Ability to dump fuel

[ammonia_ocean]

A while ago, I was returning from Jool after a botched and completely pointless Bop flyby that wasted a thousand m/s of delta-V, and realized to my dismay that I was about 150 m/s short for my transfer burn. So, after deliberating, I realized that I had about a thousand liters of unused (and now-useless) RCS fuel, and that if I could get rid of it, I could increase my delta-V by reducing my ship's weight. Therefore, I turned on ASAS and mashed WASD for fifteen minutes, until I had dumped two tons of monopropellant and gained approximately 200 m/s of delta-V.

Afterwards, I realized that this was a valid tactic, and could be used to maximize delta-V where necessary; however, I really didn't want to mash my keyboard until my arms ached every time I needed to get rid of some monopropellant. So my suggestion is: why not include a button to vent/dump fuel? While the amount of situations in which this might be useful for liquid fuel is limited (landers?), it would be both useful and quite realistic in the case of RCS. What do you think?

[Beeman]

It'd definitely be nice, even if you could only dump fuel from certain tanks. I often pack on too much mono-propellant and sometimes it'd just be nice to get rid of some of it, rather than crashing into something or winding up lost in space.

[ammonia_ocean]

Is there a mod for this? I've thought about using the empty tanks mod and just sticking on an empty RCS tank with a decoupler, but that would be awkward at best and severely limiting at worst.

[Kerbal01]

There is a mod(from .18 ish), it was a .cfg edited inline probe engine with zero thrust and a high fuel usage

[Spica]

There is actually a way to do this with rockets and jet engines. In order to dump fuel from a rocket engine, disable ALL oxidizer flow from every single tank, and throttle up. To dump oxidizer, do the opposite. However, this method can be tricky if you want to partially empty a tank, then you may have to do some math to figure out how much fuel and oxidizer you need. For jet engines, close all intakes and throttle up.

MATH INCOMING

To find out how much propellant you need, you can use these formulas:

LiquidFuel/0.8181=Oxidizer

or

Oxidizer/1.2222=LiquidFuel

Spica

[Zeroignite]

TAC Fuel Balancer allows for dumping as well. That was the main reason I picked it up actually...

[RickyKSP]

Idk about this though, I always attach drop tanks to my interplanetary ships

[DannySwish]

It's a good idea.

[Armchair Rocket Scientist]

A while ago, I was returning from Jool after a botched and completely pointless Bop flyby that wasted a thousand m/s of delta-V, and realized to my dismay that I was about 150 m/s short for my transfer burn. So, after deliberating, I realized that I had about a thousand liters of unused (and now-useless) RCS fuel, and that if I could get rid of it, I could increase my delta-V by reducing my ship's weight. Therefore, I turned on ASAS and mashed WASD for fifteen minutes, until I had dumped two tons of monopropellant and gained approximately 200 m/s of delta-V.

While I don't know how heavy your ship was, how much fuel it had, etc, it seems like using that RCS fuel to add to your velocity would have gotten you an extra 200 m/s much faster than just dumping it. Holding H for five minutes vs. WASD for fifteen or something like that.

[ammonia_ocean]

There is actually a way to do this with rockets and jet engines. In order to dump fuel from a rocket engine, disable ALL oxidizer flow from every single tank, and throttle up. To dump oxidizer, do the opposite. However, this method can be tricky if you want to partially empty a tank, then you may have to do some math to figure out how much fuel and oxidizer you need. For jet engines, close all intakes and throttle up.

MATH INCOMING

To find out how much propellant you need, you can use these formulas:

LiquidFuel/0.8181=Oxidizer

or

Oxidizer/1.2222=LiquidFuel

Spica

TAC Fuel Balancer allows for dumping as well. That was the main reason I picked it up actually...

Thanks, these both look good. I'll check on TAC Fuel Balancer as soon as I have some free time.

While I don't know how heavy your ship was, how much fuel it had, etc, it seems like using that RCS fuel to add to your velocity would have gotten you an extra 200 m/s much faster than just dumping it. Holding H for five minutes vs. WASD for fifteen or something like that.

I tried this, but my ship was pretty large with only a moderate number of ports, making acceleration from RCS negligible. Also, holding H didn't dump fuel nearly as fast as mashing all the directional keys at once.

Edited August 4, 2013 by ammonia_ocean

[Kyne]

Certainly needs to be implemented. Would certainly make transporting my Kethane refining rigs easier.

[danet88]

I know that with the Lazor system mod (http://kerbalspaceprogram.com/lazor-system/) when using one of the Lazors you can use that to dump fuel through one of the subsystems.

[MrKicker]

I think this should be implemented as a butten on right click menus on tanks.

[montyben101]

It would be useful to do this with space planes so if you cripple it you can dumb lots of fuel and land a lot lighter.

[Anizer]

I don't think it's realistic to allow rockets to leak fuel out of the tanks while in flight/orbit.. Try designing your rockets better so you can drop fuel that isnt needed.