From the manual:

Red Star / Blue Sky is a collection of scenarios, campaign systems, aircraft data cards and new rules for use with the Red Sun, Blue Sky or Black Cross, Blue Sky miniatures games. Red Star, Blue Sky accurately recreates tactical aerial combat on the Russian Front during World War II. Simple game mechanics lets you focus on leading a squadron or more of aircraft against the hated enemy aircraft and ground forces.

Expands:

• Red Sun / Blue Sky