Still Trim issues with Sp1b

[whoispankaj 51]

 

 

But I really do not like it when people are trying to say we can close this thread now just because they do not have a problem.

I think you just missed the sarcasm in here.

that's fine, thx for the info.

I have the same....no Windows game controller deadzone and FMC deadzone at default....which was the minimum.

I do use FSUIPC.
I could try linking my controller trim buttons to FSUIPC key select Num1 and Num7 but I dont think it will make a difference.
At the moment FSUIPC has the trim button inputs routed directly to FS for trim control (so not linked via key stroke).
Thx for that detail!

Willl post my settings too if that helps you..I have configured through FSUIPC. My dead zone is 10% in the FMC.Need to see if i have any curve set up in FSUIPC.Will check in the evening and post it here.

[PerWel 23]

I could try linking my controller trim buttons to FSUIPC key select Num1 and Num7 but I dont think it will make a difference.

 

Try trimming with the num keys directly on the keyboard instead of going through FSUIPC. That way you can test if FSUIPC play any dirty tricks with you

[kevinh 409]

Oh and Kevin - the real airplane actually does allow you to input trim opposite the direction of yoke deflection. We had this tried in the real airplane by someone we trust completely and he confirmed it. The limitation with it is that the stabilizer itself cannot move in this situation - the elevator however can and does. It just won't be offloaded/streamlined until after the yoke deflection is released. This is all modeled in SP1.

I'm more than happy to accept it's programmed correctly in SP1.

 

I was going by what I read in Boeings 777 CBT course, that the column being able to override trim switch inputs, and also a comment Rob (777simmer) made in another thread. Taken together that implied the trim reference wouldn't change opposite to column input. What you say here about only trim motion being inhibited clarifies the situation. Inhibiting trim motion is the main issue of course. Why Boeing chose to allow the trim reference speed to change opposite to column input is an interesting question but the column input will win all the time it is out of neutral so I suppose it's also a moot point.

 

Edit:

 

The fact that trim motion is inhibited with opposite column input could well explain the observation some users make that trim moves all at once when the column is released to neutral. If the column was held in opposition to the trim input made then that is quite likely to happen and would be correct.

[777simmer 117]

I think you just missed the sarcasm in here.

Willl post my settings too if that helps you..I have configured through FSUIPC. My dead zone is 10% in the FMC.Need to see if i have any curve set up in FSUIPC.Will check in the evening and post it here.

Yes I did miss the sarcasm.

 

Yes please post settings. The more people do, the more we can compare and establish a pattern (if there is one).

Try trimming with the num keys directly on the keyboard instead of going through FSUIPC. That way you can test if FSUIPC play any dirty tricks with you

ok yes, even better idea.

[fro2do 10]

Just accelerate from 250kt to 300kt and holde fwd pressure on the yoke to prevent the aircraft froom climbing too much.
But allow a shallow climb of 100-300ft/min......this would guarantee constant fwd pressure on the yoke and never going through neutral.
while holding that constant fwd pressure, trim nose down....way down.
Without changing the yokes deflection....with all that nose down trim added to it.....if the triminput takes effect, the aircraft would nose down.

Does it?

could you please show us a video of that?
I for one would be greatfull!

And also one in the opposite direction please, where you decelerate from 300kt to 250kt or so while holding constant back pressure but allowing a slight descned to prevent again the neutral position.
Does the nose go up sky high like a rocket while trimming?
 

This is me Giancarlo trying this experiment Fro2do...

 

I tried this experiment everything works just fine with me ...

I also have the Saitek Yoke and rudder equipment.

My PMDG SETTING IS 1.0%

My Yoke is Calibrated with FSX NOT FSUIPC.

MY trims are also set in FSX

I do not need to set the yoke to neutral for the trim to work.

I followed your experiment 10 times and each time the forward pressure and the back

pressure was applied and while doing this I applied the trims and they

functioned accordingly.

Try my settings and see if they work.

thanks

[777simmer 117]

All I wanted to do is try to fine tune my CDU dead zone settings a bit, and get some help from you guys doing so, but instead, I am afraid this is going to end up in a series of 2 or more rather looooong posts on understanding the PMDG777 FBW system, trouble shooting FBW (trim) problems as well as a "tutorial" (not trying to sound like mister know it all here.....just have no better word for it) on how I suggest you fly the PMDG777.

 

This 1st post starts with some observations I made about yoke sensitiviy.

(My next post will have more observation about my actual problem.....about trim not allways working right.)

I would appriciate it very much if others can try to repeat the same flight and see if they get the same results.

But I also realize that not everyone has the time to do so.

We shall see who joins in.

 

The last part in this post, under 2), is that "tutorial" I mentioned.

A few days ago someone asked for tips on trimming and I gave some.

After todays testing and messing around I felt the info I gave a few days ago is not complete and not very accurate......so that is why I have updated it here.

 

 

The test parameters:

 

PMDG777LR SP1b

 

CDU deadzone settings:

CTL column null zone - 1.0%

CTL wheel null zone - 1.0%

 

location: LOWW Rwy29

 

Day 13:00LT, summer

Fair weather (gave me 14C outside)

 

Performance:

TOM 309.000KG, . (Payload max, Fuel 100.000KG)

Crz FL340 in FMC and MCP.

CI 25 (but it should not matter)

 

Thrust lim:

Full thrust take off, no derate.

 

Take Off Ref page 1:

flaps 5

my Cg was at 30

V1 163, Vr170, V2 176

STAB for take off 4.0.....check you have this set on the FCTL page!

 

enter a manual climb speed on the Vnav Clb page of 310kt (default is 320kt but that is to close to overspeed for our experiments).

Trans Alt is 5000ft there.

Delete the 250kt below FL100 restriction!

 

Arm Vnav for take off. I left Lnav disarmed as I just want to go straight ahead.

 

Make sure there are no speed or altitude restrictions in the FMC, delete all of them!

 

set MCP altitude window to FL340 to prevent a level off anywhere during our wild ride :-)

All checklists completed?

Ok now keep the FCTL page open somewhere if possible (popup) so you can see what the STAB is doing!

 

I saved my flight here and I suggest you do the same......we will need it again :-)

 

 

1) acceleration to 310kt (in one go, without 250kt limit) without trimming:

 

After flaps are retracted keep a constant 7.5 degrees pitch (results in about 1200ft/min while accelerating to 310kt).

 

Note: try to not allow the yoke (elevators) to go through neutral after flaps up!

And do not trim!

As long as you keep some fwd pressure you will see that the STAB trim stays fixed at around 4.5 units

 

Once you pass 270kt notice how insensitive the yoke has become!

Even pushing it full fwd does not do much anymore.

STAB trim was 4.5 units in my case (I did not do that.....it must have been the FBW system compensating for the changed configuration....ok fine).

Even a full yoke down deflection is now hardly able to decrease pitch!

1)YOU GUYS HAVE THIS TOO? (not screaming.....just wanted to highlight where I need feedback)

 

Note: the insensitive yoke is not a problem for me. Normally you WOULD trim and you would thus never get into this rediculously large out of trim situation anyway.

I am just establishing facts and want to know if you guys get the same result.

 

1b) ok, now as you reach 310kt let the yoke go through neutral.

Observe how the nose goes up as the aircraft wants to go back to that slow trim ref speed that was set for take off (STAB setting). This is normal.

 

Observe how the STAB trim automatically increases to 5.0-5.25 now. (this is normal I guess as the airplane wants to get back to that slow trim ref speed it will give an increased pitch up command).

Now I have absolutely no elevator nose down effectiveness anymore.

(yoke full fwd......but elevators on FCTL page hardly deflected).

I can not push the nose down even with full yoke fwd!

Within 10seconds I have a pitch attitude of +20 degrees even though I am holding full fwd yoke deflection.

Speed is now decreasing.

As speed decreases I get closer to my trim ref speed and somewhere around 280kt I have enough elevator effectiveness again that the nose starts coming down (with full fwd yoke deflection).

 

Push the nose down all the way to the horizon (0 pitch) and see the aircraft accelerate. At 300kt, let go of the yoke again.

See the nose pitch up again and now my STAB trim increased even more to 5.5 units.

Now the whole cycle just repeats.

As the nose reaches about +15 you will still be around 300kt and even full fwd yoke can not bring the nose down. Speed decreases again untill at around 280kt elevator effectiveness returns.

1b)YOU GUYS HAVE THIS TOO?

 

Ok. This is probably not realistics but as Ryan from PMDG said, this is what they had to do (vary elevator effectiveness) to simulate a FBW system.

That is ok with me.

I am not a programmer. I have no clue.

If he sais so I have to believe that.

And again......it does not matter anyway because who flies like this??

 

 

2) New take off, same conditions.

This time we are going to use trim BUT with the trim ref speed displayed.

So a normal take off......just to show how nicely things go on my setup when the trim ref speed is dislayed.

So turn it on in the FMC now.....

 

Ok here we go (this is for the newbies here.....experienced people...dont take this as condescending please)

80kt checked

V1

rotate.

count 21---22----23-----24 seconds (you should now be at 10 pitch when the proper rotation rate is used-----25-----26 seconds and you should be at 15 degrees pitch.

 

pos rate - gear up

 

I needed about 18 degrees pitch to keep the speed constant (and that was where the FD was waiting for me also).

 

then - boom FBW trim speed is displayed, mine was at 197kt that is V2+21kt so within limits (max+25kt) but on the slow rotation side of things.

The moment that trim ref speed displays and you have that correct pitch of (in my case 18 degrees) you can let go of the yoke and pitch attitude will stay right there because you are now at a constant speed.

Stable as can be.

Hands free....easy does it :-)

 

At 1000ft Check Vnav speed engages (400ft above ground).

At 1600ft (=1000ft above ground) acceleration is commanded (magena speed bug goes up)

drop the nose to about +10 degrees. just push the nose over....no trim required for a pitch change!

(dont worry if the FD is a degree higher or lower.....it is there for guidance only)

 

Things are going fast now......try to keep up ;-)

 

 

PAUSE: my method requires a series of short trim inputs (like 15-20 times 1/2 a second) while staying quote close to actual speed. The problem with that is that the BLIB feature keeps messing with you. Trim ref speed will jump in the wrong direction at times. Just disregard that and hold your trim switch untill the trim ref speed has moved where you wanted it to.

UNPAUSE.

 

 

Now trim so the FBW trim ref speed is a bit (5-8kt or so) above your actual speed. You should be able to pretty much let go of the yoke and the nose should stay pretty close to +10 degrees.

(because you are not out of trim by very much so the FBW system will act quite stable..... no crazy pitch changes will occur)

 

when the green 5 passes - set flaps 1

 

You have probably just passed the FBW trim ref speed so move that up again so it is about 5-8kt above your actual speed again.

 

Again, you should not have to yerk around much on the yoke ;-)

 

The nose should stay at about 10 degrees (unless you trim too much (like actual speed plus 15kt or so).... then the nose will drop more than we want).

And again, dont worry too much about the FD.....it will stay pretty close to what we are doing because we are doing things correctly.

 

as you accelerate through your FBW trim ref speed, trim again.

Again move the trim ref speed up about 5-8kt or so

At the green 1 - set flaps up

 

again you will pas through your trim ref speed.

Just keep moving it up by about 5-8kt each time and then allow the speed to catch up to it.

Then up it again by 5-8kt, etc, etc

 

Untill you reach the magenta speed bug.

Stop trimming when trim ref speed = magenta speed bug.

 

Now adjust pitch a bit with the yoke if required (follow the FD) eh voilla....You just did the perfect take off and clean up and are now in a stable climb at 310kt :-)

 

The above method works beautifully for me and that is why I keep saying:

"With the FBW trim ref speed displayed this simulation is great fun and I can fly the PMDG777 as smooth as the real thing"

[johndrago 4]

The problem with that is that the BLIB feature keeps messing with you. Trim ref speed will jump in the wrong direction at times. Just disregard that and hold your trim switch untill the trim ref speed has moved where you wanted it to.

 

I see this as well, and it screws me up.  Why does it go in the wrong direction when using the BLIB feature?

 

Thanks for helping adapt to this.

 

John

[Arnold Bruce 0]

@Rob,

 

Displaying the FBW trim reference speed on the ADI does work quite nicely, yes, but by utilizing this method one is now trimming by sight instead of feel.     Personally, I feel that resorting to this method undermines all of the other built-in fidelity of the PMDG sim (in terms of hand flying) as this is so far removed from the normal flying experience.    I will note, however, that you are indeed a real-world Boeing 777 pilot and if you feel this is the best compromise at present under the circumstances, I have nothing then but complete respect for your professional-level observations and advice.    

 

I remain at a loss as to why the PMDG 777 is such a different experience trying to fly by 'feel' than the PMDG 737 NGX.    I fully understand the limitations of plastic, hobby level control yokes and joysticks having to interact with very complex software dynamics, but I nevertheless easily 'sense' the 737 NGX react to trim input and I can intuitively trim it precisely and predictably on every flight.     The PMDG 737 is a joy to hand fly quite frankly.     The 777, for me personally, is quirky and unpredictable to trim.      Shouldn't these two sims be just as easy to trim as the other, given use of the exact same hardware?     

 

Signed,

 

Arnold Bruce

[fro2do 10]

@Rob,

 

Displaying the FBW trim reference speed on the ADI does work quite nicely, yes, but by utilizing this method one is now trimming by sight instead of feel.     Personally, I feel that resorting to this method undermines all of the other built-in fidelity of the PMDG sim (in terms of hand flying) as this is so far removed from the normal flying experience.    I will note, however, that you are indeed a real-world Boeing 777 pilot and if you feel this is the best compromise at present under the circumstances, I have nothing then but complete respect for your professional-level observations and advice.    

 

I remain at a loss as to why the PMDG 777 is such a different experience trying to fly by 'feel' than the PMDG 737 NGX.    I fully understand the limitations of plastic, hobby level control yokes and joysticks having to interact with very complex software dynamics, but I nevertheless easily 'sense' the 737 NGX react to trim input and I can intuitively trim it precisely and predictably on every flight.     The PMDG 737 is a joy to hand fly quite frankly.     The 777, for me personally, is quirky and unpredictable to trim.      Shouldn't these two sims be just as easy to trim as the other, given use of the exact same hardware?     

 

Signed,

 

Arnold Bruce

You are correct when you mentioned his competence with this aircraft and I totally agree with

you because I tried his methods and techniques just now and it works...

 

Ok I'm going out on a limb here...but everyone mentions the Pmdg 737 trim functions and how

well it works as well as me but...could it be that 737 has the noise factor where you also see and hear

the trim wheel in action so you can adjusted your trims accordingly?

The 777 will not...you have to look at your instruments to get the same feel but when you do 

its the same thing it just feels right...

Cool Insights,...AB

 

Just a thought.

[Arnold Bruce 0]

 

 

Ok I'm going out on a limb here...but everyone mentions the Pmdg 737 trim functions and how

well it works as well as me but...could it be that 737 has the noise factor where you also see and hear

 

You know, I actually thought about this, lol.    Perhaps some kind of aural trim feedback would indeed actually be beneficial in regard to the PMDG 777.     However, with the PMDG 737, I personally only hear the trim wheel sound intermittently whilst trimming in either direction, so there is more in the feedback loop with it than just sound.     Again, somehow you can just 'feel out' the 737 in a trimmed state, whereas with the 777 you seem to be trimming by hit and miss; thus you never seem to know what it wants to do until you neutralize controls.    It's so weird.   

 

Signed,

 

Bruce Arnold

[pete_auau 1,159]

Any of you guys actually submitted  a support ticket  in yet,  since looks like it  user  specific   issues here since if it were  a problem than everyone  would have the same issues, which is  the strange part,   where others have this issue   and others not./

[777simmer 117]

@Rob,

 

Displaying the FBW trim reference speed on the ADI does work quite nicely, yes, but by utilizing this method one is now trimming by sight instead of feel.     Personally, I feel that resorting to this method undermines all of the other built-in fidelity of the PMDG sim (in terms of hand flying) as this is so far removed from the normal flying experience.    I will note, however, that you are indeed a real-world Boeing 777 pilot and if you feel this is the best compromise at present under the circumstances, I have nothing then but complete respect for your professional-level observations and advice.    

 

I remain at a loss as to why the PMDG 777 is such a different experience trying to fly by 'feel' than the PMDG 737 NGX.    I fully understand the limitations of plastic, hobby level control yokes and joysticks having to interact with very complex software dynamics, but I nevertheless easily 'sense' the 737 NGX react to trim input and I can intuitively trim it precisely and predictably on every flight.     The PMDG 737 is a joy to hand fly quite frankly.     The 777, for me personally, is quirky and unpredictable to trim.      Shouldn't these two sims be just as easy to trim as the other, given use of the exact same hardware?     

 

Signed,

 

Arnold Bruce

I totally agree with everything you say.

But I will get to that in a next post.

 

I was too tired last night to get into trimming by feel last night, which must of course be the goal. If trimming by feel is not possible on my system because of my type of yoke then I can live and will still ejoy the PMDG777 with my "trim by look" method......but yes, that would make the NGX my all time favourite as well then.

 

Thanks for the compliments......but it could very well be that my "expertise" ends here......and I have some dead band setup all wrong.......that is where I am going to need you guyses expertise then!

You are correct when you mentioned his competence with this aircraft and I totally agree with

you because I tried his methods and techniques just now and it works...

 

Ok I'm going out on a limb here...but everyone mentions the Pmdg 737 trim functions and how

well it works as well as me but...could it be that 737 has the noise factor where you also see and hear

the trim wheel in action so you can adjusted your trims accordingly?

The 777 will not...you have to look at your instruments to get the same feel but when you do 

its the same thing it just feels right...

Cool Insights,...AB

 

Just a thought.

ok, great that this works for you as well :-)

 

I do not think sound matters to be honest.

I do not have the NGX installed at the moment (I am using a fairly vanilla FSX install to make sure nothing else causes my problem) I never trimmed the NGX by sound......that was purely by feel.

 

But you can do an easy test......turn the volume off and see if you can still trim the NGX ;-)

Any of you guys actually submitted  a support ticket  in yet,  since looks like it  user  specific   issues here since if it were  a problem than everyone  would have the same issues, which is  the strange part,   where others have this issue   and others not./

I can not speak for the others but I have not.

 

But its not like PMDG is unaware of our struggles......Ryan (from PMDG) is monitoring and assisting in this very thread.

 

I first want to get to the bottom of my problem.

Then if I know what causes it, or if we fixed it, or if we did not fix it and I dont know what else to try....then I will submit a ticket.

 

So we are not quite there yet, just bare with me a little longer :-)

 

Hopefully later today I have been able to test and report about trimming by feel and how various CDU dead zone settings and joystick driver level dead band settings effect this.

[pete_auau 1,159]

So we are not quite there yet, just bare with me a little longer :-)

 

Its ok  just want  for all you guys  to get its fixed one way or  the other

[Arnold Bruce 0]

@Rob,

 

One additional thing to try is to manually fail the PFC's into Secondary Mode via the CDU aircraft options menu and simply leave your hardware setup as it normally is in terms of calibration/dead zone.      If this were to have a significant impact on the manual trimming issue in terms of precision, it would be revealing.

 

Signed,

 

Bruce Arnold   

[kevinh 409]

What works well for me is trimming intuitively. I've stopped thinking about it as if it was something special. I've stopped looking for trouble with it. I've stopped trimming when I don't need to simply to see if I can feel a change.

 

I tried flying with the FBW marker displayed but that ruins the experience and stops you learning how to adapt to trimming the 777 by feel. It certainly does feel different to the NGX but this may be the best compromise PMDG can achieve.