On Saturday 08 December 2001 2:38 pm, you wrote: > David Findlay wrote: > > Curt Olson wrote: > > > So for instance if you want to try Andy's YASim 747 model, and check > > > out his alternate (blade element-ish) approach to modeling the flight > > > dynamics > > > > So what exactly does blade element-ish mean? Is this sorta like a > > realtime > > > digital wind tunnel sorta thing? Thanks, > > Sorta. Blade element is a term from propeller theory, but the basic > idea is the same. The airframe is broken up into a bunch of "surface" > objects, each of which gets an independant force calculation. Since > they're at different positions, they will have different velocities > due to aircraft rotation or orientation. So you get some cool stuff > "for free" as it were: asymmetric stalls, where one wing stalls before > the other and puts the aircraft into a nasty orientation or spin(-like > state); or adverse yaw -- crank the ailerons hard to one side and the > aircraft will yaw to oppose the turn due to the extra drag on the > upward-moving airleron. > > Eventually (hopefully soon), this will be extended to support > turbulence and wash effects at each surface. There are some > performance worries there, though, since if each surface depends on > the wash effects of all the others you go from O(N) to O(N^2) in the > number of surfaces. I think it'll work, but might require some > surgery. > > Actually, the coolest feature of YASim (well, the one I'm most proud > of) isn't the low-level simulation mechanism. It's the high level > performance matcher/solver. In a YASim configuration file, you simply > ask for "a plane that weighs so much, cruises at this speed, has this > big an engine and has an approach speed of XXX knots at NN degrees > AoA" -- and that's what you get. This radically reduces the amount of > "tweaking" that needs to be done. Climb rates tend to be right about > where they should be, etc... There's still lots of tweaking (or can > be -- I haven't really tuned the existing models much), but you start > out with a working aircraft from the very beginning. > > Andy
http://www.risingup.com/planespecs/info/ This site would come in handy then, if you haven't seen it yet TTYL J _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
