What specs have you? It doesn't need much compared to some other flight sims, and the required specs seem to be getting lower every patch.
It's also free* to download (I know, I know, it'll take you a while) with two aircraft to try. When I first got it I was seriously underspecced and it worked ok and there are lots of threads on the RoF fora about specs under and over. You can also drop the resolution down to 800x600 to improve framerate until you get a new(er) PC.
*Not the Channel Battles Edition from Steam.
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