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Calibration Curve only half the range


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I'm trying to make my throttle calibration a simple S-curve. When I use the scrollbar to manipulate the "response curve" up or down, it only affects half the range. The range It is only the top half of the S, if you will. I do not have the same problem when setting curves for prop pitch or mixture. The range of each throttle has been correctly calibrated from approximately -16800 to +16000, and I double checked it, so there should be nothing limiting the range of the S curve from 0 to 16000. This has been something happening for years, but I never had the need to resolve it until now.

Here is a screenshot:

post-16620-0-10355800-1294608256_thumb.j

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I'm trying to make my throttle calibration a simple S-curve. When I use the scrollbar to manipulate the "response curve" up or down, it only affects half the range. The range It is only the top half of the S, if you will. I do not have the same problem when setting curves for prop pitch or mixture. The range of each throttle has been correctly calibrated from approximately -16800 to +16000, and I double checked it, so there should be nothing limiting the range of the S curve from 0 to 16000. This has been something happening for years, but I never had the need to resolve it until now.

The calibration for the separate throttles only affects forward thrust (0 to 16k OUT values), not the reverse, which is therefore left linear. This is because the actual useful reverse zone varies from aircraft to aircraft (eg -4096 to 0). The graphic for the slope merely reflects this, and it isn't regenerated just because you adopt the NRZ (No Reverse Zone) option -- all that does is spread your -16k - +16k over the 0 to 16k area, following the selected upper part of the slope.

Regards

Pete

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The calibration for the separate throttles only affects forward thrust (0 to 16k OUT values), not the reverse, which is therefore left linear. This is because the actual useful reverse zone varies from aircraft to aircraft (eg -4096 to 0). The graphic for the slope merely reflects this, and it isn't regenerated just because you adopt the NRZ (No Reverse Zone) option -- all that does is spread your -16k - +16k over the 0 to 16k area, following the selected upper part of the slope.

Regards

Pete

Thanks for the explanation. I didn't know that, and its been bugging me for literally years! It is only on this plane, the Stratocruiser, that I have such problems with Calibration. Throttle sync points don't seem to work very well for this plane and actually lead to a lot of jitteriness

Now, the dumb questions:

1)An S-curve throttle profile is not supported then, right? I want my throttles to be less sensitive at both ends of the range, high and low, but "normal" at the center of the range. Right now, things are great when I'm close to max throttles, but way too sensitive down near the idle range. I'll keep fooling around with it, to try and find the perfect compromise, but any advice would be appreciated.

2)No way to start with a Curve, and then additionally add throttle sync points?

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1)An S-curve throttle profile is not supported then, right?

Correct. The flat part of the "S" should be around idle, right? Obviously, then, it couldn't be an "S" for an NRZ option in any case, as the idle point is then at one end. With a reverse zone it's a sort of S curve but with the reverse part kept linear because of its limited and variable range.

2)No way to start with a Curve, and then additionally add throttle sync points?

Sync points are used to match positions on separate Throttles 2, 3 and 4 to whatever you calibrate for throttle 1. So do on throttle 1 whatever you need then use the sync point facilities to make the others match.

Regards

Pete

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Correct. The flat part of the "S" should be around idle, right? Obviously, then, it couldn't be an "S" for an NRZ option in any case, as the idle point is then at one end. With a reverse zone it's a sort of S curve but with the reverse part kept linear because of its limited and variable range.

Sync points are used to match positions on separate Throttles 2, 3 and 4 to whatever you calibrate for throttle 1. So do on throttle 1 whatever you need then use the sync point facilities to make the others match.

Regards

Pete

I tried what you suggested: I set a slight curve on throttle #1 and then did 4 or 5 sync points. Unfortunately, throttles 2 through 4 reverted back to a more or less straight line, with some slight deviations for the sync points. Basically throttle 1 retained the curve, and it looks like the other 3 sychronized with the raw values of throttle 1, and not the ones modified by the curve. So that doesn't look like its going to work for this situation. I'll keep trying to get these calibrated, and like I said, I only have these types of problems on this one aircraft. Thanks for your help.

EDIT: In future releases would it be possible for you to include an option to turn up the gain on your Filter. I know from a previous post that the only reason you put the filter in there was to compensate for fluctuating voltages in the third world. I don't have that problem here :rolleyes: but I'm probably not the only person that has crappy throttle quadrants and/or dirty potentiometers, and as a result get an alarming amount of spikes. :cry:

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I tried what you suggested: I set a slight curve on throttle #1 and then did 4 or 5 sync points. Unfortunately, throttles 2 through 4 reverted back to a more or less straight line, with some slight deviations for the sync points. Basically throttle 1 retained the curve, and it looks like the other 3 sychronized with the raw values of throttle 1, and not the ones modified by the curve.

Yes, the sync points give it different points to aim at. To transform the curve (which is also only a set of points) to match any randomly chosen sey of sync points would require a level of maths that UI am not really wanting to either delve into nor have FSUIPC spend tits time doing. Linear interpolation is fast and easy. But you can have more than -- up to 63, which is not so far from the true resolution of most joysticks that you cannot make it follow the curve quite closely. The documentation recommends AT LEAST 4 points, not "only 4 points".

The documentation also points out that the slope doesn't apply -- the up-to-63 points you define replace that slope, and you can see it by pressing the Slope button. Please do check things like documentation when you have such questions. Things are often answered there.

In future releases would it be possible for you to include an option to turn up the gain on your Filter. I know from a previous post that the only reason you put the filter in there was to compensate for fluctuating voltages in the third world. I don't have that problem here :rolleyes: but I'm probably not the only person that has crappy throttle quadrants and/or dirty potentiometers, and as a result get an alarming amount of spikes. :cry:

I've tried all sorts of values for the filter, and to make it more effective it needs to sample a lot more values which introduces too much latency, in turn making it difficult to control the aircraft. Kind of like trying to fly with a display frame rate of 2 or 3 fps or so. Maybe there are better formulae around, but I did a lot of research and came up with the only one which was at least reasonably effective without toonoticeable a latency.

Good potentiometers are cheap enough, even slide ones. Why not replace the ones in your quadrant? Or at least try to give them a clean with some electrical cleaning spray like Servisol. If find it does the world of good!

Regards

Pete

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  • 1 year later...

Hi Pete,

This is a kind of follow on to the above, as I was having the same queries relating to the PMDG B747-400X. I am finding the raw throttle response in the model different to real life (yes, I did, for many years!). In aircraft terms, when at 'flight idle' the response of the engines to commanded thrust was slow, then when the EPR gauges showed above about 1.08 the thrust response to lever movement noticeably quickened. In the model the raw response remains very slow until above an indicated EPR of about 1.30, when it then becomes more realistic. Is there any way I can slew the response graph to replicate the real-world? As per quarterback85 the graph only adjusting in the upper half is throwing me slightly.

regards,

John

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the graph only adjusting in the upper half is throwing me slightly.

If you mean the FSUIPC "slopes" graph, ignore that part of the graph it isn't relevant to throttles. It relates to things like ailerons, elevators and rudders, and the lower half then is always a mirror image of the upper. That makes no sense for throttles hence the lack of effect in the unused half. I can't see why that should upset you.

Pete

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:huh: Not upset, but it made me think the problem I'm trying to solve might be being caused by the unexpected shape to the response curve. Now, I don't think it is.

Actually, I think the problem I have is with the PMDG modelled response time to initial thrust lever movement from idle, not the thrust lever movement to movement reponse. In the real world, as I'm sure you know ( :mrgreen:), with bigger and bigger jet engines, when they are at flight idle, they take longer and longer to respond to thrust lever movement, than when they are moved within their mid and upper ranges. The PMDG B747-400X takes even longer than the real aeroplane and I was trying to find a way to compensate for this using the response curve adjustment within FSUIPC4. I now believe this is not possible, as, no matter how responsive I make the response curve, the engine modelling will still only allow a set rate of acceleration.

Do you see where I'm coming from? I don't think I explained it very well previously.

Cheers,

John

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Actually, I think the problem I have is with the PMDG modelled response time to initial thrust lever movement from idle, not the thrust lever movement to movement reponse. In the real world, as I'm sure you know ( :mrgreen:), with bigger and bigger jet engines, when they are at flight idle, they take longer and longer to respond to thrust lever movement, than when they are moved within their mid and upper ranges.

Well, no, I don't really know about such things. But if that is so I would expect that to be taken care of in the aircraft modelling, not by fiddling the input.

The PMDG B747-400X takes even longer than the real aeroplane

Really? It's most unlike PMDG to make such mistakes, and they certainly boasted that it was all checked by their own frienly 747 captain. I assume you are one too? Have you told PMDG about this? They are usually very careful about getting things just right.

Regards

Pete

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Yup, 'fraid so! Retired now so FSX, PMDG and FSUIPC4 connects me to my youth.

Yes, I should take it up with PMDG. It might just be the modelling of the RR524 engine. When taxying RW you could use the EPR gauge, but you have to use the N1 readings in the PMDG B744. Maybe it is my memory playing tricks, but it does seem slow to build thrust from 'ground' idle setting.

I shall talk to them as I know they are very approachable. I shall report back!

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