public void setDefaultVerticalRotation(float angleInRad) {
        vRotation = angleInRad;
        targetVRotation = angleInRad;
    }
sets the default vertical rotation in radian of the camera at start of the application

@param angleInRad the desired angle (in radians, default=Pi/6)
jme3-core/src/main/java/com/jme3/input/ChaseCamera.java