This is a pretty straightforward Photoshop painting. The airplanes are a reworking of an illustration I did a couple of years ago. Their somewhat fanciful (as in "not-especially-aerodynamic") design is somewhat inspired by the UH-60 Black Hawk helicopter - but in terms of their function they're probably more akin to the A-10 Warthog.
I only painted one aircraft, and then just copied it at reduced size for the background planes - truly a shameless cheat (but a big time saver)
The sky was painted using the Smudge/Blend tool to smear large blocks of color together into a cloudscape. It's always fun - and surprising - to use this technique, and see what effects the various brushes have
The lightning was an area grabbed from a photograph, and unfortunately I've had the photo in my files for so long I no longer have any recollection of the source
I wanted to capture the feel of "model kit box art", but with a sci-fi aircraft as the featured item...