PSA: You can reduce your payload mass by lugging a refinery around - "The Martian" style

[ShadowZone]

Anyone else here read "The Martian"? There was an interesting concept in there, the MAV (Mars Ascent Vehicle): It lands empty and creates its fuel while on the surface waiting for the astronauts wanting to get back up into orbit (they land in a different vehicle).

So I tried it out. Turns out, my >200 ton Eve return vehicle weighs only a little more than 100 tons after emptying it and slapping a refinery and drill on there. This makes getting it into space from Kerbin easier. It reduces dV requirements for transfer burns and it reduces risk during Eve descent. I am pretty sure you can use this concept on other planets with big dV requirements as well (Laythe comes to mind - or Tylo).

So here's my attempt of utilizing this concept for an Eve vehicle:

[Sharpy]

When I get a better computer, I'm gonna do the Jool-5 challenge in a single stage.

Lugging the refinery with me. Visits to Pol or some other light moon before each landing on any heavier of the moons.

[selfish_meme]

A few of the Eve landers lately have done this. I think the lander itself can be done in 100t or so full. Which for me is better than waiting for weeks to refill tanks. But kudos for getting there and back anyway, big achievement.

[magnemoe]

For Eve I prefer to top it up at Gilly, note that you can use an tug to get it from Eve orbit to Gilly orbit, then use tug to get it into low Eve orbit again.

Yes for an planting the flag mission mining on Eve works but you will be limited to areas with ore.

Benefit is larger doing Jool 5 type missions. Tylo has some of the same challenges as Eve.

[Sharpy]

BTW, 1 unit of ore (10kg/unit) produces 2 units of fuel (0.9 lf + 1.1 ox), both 5kg/unit, meaning 10kg of fuel. While that's a zero net gain of mass, the large ore tank holds 1500 units of ore in volume of a Rockomax X200-16 Fuel Tank which holds 1600 units of fuel (720+880) . That means it holds potential 3000 units of fuel in volume normally occupied by 1600 units of fuel. less drag, smaller size, more compact.

(also, ton for ton dry mass, 1 ore tank (dry mass 2t) weighs as much as 2 lf+ox tanks (dry mass 1t) it could fill.)

The Orange Tank holds 2 880 + 3 520 = 6400 units of fuel. An ISRU unit plus two large ore tanks occupy the same volume with 6000 units of fuel, weighing 4.25 t + 2*2t + 2*15 = 36.25t. The orange tank, full, weighs 36t. So, slightly worse. Now let's add 4 more ore tanks. 4.25 + 6*2t + 6*15t = 106.25t for ISRU and 6 large tanks. That's fuel volume of almost three orange tanks (which would weigh 108t) in volume of two orange tanks, which would weigh

Simply put, instead of carrying fuel to orbit, carry an ISRU unit and some full ore tanks.

Edited June 22, 2015 by Sharpy

[ShadowZone]

BTW, 1 unit of ore (10kg/unit) produces 2 units of fuel (0.9 lf + 1.1 ox), both 5kg/unit, meaning 10kg of fuel. While that's a zero net gain of mass, the large ore tank holds 1500 units of ore in volume of a Rockomax X200-16 Fuel Tank which holds 1600 units of fuel (720+880) . That means it holds potential 3000 units of fuel in volume normally occupied by 1600 units of fuel. less drag, smaller size, more compact.

(also, ton for ton dry mass, 1 ore tank (dry mass 2t) weighs as much as 2 lf+ox tanks (dry mass 1t) it could fill.)

The Orange Tank holds 2 880 + 3 520 = 6400 units of fuel. An ISRU unit plus two large ore tanks occupy the same volume with 6000 units of fuel, weighing 4.25 t + 2*2t + 2*15 = 36.25t. The orange tank, full, weighs 36t. So, slightly worse. Now let's add 4 more ore tanks. 4.25 + 6*2t + 6*15t = 106.25t for ISRU and 6 large tanks. That's fuel volume of almost three orange tanks (which would weigh 108t) in volume of two orange tanks, which would weigh

Simply put, instead of carrying fuel to orbit, carry an ISRU unit and some full ore tanks.

Yeah I also made an interplanetary ship based on similar calculations. Looks a bit funny but does the job

[Foxster]

Jeez, another PSA

[GeneCash]

Well, actually that comes from Zubrin's original "Mars Direct" proposal in 1980.

https://en.wikipedia.org/?title=Mars_Direct

The first flight ... would bring an unmanned Earth Return Vehicle to Mars after a 6-month cruise phase, with a supply of hydrogen, a chemical plant and a small nuclear reactor. Once there, a series of chemical reactions (the Sabatier reaction coupled with electrolysis) would be used to combine a small amount of hydrogen (8 tons) carried by the Earth Return Vehicle with the carbon dioxide of the Martian atmosphere to create up to 112 tonnes of methane and oxygen. This relatively simple chemical-engineering procedure was utilized regularly in the 19th and 20th centuries, and would ensure that only 7% of the return propellant would need to be carried to the surface of Mars.