LV-909 burns up oxidizer faster than liquid fuel

[davidparks21]

I'm trying to build my first lander and am using the LV-909 engine. But I notice it burns up oxidizer fast and leaves a ton of liquid fuel left. What's the reason there? Am I doing something wrong by attaching the standard liquid fuel tanks to it?

[NQMT]

There's more oxidiser than liquid fuel, so they both run out at the same time.

If it's not that, could you please clarify a bit more?

[Streetwind]

Tanks in KSP are built to contain exactly the right ratio of oxidizer and liquid fuel so that they both run out together. The only way you can have liquid fuel left over after oxidizer runs out is if you are building with tanks that don't contain oxidizer, such as the jet fuel structural fuselage - or, if you accidentally removed oxidizer from your tanks by rightclicking and dragging the gauges in the VAB.

In general, a picture says more than a thousand words - show us a screenshot of your lander, ideally with the resource info panel open.

[Kasuha]

An engine should always consume appropriate amounts of liquid fuel and oxidizer - 11 units of oxidizer per each 9 units of liquid fuel. Rocket fuel tanks are built to contain exactly the right ratio.

In certain cases, though, an engine may draw liquid fuel from one tank and oxidizer from another tank. Example of that happening is here:

And of course another option is that this might be caused by some of your mods.

[wasmic]

I'm trying to build my first lander and am using the LV-909 engine. But I notice it burns up oxidizer fast and leaves a ton of liquid fuel left. What's the reason there? Am I doing something wrong by attaching the standard liquid fuel tanks to it?

Aye, you need tanks with both LiquidFuel and Oxidizer. If you have any tanks with only LiquidFuel, your problem will happen.

[Whirligig Girl]

I'm trying to build my first lander and am using the LV-909 engine. But I notice it burns up oxidizer fast and leaves a ton of liquid fuel left. What's the reason there? Am I doing something wrong by attaching the standard liquid fuel tanks to it?

You need to use the Liquid Fuel+Oxidizer tanks. DO NOT use the plane fuel tank that has only Liquid Fuel. IT's not burning up the Oxidizer faster, you just don't have enough Liquid Fuel

[davidparks21]

Here's the final stage of my moon lander. There was one previous stage which also used the LV-909 engines. I'm playing in career mode, so I only have a very limited set of equipment to choose from, rockets only (I've only earned about 150 science points in total).

Each of the 3 LV-909 engines has 2 FL-T400 tanks above them. This image shows the lander in its final stage, you can see that while almost no liquid fuel was burned at this point, the oxidizer is already down to half, and by the end the oxidizer is burned up and the engines stop well before the liquid fuel.

[cantab]

I wonder if some mod, or maybe a file being corrupted, has affected the engine. Do some tests back on the pad, simplest possible ships

[demian_travis]

You are using the wrong tank! Mk1 fuselage has no oxidizer...

[Kasuha]

Here's the final stage of my moon lander. There was one previous stage which also used the LV-909 engines. I'm playing in career mode, so I only have a very limited set of equipment to choose from, rockets only (I've only earned about 150 science points in total).

Each of the 3 LV-909 engines has 2 FL-T400 tanks above them. This image shows the lander in its final stage, you can see that while almost no liquid fuel was burned at this point, the oxidizer is already down to half, and by the end the oxidizer is burned up and the engines stop well before the liquid fuel.

http://i.imgur.com/IUQhMbh.png

That engine should definitely not do this so if your final stage was full of both types of fuel before you started the engine, it's probably corrupted installation and it would be a good idea to backup your saves and screenshots directories and reinstall the game.

If you're not sure that the oxidizer was not sucked off by something on previous stages, it might help to post image of whole ship. VAB or well lit launchpad shot would be preferred.

[Yasmy]

Are you sure you didn't accidentally tweak the amount of oxidizer in the VAB?

I would quicksave (F5), open the quicksave.sfs and manually set the oxidizer level to 11/9 times the liquid fuel level, then reload (F9).

If it continues to happen, then I would worry.

[Wooks]

If you used any Fuselages (Jet Fuel Tanks) in your previous stages the mistery is solved, fuselages only contain Liquid Fuel.

[davidparks21]

Are you sure you didn't accidentally tweak the amount of oxidizer in the VAB?

I would quicksave (F5), open the quicksave.sfs and manually set the oxidizer level to 11/9 times the liquid fuel level, then reload (F9).

If it continues to happen, then I would worry.

Well that sounds plausible... I read someone else saying that that's possible accidentally from the UI right? I'm quite new to this thought (just a few days into the game). I found a file called Auto-Saved Ship.craft (next to the saved version of my rocket). Is this correct? I don't see any obvious Oxidizer to Fuel ratios in there though. Here's the ship:

http://pastebin.com/AGc9a7ab

Here's an image of the whole thing in the hanger:

And here's an interesting one showing the final stage, it actually appears that the ratio of usage is correct here on the final stage LV-909 engines. Perhaps the problem occurs earlier? But I would think that fuel could not flow past the decouplers, so when I get into this stage I don't see a reason why half my oxidizer would have been used already.

[jfull]

That is very strange. I can't see anything in your design that would cause that

[TheD007]

in VAB right click all tanks and see if they have all fuel (both kinds) in each. you probably just tweaked one by accident. also check lower stages in case you have a cross-feed problem and you siphon fuel off the upper stage somewhere.(see if all engines on all stages run out of fuel together.)

[Kasuha]

Sure enough, you managed to build your ship with one set of fuel tanks with no oxidizer.

Just tweak it back in VAB and everything should be fine.

[davidparks21]

Well that just makes sense. I didn't even realize I could do such a thing to myself, I actually just caught myself doing that same thing again in another case. Thanks for taking the time to look at my design and spot that mistake!

Sure enough, you managed to build your ship with one set of fuel tanks with no oxidizer.

Just tweak it back in VAB and everything should be fine.

http://i.imgur.com/idydvrd.jpg