X-Plane is the world's most comprehensive and powerful flight simulator for personal computers. With the most realistic flight model available for home users, X-Plane is not just a game--it is an engineering tool that can be (and is) used to predict the flight characteristics of nearly any aircraft with incredible accuracy.
X-Plane works by reading in the geometric shape of any aircraft and then figuring out how that aircraft will fly. It does this by an engineering process called "blade element theory", which involves breaking the aircraft down into many small elements and then finding the forces on each little element many times per second. These forces are then converted into accelerations, which are then integrated to velocities and positions