Rocket keeps flipping

[Lewie]

I sent an eve probe into kerbin orbit, but only the lander. The lander and transfer stage were too much for the second stage of my rocket to handle, even with lots of reaction wheels. Can someone help me out? I consinder myself to be decent at ksp, but this is just horrible and embarrassing. does anyone have any good tips?

[Grogs]

Without seeing a picture, I can only offer general suggestions:

 

1. If the lander is irregular, put it inside a fairing. I'm picturing lots of legs, side tanks, and heat shields for an Eve lander and that drag will make it hard to control.

2. Add more control surfaces on the bottom stages. Not just the fins, but the ones that actually steer.

3. Use engines with lots of gimbal to help hold position when the nose starts to slip.

 

If none of these work, try flying straight up longer and doing a less aggressive gravity turn. I had one very heavy lifter that was so unstable the only way I could avoid flipping was to go straight upwards to 20,000 meters, and then ever so gently tilt 5 degrees and fly prograde. Once it cleared the the atmosphere, I would turn it horizontal and burn until I got an orbit. This will burn more fuel, but you can always strap on more boosters to compensate.

 

Good luck!

[bewing]

If the first stage works, but the second stage flips, that means several things. The first thing it means is that "atmospherics is keeping your rocket stable". It's once the atmospherics are gone that you lose stability.

So what that means is that control surfaces are out as a method for retaining stability. You have to count on vacuum-type thingies for retaining control. Which means RCS and gimbal.

Fairings are the typical answer -- but they can be clunky, and if you are playing career you may not have them. In this game, fairings are actually a really silly answer to the problem.

The good answer, as Grogs said, is to launch straight up. It really really helps with your stabilty, and the fuel cost of not making a gravity turn is a lot lower than people make it out to be.

[N_Danger]

You could use RCS or Verniers to provide control. But launching straight up will always work with enough fuel.

[Snark]

23 hours ago, Lewie said:

I sent an eve probe into kerbin orbit, but only the lander. The lander and transfer stage were too much for the second stage of my rocket to handle, even with lots of reaction wheels. Can someone help me out? I consinder myself to be decent at ksp, but this is just horrible and embarrassing. does anyone have any good tips?

Could you post a screenshot of your lander?  Hard to offer concrete advice without knowing what your design looks like.

In general, if you want to keep the heat shield pointed , you need to have your CoM as close as possible to the front (i.e. close to the heat shield), so something low and squat.  This is important, because the heat shield is big and draggy and will want to flip around behind you like a parachute.  Don't even try to make it work with reaction wheels-- the torque forces generated by aerodynamics during the most intense part of reentry are insanely higher than what reaction wheels can do.  The only solution is to be aerodynamically stable.

One gimmick that can help is, put a heat shield at both ends of the craft-- i.e. one on the front, and one on the back.  That way, it doesn't matter which end of the craft ends up pointing or ; both are protected and it'll be fine whichever way turns out to be the stable configuration. 

[Lewie]

Thanks Snark! I also found that moar reaction wheels helped. I forgot to add them...