Need some help with my rocket model (Shaky and Unstable after 12km)

[Strece]

Hey,

I tried to build my own ISS, so I started and built the Proton-K russian launcher rocket.

On top I attached a Clamp-O-Tron Docking Port, for the connection of the ISS modules. So my first module was the Zarya, I attached it to the Proton-K rocket and added some struts to stabilize the docking ports.

My problem is, that after liftoff the module began to shake, so the rocket is hard to controll. After the gravity turn, it goes on with shakes till the rocket break in half a little under the docking port.

I tried many things, like use decoupler instead of the docking port on the Proton-K (on the Zarya I need the docking port), tried with other docking ports, with more struts but nothing helped.

Here are the craft files (only proton-k rocket and with module).

http://www./?64i2sskhc53iizn

I hope someone has some tipps or solution for me. You need MechJeb 1.9.8 with the parts for my craft files.

Greetings, Strece

Edited July 10, 2013 by Strece

[Rradley]

how fast is your takeoff speed? if its too fast the larger rockets will become unstable. for better fuel efficiency i take off at 150 - 300 ms^-1

[Strece]

Thx for your answer.

I gave MechJeb the takeoff part, the takeoff speed is about 120 m/s. But it's not the large rockets which makes it unstable, its the module which starts to shake and wobble.

[sgt_flyer]

i tried to have a look, but it has mods in it

[Strece]

You need MechJeb 1.9.8 with the parts for my craft files.

Yes I said it in my topic , but maybe you can install, try and delete after this?

[SRV Ron]

I'm assuming that you have multiple gimbals engines upon takeoff doing either asparagus or onion staging. Set up an action group to lock the gimbals on all but the center engine. That will greatly reduce the shaking with only the center engine gimbaling for steering.

Going to look at it now and comment on what I find.

Ops, custom parts that I haven't installed.

Edited June 30, 2013 by SRV Ron

[Strece]

As you can see, I write down that MechJeb + parts 1.9.8 is required to load my craft file.

Thx for your suggestion, but I tried this (hope I did it right), but it changes nothing.

EDIT: Ok after some lesson in action groups I made it to lock the gimbals and for my surprise now the rocket goes straight up without any shake (MechJeb is doing this job), but at the gravity turn the ships broke beetween the rcs fuel tank and the engine on the bottom. But the flight is really still.

Is is at problem of the length?

Edited July 1, 2013 by Strece