Cannot design a rocket that won't flip(career mode)

[UndyingWar]

I used to be able to play ksp with barely any struggle. Now I can't design a rocket that won't flip before leaving the atmosphere, I have been trying for days. I've put lots of tail fins at the bottom of my rockets, I'm using plenty of gimbal engines, and SAS from my pilot. I don't have reaction wheels unlocked yet, or RCS thrusters. I have no clue what to do. I've tried to design expensive complicated rockets to solve the problem, and I've also tried very simplistic rockets but nothing seems to work.

I have mods enabled, but nothing that changes the atmosphere or aerodynamics... I even make sure that the rocket isn't travelling too fast as to limit air resistance. I don't even try a gravity turn, even when flying perfectly straight up it finds a way to start flipping. Any help would be greatly appreciated

[Starman4308]

Top heavy, bottom draggy. That's it.

Ensure the payload is either fairly aerodynamic, or encapsulated in a fairing. Ensure the fairing isn't much wider than the rocket it's launching on. Don't leave small stuff laying around on the surface of your rocket, unprotected by a fairing. If that's not enough, put some fins way down low to help pull center-of-pressure beneath center-of-mass. I feel this trick is a bit cheaty, but you can also set fuel priority to drain from the bottom tanks first.

Past that, it would help to have screenshots.

[Vanamonde]

Common issue since the atmosphere was reworked a while back. Reduce drag up front and add some fins toward the back.  

Also, thread moved to Gameplay Questions. 

[Deddly]

@UndyingWar, if you could give us an example picture of your rocket, that would help us give more specific advice

[Snark]

On 2/23/2018 at 7:41 PM, UndyingWar said:

I used to be able to play ksp with barely any struggle. Now I can't design a rocket that won't flip before leaving the atmosphere, I have been trying for days. I've put lots of tail fins at the bottom of my rockets, I'm using plenty of gimbal engines, and SAS from my pilot. I don't have reaction wheels unlocked yet, or RCS thrusters. I have no clue what to do. I've tried to design expensive complicated rockets to solve the problem, and I've also tried very simplistic rockets but nothing seems to work.

As @Deddly mentions above, we really need to see a screenshot of your rocket before we can offer any specific advice.  I can assure you that building a nicely stable rocket is fairly straightforward in KSP-- it's not hard, but it's necessary to understand How Things Work.  My guess, if you're having persistent difficulty, is that there's probably some aspect of it that you're unaware of, and that's what's biting you.  Post a screenshot of an example rocket with this problem, and we'll have this cleared up in a jiffy for ya. 

One thing to check, in the VAB:  where is your center of mass?  (You can easily see this by clicking the little VAB button that turns on the black-and-yellow checkered sphere that shows CoM location.)  You need that CoM to be up near the front of your rocket.  If it's down in the back of the rocket, you're going to flip, and fins won't help you (because they only work if they're well behind the center of mass).

Anyway... screenshot, please?

[GrouchyDevotee]

Don't build "up", build "around", radial decouplers are your friend.