Well, a free
demo anyway. Off hand, I can't remember what restrictions there are, compared to the full payware version. No doubt you will find the answer on the RoF homepage somewhere.
It's one of those sims in which you need to put some effort, in order to gain the full benefit. Setting up the controls for example - you can have control settings that are common to all the aircraft, or you can have custom settings for some of them. So, you might find that one control set-up is good for both the Albatross and S.E.5a. but the Camel, with its rotary engine, needs settings of its own. Similarly, the large bombers, such as the HP 0-400 and the Gotha, require something else again. My recommendation is that you pick one aircraft, and experiment with the settings to get an idea of how they influence the handling. On top of that, some of the aircraft are tricky to fly anyway ( apparently, as they were in real life ) - be prepared for a lot of ground looping until you get used to them.
It is a beautiful sim - the best WW1 sim we could have hoped for, in my opinion.
