View Full Version : turns with 734
12-29-2001, 02:54 PM
1) making turns with the DF734 in FS2000 is no problem. As in the real aircraft, the plane banks to an appreciable angle (depending on how far the plane must turn) and banks back to normal at the end of the curve.
HOwever, in FS2002 the DF734 banks, say 5° (let's say we want to turn from 120 to 140°) then banks back to say 2°, then goes back again to 5° and so forth, which brings in a oscillation. The more narrow the turn is, the less pronounced is this misbehaviour.
Anyone has a solution to this?
2) I have a 800MHz, 521MB machine and have set the altitude capturing capability on "recommended" during the update installation of DF734.
Anyone knows, how to change this to "fast", withouth having to install the whole thing again?
You can change the altitude acquire setting on the FMC settings page (click right on FMC to bring up the menu). However, this setting has absolutely nothing to do with turns. I haven't seen this behavior at all with HDG SEL. Do you have FSUIPC 2.80 by chance?
Lee Hetherington (KBOS)
12-29-2001, 06:10 PM
LAST EDITED ON Dec-29-01 AT 06:11PM (EDT)[p]Hey Knueppelruehrer,
komischer Nick, was bedeutet das denn? :-eek
12-29-2001, 06:30 PM
You prpbably hit the bank limiter switch by mistake when selecting a heading in the MCP. If you look real close you will see two orange colored "handles". There are four hot spots around the heading select knob, the upper + - are for the heading select and the lower + - are for the bank limit. Click the hot spot to make the orange upper handle point to about 11:00 oclock and you should be in business..
12-29-2001, 07:58 PM
LAST EDITED ON Dec-29-01 AT 08:09PM (EDT)[p]I think he's referring to LNAV...as the aircraft closes in on a waypoint, it starts to make these little incremental turns. It's not as fluid as it could be. As he described...at first its a little bank of maybe 5 degrees, then it rocks back to 2, then to 5 again, and back to 2, then maybe to 10 degrees, then to 5...eventually, the waypoint is cycled and the aircraft enters a much steeper turn which is more stable. Part of this, I think is anticipation of the turn, the other is that as you close in upon a waypoint, small deviations become more pronounced more quickly...which is another reason I think the A/P becomes more "reactive" as you near waypoints.
HDG SEL w/ bank limiting can be a little "wobbly" too...I find this can be minimised by choosing a steeper bank angle (like 30). But if you have your bank selector set to 15, and make a 180 degree turn, for instance, the aircraft will bank to just shy of 20, and then settle back to 15. You can see this behavior most notably when looking out the wing view during a turn.
Part of this, "wobbling", I believe can be attributed to changing wind vectors relative to the nose of the plane as the aircraft changes direction. The relative velocity of the air moving over the wings is constantly changing during a turn. The "wobbling" is the autopilot trying to hold the desired course in these changing conditions - it could stand some refinement, yes, but on the whole LNAV tracks pretty well through turns. I think you'll find much of the wobbling is minimised in a "winds-zero" environment.
This implementation differs from other panels, like PIC and PSS which dynamically calculate the turn radius for a given airspeed, and then cycle to the next waypoint once the aircraft passes within that radius. At that point, the aircraft enters a full standard bank and levels off as it closes on the desired heading. This technique looks smoother to the eye, but it's less "granular" and "incremental" and subject to problems of its own. If you have a series of closely spaced waypoints with tight turns (the turn radii overlap each other - a good example of this is the PDZ4 arrival into LAX), because the autopilot is making large sweeping turns, it ends up over shooting and chasing waypoints in a slalom-like pattern.
12-30-2001, 06:42 AM
Knueppelruehrer ist oder war der Name einer kleinen Kneipe am Flughafen Merzbrueck (Aachen).
01-02-2002, 04:01 AM
I tried it, and haven't really figured out yet if it improves the alt capt situation, but thanx anyway.
01-02-2002, 04:03 AM
I know about this and have tried different settings, but it doesn't improve the situation. The oscillations don't get any better. I forgot to say, that this is only in VNAV mode, and not, when I use HDG mode.
01-02-2002, 04:07 AM
thanx, your description sounds pretty convincing. I hope DF improves this in another patch. It was so much better in FS2000. The real plane just doesn't do it and you get seasick after a while.
I agree, that VNAV get's you through the FMC's flight plan with no serious problems (except, when turns are too steep and the aircraft's speed is still fairly high, but then on the other hand, one can remove the new wpt easily and fly to the next one [which works pretty good on approaches with a large number of very close wpts.])
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