Mysterious flipping force

[theperson0719]

Hi, so whenever i try to launch a new vessel it does fine for a few seconds, after firing the engines on full, then is mysteriously flipped over to fire retrograde. The vessel isnt misbalanced becasue nothing can misbalance it. It is 2 fuel tanks below a cockpit with a small engine beneath... any suggestions?

[Harry Rhodan]

Your center of mass falls below your center of pressure and the aerodynamic forces push you over and make the part with more mass fly in front. The solution is adding draggy bits like fins at the verry bottom of the rocket to keep your center of pressure down and/or to add a second stage that will keep the center of mass somewhat at the top of your rocket.

[sal_vager]

Also add wings to the bottom of your rocket, and/or add enough gimballing engines to keep control.

Also, back off the throttle, the faster you go the higher the aerodynamic forces and the greater the drag on the upper parts of your rocket, causing a flip, I try to keep my acceleration to 2g's maximum.

This is not some mysterious force by the way, it's lift and drag acting on your craft.

Moving to gameplay questions.

[Snark]

Also, back off the throttle, the faster you go the higher the aerodynamic forces and the greater the drag on the upper parts of your rocket, causing a flip, I try to keep my acceleration to 2g's maximum.

And bear in mind that the drag force spikes dramatically upwards when you pass Mach 1, which is around 340 m/s at Kerbin sea level. (If you notice that your rocket seems to fly just fine for a while and then suddenly wants to flip, that's likely why.) This is really bad not just for stability, but also for fuel efficiency.

So keep an eye on your speed, and don't let it climb much over 300 m/s until you get over 12 km or so. (And watch out for those wispy Mach shockwave F/X showing up... they do look cool, but they're not something you want to see unless you're flying a spaceplane.)