a small space will result in explosive disassembly!

- The diving bit will be very small and very heavy, as a result it is very prone to wobble and will massively destabilize any craft when moving at any kind of speed. It will thus require securing to the deployment craft with multiple struts, which will have to sheered with decouplers before diving.

All my testing was done just offshore of KSP. . . once I had something that looked like it might work I strapped it on a rocket and shot it off to an actual Kethane field.

My first attempts were kinda "traditional" drilling rigs, surface based floating platform and a VERY long line going down to a small drilling platform on the sea bed. . . or at least that was the idea. This didn't work.

The core of the drill head was basically one of these, with 2 drill heads attached and about 8-10 anchors crammed in in such a way so as it didn't explode!

Each KAS winch has a max extended length of 50 meters, most of Kerbin's underwater Kethane is in at least 800m depth. . . some of it is up to 1200m. So this would need 16-24 fully extended winches to reach. I gave it a go but couldn't get more than the first 3 winches fully extended before it wouldn't sink any more:

I could improve this a little by adding 2 additional anchors to every other winch segment. . . this got me to 5-6 full extended winches.

This clearly isn't gonna work to get the required ~20 would seemingly need an insane amount of anchors / weight. . . I also had my doubts as to the stability of a 1 km long craft. As part of this testing in frustration I unplugged the drill head . . . to the the drill head drift calmly to the bottom. Which gave me an idea, I don't really have to stay connected to the surface at all. . . . I mean it would be lovely to pump it all up but it doesn't appear practical, a diving and resurfacing extractor might be best!

So I started designing a small prototype, the diving bit is basically a modified version of the drill head of my rig, with one drill, one small kethane manifold and a lot more anchors. half the anchors are detachable with a small decoupler for shedding weight for ascent of the sea bed. Oh and a battery and a few RTG's for power + smallest probe core and some lights for aesthetic value!

I learned the following;

- As soon as you start separating small girder parts with lots of anchor parts attached with decouplers they become SUPER unstable, too many struts to try and secure them and they don't separate properly. It was a nightmare building a stable diver this small.

- Any kind of fuel tank (including kethane Storage tanks) are really very buoyant . . the number of anchors is now around 16-20 to get it to sink.

So here we see a the final prototype (very) small scale submarine extractor on decent from orbit to a kethane field:

in the second images you can see several small decouples that have been fired. . these had the securing struts attached to them . . now the decent is slow and straight wobble isn't a problem.

So, lets deploy!

Once winch was fully extended the diver was freed to fall

Here we are approaching the sea floor, final decent rate of 9.7 m/s is a little alarming!

But it touched down safely on the sea bed just over a km down and it was time to drill baby, drill!

As the drill used up power far faster than the 2 RTG's could provide it, drilling was therefore separated into drill, recharge, drill, recharge etc

Kethane Tank full it was time to ditch about half the anchors and see if it would float up . . . Success! ascent rate of about 3-4 m/s

How much weight to ditch is a tricky one. . . as I found during testing ditch too much and you shoot up like a rocket either colliding with the surface rig and exploding or shooting clear of the water before falling back down and exploding!

Once the diver had surfaced Billy-Bobby Kerman went for a swim to reattach the winch cable before returning to the rig.

And there we are, 150 units of submarine kethane extracted to the surface!

But lets face it. . . 150 units isn't worth anyone's time and effort. . . can this be improved? Tune in next post!

Edited May 19, 2014 by Bishop149

[Speeding Mullet]

Once you've got it nailed down I'm sure everyone would like to see a sustained mission to Laythe including your underwater drill rigs!

[Bishop149]

Ok so numerous larger prototypes were tried and the following was learned:

- This is an obvious (and large) weight difference between a full kethane tank and an empty one. . . logically this would affect the buoyancy and indeed it does, some designs that ascended fine during empty testing after losing some anchors did not ascend at all once the tank was full.

- The drill / recharge cycle was ok with a tiny quickly filled tank, but with big ones was a WAY too slow, I need the drills running constantly.

I initially tried just giving it a HUGE amount of electric charge but batteries are quite buoyant and even with a quite a few huge ones I was still gonna run out of charge before the tank was full. So recharge > drain it then. I didn't try solar panels . . . I mean I'd imagine the game might allow them to work underwater but this is colossally unrealistic and panels are also quite buoyant. RTG's it was. . . . to run each small drill 10.6 of them will be required, I ended up using 22 for 2 drills. Fortunately RTG's both aren't especially buoyant and come with two attachment points for additional anchors to be attached to.

- I found that these decouplers are ideal both for ejecting stablising struts post landing and for ditching anchors.

They aren't very buoyant which means that the sink well and don't bounce annoyingly on the surface when the stablising struts are ditched whilst the rig is floating, additionally I could fit up to 6 anchors on each one.

- Both time warp and loading quick saves are inadvisable for a ship sitting in the seabed . . . both tend to cause the ship to spontaneously explode! I recently have gathered the feeling that this might be ameliorated by the tank sitting on landing legs rather than directly on the bottom.

- The current design is not reusable as it explosively ditches bits of its self to ascend. I tried using the KAS part can both ditch anchors and that Kerbs can attach and fresh anchors to as a means of reversibly ditching weight for ascent. This did not work, the part can only hold one anchor and its own buoyancy is not countered by the anchor it carries. Non-starter!

So after about 5 or 6 prototypes I came up with a design based around an 8000 unit Kethane Tank, here it is on decent:

It came down at night and I used my standard Kethane miner illumination!

Rate of decent was perfectly acceptable at ~5 m/s and touch down at ~930 m down on the sea bed

Drilling began took quite a long time, tank was filled at 2.5 units / second which translates as almost an hour to fill an 8000 unit tank. No bloody time warp so I went and watched a TV show and left it too it! Increasing the drill speed isn't really practical, I already need 22 RTGs to run only 2 drills, more / bigger drills will require an absolute LOAD of RTG's . . . most of which will need more anchors to weigh them down.

So, ascent!

Empty and sinking the diver weighed 71,330 kg

Once full the diver weighed 87,330 kg which worked out correctly at 2kg / unit kethane, a 16,000 kg increase

The weight ditched for ascent was 50,260 kg and it only JUST ascended, rate began at 1.1m/s and finished at ~0.85m/s on the surface. So it seems perhaps that ditching 3.2x the weight gained in kethane may be a minimum for ascent.

During ascent something glitched out and the surface rig some how ended up on the bottom, switching to it just made it explode. . . so I recovered it.

After surfacing Jeb arrives in a hydrofoil kethane tanker to drain the kethane and ship it back to KSP's stores!

So successfully recovered 8000 units of submarine Kethane, as seen in the comparison image below:

Future plans for this thread:

- I need to see if the landing leg impression is correct, both warp and quicksaving would be nice to have back!

- I might as well try it with the largest Kethane tank; 16,000 units might make the whole thing worth it!

- I have an idea how I might be able to make my original drilling rig idea actually work. . . . needs testing!!

- I'm gonna try underwater bases / submarines!

[Deadpangod3]

Wait so things will ONLY sink if the anchor is planted on the ground underwater, or if its floating freely?

[ThirdHorseman]

You can edit the CFG file for the winches to increase the length of the line.

[Bishop149]

Wait so things will ONLY sink if the anchor is planted on the ground underwater, or if its floating freely?

The way I have always done it is:

- Design sinking craft with x anchors attached, usually via the RTG hardpoints or that tiny physics neutral girder that can be radially attached and has a hardpoint on either end.

- Attach sinking craft to floating platform via a single winch. Secure the sinking bit to the floating bit with struts that can be blown off with a decoupler before deployment, if you don't to this it will wobble itself to bits.

- Drop in sea at <10m/s, whole craft should float with not too much below the waterline.

- Blow the securing struts and lower away with the winch, sinking bit will then either:

a) Drop into the water to max winch depth (50m) in which case it will probably sink ok when you uncouple it from the winch.

Float, and winch will keep spooling out but to no effect and nothing will sink. . . in which case try again and increase x.

I did once get a bit bored of the whole floating winch platform thing and tried just dropping the sinking bit with only a detachable parachute section above it, didn't work . . . the problem here I think was that if too much of the craft submerges upon impact with the water the craft just breaks apart.

You can edit the CFG file for the winches to increase the length of the line.

A little cheaty for me that one. . . . I might do it, but will be as a last resort! I find it more fun to find ways round the games limitations. . .

Edited May 19, 2014 by Bishop149

[Geschosskopf]

Great job, Bishop! You are having much more success than I.

My own attempts to do this were based on using a rocket to push the Kethane equipment to near the bottom, at which point I'd fire a grapple from a winch to keep it down and lower it the rest of the way until the drills could reach the bottom. The rocket would be refueled on the bottom as well to keep speed from getting too high on the way back up. I thought all this was a great idea and would be totally reusable but, sadly, it didn't work. Kethane tanks tolerate very little speed through the water so were always exploding on me early in the descent.

At some point, I intend to try this again with Firespitter electric props or helicopter rotors instead of rockets, in hopes of gaining more control. Power would come from nuclear reactors from either Near Future or Interstellar. But as yet I haven't gotten around to this.

[Bishop149]

So . . underwater bases.

Firstly. . will a Kerbal sink if carrying a one ton anchor to him?

Well of course he will!

I then made a very very simple base out of a MkII lander can + some legs, a ladder, a few RTG's for power, some lights and enough anchors to make it sink.

Here it is being deployed and sitting on the bottom.

Here is the IVA view, turns out you can't see the water.

My plan was to EVA a Kerb, and immediately have him grab an anchor off a holder so he could wander round the bottom. This didn't work, turns out that the Kerbs buoyancy rips him from the ladder and sends him surfacewards the second he EVA's, so no chance to grab the anchor.

I got the shot below by dropping the Kerb and the base separately. Once on the sea bed he can walk around, take samples, plant flags etc. . . he can also climb the ladder and board the base, although his anchor falls to the ground when you do. I took a "surface sample" from the water. . . dunno if this is the only way to get this or if standing in the shallows would do the same. I hadn't got this sample before anyway

So putting a base on the sea bed and descending and ascending Kerbs to it is not a problem. . . although once they board the base they ain't going anywhere but back up again afterwards!

[Bishop149]

Ok so my probes aren't reusable

My first idea was to make a jet powered sub to sink but able to thrust horizontally through the water and tilt up and down. Although jet engines work perfectly well even with all the relevant bits submerged (I'll just pretend its some kind of water turbine instead!) this didn't work. I was lowering the prototype sub into the water with its tank horizontal. . . . and the damn thing would not sink no matter how many anchors I put on it.

Just to test an idea I lowered exactly the same sub into the water with the tank vertical. . . . sank fine.

So clearly attitude of the parts (cross sectional area?) has something to do with sinkingness.

Also once sinking vertically I couldn't seem to significantly change direction at all. . . even under thrust.

My own attempts to do this were based on using a rocket to push the Kethane equipment to near the bottom, at which point I'd fire a grapple from a winch to keep it down and lower it the rest of the way until the drills could reach the bottom. The rocket would be refueled on the bottom as well to keep speed from getting too high on the way back up. I thought all this was a great idea and would be totally reusable but, sadly, it didn't work. Kethane tanks tolerate very little speed through the water so were always exploding on me early in the descent.

So my next idea is kind of the opposite of yours, make something that sinks (but only just) and then try and thrust it with jets back to the surface.

I was also going to try and grapple the floating platform to hold it on the surface

This does work. . . well all except the last bit.

I tried to come up directly under the floating platform to shoot the grapples straight up into it but never managed it, always came up a bit off from the platform (due to the ascent having a very slight tilt and having bounced a bit sideways on the bottom) and I had almost no control over the direct of ascent. I might see if control surfaces will help with this but I doubt it SAS modules don't help so it would seem that when moving up and down in the water column there is little you can do to gain directional control.

Just before I left KSP this morning I had an idea . . . I can perhaps exploit the apparent difference between vertical and horizontal sinkyness.

I did one quick test where I sank a bit, thrusted up with a jet and then upon breaking the surface fired a single radially mounted rocket to try and tip it horizontal.

This was very promising. . . .whilst I didn't manage to tip it fullyhorizontal the thing that sank did actually float once the rocket was out of oxidizer! But it wasn't SUPER convincing!

As you can in the background see the unbalanced thruster on one side of the diver was pretty disastrous for the rig, it fell over, but still managed to deploy!

To fix this and perhaps improve the result I will add another upside down radial thruster on the other side, to both balance it and increase the rotation force!

I have high hopes this might work . . . . . once I get it floating horizontally I can use the rig to winch it back vertical and drop it again.

[Bishop149]

The search for a reusable version is not going well.

The spin horizontal with radial rockets idea doesn't really work. . . craft is so bottom heavy (as it has to be to sink) as soon as you cut the rockets it just falls vertical again.

Sometimes they float but it isn't reliable.

I have also tried Geschosskopf's idea of thrusting a buoyant craft down and latching onto the bottom with grapples but is doesn't seem to work.

The craft has to be only JUST buoyant or the jet won't be strong enough to push it down, I reckon that once the Kethane tank is full it will just lose this little remaining buoyancy

Also I found you can't fire grapples underwater . . . they just shoot upward as soon as you fire them, even when weighed down with 4 anchors! You don't NEED to fire a grapple in order for it to grab but it does need to hit the ground pretty fast. . . faster than I can dive my probe apparently.

So, fall down and thrust up?

This did work as I noted in the post above, however directing ascent towards the surface rig is pretty much impossible. . . a ton of SAS modules, control surfaces (I even tried RCS) does nothing to give you any significant control over your heading upon ascent and its very unlikely you'll come up directly under the surface rig to grapple it.

Remaining ideas:

- Thrust up and fire grapples in all directions upon breaking the surface, hope full at least one will hit the nearby surface rig and latch. (probably best remaining idea)

- Empty tanks seem more buoyant than full ones. . . perhaps my "weight" can be ditched by burning fuel. . . . although if it costs more in fuel than I can make from the kethane it won't really be worth it!

In other news I have made a 16,000 unit Kethane version of the original non-reusable probes which should work, and designed a rig to use if I want to cheat and just extend the length of winch cables!