Wargamer and Teacher Matt Fritz has written MiG Madness, a set of free wargames rules for playing air combat in the Korean War.
Canvas Eagles is a set of free wargames rules for WWI Dogfights
Rabbidgerbal’s Biplane Dogfight Game is a set of free wargames rules for WWI era aerial combat.
The Battle of Britain is a complete strategic game for refighting the epic battle of 1940.
Fantasy Flyers is a set of free miniatures wargames rules for aerial skirmishes. You can construct your own flyers
I think it would be a good alternate game if you own some of those old Man O’War flyers — the Dwarf Gyrocopter, Manticore Riders, Wyvern Riders, etc. You also could use 15mm flyers (although I can’t recall if I’ve ever seen a good variety of those), or possibly 25mm fantasy figures (but I think the distances may have to be modified for this).