From the announcement:
One Pound Wargames is delighted to announce the release of the second volume in our HorizonWar Trilogy, AirFrame!
This companion game to break-out hit, MechaWar, uses similar mechanics that allow you to run air-to-air battles as standalone games or to combine forces with ground mechs to add a new dimension and powerful new abilities to your battlegroup. And, best of all, like it's older brother, AirFrame is just £1.00!