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YASim: Difference between revisions
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(link to Gary Neely's guide to yasim) |
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YASim is one of three flight dynamics models commonly used by Flightgear. | |||
The flight dynamics model (FDM) determines how the aircraft moves and flies. | |||
Andy Neely wrote in his [http://ltts.crlt.indiana.edu/grn/flightgear/yasim_1.html introduction to YASim]: | |||
:The FDM is the mathematical model that controls the physics of flight within the simulator. The physical 3D aircraft model has nothing to do with flight dynamics-- in essence it's just a picture to look at. It's the FDM that dictates how the model flies. | |||
:Why YASim? YASim uses the geometry of the aircraft to generate the base flight characteristics. While this suggests a 'realistic' or out-of-the-box approach, it is a only rough approximation that will require much tweaking before you get a result that approaches realism. Contrast this with JSBSim which relies on pre-generated tabular data to build up the flight model. If you have solid flight data for your aircraft such as wind-tunnel data or you are looking to eventually generate a hyper-realistic simulation, JSBSim is probably a better approach. If you lack such data but know the geometry of the aircraft and have access to the same flight characteristics and limits as a real pilot would, then YASim can provide a solution that is more than sufficient for most simulation needs. | |||
'''Coordinate system notes:''' | '''Coordinate system notes:''' | ||
All positions specified are in metres (which is weird, since all other units in the file are English). The X axis points forward, Y is left, and Z is up. Take your right hand, and hold it like a gun. Your first and second fingers are the X and Y axes, and your upwards-pointing thumb is the Z. This is slightly different from the coordinate system used by [[JSBSim]]. Sorry. The origin can be placed anywhere, so long as you are consistent. I use the nose of the aircraft. | All positions specified are in metres (which is weird, since all other units in the file are English). The X axis points forward, Y is left, and Z is up. Take your right hand, and hold it like a gun. Your first and second fingers are the X and Y axes, and your upwards-pointing thumb is the Z. This is slightly different from the coordinate system used by [[JSBSim]]. Sorry. The origin can be placed anywhere, so long as you are consistent. I use the nose of the aircraft. | ||