Basiclly its tamiya smoke thinned to almost watery consitancy while holding kit as if it was in a nose dive and holding airbrush at a 45 degree to the leading edge of the wing.usimg a dual action airbrush i bepress brush for air to start then slowly draw back the trigger until a small line if paint comes out start spraying and bend a few flicks of your wrist backwads untill u have the desired effect..
Your looking for more of a build up of paint at the muzzle of the gun and a feathered effect moving back just takes a bit of practice
Also u can ting the tamiya smoke with a brop of a colour for various uses
E.G ..exhausts on motorcycles buy using tamiya clear colours to replicate a tempered metal fiinish
pics of my bikes as example below
imagizer.imageshack.us/.../dscf1695xk6.jpg
imagizer.imageshack.us/.../dscf1932cj5.jpg