As the diagram indicates,
the Split S is really nothing more than an Immelmann in reverse,
instead of climbing you are performing a dive. In fact if you
combined an Immelmann with a Split S you would wind up flying
in a complete loop. Like the Immelmann, the Split S can be used
to effect a sudden reversal of direction but it is most effective
as a means of instantly increasing your speed.
The first step in performing a Split
S is to roll 90° so that your aircraft is now inverted.
This is done so that you are pulling back on the stick to enter
the dive rather than pushing it forward. (Your body can withstand
positive Gs better than it can negative.) Rolling inverted from
level flight telegraphs your intentions so wait until you are
ready to dive before starting your roll. Pull the nose of your
aircraft down to enter the dive and keep back pressure on the
stick until you are vertical. (Again, use the Virtual Cockpit
view or HUD pitch ladder to judge your aircraft's attitude.)
Reduce your speed to stay near your corner velocity and avoid
losing too much altitude. Either cut the throttle before you
enter the dive or slow the aircraft by opening your speed brakes
(the B key). To complete this maneuver, pull back sharply on
the stick, bringing the nose of the aircraft up to a level flight
attitude. Like the Immelmann, you can wind up heading in any
direction you desire by rolling slowly as you dive.
The Split S is a great maneuver but you
must use caution. Be careful not to engage this maneuver at
too low an alititude, you may not be able to pull out of it
in time.