Space-Shuttle Rocket starts spinning at 35km height

[Toxicterror]

Hi there

I'm trying to build a spaceshuttle launcher rocket.

So far everything went well up to 35km, but then the rocket starts to spin in all directions.

Has anyone got an idea why it does so?

here's a pic of my rocket. if you need more details, just ask pls

- using mechjeb to ascent

- actiongroup1 = disabling rcs thrusters on spaceship

Edited September 17, 2013 by Toxicterror

[Moar Boosters]

Its likely to be a thrust / center of mass issue, as these are really difficult to balance on shuttle style designs.

You could try and put more SAS units on the orange fuel tanks. More torque will give you a greater chance of countering the spin when it tries to flip your craft.

[Sirine]

I have a solution, but that will 'ruin' your design out look. Private message me if you are interested.

[Toxicterror]

got it working with more rcs on the orange tank. set the max acceleration to 20m/s^2 as soon as i go into gravity turn plus having the space shuttle on the top part (when horizontal) of the orange tank.

i think it just didnt have enough "power" (torque whatever) to hold the nose of the orange tank down and it always flipped back which then caused the uncontrolled spinning.

[SRV Ron]

Your center of thrust gets out of whack with the center of mass during flight. It starts off OK since the gimbals can compensate and the smaller engine is balancing the shuttle mass during liftoff, but at 35,000 meters due to the mass of fuel that has been used out of the big orange tanks, your center of mass has changed to the point that no amount of gimbals, SAS or RCS can compensate for the imbalance now taking place.

The real space shuttle angled its three main engine to the center of mass halfway in flight as well as had the ability to gimbal a lot further then the KSC engines you are using.

Edited September 17, 2013 by SRV Ron

[Sirine]

[Toxicterror]

Landed my space shuttle savely at KSC

My so called SpaceDrago M2 made it to my KAOS (space station), swapped a kerbonaut with another one and savely landed at the KSC again.

The RCS can hold the orange lifter-rocket in its path to just about 75km AP. There's just a bit of fuel left in it which i dont need and jetison with the orange tank.

I then timewarp to over 70km to switch to the space shuttle, letting the orange tank deorbit and then do the rest of my journey to the space station at 250km with the space ships engine.

After swapping kerbonauts I then retroburnt to KSC and landed the shuttle on the runway.

(all with a lot of help of mechjeb. would like to be able to do it without though ^^)

but thanks for all the explanations WHY it actually started spinning. always good to know what the actual problem was, altough i found another way around the problem