Best way to launch this?

[annallia]

This is one of two fuel modules I want on my station. I had originally had a different (somewhat smaller) design in mind but due to a screw up in the stations construction and my not wanting to run two more flights just to fix it, or one more but require me to de-orbit part of the station and rebuild it... I redesigned the fuel tanks. Plus I like the new design.

All in all it weights 150 tons and holds 13,032 fuel. My problem is it will be awkward to lift it due to the new design.

I need 2 of them (separate launches are ok by me) and they have to go where the poorly drawn arrows point here:

Edited August 4, 2013 by annallia

[shand]

my advice would be to send them up empty - or more accurately use the fuel they contain as a final payload. this will greatly reduce the size of your launch vehicle. then you can design a fueler that uses a Big Orange Tank that you can use to send regular fuel top ups

You will need much strutage - and i would suggest running struts TO your payload, not AWAY from - so you dont leave strut points when you decouple it

[annallia]

Yes I know struts... struts, struts, and why not a few more struts. I will strut the hell out of it, that is for sure.

That said emptying it/using the fuel is not an option I am hoping for. I could easily bleed off the fuel in the tanks (that will take a while...) but I would rather not, trying to finish this station with as few missions as possible. This requires full tanks to be launched for fueling so I don't have to launch a refueler (would take a hair more than 4 orange tanks to fill this beast!).

And really the important part is the tug that has to dock it... My current tug cant do it it would be too unweildy even in space, getting it to orbit isn't the hardest part.

[ASnogarD]

I struggle with 130 tonne lifters but here are a few ideas you could consider...

1 - Typically I build my lifters a standard centre stack with a ring of stacks as boosters (stack = fuel tanks + engines), I make the centre stack short and feed it fuel from the outer ring which allows me to put my payload lower into the lifter instead of perching right at the top.

2 - Consider draining the fuel out of the payload to lighten the load (there are a few complicated ways to do this, but you could just allow the docking ports to cross feed and burn off the fuel with the main engines while it sits on the pad held in place with launch clamps... or even design the lifter to use the fuel in the payload and put less fuel tanks in the lifter), it may sound silly as you want the fuel for re-fuelling craft at the station but that design is eye candy then you can build a ugly but practical fuel delivery craft to fill it up. Nice looking station and full of fuel.

Good luck.

[annallia]

I know it is eye candy. But I made my own mission. To build a super station capable of housing its crew (10 kerbals) and storing fuel for interplanetary missions to come. As I overengineer things as a habit the budget is killing me, the easiest way for me to meet that part of the goal is to minimize the launches. I have 3 launches left on my heavy lifters before I break the bank which means I cannot really launch these empty (maybe partially) or I break the budget.

My heavy lifters though redesigned to be more efficient still cost a fortune to launch, however I managed to get that whole rig up there with only 3 launches already.

[Johnno]

I've done some recent heavy lifting, I'd advice you to build your launcher around the payload rather than trying to make one under it. I'm sure there's better ways than what I do, but as I dislike asparagus staging I go for raw power. If your budget is about number of launches rather than cost/mass/parts you can go wild and just add until it flies.

Here's a picture of a launch I did just now with a saved launcher, so it's easier to see than in the VAB. The payload is 200 tons with the launcher built around it, the whole thing is open down in the middle as you can tell. You could do your 150 ton fuel depot and add a bit of fuel+engine (and RCS) below it for orbital manouvers, unless you have a tug in orbit.

First stage: 24 orange tanks worth of fuel, 16 mainsails.

Second stage: 9 orange tanks worth of fuel, 8 skippers, 16 radial engines. The radial engines were added late in the design process for extra oomph since I didn't want to redo the entire first stage. Still, it works.

[annallia]

That may work Johnno, though that would make me push back the time frame on making the station operational, or force me to redesign the crew delivery rocket to do it in less launches (which isn't a horrible idea).

Given that I am using NovaPunch mod I have access to stronger engines than mainsails and could probably build it with less engines for the same TWR which would mean less fuel being used and let me take out an odd tank here and there...

As to my budget, it is cost of parts + imagined cost for R&D (I use a RNG but it ranges from 20-50% of the whole) + cost of fuel.

That is for new rockets, if using a previously designed rocket it is cost of parts + building cost (included in the R&D) which is again generated from an RNG at 5-10% + cost of fuel. There are other incidentals that I add in after launch. Such as if the stages crash rather than land there is a cleanup fee and whatnot. Fortunately I gave myself a fairly large budget but this station is eating most of it...

[allmhuran]

Add a platform of structural parts below the payload. Strut from the structural parts to the payload, and build your rocket underneath it. A "plate" of structural parts can absorb the forces being put out by the rockets without having pieces tear off.

I just used this technique to launch 750 tons (20 jumbos) into LKO:

[annallia]

Woot its in orbit, well one of them are I went in a hair over budget so I have some deciding to do on where to go next... That said I took your suggestion Johnno and said to hell with the asparagus go for raw power!

On the pad, needed 12 of the support tower things to hold it up, started with 6, but it collapsed so I just doubled it and threw it against the wall.

I had to manage the core stage engine shutting it down and back on to prevent overheats, if I left it off the rocket didn't have enough lift. So I would shut down until it cooled, restart it and shut it down again... That is until booster separation. After that it was ok.

Didn't get booster stage separation but here is the core stage separation:

And because I was afraid it would be top heavy in the gravity turn if I left the fuel tank full I let it feed the core stage. This however left enough fuel in the core stage tanks to refill the tank + 1400 units left which will be used to refill the tanks on my tug before I de-orbit it.

Refueling done, final separation in progress:

[shand]

Congrats. what you using for your tug?

[annallia]

My standard issue tug, this is it in 0.20.2 it has been updated slightly, more fuel, less monopropellant using the new radial tanks I also ditched the 3 nuke engines in the center.

[Johnno]

Woot its in orbit, well one of them are I went in a hair over budget so I have some deciding to do on where to go next... That said I took your suggestion Johnno and said to hell with the asparagus go for raw power!

Well done!

There's no power like raw power.