Rise Of Flight.
The next best thing in WW1 flight simulation. Go try it........ you can find it here
The basic game is free, it comes with a few flyable planes. If you want more flyable planes, you can buy them.
-excellent graphics / flight model / single and multi player / supports multiple sticks/pedals / good AI / mission design tool for SP and MP.
realistic physics (even the grass moves in the wind.........)
The first SPAD - screenshot below is with lowest quality possible. (card = 8500GT nvidia, the card cannot handle more....)
The second one is with medium quality settings ( card = nvidia 250 GTS 1 GB ). The 250 GTS can handle highest quality possible with ease.
The third one shows with high quality settings (nvidia 250GTS again)
Rise of Flight is working well on Linux.
I tried with crossover from codeweavers.com, running on openSuSE LEAP 42.3
installation and gameplay / config works without a hitch. ( core i7, 8 GB, SSD, intel HD5500 graphics )