How to not Spaghetti Rocket?

[RAINCRAFTER]

Okay, so ever since my last thread posted in this subforum (http://forum.kerbalspaceprogram.com/threads/119024-Why-does-this-flip-out), Jeb got stranded on Minmus due to a lack of fuel in his rocket. I don't want to risk getting home on half of his EVA pack fuel, so I'm sending a rescue mission. Unfortunately, the rocket is HUGE. Therefore, all of the test flights ended in explosions through losing control (not because of aero. Also, using 1.0 for this; which makes aero easier.). Last but not least, before you say, "STRUTS!", they won't go as long as I want them to do. I'm in a science save with 0 science, so I need help.

Since I learned from last time, pics: Top of the rocket:

Bottom:

And my tech tree and science, so you can get a picture of how bleak my situation is:

Also, a .craft file for good measure.

https://drive.google.com/file/d/0B6kMiFN2UFJoYmpQSUpDVXJQazQ/view?usp=sharing

Good Luck to you guys, RAINCRAFTER out.

Edited May 11, 2015 by RAINCRAFTER

[sal_vager]

I saw a craft like this yesterday which I fixed for a member, I placed some of the new fins part way up and ran struts to it from the top and bottom of the rocket, making triangle reinforcements.

I think you'll want at least two sets of small fins, a third of the way for each set, and run your struts from top down.

[smjjames]

Use KJR? But even then, it'll only help so far.

Another option is a squatter rocket and use LF/OX boosters (aka tank stacks strapped to your rocket).

Also, how much science have you done with Kerbin biomes?

[Chaia]

That rocket is very overengineered. A very good tip is to split up in more stages, this will shred much dead weight of empty fuel tanks. If this is a rescue mission, why do you pack three material bays? Also how do you plan to get Jeb into that ship and back to kerbin? You only have one pod and no probe control, as far as I can see on the screenshots.

Those landing legs are unsuited for that kind of engine on your second-last stage. Engine is simply too long for the legs.

For the tumbling reasons, do you rocket even can lift into space? It looks like you got very much fuel, but just a few engines.

Try to make your last stages smaller and then design the other stages accordingly

[sal_vager]

Here try this, it will never be perfect but it's a lot more controllable.

[Pastebin link]

Edited May 10, 2015 by sal_vager

[Hcube]

That rocket is very overengineered. A very good tip is to split up in more stages, this will shred much dead weight of empty fuel tanks. If this is a rescue mission, why do you pack three material bays? Also how do you plan to get Jeb into that ship and back to kerbin? You only have one pod and no probe control, as far as I can see on the screenshots.

Those landing legs are unsuited for that kind of engine on your second-last stage. Engine is simply too long for the legs.

For the tumbling reasons, do you rocket even can lift into space? It looks like you got very much fuel, but just a few engines.

Try to make your last stages smaller and then design the other stages accordingly

^ pretty much this. Are you going to Minmus (and yes by the way its called MINMUS NOT MINIMUS god damnit) or to Jool ? Cause that's a pretty big friggin rocket ! Remove the materials bays, either use a probe or another pod since you want to get bill back too, and make more stuff radial. This is very spaghetti, it will never get to orbit. Try something like 2pods/lander (909 and a 360 LF tank will do)/transfer stage (a 180tank+720tank and a T45 are fine) and then get a first and second stage to get this whole stuff into orbit.

Dont be afraid to make stuff radial, moar boosters, tons of fins, and engine clusters with modular girders, as well as a s**tload of space tape

[CalculusWarrior]

I echo the others in this thread, shorten the rocket, and add radial stages if you can. You shouldn't need such a large rocket to get to Minmus. Kebal Engineer is a fantastic mod for this, it allows you to read out exactly how far the ship can go, and cut down on unnecessary mass.

While long rockets are now favoured due to the new aero, extremely long ones like yours are not only structurally unstable, but very difficult to impart control authority over.

[DoToH]

If you want to prevent structural failures in big rockets: Whackjob youtube channel

If you want to reach minmus: you can achieve it with much smaller rockets.

[Starwhip]

Holy Kraken, that thing is HUGE!

Making it shorter will certainly help. You shouldn't even need that much rocket to get to Jool!

[SmashingKirby148]

I'm pretty sure your problem is your over loading it. You do not need that abundance of fuel just to get to Minmus and back.

[RAINCRAFTER]

Mhm. Thanks, just trying to get a design that works on the Mun too... and all that...

I'm trying the rocket sal_vager made now.

EDIT: File didn't work. Now redesigning everything.

Edited May 10, 2015 by RAINCRAFTER

[DeMatt]

I'd say cut down on the payload. You've got three Materials Bays and two Service Bays on there; why not fly with a scientist (they can reset experiments, now) and reduce that to one?

[Northlight]

For comparison, this is what I used to rescue my stranded kerbal from Minmus.

(It requires in addition to what tech you already have, the "Advanced Rocketry" for LV-909 and Mk-55, and "Fuel Systems" for the external fuel ducts to balance out the fuel-use on the first stage.

Oh, that is 1x T400 in the L&R craft.

Edited May 10, 2015 by Northlight

[n0xiety]

Another option you have is to build absurd looking rockets that have point of thrust over the point of mass. If you pull the rocket up instead of pushing it up you don't even need to use any struts connecting everything each other. You can just keep your engines at the sides of the craft and drop fuel tanks as you go up under the craft. This way you actually save on engine cost and additional engine mass since you will be using the same engines all the way. Ofc this strategy needs an engine which is efficient in both vacum and atmosphere.

[Juicy]

As for the science points you're missing: make a really small 1-stage rocket with liquid engine, a whatever to adjust your trajectory, a parachute (just in case) and a couple of science instruments. Launch, aim to land at different locations within your base, (including tops of several roofs), and do experiments after landing. Even with just Goo, a thermometer and a science jr, there are easily 400 science points in your main base, if not more. Just launch, land, experiment and recover a few times. With rovers and some more experiments it's even better, there should be over a thousand science points just in your main base!

[sal_vager]

Mhm. Thanks, just trying to get a design that works on the Mun too... and all that...

I'm trying the rocket sal_vager made now.

EDIT: File didn't work. Now redesigning everything.

It downloads as a .txt, it needs changing to .craft

[RAINCRAFTER]

It downloads as a .txt, it needs changing to .craft

Tried that before you brought it up, but it still didn't work. Now I'm experimenting with an SRB launcher! I'm just gonna change this to answered.

EDIT:

For comparison, this is what I used to rescue my stranded kerbal from Minmus.

(It requires in addition to what tech you already have, the "Advanced Rocketry" for LV-909 and Mk-55, and "Fuel Systems" for the external fuel ducts to balance out the fuel-use on the first stage.

Oh, that is 1x T400 in the L&R craft.

http://tunefix.net/img/MR1.png

How did you get the image?

[Beowolf]

Probably this mod: http://www.curse.com/ksp-mods/kerbal/224287-kronal-vessel-viewer-kvv-exploded-ship-view

[Nurph]

Here's my take on it: https://www.dropbox.com/s/1lmpfcathl9uuf1/Lander%203.craft?dl=0

It's able to land and return from the Mun with fuel to spare (~1k Dv). In general, anything that can get you to the Mun and back will work just as well for Minmus.

1) I removed all the science stuff (it is a rescue mission after all), but you could prob add 1 or 2 back on.

2) Removed 2 tanks off the lander and 5 tanks off every other stack. This is probably the most important part, you just have too much mass for too little engine power and the rocket looses velocity after SRB burnout. You always want more Dv, but it doesn't do you any good if you have to burn all of it before you get to orbit. Also makes it way less bendy.

3) I WILL say STRUTS ! There were no struts on the lower stage or SRBs. You've got 5 long fuel tank spaghetti's for your first stage. Just because the stacks are touching does not make them connected and might make things even worse! Part clipping can do weird things. The 4 outside engines were also drawing fuel from the center stack for some reason, stuck a decoupler in there to stop that.

Bigger is rarely better when it comes to (sane) rockets. (I'm looking at you Whackjob <3)

[Northlight]

Probably this mod: http://www.curse.com/ksp-mods/kerbal/224287-kronal-vessel-viewer-kvv-exploded-ship-view

Abolutely correct! And then add the text and arrows.

[RAINCRAFTER]

Good, heard of Kronel already. Just didn't know where the arrows came from.