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brdavies

Control movements

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Hi there, don't mean to be picky but are the control movements of the md11 suppose to be so twitchy? I find that the autopilot responses to pitch and roll are quite jerky at times and from the vc the control coloumn seems to be moving fast. Is this just how the sim is modelled or can this be adjusted in anyway? I would like the autopilot to respond more smoothly to commands. Does anyone else find this happens?Thanks Barrie

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I think you mentioned two different observations: One is the flight characteristics of the simulation and the second is the visual appearence in the VC cockpit of the moving yoke and throttles. On the first item, I do not notice any jerkiness or abruptness in autoflight. Regarding the second item, yes the yoke and throttle movement is artificial but that is more the fault of MSFS than the add-on aircraft. My understanding is that the autoflight code is external to the msfs platform but the inputs from the pmdg module to the msfs ends up being used by msfs to animate visual controls animation and yes, it is done in typical microsoft fashion that is optimized for a C-172.

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Yeah I'd love to know what these complaints are about as well - I've never noticed anything I'd call jerky in how the AP flies the plane.

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Yeah I'd love to know what these complaints are about as well - I've never noticed anything I'd call jerky in how the AP flies the plane.
I don't think jerky is the right word, but it can be quite "choppy". An example is a deceleration. If you're descending in IDLE CLAMP at 250kts, then select 220kts and pull the selector. The autopilot will make a rather abrupt pitch up. In the real aircraft this would definitely pull some noticeable G's and be a bit uncomfortable :-)Regards,Martin Neep

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The autopilot will make a rather abrupt pitch up. In the real aircraft this would definitely pull some noticeable G's and be a bit uncomfortable :-)
Agreed! I've noticed it both with pitch and heading changes. With heading changes the first 1/2 second is sometimes far to abrupt, as if the MD11 has no inertia/mass at all. Ive not noticed it so much with the 1.2 patch (but then ive not used it much yet) but before 1.2 I used to notice it quite often. Comparing to the LDS767, the 767 is very very smooth and gives a sense of mass. It's not a big criticism but when it happens i notice it. Surely others have noticed the same?

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I don't find the AP twitchy or jerky at all, I do find it very much faster to respond then the AP in most non PMDG aircraft but I think PMDG have it closest to real life. Try this simple experiment, dial in a 180 heading change and time how long the aircraft takes to complete it. If it takes 60 seconds, then it is a "standard turn", if it takes longer, then it is not realistic. I have heard it said that the MS AP (and most others) use trim to control the aircraft, but PMDG uses the primary flight controls just as the real aircraft would. This may also be why the stick moves so much in the VC.

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I don't think jerky is the right word, but it can be quite "choppy". An example is a deceleration. If you're descending in IDLE CLAMP at 250kts, then select 220kts and pull the selector. The autopilot will make a rather abrupt pitch up. In the real aircraft this would definitely pull some noticeable G's and be a bit uncomfortable :-)Regards,Martin Neep
Yes this is what I meant to say, it is also true of turns using the autopilot. Just wondered if anyone esle noticed it or not.Barrie

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Try this simple experiment, dial in a 180 heading change and time how long the aircraft takes to complete it. If it takes 60 seconds, then it is a "standard turn", if it takes longer, then it is not realistic.
I'm sorry, but this has nothing to do with A/P performance. The rate of turn is a function of bank angle vs airspeed. Granted, if the A/P were extreemly slow and took ages to roll to the required bank it would eventually have an effect, but that's not what we're talking about. We are referring to how many degrees of BANK or PITC the A/P achieves per second. I'd say when the aircraft pitches up to decelerate it can be as high as 5deg/sec, but it does seem to tail off.RegardsMartin Neep

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I'm sorry, but this has nothing to do with A/P performance. The rate of turn is a function of bank angle vs airspeed. Granted, if the A/P were extreemly slow and took ages to roll to the required bank it would eventually have an effect, but that's not what we're talking about. We are referring to how many degrees of BANK or PITC the A/P achieves per second. I'd say when the aircraft pitches up to decelerate it can be as high as 5deg/sec, but it does seem to tail off.RegardsMartin Neep
A Standard turn is three degrees a second, if the AP takes longer then a second to bank to turn three degrees, then either it is not doing a standard turn (which makes it useless) or it has to do some seriously fancy maths to compensate for the roll in/roll out times. Since, as you correctly pointed out, the turn rate is a function of bank angle and airspeed, at higher speeds, the AP must command higher bank angles, and they must be acheived quickly. These can easily (and comfortably) mean roll rates of 15 to 20 degress a second without any passenger discomfort. Pilot commanded roll rates in excess of 60 degrees a second are not unknown in avoidence situations.

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A Standard turn is three degrees a second, if the AP takes longer then a second to bank to turn three degrees, then either it is not doing a standard turn (which makes it useless) or it has to do some seriously fancy maths to compensate for the roll in/roll out times.
I would be seriously concerned if a "heavy" was rolling 25/30 deg of bank in 1 sec! The time taken for the aircraft to transition from a steady heading, to an xxx rate turn, is largely irrelevant, because this is factored into the programming of the autopilot. It could take the autopilot 10 sec to reach the required amount of bank (not that this is normal), but as long as the roll is initiated earlier, the aircraft can still roll out on track.This is all totally irrelevant to this sim, because in my opinion the roll rates of the MD11X are pretty close to normal. It's the pitch that can sometimes be rather abrupt.

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