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aceridgey

Still Trim issues with Sp1b

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It is best if you stick exactly to my instructions (post 141) .......to make sure we are comparing the exact same things!

 

I just tried the experiment (post 141), trying to do it as exactly by the instructions as I could, and my results are that the yoke effectiveness decreases in both situations (FBW trim speed extreme above AND below actual speed).

 

Very very strange indeed that your system is doing something completely different!


Henrik Denerin

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I just tried the experiment (post 141), trying to do it as exactly by the instructions as I could, and my results are that the yoke effectiveness decreases in both situations (FBW trim speed extreme above AND below actual speed).

 

Very very strange indeed that your system is doing something completely different!

Thanks for that feedback Henrik.

That would be two users with completely different (and more logic) yoke/elevator response as I have.

 

Are you using FSUIPC like I am?

 

 

I guess the first thing for me is trying different FSUIPC settings (like calibrated by FSUIPC, not calibrated by FSUIPC and send direct to FS).

 

If that does not change things then I will completely uninstall FSUIPC and use FSX settings only for yoke control.


Rob Robson

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Thanks for that feedback Henrik.

That would be two users with completely different (and more logic) yoke/elevator response as I have.

 

Are you using FSUIPC like I am?

 

 

I guess the first thing for me is trying different FSUIPC settings (like calibrated by FSUIPC, not calibrated by FSUIPC and send direct to FS).

 

If that does not change things then I will completely uninstall FSUIPC and use FSX settings only for yoke control.

Yes, I am using FSUIPC.

I use "Send to FS as normal axis" and I don't calibrate in FSUIPC.

 

I have a Saitek pro flight Yoke, Saitek Pro flight rudders and GoFlight TQ6 throttles.

I did the test in 777-300ER, British Airways livery.

(If any of these things matter)


Henrik Denerin

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Yes, I am using FSUIPC.

I use "Send to FS as normal axis" and I don't calibrate in FSUIPC.

 

I have a Saitek pro flight Yoke, Saitek Pro flight rudders and GoFlight TQ6 throttles.

I did the test in 777-300ER, British Airways livery.

(If any of these things matter)

everything matters!

 

I will try now with the same FSUIPC settings you have.

 

If that does not work.....can I then ask you to try the same in the 200LR? (with the same FSUIPC settings) Because I do not have the -300.


Rob Robson

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everything matters!

 

I will try now with the same FSUIPC settings you have.

 

If that does not work.....can I then ask you to try the same in the 200LR? (with the same FSUIPC settings) Because I do not have the -300.

I get the same results as before in the 200LR (British Airways (Fictional) livery (decreased effectiveness on both) .

 

My trim buttons (A1/A2 on the yoke, button 2/3 in FSUIPC) are assigned in FSUIPC to:

-Buttons + Switches
   - Control sent when button pressed
   - Elev Trip Up/Down

Henrik Denerin

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I tried several things to correct my hyper sensitive PMDG777 behavior when flying wel below FBW trim ref speed:

 

- Deleted FSUIPC.ini - did not help

- Reprogrammed FSUIPC wirh direct to FS with "AXIS elevator set" method - did not help. (I also tried all other options, including "calibrated by FSUIPC, but that was even worse....as in unflyable)

- Deleted FSUIPC.ini + FSUIPC.dll, downloaded and installed the latest FSUIPC v4.936 and again programmed the yoke with "axis elevator set" - same same

- Closed FSX, rebooted PC and started a new flight - nope.

- Closed FSX, started a new flight but with 777F - same same

 

No matter what I do, I still have hyper sensitive PMDG777 behavior when flying wel below FBW trim ref speed (less than 1/2 yoke deflection required for full elevator deflection)

 

Only thing left to do now is get rid of FSUIPC completely.

And if that does not help......maybe one has to buy the -300 for SP1b to work 100%, lol.

 

 

EDIT: no, even with FSUIPC uninstalled (deleted) it still have same behavior :-(


Rob Robson

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Haha..anyways 300 is also worth it..and who knows magically fixes ur problem too.Anyways could not try yesterday as captain of my home airlines took over..today captain is happy so I can find time in the afternoon to try those scenarios..


Thanks,
Pankaj Dekate
 

Boeing777_Banner_Pilot.jpg

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@ Rob Robson (amazing how many Robs are into simming!)

 

Sorry could not try your experiment on Sunday as planned - my kids insisted it was Dad's day with them (quite rightly!)

 

Ok so here are my results from a Monday morning test.

 

fbw trim at 230kts - increase speed to 310kts - increasing forward pressure needed to maintain level, till at 300kts full forward yoke against the stops - elevator effectiveness gone completely - goes into a climb (2000ft/min) and can do nothing to stop that as no more yoke control (other than to trim nose down to regain elevator effectiveness).

 

fbw trim at 310 knots - decrease speed to 230kts - required backpressure to stay straight and level, but initially only small amount (so was a difference I felt for sure). At 230 kts did not have to hold full back pressure to keep level (about 1cm from full-back); so still had elevator control.

 

So far similar results to you; is a difference.

 

Now here is the strange part. I then pulled back to the full yoke-stop (remaining 1cm) and she went into a climb, eventually around 2100ft/min. Then I returned the yoke to nuetral, she leveled off and then slowly went into a 2000ft/min descent (@ about 235kts). NOW if I tried to pull her up to level off, even full-back pressure on the yoke - no go! Elevator effectiveness totally gone. To stop this descent, I had to trim nose up to regain elevator control.

 

This is with the -300 BTW.

 

So similar results to what you get (initial difference in elevator effectiveness behaviour, maybe not as extreme as you note), but after "using up" what elevator control I had in the "fbw-trim way above speed" test, I lost all elevator control and effectiveness was the same as "fbw-trim way below speed" test.

 

Rob


Robin Harris
 

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Here are my results:

 

Aircraft: 777-300

Payload: Max

Fuel: 100.0

Control wheel and control column null zone:  10% in FMC.

FSUIPC: Elevator and Aileron slope is 0

Controls set through and calibrated in FSUIPC

 

 

1. Speed at 310 and FBW at 220: I had to push the yoke full forward.Depending on when I push the yoke (climb rate at that moment) I had the yoke elevator effectiveness varying accordingly and could control her.Brought the yoke to neutral and tried pushing the yoke after it had a climb rate of more than 3000.The yoke became insensitive..But I had to keep it pushing down for a few seconds(with a slight push/pull) and it slowly started having yoke effectiveness .But i had to keep the yoke pushing down for around 15-20 seconds until it slowly arrested the climb rate and I could get her to level off.

 

2. Speed at 220 and FBW at 310: After descent rate increased to more than 3000 i started pulling on the yoke to keep her level off.But this time yoke sensitivity was way different than point 1.I could still get her to level off and had good amount of yoke sensitivity even at 6000ft/min descent rate.

 

Now my question is whether the differing sensitivities are because in one case we are trimmed to slower speed and yoke effectiveness(or simulated load feel) has been programmed to decrease a lot at slower speed and out of trim condition.Because in descent, even though I was expecting the same , I had good amount of yoke sensitivity.Was  this because we were moving to higher speed and hence had some good yoke sensitivity still left as compared to point 1?


In short the elevator effectiveness in point 1 and point 2 are different.And the only reason I can think of is airspeed.


 

 


fbw trim at 230kts - increase speed to 310kts - increasing forward pressure needed to maintain level, till at 300kts full forward yoke against the stops - elevator effectiveness gone completely - goes into a climb (2000ft/min) and can do nothing to stop that as no more yoke control (other than to trim nose down to regain elevator effectiveness).

Try this when you have some time: For this scenario,once you have pushed the yoke completely and effectiveness becomes 0,Pull the yoke a bit and push it again.Keep it for a few seconds.If you still dont feel the effectiveness pull it a bit and then once again keep it pushed for few seconds..Can you check if it slowly starts getting the effectivess back?I had to keep it for a long time..around 20-30 seconds depending on the climb rate at that moment.


Thanks,
Pankaj Dekate
 

Boeing777_Banner_Pilot.jpg

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Try this when you have some time: For this scenario,once you have pushed the yoke completely and effectiveness becomes 0,Pull the yoke a bit and push it again.Keep it for a few seconds.

 

Tried this and indeed that is what happens. Have to pull back then push forward and hold for about 20-30 secs and one gets elevator effectiveness again, but only briefly, then its lost again.

 

Reason is, have a look at what happens in detail. You pull back briefly, and she starts climbing, airspeed drops, and once it drops to a certain value (about 290kts) elevator effectiveness comes back in again, so yes, you are now pushing the yoke flat-out forward agin, you arrest the climb, she levels out, but just short of 310 kts, elevator effectiveness is gone again, and one cannot again arrest the slight climb that starts (and increases); repeat, same thing.

 

So I think we have confirmed that elevator effectivenss will eventually be lost if speed is very different from fbw trim.

 

Not that one would fly like this, just that Rob is, I think, trying to establish control strick behaviours, and software behaviour under a given set of conditions, to see what differnt setups are getting (same, similar or very different).

 

Rob


Robin Harris
 

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Thanks..just wondering the reason why they feel separate in two cases.Not that i am saying if its right or wrong


Thanks,
Pankaj Dekate
 

Boeing777_Banner_Pilot.jpg

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everything matters!

 

I will try now with the same FSUIPC settings you have.

 

If that does not work.....can I then ask you to try the same in the 200LR? (with the same FSUIPC settings) Because I do not have the -300.

Hi Rob,

 

I decided to try your extreme tests for the -200LR and -300ER and have come up with some interesting results. I think you are definitely on to something important. Thanks for sticking with it and making me re-think.

 

I set the aircraft up with short range fuel and used the payload as initialised. I too get the extreme elevator insensitivity when there is such a large difference between trim speed and airspeed. I don't get the increased sensitivity you see at one end of the speed range. For me it's insensitive at both high and low speed. However the reduced sensitivitiy is in one elevator direction only, it is full in th eother direction. That might explain why you feel it differently as the reduced sensitivity switches in and out as you move the column.

 

In both the -200LR and -300ER, with a 100 knot trim error, the elevator authority (in the direction needed to trim) is reduced to about one third of maximum travel, hence the gross insensitivity. So if I need to pull nose up to maintain trim the max elevator angle I can get is 33% of full according to EICAS. Nose down elevator is still 100% effective in that case. Vice versa if nose down column if needed to maintain trim..

 

As you reduce the trim speed error the elevator authority eventually starts to increase (from memory this happens somewhere around a 50-60 knot error). By around 30 knot error it is about 66%, and in this range trimming by feel becomes possible. Reducing the trim error to zero increases sensivity to 100% of course.

 

Now the interesting part. In the -200LR (TOGW 212 tonnes) at 210 knots the stab trim is 4.75 units. At 310 knots it is 4.25 units. So aerodynamically the difference in trim position required over that speed range is just 0.5 units. It's no wonder the -200LR feels so loose with a 100 knot trim speed difference because aerodynamically it is nearly in trim yet in one direction the elevator has only 33% authority.

 

Correspondingly for the -300ER (TOGW 232 tonnes) at 210 knots trim is about 6 units, but at 310 knots trim is 4.5 units. So although it wallows about with the insensitive elevator it is 1.5 units out of trim so feels more like a trim input is necessary. This may be why the -300ER feels better in manual flight.

 

So from this I would say for normal operation (trim speed errors of 30 knots or so) the -300ER (which I've been flying mostly) is trimmable by feel. The -200LR much less so. I also think the way PMDG has reduced elevator authority when out of trim is causing seriously handling problems. Full authority must be available for a good elevator feel simulation. It's something you simply shouldn't mess about with in a flight sim.

 

Rather than reducing elevator authority to force the user to apply a large column input (and so feel a larger spring force) I think PMDG need to add apply larger offset in the FBW law that forces the nose down (or up) in proportion to the trim reference speed error. The amount of the out of trim pitch applied would have to be adjusted by trial and error and a limit on the error may have to be applied because you could easily run out of control authority with a large error. The end result would be the need to apply a larger pitch control input but without the undesirable reduced sensitivity. If for some reason this is not possible then please, PMDG, remove the elevator sensitivity changes. They are doing far more harm than good.

 

Another thing I've noticed is that the trim doesn't seem to move while you have any column input. The FCOM implies the FBW should move the trim so that elevator deflection reduces to zero (faired in line with the trim). I haven't seen this happen when trimming with the column deflected. I don't know whether the FCOM is correct in this case, but if correct such trim movement would help maintain elevator pitch authority with large trim ref speed errors.

 

I don't use FSUIPC for control calibration or to assign trim inputs. Everything in my set up is "pure" FSX.

 

Kevin


ki9cAAb.jpg

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Interesting topic here. I'm having trouble hand flying this bird. I too seem to have the issue of no trim being applied until controls are neutral input wise. This means when you trim you can't feel when you're in trim until you release the column to neutral, meaning you're guessing effectively.

 

I have severe difficulty on approach and landing, it seems I can't get her in trim for landing even when I'm at a constant speed, I have to maintain back pressure on the yoke otherwise the nose drops, and trim isn't applied until a few seconds after neutralising the controls and therefore I've dipped out of the glideslope by miles.

 

None of it feels intuitive like it should.


captainhenrychen-1.jpg


Boeing777_Banner_Pilot.jpg


 


James Bennett

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So similar results to what you get (initial difference in elevator effectiveness behaviour, maybe not as extreme as you note), but after "using up" what elevator control I had in the "fbw-trim way above speed" test, I lost all elevator control and effectiveness was the same as "fbw-trim way below speed" test.

 

Rob

Ok, thx a lot for that feedback Rob.

 

Interesting to see that you first have the same as I do and that it then changes.

Here are my results:

 

FSUIPC: Elevator and Aileron slope is 0

Controls set through and calibrated in FSUIPC

 

Interesting that you can actually calibrate your flight controls through FSUIPC!

If I try that I can only roll in one direction and Pitch in one direction??!!

Totally weird.

So I use FSUIPC to detect, and then "send direct to FS"......."axis elevator/aileron set".

 

I am telling you I think I need a new control wheel.....this one has served me long enough anyway. (19 years old CHPro.....analog edition (game port connector, not USB) and to make it work on todays PC I have had to plug it into an analog to digital USB converter)

 

I would like the PFC SAAB.....but it is very exspensive :-( so I will probably order the Saitek Cessna yoke.

In short the elevator effectiveness in point 1 and point 2 are different.And the only reason I can think of is airspeed.

 

Good, thx for that feedback.

 

You got basically the same response as Geopilot and I.

Try this when you have some time: For this scenario,once you have pushed the yoke completely and effectiveness becomes 0,Pull the yoke a bit and push it again.Keep it for a few seconds.If you still dont feel the effectiveness pull it a bit and then once again keep it pushed for few seconds..Can you check if it slowly starts getting the effectivess back?I had to keep it for a long time..around 20-30 seconds depending on the climb rate at that moment.

And that is an interesting observation as well.

 

I have not had the time to to take a look at that....maybe in a few days, possibly with a new yoke :-)

Not that one would fly like this, just that Rob is, I think, trying to establish control strick behaviours, and software behaviour under a given set of conditions, to see what differnt setups are getting (same, similar or very different).

 

Yes......I am trying to understand how the system works.....compare it with others......to then hopfully find out why my system will not trim by feel as well as that of others.

Rob Robson

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