GWMobile wrote: >What about changing the aerodynamic computation so they take place based >on radius from the earth and at what would be sea level change the air >density to that of water. >Then any object below sealevel "flys under those equations. It would >allow for surface ships and submarines. > >And load in the whole terrain map of the world including all >bathespheric data > > >
I'd considered this, but I don't have the knowledge of hydraulics necessary to try and "parameterise" a ship's behaviour to suit (say) jsbsim. I think we'd need to spend some time running model hulls through water tanks or flumes if we were ever to gain that sort of data, and that means waiting until some Ph.D ship design students fancy getting into the project! I'm thinking more modestly for now, i.e take Peter Davis's "surprise" FDM as a starting point. It doesn't handle any of the flotation aspects of a ship - just assumes the ship is at water level (which is OK until you want to try handling behaviour in waves). Davis's sim basically deals with thrust on sails up masts at various heights with yardarms set at given angles. Oh, and a rudder of course. It does consider heeling though, and in a true "FDM" for a ship I believe a heeled-over hull (as long as it is moving) is a significant contribution to being able to steer the thing. I've not dug in deep enough to see if Davis deals with heeling effects using real data or just fudge-factors. Either way, I think it'll be OK for a starter. FG's world model doesn't even need bathymetric data to start with. Basically you could get away with "if (ship within 50m of land) then you've run aground;" as a starting point. Worry about bathymetrics *after* getting the rest of it to work. But you're right about submarines of course. They do fly in the water. Boats are the special case. Steve. _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
