Re: [Flightgear-devel] Presets menu
Curtis L. Olson wrote: BTW, Andy, how hard would it be to accept an initial airspeed for the YASim models so we can do in-air starts with those? Not hard at all. The only reason it doesn't is that, heh, I got really confused about how to figure out the units and precedence rules. Speed can be set in about a zillion ways (roll/pitch/heading vs. x/y/z vs. north/east/down coordinates, IAS, TAS, knots, m/s, mach, etc...), and it seemed like the FDM is responsible for figuring out what goes where. If you can point me at a property to read for an authoritative velocity source, I'm there. :) A slightly harder problem is getting the aircraft trimmed for the selected environment. A really annoying property of most (all?) sims is that they start you out at the right point, but way out of trim and you wreck the setup trying to get stabilized. I can probably canibalize some of the solver code for that. Andy -- Andrew J. RossNextBus Information Systems Senior Software Engineer Emeryville, CA [EMAIL PROTECTED] http://www.nextbus.com Men go crazy in conflagrations. They only get better one by one. - Sting (misquoted) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
re: [Flightgear-devel] Presets menu
Curtis L. Olson writes: BTW, Andy, how hard would it be to accept an initial airspeed for the YASim models so we can do in-air starts with those? Andy's concern has been the obfuscation around velocities. We have - calibrated airspeed in knots (forward from the nose of the plane) - mach number (ditto) - UVW wind/body speeds (u/v/w) - NED speeds The NED *should* be the ones we save and restore, since they are the only independent ones (we don't have to set the orientation first); however, because of problems with LaRCsim, we had to make UVW canonical quite a while back. It would be nice to fix that and make NED canonical first, then twist Andy's arm until he supports them in YASim. There's also more to the problem. If we're restoring a saved flight then everything's fine, since all of the FDM state is already valid. If, on the other hand, we're starting in the air, then we need a general trimming routine like the one Tony wrote for JSBSim and LaRCsim to avoid violent oscillations at startup. All the best, David -- David Megginson, [EMAIL PROTECTED], http://www.megginson.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Presets menu
On Mon, 2002-11-18 at 14:17, Andy Ross wrote: Curtis L. Olson wrote: BTW, Andy, how hard would it be to accept an initial airspeed for the YASim models so we can do in-air starts with those? Not hard at all. The only reason it doesn't is that, heh, I got really confused about how to figure out the units and precedence rules. Speed can be set in about a zillion ways (roll/pitch/heading vs. x/y/z vs. north/east/down coordinates, IAS, TAS, knots, m/s, mach, etc...), and it seemed like the FDM is responsible for figuring out what goes where. If you can point me at a property to read for an authoritative velocity source, I'm there. :) A slightly harder problem is getting the aircraft trimmed for the selected environment. A really annoying property of most (all?) sims Almost all professional sims have a trimming routine. They are not only useful for the instructor, but also very helpful when using a motion base and control loaders. is that they start you out at the right point, but way out of trim and you wreck the setup trying to get stabilized. I can probably canibalize some of the solver code for that. It is not a terribly hard problem to solve, but does require some patience in discovering and covering most situations. Andy -- Tony Peden [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
re: [Flightgear-devel] Presets menu
On Mon, 2002-11-18 at 14:41, David Megginson wrote: Curtis L. Olson writes: BTW, Andy, how hard would it be to accept an initial airspeed for the YASim models so we can do in-air starts with those? Andy's concern has been the obfuscation around velocities. We have - calibrated airspeed in knots (forward from the nose of the plane) - mach number (ditto) - UVW wind/body speeds (u/v/w) - NED speeds The NED *should* be the ones we save and restore, since they are the only independent ones (we don't have to set the orientation first); however, because of problems with LaRCsim, we had to make UVW canonical quite a while back. It would be nice to fix that and make NED canonical first, then twist Andy's arm until he supports them in YASim. There's also more to the problem. If we're restoring a saved flight then everything's fine, since all of the FDM state is already valid. If, on the other hand, we're starting in the air, then we need a general trimming routine like the one Tony wrote for JSBSim and LaRCsim to avoid violent oscillations at startup. For the record, I did not write a trimming routine for LaRCsim. All the best, David -- Tony Peden [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Presets menu
* [EMAIL PROTECTED] (Curtis L. Olson) [2002.11.18 15:47]: I created a /sim/presets area in the property manager which is where all the FDM initial conditions can be batched up. Things like: snip/ runway (i.e. 1R) snip/ Woohoo! That's been on my wishlist[1] from when I first started using FG. Nice work, Curt. [1] http://unbeatenpath.net/software/fgfs/Wishlist.html -- Cameron Moore / Just think how much deeper the ocean \ \ would be if sponges didn't live there / ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
