Jim Wilson wrote: > Not sure if this relates to the air pressure issue, seems to be a bit more > than that would account for. A few days ago someone reported unusual flap > effects, prior to the corrections to the YASim flight model.
It's a known bug. Curt found it a few months back. The fix is nontrivial, and I've been lazy. I'll see if I can get some time this week to work on it. > It appears that not only do the flaps not increase drag in the 747, but they > decrease it. Not exactly. Flaps do increase drag at the same AoA. But they also increase lift, which means that you need to hold a lower AoA to avoid climbing. The lower AoA produces less induced drag. Flaps need to increase the drag that *would* have been produced had the aircraft been flying without flaps at an AoA high enough to produce the same lift. It's that level of reverse-intuition that makes the solution hard to implement. > Under the right conditions, not observed in a > reproducable/reportable way (but generally lower airspeeds and > altitudes) the aircraft can speed up drastically and skyrocket into > the air at a rate over 10kfps. This seemed to be implied in a bug report last week, too (someone posted a screenshot at 140k MSL). I've never seen this effect. It's more worrisom, as it's clearly non-physical. Whatever forces are generated by the YASim flap handling, they should be some reasonable multiple (i.e. near 1.0) of the force generated without flaps. They should clearly *not* be this big. This isn't part of the bug I detail above, and points to a blowup condition somewhere else. Like I said, I've never seen it happen. If you could play around and see if you can get something pseudo-reproducible (even something like "do this, and it'll blow up one time in ten"), I'd be grateful. Andy -- Andrew J. Ross NextBus 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
