Andy Ross <[EMAIL PROTECTED]> said: > > This will give you too much power at takeoff, as YASim doesn't yet > implement an engine governor. But the performance at altitude might > match what you want to see more closely. Try it out and see how it > feels. > Actually I tried all the way up to 80,000lbs and still ran into problems in the 25000ft range. There is a little uncertaintly in just what I'm observing. Basically there is a steady decrease in attainable airspeed.
IIRC the "required thrust" should fall off as well, resulting fairly good performance all the way up to 35,000 to 40,000ftASL with performance gradually decreasing up to max altitude. It could be the lift or it could be the drag, not sure, but something definately isn't right. With my most recent tests I'm kind of thinking the drag is too much at higher altitudes, because even with the nose pitched down I'm not able to recover much airspeed at full throttle. On the other hand it could be lift. A possible clue: when I'm having trouble the "mach" reading seems to be way too high as compared to the KAIS reading just above. Examples: @ 19000ft 419KIAS MACH=0.91 @ 23000ft 344KIAS MACH=0.83 Both of these examples are at full throttle and cruise attitude...just as an indicator of how bad the problem is. With time the max speed at 23000 falls to 327KIAS and then stays there. BTW folks can test this quickly by starting up flightgear with 747-yasim, KSFO. Hit the throttle full. Set Autopilot altitude to 19000. After reaching 50ft altitude hit CTRL+H to lock the heading. Hit "g" to retract the gear. Hit "a" four times to speed up time. You should be at 19000ft in about 2.5 minutes. Best, Jim _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
