To begin, select the side view, and insert a new track segment. Have the entrance on the horizontal, and the second vertex needs to be upside down and above the entrance. Select "rell roll" on the second vertex to ensure that the track is inverted at that point. Move the control points so that there is a smooth upwards curve into the inverted position.

This is where it becomes more tricky. From the top view, insert a new segment of track which turns 90 degrees to the half loop, and also returns to 0 degree banking.

Now from the front view, lower the vertex slightly, so that you create a half cobra roll, or Immelman. Make sure that the vertex added is horizontal and bank it approximately 20 degree towards the centre of the cobra roll.

This time, select the vertex and raise it so that it is of equal height to the top of the half loop. The vertex should also be banked 180 degrees so that the track is inverted at that point. You may also need to alter the vertex in the middle (as seen in the picture below) to produce a nice smooth, pump-less curve.

Now we need to add the last segment of the cobra roll. This segment is exactly the same as the first segment added. Insert the new segment and shape it, by looking at the side view, so that it is exactly the same as the first segment.

We now have the basic shape of the cobra roll, however it is more realistic if the base of the cobra roll/images/coastergames/nltutorials/cobra_roll_files/cobra_11.jpg is narrower than the top. To do this, select the entrance vertex and move it in towards the middle of the cobra roll. Do that same with the exit vertex. You should now have the perfect shaped cobra roll.

Finally, a big problem with cobra roll's are the high lateral g forces. If forces are too high, try to change the banking on some of the vertexes.