Duna spacestation

[bjerrang]

Hi

Got a ore and spacestation ship enroute duna.

Is it better to have them both on ike , since a launch from duna costs alot of dV.?

[Cpt Kerbalkrunch]

The short answer is yes. You could use chutes to land on Duna for almost nothing, but that will probably balance out when launching a fully loaded fuel shuttle back to orbit. Wings could also be utilized on Duna (if done right), but that would have to be planned for in the design.

Ike would be your best bet. I've had a refueling base there for a long time. I don't use it much anymore, but it worked great when I did. Ike is so easy to encounter (and just as easy to escape back to Duna), that it works about as well for operations in Duna's orbit as its own. I think it'll work well for you.

[DrLicor]

It depends, if you can aerobrake the spacestation and ore module.

A simple example:
Aerobraking on duna will creatly reduce the orbit circulation cost of Duna. This is for when you want a station around Duna, for refuel mission from and to Duna. The best is a mining outpost on Duna, with a little tug transfering the fuel between the outpost and the station.

You could also land the mining outpost without the little tug on Duna, so your missions to Duna could refuel at Duna itself without having to dock to the station, however, your mission will be limited to one spot on Duna this way.

The math behind this:
The delta-v required after capture at the Duna system to landing on Ike -> orbit Duna = 250m/s -> capture + circulation on Ike = 210 m/s -> land on Ike = 390m/s     total cost = 850m/s (for the ore module)
The delta-v required after capture at the Duna system to circulation of Duna really depends, without a heatshield, it would be 230+360=590m/s, however, with aerobraking you can reduce those to 100m/s or less.
The delta-v required for a landed tug on Ike to the spacestation -> orbit Ike = 390m/s -> escape Ike = 210m/s -> match orbit with spacestation +/- 360m/s    total cost of 960m/s
The delta-V cost of a retour from Ike to the station is 1920m/s. While getting to orbit on Duna costs 1450 m/s, landing can be done with shutes a a very little amoumt of fuel.

However: because the lander tug is much lighter on his descent than on is ascent, the fuel cost to Ike is much less. Because only half of it's journey, it's on his max weight. 
So you also might consider a outpost on Ike, when your tug is really light, it's profitable for sure, it get's trickier when your tug is quitte heavy.


I once builded 2 different stations with 2 tug and a mining outpost. Mining outpost on Ike, with station orbiting it and the 2 tugs. One tug was used for getting the fuel from the surface to the Ike station. The other tug was used to transport large amounts of fuel to the Duna station, which functioned as a refuel station and habitat for big missions.

 

The good old time I still played the stock system  
 

Edited September 27, 2017 by DrLicor

[bjerrang]

Landed on ike with 150dV left as ill keep the space station there aswell. 

Spacestation has a small lander , that can do landing on duna and return to ike. 

Next problem was that the ore ship does not get enough power. (has the same setup as on mun/minimus)

2 gigantor solar panels , 2 big drills , small convert o tron , 2 small fuel cells.

Guess i have to micro manage it and build a new one and sendt at next launch window. 

Can i survive with this or do i need to build a new one ? and if so how many gigantor panels do i need ?

[DrLicor]

That's why I always leave my ore miner on the surface. It's just extra weight you're tranferring. 

[Cpt Kerbalkrunch]

13 minutes ago, bjerrang said:

Landed on ike with 150dV left as ill keep the space station there aswell. 

Spacestation has a small lander , that can do landing on duna and return to ike. 

Next problem was that the ore ship does not get enough power. (has the same setup as on mun/minimus)

2 gigantor solar panels , 2 big drills , small convert o tron , 2 small fuel cells.

Guess i have to micro manage it and build a new one and sendt at next launch window. 

Can i survive with this or do i need to build a new one ? and if so how many gigantor panels do i need ?

More solar panels won't help much when the sun is down. Part of your problem is the small converter. Though it uses less power, it is horribly inefficient, throwing away a ton of ore. Thus it has to run a lot longer. Two large drills and the large converter, coupled with a fuel cell array or two (rather than the small cells), will produce enough to power itself and still fill your tanks; even in full dark.

Hopefully you also have your best engineer and a couple of thermal control systems on board.

[bjerrang]

27 minutes ago, Cpt Kerbalkrunch said:

More solar panels won't help much when the sun is down. Part of your problem is the small converter. Though it uses less power, it is horribly inefficient, throwing away a ton of ore. Thus it has to run a lot longer. Two large drills and the large converter, coupled with a fuel cell array or two (rather than the small cells), will produce enough to power itself and still fill your tanks; even in full dark.

Hopefully you also have your best engineer and a couple of thermal control systems on board.

Engineer onboard yeah , thus only 2*

Tried the fuelcells on mun/minumus , it uses so much lf/ox that is was nearly eating up all produced lf/ox.

And the large converter is like 4.5 ton its alot to transfer with. Then i guess i need a craft that connects to the "ore machine" , but that docking will be to hard for me. 

[Cpt Kerbalkrunch]

56 minutes ago, bjerrang said:

Engineer onboard yeah , thus only 2*

Tried the fuelcells on mun/minumus , it uses so much lf/ox that is was nearly eating up all produced lf/ox.

And the large converter is like 4.5 ton its alot to transfer with. Then i guess i need a craft that connects to the "ore machine" , but that docking will be to hard for me. 

It does eat up fuel, but the combo of large drills, large converter, large fuel cells should be self-sufficient. This is all provided that you want to run day and night, however, which isn't entirely necessary. You could warp through the night and refuel during the day. Duna gets good solar power, so it should work fine. Though the small converter will definitely slow things down.

I'll have to double-check when I get home, but I might be using four fuel cell arrays instead of two. It works even on Pol and Bop, where there isn't much solar power to be had.

Edited September 27, 2017 by Cpt Kerbalkrunch

[Spricigo]

17 minutes ago, Cpt Kerbalkrunch said:

It does eat up fuel, but the combo of large drills, large converter, large fuel cells should be self-sufficient.

More to the point, more fuel produced over time than than a craft with that will stop production for too long  waiting the sunrise.

@bjerrang You can test several things right at the launchpad/runaway and calculate a lot more, a lot better than commit to design and find its shortcoming after landing on Ike.

I will try to give a simplified explanation, (this guide offer more detail).

First thing lets talk about cooling, drill and converter have a required cooling and a maximum cooling. If a part receive less cooling than required it will overheat and lose efficiency (end eventually turn off).

Drill requires and can receive 50kW(small)/100kW of cooling.

The small converter require 100kW per process but have a max cooling of only 50kW. That means that no matter what the small converter cannot run constantly.

The large converter requires 200kW per process and have a max cooling of 500kW. That allows it to run two process constantly.

 

Next lets consider energy consumption.  Will assume a large converter running 2 process constantly and large drills also running constantly. I also will assume, for now, that you have a high enough yield to keep the converter feed at all times.

Each converter process will consume 30*[engineer bonus] E.C. Each drill will consume 15*[engineer bonus]E.C.

Assuming a 2* engineer that results in 19.5E.C/s per process and 9.75E.C/s. per drill.

For a 5* engineer that tops at 37.5E.C/s.  and 18.75E.C. respectively. (that is the worst case scenario in terms of energy consumption)

 

Ok, now lets consider how many drills we need to provide enough ore to the converter . Lets assume we want 2 simultaneous process (LFO and LF)  that will consume, with our 2* engineer, 0,6175ore/s, lets just round it up to 0,65/s so we can run a 3rd process or do a mining contract from time to time. Each drill will harvest (0,975*[ore concentration]) /s for a concentration of 10% we need at least 7 large drill to reach our quota.

Lets suppose that setup work for us, we will have a energy consumption of 107.25EC/s just for our drills and converter in normal operation. And will be producing (0.8775LF +0.3575ox).

 

At this point is time to decide about the energy production and storage. Solar panels have a good output for their price and mass but only during the 'day', RTG's low output make then impractical and the high amount of E.C required makes sustaining it with batteries virtually impossible. Fuel cell have good output but consumes LFO.

We can provide 108EC/s with 6xFuel Cell Arrays at the cost of (0,1215LF+0,1485ox)/s, so we can run our drills and 2 process, we end up with (0.756LF+0.209ox+0,75ec)s. For comparison that is the same output of 144RTG.

 

 

[Geschosskopf]

On 9/27/2017 at 6:55 AM, bjerrang said:

Hi

Got a ore and spacestation ship enroute duna.

Is it better to have them both on ike , since a launch from duna costs alot of dV.?

It depends on what you're using the fuel for.

If the fuel is for use by space-going ships, then you want to get the fuel from the place with the least gravity, in this case Ike.  If you're using the fuel on Duna, then it's better to get it from Duna.  Thus, depending on what your mission entails, you might need 2 separate fuel systems, one on Ike and another on Duna.

Ike system is for:

• Ships going returning to Kerbin (crew rotation, resupply, science return, etc.)
• Ships going between Ike and Duna (in-system tugs and transports)

The Duna system is for:

• Refueling reusable shuttles that go back and forth between Duna's surface and low Duna orbit.
• Refueling rovers and aircraft that explore Duna