im in parts files for fuel tanklong and i want to know how to change fuel mass.

[OKOKIWILL]

I only have the demo but i really want the full game maybe next paycheck, Im in the parts files for fueltank long and i want to figure out how to make it not way so much because of the fuel amount

heres the code ive messed with

// Kerbal Space Program - Part Config
// FL-T500 Fuel Tank
// 

// --- general parameters ---
name = fuelTank_long
module = Part
author = NovaSilisko

// --- asset parameters ---
mesh = model.mu
scale = 0.1


// --- node definitions ---
node_stack_top = 0.0, 15, 0.0, 0.0, 1.0, 0.0
node_stack_bottom = 0.0, -15.1, 0.0, 0.0, 1.0, 0.0
node_attach = 5.01, 0.0, 0.0, 1.0, 0.0, 0.0, 1


// --- editor parameters ---
cost = 1600
category = Propulsion
subcategory = 0
title = FL-T800 Fuel Tank
manufacturer = Jebediah Kerman's Junkyard and Spaceship Parts Co.
description = A stretched variant of the FL-T400, the FL-T800 holds twice the fuel in a slightly stronger container. The black stripes along the side make the rocket go faster, our engineers tell us.

// attachment rules: stack, srfAttach, allowStack, allowSrfAttach, allowCollision
attachRules = 1,1,1,1,0

// --- standard part parameters ---
mass = 0.0000000001
dragModelType = default
maximum_drag = 0.2
minimum_drag = 0.3
angularDrag = 2
crashTolerance = 6
breakingForce = 50
breakingTorque = 50
maxTemp = 200000

RESOURCE
{
 name = LiquidFuel
 amount = 9999
 maxAmount = 9999
}

RESOURCE
{
 name = Oxidizer
 amount = 250
 maxAmount = 250
}

Edited April 20, 2014 by OKOKIWILL

[Taki117]

Well that's an awful lot of liquid fuel you have there for not a lot of oxidizer. You might want to change the ratio to be 9:1 LF to Ox, (Meaning you should have about 2250 LF (But I think my math is off)) If you want to change the weight of the LF and OX you want a file called Resources.cfg (Located in the Resources folder in the Squad folder) and you want to change the density to something very low.

[Claw]

Actually, for those numbers you need 1.1 oxidizer for every 0.9 fuel. The 9:1 is a weight ratio when considering fuel tank mass.

So if you want 250 Oxidizer, you need 204 liquid fuel.

(250 / 1.1) * 0.9 = 204

Here are the original values for that tank if you want to simply put it back how it was.

RESOURCE
{
 name = LiquidFuel
 amount = 360
 maxAmount = 360
}

RESOURCE
{
 name = Oxidizer
 amount = 440
 maxAmount = 440
}

[BudgetHedgehog]

Keep in mind, if you lower the density of either fuel, the more of it you'll use (because it weighs less). That means that unless you mod the engines as well, you'll burn through your fuel quicker. As Taki said, you need to keep the ratio the same (but it's 9 units of fuel to every 11 units of oxidiser EDIT: Claw is a ninja) so you'd need a lot more oxidiser or a lot less fuel.

In short, there's no easy way to do it. It's one of the realities of this game - that is how much it weighs, you have to take that into consideration. Want it to weigh less? You gotta use a smaller tank. No two ways about it.

[Taki117]

Thanks for that Claw, I knew the 9:1 was somewhere.

But anyway, let's get down to brass tacks.

Why exactly are you trying to mod this particular fuel tank? What are you trying to accomplish? What's your mission goal?

[cantab]

In the demo the file Resources/ResourcesGeneric.cfg has the fuel densities in it. Changing them, though, won't help, since the engine fuel consumption goes by mass. Change the fuel density from 5 kg per unit to 1 kg per unit and the engines will just draw five times as many fuel units per second at the same throttle setting.

If you want to make your engines do more on less fuel the only way is to increase their specific impulse. This is under the atmosphereCurve section in the engine's cfg file. The higher figure is for vacuum, the lower for sea level.