Liquid fuel: How to get the most into orbit?

[Skorpychan]

So. My Duna mission has become a failure. Mostly due to lack of fuel.

The nuclear-powered mission used up all it's liquid fuel. Then all the liquid fuel from the auxiliary fuel tank. The LFO mission's interplanetary stage suffered a catastrophe; an adapter exploded 'due to overheating' when I quicksaved. The lander got down and back up fine, but there's not enough fuel to get back to Kerbin.

Thus, I need to get more fuel out there. Ideally liquid fuel, rather than LFO. The problem, however, is getting that much fuel up off Kerbin. Or rather, the tanks to contain it.

LFO is easy. Just use a big tank. But liquid fuel ONLY comes from aeroplane tankage, which tends to produce lift. That's not something you want when climbing vertically on the top of a rocket.

How do I pack/stack fuselages to cancel out lift? Or, failing that, how do I pack together mk1 fuselages so I get a nice clean fairing-able shape for the lifting?

(Yes, I know fairings aren't weight-efficient, but they're CLEANER than something with a lot of draggy parts. Easier to control.)

Edited July 6, 2015 by Skorpychan

[Grumman]

I would use Mk 3 LF fuselages. You could also send an almost empty refinery to Minmus and fill up there before carrying on to Duna. Doing it this way also means that you've got the tools necessary to refill at Ike for the return trip if need be.

Edited July 5, 2015 by Grumman

[Superfluous J]

Take an orange tank, instead of the LF only tank. Drain it of Oxidizer in the VAB.

EDIT: Also, are you SURE you don't have the fuel to get home? To get home from Duna orbit you only need about 2x the fuel you need to get home from Mun orbit. If you have good aim

[Xannari Ferrows]

Always use the plane parts. The structural mass is lower than rocket fuel tanks, and they have more pure liquid fuel capacity. It is overall more space efficient.

[Skorpychan]

I would use Mk 3 LF fuselages. You could also send an almost empty refinery to Minmus and fill up there before carrying on to Duna. Doing it this way also means that you've got the tools necessary to refill at Ike for the return trip if need be.

There's a refinery already out there in Duna orbit, stranded due to lack of fuel. Along with a science lab and 8 kerbals, a lander, a fuel miner, and a bunch of empty tanks.

Do the mk3s generate lift like the mk2s?

Take an orange tank, instead of the LF only tank. Drain it of Oxidizer in the VAB.

EDIT: Also, are you SURE you don't have the fuel to get home? To get home from Duna orbit you only need about 2x the fuel you need to get home from Mun orbit. If you have good aim

I'm sure I don't have fuel to get back. Absolutely positive.

I don't have fuel to get out of Duna orbit, even.

[Superfluous J]

I'm sure I don't have fuel to get back. Absolutely positive.

I don't have fuel to get out of Duna orbit, even.

Ouch

Just remember. You don't need massive amounts of fuel to get home. You don't need to bring up 3 orange tanks' worth or LF. Or one. Without seeing your ship I can't tell you what you need, but if you are in LDO (say 50-100km over the surface) and can burn up to Ike's orbit, you can easily get home with 3x the fuel you have right now, and maybe even 2x.

[Dispatcher]

Go ahead and use "lifting body" fuel tanks; but do so as parts of a spaceplane. The forums are rife with people who excel in shipping fuel to orbit. You might even consider going "above and beyond" and send up a spaceplane capable of shipping fuel to Duna. I don't have those skills, but I'm pretty sure others here do. Good luck!

PS-- have a look at this graph to see my vertical launch flight results of maxing out mass and altitude with 40% propellant mass ratio craft. Of course if you isolate your fuel cargo so it can't be used by engines, it will count as "dry mass".

http://forum.kerbalspaceprogram.com/threads/127487-Engine-test-graph-KSP-v-1-0-4

[Juicy]

Attach lifting body Mk2 tanks radially in a symmetric manner? Like, 4 of them with their top or bottom side facing towards the center of the rocket? Sure, they might cause a bit of drag, but it should still be stable?

[Frank_G]

Use the large Mk. III shuttle LF fuselage and put a fairing around it. Smallest solution, weight efficient and no lift. 10.000 units in one tank...

[Nich]

I have seen ppl use 2 lifting engines on the sides of there LF tank keeping the COL close to the COM with a couple of fins

Edited July 5, 2015 by Nich

[Chaos_Klaus]

Every part will create body lift now. I don't know how they handle the mk2 parts now. Could be that the y have the same lift model as the wings (that is different to the rest of the parts).

MK3 parts should be safe to use though.

- - - Updated - - -

Attach lifting body Mk2 tanks radially in a symmetric manner? Like, 4 of them with their top or bottom side facing towards the center of the rocket? Sure, they might cause a bit of drag, but it should still be stable?

No ... the lift is not applied "upwards" as seen from the part. It is based on angle of attack. So if you attach mk2 parts at the top of your rocket, it is the same like putting giant fins there.

Use a small MK3 tank. Or .... efficiency and send up a LFO tank without oxodizer. It's not hard. Just make sure you deactivate fuelflow from this tank.

[Kryxal]

Or if you want to have fun, send LFO tanks WITH oxidizer and use some LF tanks in an earlier stage with fuel ducts to use that oxidizer.

[Jarin]

I've launched Mk2s as the core of a rocket before and didn't see it causing all that much trouble with control. I mean, make sure you've got fins on the back, but otherwise, it shouldn't be too difficult to launch as normal.

[StrandedonEarth]

Stock Fuel Switch lets you make any tank LF only. I didn't even want to use nukes because of tank restrictions until regex suggested this mod.

[Skorpychan]

Stock Fuel Switch lets you make any tank LF only. I didn't even want to use nukes because of tank restrictions until regex suggested this mod.

That's totally awesome.

Nukes are still boring as hell to use, though. Set burn, chew nails watching gauges.

EDIT:

Augh, bundled with firespitter, which is incompatible.

Edited July 5, 2015 by Skorpychan

[Borogove]

Nukes are still boring as hell to use, though. Set burn, chew nails watching gauges.

MechJeb has a "prevent overheat" utility option.

[GoSlash27]

From all these options, it seems to me that the fixes for using jet fuel tanks on a vertical lifter would yield a lower wet/ dry ratio than just using an LF&O tank and draining the oxidizer.

If I'm going to lift a bunch of fuel in a fuselage that generates lift, I'd just as soon build a tanker spaceplane and call it good. Spaceplanes have a very respectable payload fraction in 1.04.

So if it's me, I'd do it like this:

1) Launch my fuel mover (made from jet fuel tanks) into orbit dry.

2) Fuel it in orbit from SSTO spaceplanes

3) ???

4) Profit!

Best,

-Slashy

[Snark]

Do the mk3s generate lift like the mk2s?

Nope. Just think of them as slightly oddly-shaped 3.75m tanks. They're big, they're mass-efficient, they hold a metric crapload of fuel, they're just what the doctor ordered.

[Skorpychan]

I just went with the tweakable tank mod, to go with the old-school nuclear stage designs. Which now get twice the DeltaV because it's carrying twice the amount of fuel. The LFO-only changes effectively doubled the ISP of the nukes, in terms of weight of propellant you're dragging around.

Although I'm unhappy with the way they heat everything up, so I've added whacking great radiators to them to see if that helps. And I'm going to move some stuff to stop that being heated.

After I've got the Duna mission sorted out, the science mined, and everything back, I can run more missions. Eve sample return, Moho, Jool grand tour, the lot.

[Sharpy]

MK3 hull parts (like the large fuselage) don't produce any lift. It's MK2 that is the troublesome child.

Just get them into Minmus orbit (with a dockable refinery) and fetch the ore from Minmus surface (better energy density than fuel plus you can pack them full)

Your mining operation shouldn't occur on Duna but on Ike. All you need is enough fuel to land your refinery + some tank on Ike.

Also, if the rocket flips, forfeit gravity turn. Perfectly straight ascent until 30km, with some Vernors to aid in stabilization can get pretty much anything into orbit.

That's a bunch of MK3 parts here. The tip is covered with Vernor engines. No, it didn't flip, it entered the orbit just fine.

Edited July 6, 2015 by Sharpy