do launch vehicles fly at negative angle of attacks after pitch over maneuver?

Question

At early seconds of flight, launch vehicle goes up vertically. at the beginning of pitch over, it has vertical velocity and simultaneously pitching which makes the wind to flow from upward direction. is this an actual situation in launch vehicles? does the angle of attack change to positive, that means wind flow from below the vehicle?

Answer 1

It is somewhat a matter of definition depending on how the vehicle coordinate system was defined. For the Saturn V

At this point, it is worth outlining the vehicle's coordinate system. The Saturn V's plus-x axis ran along the length of the rocket and out through the top of the escape tower. Its plus-y axis ran through the vehicle towards the umbilical tower and therefore was pointed north. The plus-z axis ran through the vehicle to the west. As the crew lay on the couches, their heads aimed east and therefore towards the minus-z axis.

(Quote quoted from Pitch and yaw axes of rocket systems such as Apollo)

Using this system, the Saturn V angle of attack never went negative during ascent.

Source: Saturn V AS-507 "G" Mission Launch Vehicle Operational Flight Trajectory - September Launch Month