I imagine this would be really hard to implement but wouldn't it be awesome if it was possible to set a month of the war for a game and be able to choose any planes available by that date, as the board game was often played (at least by me and my group of friends). That way you could get to fly the aircraft you want instead of those left by others in the scenario. Perhaps planes could have points values in order to stop everyone grabbing the ultimate plane available (N17/SSD1=1pt Snipe=10pts for example), then you could nominate not only the month but the number of points available to each side for example:
Aug 1918- Allies 10/ German 8, giving the possibility of a single Snipe v 8 SSD1's. Obviously this is just first thoughts and the points value of the different planes would need to be determined but just thought I'd throw it into the arena for comment

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Looking forward to your responses Rex

i still think this is a great idea and would love to see some more thoughts about it and if it would be possible to implement