Using local air density, X-Plane determines the propwash required for momentum to be conserved.ĭownwash is found by looking at the aspect ratio, taper ratio, and sweep of the wing, and the horizontal and vertical distance of the “washed surface” (normally the horizontal stabilizer) from the “washing surface” (normally the wing), and then going to an empirical look-up table to get the degrees of downwash generated per coefficient of lift. Propwash is found by looking at the area of each propeller disk, and the thrust of each propeller. Downwash, propwash, and induced angle of attack from lift-augmentation devices are all considered when finding the velocity vector of each element. The aircraft linear and angular velocities, along with the longitudinal, lateral, and vertical arms of each element are considered to find the velocity vector of each element. Ten elements per side per wing or stabilizer is the maximum, and studies have shown that this provides roll rates and accelerations that are very close to the values that would be found with a much larger number of elements. ![]() The number of elements is decided by the user in Plane-Maker. Element Break-Downĭone only once during initialization, X-Plane breaks the wing(s), horizontal stabilizer, vertical stabilizer(s), and propeller(s) (if equipped) down into a finite number of elements. X-Plane goes through the following steps to propagate the flight: 1. ![]() These forces are then converted into accelerations, which are then integrated to velocities and positions… Of course, all of this technical theory is completely transparent to the end user… you just fly! It’s fun! 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. X-Plane works by reading in the geometric shape of any aircraft and then figuring out how that aircraft will fly.
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