Help getting 50 tonne fuel module to LKO

[ScottyDoesKnow]

Edit: If anyone can tell me why my old design is about a million times stronger than my new one I will love you forever.

Old design: http://www./download/pw6p4kwfv5lgb3w/Fuel_Module_Mk-02.craft

New design: http://www./?q1if975dcwbt4fm

So I'm trying to get a fuel module into low kerbin orbit. I was having a lot of trouble so I weighed it to find it was 100 tonnes. So now I'm trying with one that's half the size but still having trouble.

The payload (remote control not included):

The launcher:

The problem is the whole top section breaks on lift off, usually at the senior docking ports. The middle section is the utility vehicle used to move the payload around once it's in space, or can use the payload for interplanetary travel.

Any help would be appreciated. And yes I could probably just put 50 struts on it but I'd rather not.

Edit: I tried stitching everything together and it still fails even before launch, now with a 25 tonne payload. I've linked the file near the top. It would be great if any changes that are made are fairly general, basically everything below the fuel payload is a general launcher I use for everything. But whatever works, works.

Edited June 15, 2013 by ScottyDoesKnow

[nhnifong]

This is making your stability worse not better. remove those things and just strut the payload directly to the boosters.

Reinforce the entire center stack with at least three vertical struts at every single joint. AKA stitching

Turn off the gimballing on all but the center engine on launch.

Control from a docking port or probe core near the center of mass on launch.

If you manage to get it to orbit without at least 50 more stuts, I'll be very interested in finding out just how you did it

[Major Healey]

When I try for massive payloads I do things like this to stop them twisting and shacking off

[Flixxbeatz]

Try draining fuel before/during the launch and refill it later if you intend it to be a station module.

[soranno]

if you would post a craft file I (among others I assume) will load it up and see what can be done

[Vanamonde]

When lifting large loads, it is often better to build the launcher AROUND the payload rather than UNDER it. For example, this is what I used as a refueling tanker: http://forum.kerbalspaceprogram.com/showthread.php/25779-Orbital-refuelling-tanker

[ScottyDoesKnow]

Try draining fuel before/during the launch and refill it later if you intend it to be a station module.

I don't plan it on being a station module, I plan on taking 1 or more into orbit. I'll leave one transport vessel so it can be controlled and then just add on the full fuel tanks. If a craft needs more fuel for a mission, it will drop by and take a tank.

if you would post a craft file I (among others I assume) will load it up and see what can be done

Added.

When lifting large loads, it is often better to build the launcher AROUND the payload rather than UNDER it. For example, this is what I used as a refueling tanker: http://forum.kerbalspaceprogram.com/showthread.php/25779-Orbital-refuelling-tanker

I'm trying as hard as I can to make it work with a generic launcher. Basically everything under the actual payload is the same launcher I use for everything.

[ScottyDoesKnow]

OK there's definitely something just wrong with that design. It just broke in the middle trying to launch a 7 tonne payload. I tried remaking my old launcher to replace it with something better, but something's obviously fundamentally wrong.

[PringleMan]

In general the first thing is to check the mass balance. If you have a huge mass, with a small stretch in the middle, and then another large mass at the bottom, then 90% of the time it is going to buckle in half during launch.

[Sleipnir]

Instead of having the tanks spread out like that you will probably be better off using just one orange tank, then use asparagus staging. 100T isnt that hard with asparagus. 2x2x2 usually works, just use 2 orange tanks with 1 mainsail

[SDIR]

Try to keep is simple. I tend to make all of my large rockets with a common core booster, so it makes the entire design easier to debug. Looks like this, can get 70 tonnes to 300 km

[Kegereneku]

I see that you are using Asparagus staging but I think you should divide your first stage to have one stage powered by skipper engine. It should reduce the dead-weight drag significantly as well as optimize reactive mass consumption during the circularization.

That said, I personally used a 2x2x2x2 asparagus staging (without skipper engine) to put 115 tons ... into a 200 km orbit.

[ScottyDoesKnow]

Managed to get one of the small ones into orbit using my old launcher (image is of 3 but that one didn't make it). The big thing is I even stacked 5 on there without any damage, just not enough push for orbit. So why does my new launcher break at 7 tonnes load?

http://i.imgur.com/DKunbbl.jpg?1

Old launcher: http://www./download/pw6p4kwfv5lgb3w/Fuel_Module_Mk-02.craft

[sanity]

this is my favorite launcher,

simple, reliable, hard working

not prone to explosions or interpretive dance,

stick whatever is needed on top

can lift a whole full orange tank into orbit, probably more but haven't tested

just disable or enable the outer rocket engine gimbals depending on mass of the load on top

Edited June 15, 2013 by sanity

[Heagar]

First of all: Please use an Asparagus-staging (One outer tank feed into another and that then into the center tank). That hole thing have to be done mirrored. When one pair of tanks is empty decouple them with the engines attached to them. Asparagus staging results in a much higher delta-v than that design you use currently.

Second: The upper stage you use for OMS-actions should be an centered tank (with maybe two small additional tanks adjectant to it) and two attached small engines to the side. Because a centered engine have to carry all the load and breaks up mostly under the stress from the load and the wobbeling. That is caused by KSP; it stacks every thing in the middle, in that case the engine and not the hull/airframe: The casing around the engine from an decoupler is purely cosmetic! And: The stage is much shorter, witch means less wobbelling.

Third: Don't exceed Mach 1 (330 m/s) in the lower athmosphere, in fact over 220 m/s can result in extreme wobbeling. Witch can mean: Perform your gravity turn with such a payload above 15-18 km altitude!

Fourth: Since the mainsails have too much steering-output when ASAS is used (resulting in wobbeling), you can try to deactivate the gimballing for the outer engines.

17.06.2013:

I had now played the first time in KSP 20.02 and experianced the same difficulties. The payload was intakt as the launcher, but the connection at the docking-port broke. My workaround:

1. Max struts from the payload to the stage below.

2. I used radial decouplers (the wide one) witch attatched structural tanks witch are overlapping the next stage. From the last tank then i fastened struts to the payload.

Maybe - this i havened tested yet - that interplanetary crafts, that depends on building them in LKE while using docking ports will brake apart by lauching the mission. In that case Quantum-Struts could be an solution for it.

Fifth: Strut your payload - maybe the upper stage too - to the outer tanks of your space-booster. This has two advantages: The wobbeling and the stress on the middle section/main core is decreased.

Edited June 17, 2013 by Heagar
Same difficulties witch docking ports