Tuesday, April 5, 2011
Most of the models in the Hangar use a "crash detect" system, which monitors height and g-load, and freezes the FDM when parameters are exceeded. Usually I set the limits to -1 foot and 9 g's. While adapting all the models to FG 2.2 standard lately, I noticed that many of them were failing to ground trim properly at start-up. The models flew fine thereafter, and you wouldn't have noticed this unless you routinely run FG with a console window open in order to observe the warning output. Thomas Kreitler discovered that the default FDM integration algorithm ("Trapezoidal") was causing this, and switching to another algorithm, "Adams Bashforth 2", fixed it. I'm now changing all crash detect system files to set "Adams Bashforth 2" as a default.