Hi Dan,
Thanks so much for posting these - they're great!
I never realized that the cover to
The Black Swallow of Death was by our old friend George Evans. I should have known.
Actually, the cover artist for
Stepchild Pilot is Bjorn Karlstrom. He was (is?) an aviation artist and draftsman who did some wonderful color four-views and scale plans for
American Aircraft Modeler and other mags back in the late '60's and '70's.
The cover you just posted for
Wind in the Wires bears the same painting as one of the covers for Peter Saxon's trilogy ("The Enemy Sky") that Pete Hill posted in the other thread (but which is now gone)

. However, this artist is not Brian Knight, who did the paperback covers I'm familiar with.