why do all my big rockets tip over?

[HidekiTojo]

Every single time my big rockets wobble a little bit then tip over and crash. Even when I build them to the exact same specifications as tutorials like the Apollo 11 tutorial or some youtube videos.

What am I doing wrong?

[nimper]

Every single time my big rockets wobble a little bit then tip over and crash. Even when I build them to the exact same specifications as tutorials like the Apollo 11 tutorial or some youtube videos.

What am I doing wrong?

You need launch clamps! They're under the Structures tab.

[Vanamonde]

Let's see some screenshots. Are you remembering to turn stability assist on with T before taking off?

[Spaceisbeautifulul]

Maybe you need launch clamps.

Or MOAR struts.

Or maybe some wings for stability and more gimbal'ing engines?

Screenshots would help a lot, bro.

[UmbralRaptor]

Struts, control authority, fuel drain, drag. Probably something in there.

[Spaceisbeautifulul]

A-symmetric?

[Guest]

If your centre of thrust is well behind your centre of mass, then your rocket will tumble.

[Jm419]

If your centre of thrust is well behind your centre of mass, then your rocket will tumble.

Not really. It depends on how the force of thrust acts on the center of mass. If you have your center of mass directly above the center of thrust, simple physics dictates that the resultant motion is upward, with no horizontal motion. Will tiny oscillations make more of a difference if the CoM and CoT are far, far apart? Sure. Will it automatically tumble? Absolutely not.

My guess is that the rocket is asymmetric. Let's see some screenshots.

[Pbhead]

I am suddenly having tipping over problems as well even on the simplest of rockets.

edit:

should really fly straight. but it doesnt.

Edited June 19, 2013 by Pbhead

[wasmic]

I've had problems with rockets tumbling over, with completely symmetric rockets. I think that if the CoM is much above the CoT, the rocket will tumble when you start to do your gravity turn, as that will displace the force on the craft - before gravity turn, thrust pushes vertically upwards through the CoM, and gravity pushes vertically downwards through the CoM. After gravity turn, though, thrust pushes non-vertically upwards through the CoM, and gravity still pushes vertically downwards through the CoM. Now that i write it down, though, I'm not sure if that would tumble the rocket...

[UmbralRaptor]

Ah, the aerospike drag bug claims another rocket!

Pbhead:The aerospike is missing the drag info in its part.cfg file. As such, it uses the default drag (0.1), which is lower than most parts use (0.2). Because it is less draggy, it wants to be at the front of an object, so rockets using aerospikes tend to be dynamically unstable. This can be fixed by either adding the drag info to the part file, or using another engine (eg: LV-T30). Rockets with enough control authority can simply brute force their way through it, FWIW.

[capi3101]

If you're using the 'spikes, you'll want to use launch clamps anyway. Those things get knocked off with the slightest bump. I had a ship with aerospikes and the stupid thing wouldn't launch; it turns out that they were being knocked off the ship by the launch pad. Clamps solved the problem.