Continuing from the fuselage, we'll now spend a little bit of time on the tail.

We'll start by adding a little bit of dirt to the join inbetween the rudder and the rest of the tail. This is the area you will most commonly see dirty as grime from the rudder mechanisim compononets escape from this area.

Select the Brush Tool (B), set your active colour to black and your brush size to approximately 5 pixels.

Add a new layer and add a couple of blobs to the rudder side of the join.

Select the Smudge Tool (R) and set your brush size to approximately 5 pixels.

Place the cursor on the inside of the join, click and hold the mouse button. Drag the cursor in the opposite direction to travel, whilst doing this drag the cursor downwards slightly. You're looking to create a curved effect, repeat the process as nesscairly.

Now place the cursor back on the inside of the join again. Click and hold the mouse button, work up and down the inside of the join to create the effect of dirt gathering along it. You could also go back over the streaks you have created, "wiggle" the Smudge Tool (R) with a smaller brush size over it to create a varied effect.

Set the layer opacity to around 5% to a acheive a very subtle effect.

Lets now create a more general weathering finish to the tail.

Select the Brush Tool (B) and set your active colour to black. Select a scattered type brush and set your brush size to approximately 40 pixels. I used the following brush:

Add a new layer and dot several areas along the length of the tail, place them all towards the leading edge as opposed to the rudder region.

Go to Filter - Blur - Motion and set the distance to approximately 70 pixels, hit OK.

Remove the excess using either the Eraser Tool (E) or for a more defined line (for the leading edge of the tail) the Polygonal Lasso Tool (L).

To use the Polygonal Lasso Tool (L) click on a point along the leading edge above the excess you wish to remove.

Now click along the leading edge on a point below the excess you wish to remove.

Complete the 3 other sides to the selection and hit delete. Use the following image as a rough guide:

Press Crtl+D to cancel the selection.

Set the layer opacity to around 35% and you're all set.

You could use further techniques from the fuselage weathering section, however it's a good idea not to add too much to the tail

Now on to the engines.