On Saturday 19 July 2003 05:21, Jim Wilson wrote: > Lee Elliott <[EMAIL PROTECTED]> said: > > > With the YF-23 it's > > very obvious. > > Hi Lee, > > In a separate message I've sent a patch to backout the target climb rate fix. > I was able to stabalize the A/P by making adjustments with the fix, but the > target climb rate couldn't be over 5000fpm (the YF23 is set for 20000). That > fix could be improved but it's going back the way it was for now, since that > was working with the YF23 and it might be a few days before I get to it again. > > In the meanwhile here are some other adjustments that will make the A/P work > more precisely and smoothly on the YF23 if you want to add them: > > integral-contribution = 0.008 (it was 0.005). > > By increasing this slightly the altitude hold will zero on the target. I > found it was staying a little above selected altitude. > > > zero-pitch-throttle = 0.25 (it was default). > > This setting is a rough estimation of the throttle speed at which the aircraft > is no longer pitched up by the thrust of the engine. > > > zero-pitch-trim-full-throttle = 0.2265 (it was default). > > This setting is a rough estimation of the amount of trim required to maintain > level flight at full throttle (not that you would). > > The zero pitch settings are helpful in keeping the autopilot from fighting the > tendency of the aircraft to pitch up or down. I usually estimate them by > trimming the aircraft at full throttle and then slowly backing off the > throttle and retrimming the aircraft as it slows down. These effects vary > according to altitude as well, but having something in there seems to help it > zero in to target at a variety of throttle settings. > > Best, > > Jim
Thanks for having a look and the info on what those properties do. I'll be able to customise those now instead of using the defaults. The climb rate of 20000fpm is pretty arbitrary but is going to be within reasonable bounds for that a/c. It's important to note that that climb rate is at an airspeed of 900 kts so it's a lot less at more typical speeds. Having said that 5000fpm is going to be on the low side for most mil jets - even the B-52 is supposed to achieve 6000fpm (mine can't yet though;) I'll hold off backing the patch out for a while until you've had a chance to have another look at the code. If you're fixing something that isn't right then I'd sooner put effort in making the a/c work with the fixed solution than with an older incorrect solution. Could youi give me a quick nod when there's a new vers to try? LeeE _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
