Heavy load rocket design

[MaGicBush]

Well I am taking my first attempt to get a space station into orbit around Kerbin and am having troubles with my rocket design(and honestly did on my light capsule load to orbit kerbin a bit for some reason, I am not sure if something changed in the last two updates since I last played). It seems very unstable, being hard to control as it gets into less atmosphere the higher it gets. I did a complete 180 turn and went back to the drawing board at that point lol. For some reason it as well rotates wierd(and so did my single capsule rocket), and I have to constantly use the e and q keys to keep it from rotating. I looked through tutorials and didn't see much explaining rocket design and how to stop such problems so I thought I would ask here. This may be a bit much rocket power/fuel just to get it into orbit around Kerbin, but I wanted to make sure lol.

A few key questions:

How does the center of gravity in the space center effect my rocket design? It is really low(on the floor) and not centered and I am not sure why.

How does the center of mass effect it? It is centered on the fuel tanks a bit lower than the station core which I think seems alright.

How does the center of thrust effect it? It is centered on the center engine(2-stage rocket design).

Where is it best to put the ASAS module(if I need one this will just go into orbit and stay)? I am still not sure the difference between ASAS and SAS or when they are needed.

I am not sure about the fuel lines or if they benefit at all here, but I watched some youtube videos where the guy put them between these tanks on a similar rocket design for a heavy load. Are they beneficial here at all to do what I did?

A picture of my current design:

Thanks for any information!

Edited September 13, 2013 by MaGicBush

[Dangerous_Beans]

there is a tutorial on sas here: http://forum.kerbalspaceprogram.com/showthread.php/41941-New-SAS-functionality-and-You!

generally you want them around the centre of mass.

you want the centre of mass and the centre of thrust aligned on the long axis of the craft. if either are significantly off then the engines will produce a rotational force around the centre of mass, and it will spin out of control.

the benefit of the fuel lines is you can make the engine in the centre stage drain from the outer stage tanks, so you can use all the engines from the start, and when you dump the boosters you still have a full tank in the centre.

the spinning seems to come from struts not being exactly symmetrical. put a reaction wheel on the top of each booster if it is too bad, or tail fins, otherwise it doesn't matter too much.

[MaGicBush]

there is a tutorial on sas here: http://forum.kerbalspaceprogram.com/showthread.php/41941-New-SAS-functionality-and-You!

generally you want them around the centre of mass.

you want the centre of mass and the centre of thrust aligned on the long axis of the craft. if either are significantly off then the engines will produce a rotational force around the centre of mass, and it will spin out of control.

the benefit of the fuel lines is you can make the engine in the centre stage drain from the outer stage tanks, so you can use all the engines from the start, and when you dump the boosters you still have a full tank in the centre.

the spinning seems to come from struts not being exactly symmetrical. put a reaction wheel on the top of each booster if it is too bad, or tail fins, otherwise it doesn't matter too much.

Alright thanks, I got my station into orbit finally at 199AP and 196PE with plenty of fuel to spare on the middle engine! I will work on getting a near perfect orbit at 199km and dump the main engine/fuel tanks. I was shooting for an orbit of 200km so close enough . My problem was with the ASAS and very glad you linked that . Also thanks for the information about why it spins like that.

Finished orbit:

Edited September 13, 2013 by MaGicBush