How do I stop my rocket from doing this?

[DucharmeHD]

I'm using RSS & FAR (Only 2 that are relevant, i think...), and every time I launch my rocket it does this. Obviously it's an aerodynamic problem, but I'm not sure how to fix it. Other rockets have done fine but this one isn't.

The 3rd image has the specs of the rocket, it has a TWR of 1.95, should I bring that down to make it launch slower?

I've also tried locking the gimbal on my engine, but that doesn't seem to help.

[SRV Ron]

Some mod parts don't stay together well. Stitch the offending section together with braces. If you can't get them to connect, use cubic struts to connect one end of the braces to.

Without stitching, this rocket would fall apart on the pad.

[diomedea]

I am often amazed at how spectacularly realistic some effects are in KSP (when properly modded).

That rocket is very long and has a significant lift in the aft (also because of those winglets), once it takes a significant angle of attack. Too much lift if the speed is high (a TWR of 1.95 certainly gives that high speed early), enough to exceed the structural resistance of the joint that is seen breaking.

You should avoid taking any significant angle of attack until at high altitude; that means, fine if you use a proper gravity turn but you can't force the rocket to steer too much. Or, wait until you have at least 20 Km altitude to reduce atmospheric density and therefore generated lift. But probably you don't really need those winglets.

[Taki117]

you are using both RSS and FAR so I'm going to ask a very pointed question. (please dont take this the wrong way)

how many real life rockets have winglets on them? (besides the shuttle)

if we look at real examples none of them had winglets with only 2 exeptions. (that I can think of) You have the Mercury-Redstone that had small gide fins that profided thrust vectoring, and the Saturn V rockets lowest stage, used mainly for guidance (I am almost poitive they were static). Try removing the fins and see if that helps (both sets)

[MarvinKitFox]

Im guessing you have your SAS/reaction wheels in the nose?

So your poor rocket has to coordinate torque in the nose, Engine gimbal in the back, Steering input from wings in the back, AND steering input from wings on the mostly-front.

Cure:

1) Sew some stitches + bracing into that joint.

2) Disable steeding input on the front wings, until staging makes them the *only* wings on your ship.

3) If you ARE using wings, then disable your reaction wheels until they are the only controlling factor.

Each of these actions will make your ship more sluggish to steer, but also more stabile.

In my experience, having control surfaces anywhere other than at the rear of a vehicle turns it into a sportscar. Fun to drive, but very very twitchy.

When launching rockets, you don't want a sportscar. You want a station wagon. Or even a Winnebago.

You want one, and only one, element controlling your vehicle orientation at any one time.

Gimbal rockets is best. Rear wings only if no gimbal. SAS only if in vacuum, and not running gimballed engines. And front wing/canards if you want a brown-pant experience.