I need to build an efficient Kethane mining lander for Duna.

[Galane]

I've found that lifting 8,000 units or less of Kethane from Duna is a very slow way to refuel an orbiting spacecraft. The lander I built uses four FL-T800 and one Rockomax X200-8 fuel tanks. Had to add the x200-8 so it'd have (barely) enough fuel to reach a 45KM orbit. For engines I have four Mark 56 on it.

Doesn't matter which of the Kethane converters is used, 8,000 units of Kethane doesn't fully refill the lander's tanks. I send it down with the X200-8 empty and without topping off the monopropellant tanks, then fill everything on the surface.

The little splash of fuel and oxidizer in the X200-8 is all there is for gain on each trip.

So I'm wanting to put together a Kethane lander for Duna capable of lifting significantly more than 8,000 units to orbit. Ideally it should need a lot less fuel to land with empty Kethane tank(s) than it does to lift and rendezvous.

Experiments with some of my Kethane miners for Mun have been only somewhat successful. They can land on Duna but can't make it back to orbit with full Kethane tanks. Needs more power, which needs more fuel, which needs... arrrgh!

Mods (with parts) I have installed.

Kethane

BoJaN Quantum Struts

Keramzit Procedural Fairings

Ferram4 Kerbal Joint Reinforcement

KSPX

Infernal Robotics

DROMOMAN

ReStock

Stretchy Tanks

Kommit Stockalike It's just one cubical girder block the same size as the short and long girder sections, used on my largest Kethane rover, built around a horizontal 16,000 unit tank. (Then there's my 32,000 unit lander, it's big, it's heavy, burns nearly all its fuel lifting to a 15KM Mun orbit, but it carries enough Kethane to make it not take forever to refuel ships.)

Three-in-one and two-in-one docking ports, cfg files are here and there on the forum

My own mash-up, the RockoOKTOClampo. Combines the Rockomax Brand Decoupler with the systems (but not the model) of the OKTO2 and a standard Clampotron docking port. Combined with strut guns from the Quantum Struts mod it allows for a lander or other thing to decouple then come back and solidly dock to the same spot. Will be using this for the return from Duna - when I can get the ship refueled.

Other mods.

MechJeb (2.1.x dev build, whatever is current latest)

SelectRoot

TAC Fuel Balancer

UbioZur Welding

Module Manager

[KvickFlygarn87]

Well, if you're looking for a few hints:

• Don't overdo it. 1 big drill and 1 kethoelectric generator is good enough.
  
• Use the 48-7S. They have the highest TWR in the game and are rather efficient.
  
• Use the Kethoelectric Generator. This will allow you to go on mining through the night without heavy RTGs.
  
• Bring KAS. If you want to land stuff near it and refuel.
  
• Bring lots of tanks. Not too many though, or your 48-7S engines won't be able to lift you when full.
  
• You might wanna bring a converter, so you can refuel when there.
  

Edited November 22, 2013 by KvickFlygarn87

[Virindi]

What about a spaceplane using the kethane turbine engine? I haven't actually tried it yet, but the thing is really efficient if you happen to have a bunch of kethane in your vehicle already.

[Galane]

I already have the ships at Duna http://forum.kerbalspaceprogram.com/threads/58167-Duna-mission-planning-and-R-D so additional mods are not going to save the day. ;P

The 48-7S, eh? I see the thrust has been bumped up from 20 to 30 kN in .22

Had a thought on a possibility of taking care of the issue with the resources on-site. If one of the two scanning satellites in Duna orbit can be sent to Ike, I could send the landers to Ike too, possibly even the return ship after bringing the manned lander up to dock with it.

The satellites have four LV-1R engines on an FL-T200, a pair of 6x1 solar panels, an OKTO2 and a small kethane scanner. Will have to look to see if I put anything else on them. The test design only had two engines, which took too long to make any inclination changes.

With Ike's much lower gravity the landers will become far more efficient at refueling. The return ship has no kethane converter or tanks. The mission plan-ish thing was always to leave the landers and satellites there for any future missions. A note has been made that the design for the landers that were sent is not useful for Duna.

[JakeGrey]

Maybe try breaking the mining operation into a couple of separate components? I haven't done much with Kethane yet, but my plan is to fit the mining rig to a rover that'll stay on the planet's surface and a tanker SSTO of some description to ferry it to and from a refuelling station in orbit.

[Galane]

From what I've read on that, the easiest way is to use KAS, but that requires a Kerbal on site to haul the hoses around to make the connections.

I tried doing a two part unmanned setup on Mun. Took the heavy drills off my 32,000 unit lander, added a couple of docking ports in their places, then built a rover with just the drills and an arm built of DROMOMAN and Infernal Robotics parts.

I had to hit the lander hard enough with the arm to nearly break it apart to get the docking ports to connect. Driving a rover at a lander fast enough that you're worried about breaking the rover or lander or knocking the lander over is not a fun thing, especially when it takes several attempts.

Once it hooked up I was able to release the brakes so the arm would relax back to where its joints weren't stressed. Then I deployed the two drills and the lander's tanks filled, mission continued normally.

What decided me against continuing with the method was the lander didn't use much, if any, less fuel getting back to orbit without the weight of the drills. If it had used a lot less fuel, at least saving enough it wouldn't have to make fuel to rendezvous with the tanker, it would have been worth the extra effort to connect up the drill rover.

For the current mission going on now, I was able to fly a scanner satellite from Duna to Ike, then followed with one of the kethane mining landers. Might be able to make two trips up and down from a 15KM Ike orbit before having to refuel the landers. 15KM looks to be crazy close to a few lumps on the surface. In testing I set periapsis on one of these landers to 10KM and it crashed into something on Ike.

But now MechJeb is being buggy and refusing to run the throttle on the Skipper engines since the manned lander is docked. It will only run the poodle on the lander. Yes, I know I have to set control on a part on the ship with the active engines, everything oriented the right way etc. All set right but MJ just will not throttle up. I can get the ship to Ike using the lander engine but that won't get Jeb and Bill back to Kerbin.

Soooo, I have a pair of perfectly serviceable Duna Ike kethane mining landers, but still need a way to get kethane or fuel up from Duna somewhat efficiently, preferably unmanned.

P.S. My first Duna flag is "We Come in Pieces" "You should see the trail of parts we left getting here!"

[Mathman]

Well, I just finshed off a contest with my twin brother to come in with the lowest cost solution to a "Permanent" Duna colony. To cut to the chase.. refuling via Kethane mining was key.

But why oh why bother trying to refuel from the bottom of a deep gravity well? Also, since kethane to monopropellant and kethane to liquid fuel and liquid oxygen is really inefficient why cart kethane around?

My solution was Orbiting Fuel Depots. A bunch of empty tanks with docking ports and one stabalizer module with nothing more than gyros, batteries, a few solar cells and a docking port to keep the tanks from tumbling so they can be docked with.

The Duna lander has a small drill, a small kethane processor and the tiny kethane tank. It lands on Ike with an extra empty tank or two from the depot attached at ports. (Low gravity, you can hang on more things and still land and take off). It mines kethane and converts it simultaneously without storing any but a minor amount of Kethane. Once loaded up the lander boosts to orbit, transfers excess fuel (main and RCS) to the fuel depot. Three or four round trips are enough to load enough fuel to completely fuel the lander twice, and leave the lander with a full load. How to get from Ike to Duna? Not much effort but to save fuel I use a nuclear powered tug to push the whole thing into Duna orbit. (I follow KASA guidelines in the use of NERVA units and never use them to land anywhere or in an atmosphere) I end up easily with a full lander and more than enough in orbit fuel to refuel it twice. BTW - I try and land on DUNA where I can refuel for the return trip which cuts down on refuling in orbit. Then after detaching unnecessary fuel tanks from the lander I have a lean and mean Duna lander ready to land.

So... Simple. -Don't land on DUNA to get fuel to use in space. Land on Ike. Oh, this was done with stock parts asside from the Kethane mod. Same for Kerbin system. Land on Minmus, not Mun or Kerbin.

....

Soooo, I have a pair of perfectly serviceable Duna Ike kethane mining landers, but still need a way to get kethane or fuel up from Duna somewhat efficiently, preferably unmanned.

P.S. My first Duna flag is "We Come in Pieces" "You should see the trail of parts we left getting here!"

[Captain Sierra]

As for lifting kethane off Duna, don't. It's horribly inefficient given the losses when converting to oxidizer and liquid fuel. I had an old Duna fuel lander that could lift an orange tank to orbit. How? take an orange tank. now take the largest 1.25m tank. Radially mount 8 of them around the jumbo. Now add some LV909s. Good to go. It works like a charm. SImply add a side docking port for whatever base height you are using down there.

[Rune]

As for lifting kethane off Duna, don't. It's horribly inefficient given the losses when converting to oxidizer and liquid fuel. I had an old Duna fuel lander that could lift an orange tank to orbit. How? take an orange tank. now take the largest 1.25m tank. Radially mount 8 of them around the jumbo. Now add some LV909s. Good to go. It works like a charm. SImply add a side docking port for whatever base height you are using down there.

Exactly. Lift fuel from the place where you have the mining done, not kethane. That way all you have on orbit are empty tanks, and all you need is to build a ship that has a lot of excess delta-v for the trip and is as big as you can to do it. The bigger it is, the more fuel it'll have as excess. So a huge SSTO, and the gravity of the place you refuel from defines your mass fraction and therefore the efficiency of your operation. Thus always refuel orbital fuel depots from low gravity moons if you want to minimize tanker flights.

Rune. Extra benefit: if you uninstall kethane/the mods gets outdated, all you lose are the mining/refinery rigs, which can be pretty minimal.