On Tue, 2 Jan 2007, Maik Justus wrote: >> So what's your plan here? Add optional /external/ control of a thruster? >> > Adding a hinch objects to YASim, which can be connected to a tow. The > other end of the tow can be connected to a fixed position or an > AI/MP-Object. The length of the tow can be modified (-> winch).
There may be problems with sampling interference here: In an equilibrium, the force is the same at both ends of the wire. (we will never reach an equilibrium) If one aircraft accelrates/turns (which they will, of course) there will be a change in force which (irl) will travel along the wire with a certain speed (speed of sound for the material, I'd guess, for pure longitudinal forces along the wire anyway), and so on back and forth. The wire must have a property analoguos to the concept of "impedance" in electronic engineering. Then there will be an eternal recalculating of force at each end, which travels over the wire to the other, added to the fdm calculation there and the new force vector value is sent back out on the wire and added to the wire's own force calculations before it reaches the other aircraft/cargo model, etc etc Now, the time it takes for a wave to traverse along the wire to the other end may be shorter than can be modelled even with the 120Hz default fdm frame rate and, quite likely, shorter than the sampling rate in the current MP-server system (10Hz?). We may run into a "jitter" similar to the notorious gear jitter... Or forced to use wires that are unrealistically "rubbery". ... > Yes, but we need a cargo-fdm. Any fdm engine that can take an external force into account can be used for modelling cargo. (Could even use existing models: a ch53 can easily airlift a bo105 or a light winged aircraft) A standard box-shaped shipping container, a big log, or a section of a power line tower etc are all just "aircrafts" with really lousy L/D ratios and no engines (on). > Yes. But if it is released by one aircraft, the tow will be ignored by > the other aircraft. Anyway, my point was that the towing wire shouldn't be viewed as a simple submodel of either the towed or the towing model since the towing wire can be released at either end first, and then produce drag/weight force on only the remaining aircraft, whichever model ends up with the wire. (The drag from the line can be substantial. The woing lines they use for aerotowing hang gliders with trikes, are even fit with a drag parachute to prevent the line from snapping into the trike's propeller on release, or if the rear weak link snaps.) > Do you know, if this is already possible in Flightgear? Well what do I know? ;) But it seems to me this is really an issue of architecture of all FG, perhaps more so more than fdm engine design. > Yes, you can add a thruster and YASim can simulate glieders as it is. > But with a very small patch (adding a glide angle to approach and > cruise) you don't need the thruster fake any longer. Alright, same thing but more convenient. ;) (That's what we have computers for: computing tedious calculations that we'd rather not be doing ourselves.) ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
