They're all quite playable solo, you just need to create some simple system for tailing and such. I try to pick whichever manoeuvre would be the most logical for each plane, and use dice to pick manoeuvres when there's more of a choice. For tailing and near-tailing I pick the tailing plane's cards first and pick the lead's semi-randomly, dicing for picks depending on the plane e.g. Camels will more often make right turns, SPADs will power dive etc. I've got nothing written down for this otherwise I'd post it, besides it all changes "on the fly" depending on the exact situation. Works fairly well for me.