On Tuesday 23 March 2004 02:40, Jim Wilson wrote: > David Culp said: > > > On the surface it sounds like Andy is right. But maybe I don't > > > understand the objective. > > > > > > Would this do things like implement auto land mode? How would that > > > work? > > > > Here's one example. When you engage "level-change" the autothrottles go > > into "n1-hold" mode to hold climb power or idle, depending on whether you > > are climbing or descending. The pitch mode is then set to > > "speed-hold-with-pitch". When you are within a certain distance from the > > target altitude, the pitch mode changes to "capture-altitude-with-pitch", > > and the autothrottle mode changes to "speed-hold" or "mach-hold" > > (depending on altitude). > > > > So there are several things to be kept track of here. The autoflight > > system needs to know whether it's within capture distance of an altitude > > so it can automatically switch the pitch and autothrottle modes. It also > > has to switch automatically between airspeed and mach at about FL260. > > Also, it needs to clamp the target pitch differently depending on whether > > you are climbing or descending. And it needs to handle the case where > > the autothrottle is off, since the autopilot and autothrottle are > > separate systems. > > > > Other things the autoflight system does is handle takeoff/go-around > > modes, calculate climb N1 as a function of altitude, transition between > > one roll mode, such as heading-select and another, like localizer mode. > > In this case the heading-select mode is engaged while the localizer mode > > is armed; when the localizer is captured then the active roll mode > > becomes localizer mode. > > > > And then there's autoland, which is an automatic switch from approach > > mode (a combined roll/pitch mode) to a pitch mode of > > radio-altitude-capture, and an autothrottle mode of n1-hold (target = > > idle). > > > > If all this, and more, can be done with nasal then that's great. > > Ah ok, this is what I was hoping you were talking about :-) A lot of this > sounds familiar from things I've read online, but it's very difficult for > someone who's never been in a boeing cockpit to grasp the details. Yeah > I'd tend to say it would be a bad idea to do something this complex in > nasal, even if it could be done. It is a lot more than a few short scripts > worth. > > Would it be possible to do a "semi-generic" Boeing autoflight system that > could be configured for various models using xml? I'm not sure what these > parameters would be, but it seems like there must be variation between > models. > > Best, > > Jim
Oh yes - there's considerable variation, not just between different a/c but between different weights. I've been spending quite a bit of time trying to auto-land the AN-225 but with landing weights between 1,200,000 and 600,000lbs I'm not really anywhere near solving it yet. LeeE _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
