erratic throttle pmdg 747

[denver]

I have searched extensively on the pmdg and this forum and no one seems to have an answer to this.

On the pmdg 747 I have my CH throttle left lever assigned to throttle 1 and 4 and middle lever assigned to throttle 2 and 3 and right lever assigned to reverse on all 4 engines via FSUIPC. During manual throttle operation the levers move smoothly however during autothrottle operation the throttles go crazy back and forth not only instantainiously but way out of range like they are having a seizure together. This has no effect on the engines wich are compensating normally for turbulence, all indications on the EICAS are normal. My hunch is that it has to do with the way i have set up my throttles in FSUIPC. It seems that when the AFDS compensates in turbulence for speed in speed mode the acual throttle movement is smooth (as shown on the EICAS) and real but the signal sent to the visual throttle models in VC instantly jerk to a very low setting and in underspeed they instantly jerk to a very high setting. This is visually disturbing to me because I allways fly in VC.

- the level D 767 and PIC 737 throttles behave smoothly

Could it be a 4 engine thing the way I have my CH levers set up?

[Pete Dowson]

... during autothrottle operation the throttles go crazy back and forth not only instantainiously but way out of range like they are having a seizure together. This has no effect on the engines wich are compensating normally for turbulence, all indications on the EICAS are normal. My hunch is that it has to do with the way i have set up my throttles in FSUIPC.

Well, I can't see why. Such behaviour is normally down to jitter in the actual throttle axes. Provided there are no changes seen on the joystick axes, nothing from them is ever sent to FS. (This applies always, no matter whether you use FSUIPC or not).

Normally, for all aircraft and all versions of FS, whether FSUIPC is used or not, when in auto-throttle modes you need to ensure that the actual throttle axis values aren't interfering. Unless you have absolutely clean non-jittery axes (very rare) this is normally achieved by parking the levers at idle or max settings, where you will, of course, have calibrated a reliable dead zone which therefore will not jitter.

One procedure that works well is to move the levers to max when engaging the A/T on climb, and remember to pull them back to idle some time during cruise, when or before you start descent.

- the level D 767 and PIC 737 throttles behave smoothly

Well, if it is only related to the PMDG aircraft I really have no idea what could be causing it, as jitter should affect all. Of course, it depends how the auto-throttle is actually managed in the particular aircraft. What about the default 737, for instance? And did you try inducing some real "jitter" (move the throttle levers up and down in the Level D and PIC modela with A/T engaged.

Could it be a 4 engine thing the way I have my CH levers set up?

Don't see why. Sorry. How exactly have ot assigned them in any case? You said:

I have my CH throttle left lever assigned to throttle 1 and 4 and middle lever assigned to throttle 2 and 3

but you don't say how. That is a rather unusual choice for 2 to 4 engine mappingyou get no asymmetric thrust facilities, for use when flying with an engine out or for steering assistance when taxiing. The normal mapping would be left (1+2) and right (3+4).

Regards

Pete

[denver]

"I have my CH throttle left lever assigned to throttle 1 and 4 and middle lever assigned to throttle 2 and 3"

If I program (like I would like) as you sugested then for some reason when I move the left throttle on the yoke throttles 1 and 2 move like they should but when i move the middle throttle it moves throttles 2,3 and 4. Not shure what i am doing wrong here but when I map them as they are they work fine. I thought that might have been the problem origionally.

"Normally, for all aircraft and all versions of FS, whether FSUIPC is used or not, when in auto-throttle modes you need to ensure that the actual throttle axis values aren't interfering. Unless you have absolutely clean non-jittery axes (very rare) this is normally achieved by parking the levers at idle or max settings, where you will, of course, have calibrated a reliable dead zone which therefore will not jitter."

After AT engages I do move the throttles to full but this makes no difference.

I will try programming a null zone at max via FSUIPC.

By the way that was the fastest reply I have ever gotten. Thanx!

[Pete Dowson]

If I program (like I would like) as you sugested then for some reason when I move the left throttle on the yoke throttles 1 and 2 move like they should but when i move the middle throttle it moves throttles 2,3 and 4. Not shure what i am doing wrong here but when I map them as they are they work fine.

But, I ask again, HOW are you mapping them so? not by FSUIPC at all I think. FSUIPC provides options for 1+2 and 3+4 from 2 throttles.

After AT engages I do move the throttles to full but this makes no difference.

Ah, but have you got a calibrated "dead" zone there at all?

Sorry, but I'm really not in the picture here -- what are you using FSUIPC for in this, and if not in FSUIPC where are you doing these assignments and mapping? Are you trying to use the CH manager program -- if so I think there is a better place for you to go to get help:

http://www.ch-hangar.com

Regards

Pete

[denver]

I reconfigured 1/2 for left and 3/4 for right and it works (through FSUIPC as allways), I figured out I had to delete the assignments in FS for it to work correctly. All my controlls are through FS exept throttles and reverse (through mixture lever) and a few buttons on the yoke. I dont beleive this is a dead zone issue because in one of the PMDG options there is an option to ignore the throttle position on the joystick when AT engaged, which I have unchecked (set to ignore throttle position). Now when I go into joytsick axis calibration page on page three "throttle axis" there seems to be a dead zone in there at full already i.e. just before the throttle gets to full I get to the max full calibration # +16??? forget what it is, I can then move the throttles the remainder of the way and nothing changes so I think that would be the dead zone at full.

I am not using the CH software because I got the yoke second hand w/o the disk.

On interesting thing that may help you is when I am in the VC and move the throttles foreward manually, just before the joystick throttles get to full the airplane throttles get to full and then as I advance the joystick throttles all the way foreward the 747's throttles bump back from full slightly. No matter how much I recalibrate through FSUIPC this happens.

Thanx

[Pete Dowson]

I reconfigured 1/2 for left and 3/4 for right and it works (through FSUIPC as allways), I figured out I had to delete the assignments in FS for it to work correctly.

Er .. only if you are assigning the axes themselves in FSUIPC. That is clearly documented. The joystick calibrations section can deal with FS or FSUIPC assignments -- the mapping of 2 to 4 throttles is on the 4 throttles calibration page.

I'm sorry, but your replies are leading to more and more confusion. What are you using and where? Have you calibrated at all in FSUIPC?

I dont beleive this is a dead zone issue because in one of the PMDG options there is an option to ignore the throttle position on the joystick when AT engaged, which I have unchecked (set to ignore throttle position).

In that case it won't be anything to do with the joystick at all, as that will be ignored -- unless of course that PMDG option only ignores the normal "one for all" throttle assignment, and not the individual ones. Also, there are two sets of individual assignments -- the "THROTTLEn SET" ones, which include a reverse zone, and the newer "AXIS_THROTTLEn_SET" ones, which don't. There's an option on the FSUIPC 4 throttles calibration page to avoid interfering with one set -- did you try it?

Now when I go into joytsick axis calibration page on page three "throttle axis" there seems to be a dead zone in there at full already i.e. just before the throttle gets to full I get to the max full calibration # +16???

If the IN value carries on rising whilst the OUT value stops at 16383 or 16384, then there is a max dead zone, yes. But surely you'd know this because you yourself would have set it during calibration?

On interesting thing that may help you is when I am in the VC and move the throttles foreward manually, just before the joystick throttles get to full the airplane throttles get to full and then as I advance the joystick throttles all the way foreward the 747's throttles bump back from full slightly. No matter how much I recalibrate through FSUIPC this happens.

Ignore the VC, look only at the main quadrant graphic in the 2D panel. I don't believe half of the VC graphics. And for more accuracy, seeing exactly what is going on, compare the changes in IN values in relation to the OUT values, in FSUIPC, as you move the lever.

Regards

Pete