Still Trim issues with Sp1b

[777simmer 117]

The trim on the FCTL page didn;t change going in manual flight (with a large difference in trim ref)

Your are trimming but the STAB does not change?

 

Dont look at that too much.......first the elevator will move a tiny bit and then the STAB will be trimmed. But sometimes this takes a little bit of time. Plus the STAB trim does not change that much.

 

More important is weather or not your yoke deflection has to be reduced as you trim?

If you trim, then the trim input is added to the yoke deflection you are holding.

So if you want the pitch attitude to stay the same (level in 5000ft) then you shoukd have to reduce yoke deflection.

 

If not, then are you sure your yokes trim switch is linked to the trim command correctly?

(do the VC trim switches move?....Does the FBW trim ref speed move?)

[martin-w 3,235]

But over the years my view on things changed, inter alia because when the automation technique fails, the explanations always end in "lousy pilots were unable to operate perfect flying machine.

If the expert acident investigators tell us that then who are we to argue

[kevinh 409]

Hi Kevin!

But this is what the A330 Instructor handbook tells the instructors to teach their students:

(quote)

Hence STICK FREE, the A/C maintains the flight path even in case of speed changes. Furthermore, STICK

FREE in case of Configuration changes, or thrust variations, etc… the pitching moment effects are reduced by

the feedbacks in the control law itself and compensated for by precommands. With STICK FREE in

turbulence, small deviations do occur on the flight path but with a tendancy of the A/C to regain a steady

condition.

, As a consequence the A/C is a STABLE PLATFORM and AUTOTRIMMED; it needs to be flown with minor

corrections from the pilot on the stick, when the A/C deviates from its intended flight path.

(unquote; remark: the capitals are the original format)

So IMO there is a "flying carpet" idea behind the Airbus FBW code which means a permanent autopilot which accepts some supervised overrides by the pilot.

(I know you don't like my opinion, but in this life you won't convince me of the opposite, sorry B)  )

Of course the normal input used is small, just as it is with any airliner. But the sidestick can make rapid and dynamic changes to the flight path if the pilot wishes to use large inputs. It's just not encouraged, or necessary, for line flying. If you think about it an Airbus must be just as manoeuvrable as any conventional airliner. If it was a stable magic carpet it couldn't react to avoid a collision or respond to windshear safely.

 

IIRC you said you'd flown a Lufthansa 737 simulator. If you get a chance buy some time in an Airbus full flight simulator. I can guarantee you will enjoy the experience of flying it manually. An Airbus is just as dynamic and flyable as a Boeing. It's very precise and controllable.

 

Sorry, but (exaggeratedly) I can not follow beyond the similarity of the three letters. Or let me tell it this way: Boeing's FBW will leave less question marks in case of doubt as it is by far more straight than Airbus' roundabout fashion programing:

you remember our side stick priority discussion. (Yes, it belongs to the FBW subject!) For me the "logic" behind these buttons is already "comedian style", but it's a matter of taste probably.

OK, I'll try and explain. Airbus control laws are C*, Boeing is C*U. The only difference in normal flying inside the flight envelope is the speed trimming necessary in the Boeing design. If you regard the Airbus C* as a flying carpet then so must the Boeing version be, as it works much the same. In fact neither is a "flying carpet". Remember, the Airbus was designed to handle like a conventional airliner so pilots would find it natural.

 

As for the control hand over switches, you didn't actually know how they worked in any detail in that other thread yet you drew negative conclusions about their operation. I tried to explain but you seem to have a set idea. I don't see how you can characterise them as "comedian style".

 

Don't get me wrong. You are for sure a very knowledgeable person with insights/internals to Boeing and Airbus airline operations and training, which I don't have. I might be particularly wrong, and I once asked you if you are "married with Airbus" but your answer was no (as you might be married with your wife actually), BUT everytime we got into the discussion about Airbus' philosophy your arguments seem to come directly from their latest 4-color glossy brochure. You never accept even a touch of criticism concerning Airbus. :ph34r:

What I won't accept is unfounded or ill-informed criticism of the Airbus. It isn't beyond criticism of course. Nor is Boeing. Your criticism of the Airbus design philosophy comes from reading an instructor's manual. I would respectfully suggest that without actually being on the receiving end of such instruction in an Airbus simulator or aircraft you aren't in any position to infer anything critical of the design philosophy.

 

I'm neither pro-Airbus nor pro-Boeing. I try to understand and appreciate both. In an A v B debate I'm neutral. All I would ask of you is to keep an open mind and not draw conclusions from partial information.

 

IMO Boeing has a lot of (good) reasons to differentiate from the Airbus philosophy.

So here at the FBW-crossroads of Boeing and Airbus it is clear that an FSX simulation using a "dead" Airbus sidestick would have been much easier than the "alive" Boeing columns...

There is no fundamental difference in simulating FBW control in FSX between the Boeing approach and the Airbus approach. The problem is nothing to do with the force feedback Boeing uses in the 777. Artificial feel (force feedback) applies to all powered and power assisted control systems. It is not what makes trimming in the PMDG 777 a problem. The trimming issue arises from the way PMDG have simulated the 777 FBW.

[vr-pilot 11]

Hi Kevin!

Thank you for your explanations.

 

As for the control hand over switches, you didn't actually know how they worked in any detail in that other thread yet you drew negative conclusions about their operation. I tried to explain but you seem to have a set idea. I don't see how you can characterise them as "comedian style".

 

You are right. Out of my memory I had the thought that originally the "side stick priority switch" was only on the CPT's side which was later "mirrored" to the F/O's side with quite some fundamental changes in the software over the time. So if there were two switches already from the very first layout on, my criticism regarding the hardware setup (mirroring) was unfounded. From the logic/software side I still doubt the "ping-pong"-sense though. IMO an artificial feel for the side sticks would be more useful in the "human" sense.

 

BTW: Mr. Sullenberger says in an interview that the AF447 accident would probably not have taken place with steering columns. The CPT had no chance to see or feel what the F/O did with the stick. Respectively the "priority switch" was not used while there were dual inputs (with aural alerts) over longer periods. There are other (severe) incidents concerning the priority switch and the lack of artificial feel in the sticks.

 

An Airbus is just as dynamic and flyable as a Boeing. It's very precise and controllable.

 

I never had the intention to say that Airbusses are imprecise or uncontrollable. They must be a joy to fly in RW. All what I am saying is that the AB FBW philosophy is - although highly reliable - not 100% error free. Here the problem awareness of Airbus is still from the 20th century while Boeing has arrived in the 21st century. (Man-machine coexistence instead of displacement.)

O.K. It is a philosophical question to which a lot of answers can be found in the movie "2001: A Space Odyssey".

EDIT:

https://www.youtube.com/watch? annotation_id=annotation_895695&feature=iv&list=PL4C5804B6D1FD8B96&src_vid=Ok32VyEQYYc&v=1s-PiIbzbhw

 

 

There is no fundamental difference in simulating FBW control in FSX between the Boeing approach and the Airbus approach. The problem is nothing to do with the force feedback Boeing uses in the 777. Artificial feel (force feedback) applies to all powered and power assisted control systems. It is not what makes trimming in the PMDG 777 a problem. The trimming issue arises from the way PMDG have simulated the 777 FBW.

 

Mmh. Sorry. Can not follow that. Simulating an Airbus with a (sorry, but "dead") side stick is easier than compensating for an (artificial) yoke pressure/feel that can not be felt accordingly. The trimming problems in this thread IMO seem to arise from different hardware (mechanical centering/pressure point) and null zone settings and NOT from the way PMDG simulated the 777 FBW.

That T7 FBW discussion was for sure a heavy low in the company's history. Especially from the interpersonal aspect, if you consider the dilemma with the source of "false information". So I don't see a chance for sloppy work here. Perhaps they will come out with a tool to compensate (even more) for different hardware, as I said already earlier in this thread.

Edited September 23, 2014 by vr-pilot

[martin-w 3,235]

the AB FBW philosophy is - although highly reliable - not 100% error free.

Name any system that isn't error free? The Boeing system isn't infallible either, nothing that human kind has invented is.

 

Highly reliable you said, what more do you want?

[vr-pilot 11]

Name any system that isn't error free?

 

100% error free in the whole context was meant ironically:

my impression is - e.g. in case of incidents/accidents - that the system philosophy is praised to glorious heights while at the same time the pilots are blamed for being dumb to the bones.

This "tradition" IMO has reached an uncomfortable level of improbability.

"The computer makes no mistakes" is a 20th century technical welfare misbelief. It makes no sense when machines (invented by man!) are treated with priority.

 

Again: Airbus might have a wonderful set of A/Cs on the market. Reliable, economic, easy to fly, loved by pilots and carriers. But IMO - at the same time unfortunately - they have an old fashioned problem awareness or better: way of communicating problems in public.

 

O.K. folks. I see that most - if not all - don't like or even share my opinion here. It is o.k. for me and I don't want to hijack the thread further.

I love you all  :wub:

[kevinh 409]

Hi Kevin!

Thank you for your explanations.

 

 

You are right. Out of my memory I had the thought that originally the "side stick priority switch" was only on the CPT's side which was later "mirrored" to the F/O's side with quite some fundamental changes in the software over the time. So if there were two switches already from the very first layout on, my criticism regarding the hardware setup (mirroring) was unfounded. From the logic/software side I still doubt the "ping-pong"-sense though. IMO an artificial feel for the side sticks would be more useful in the "human" sense.

 

BTW: Mr. Sullenberger says in an interview that the AF447 accident would probably not have taken place with steering columns. The CPT had no chance to see or feel what the F/O did with the stick. Respectively the "priority switch" was not used while there were dual inputs (with aural alerts) over longer periods. There are other (severe) incidents concerning the priority switch and the lack of artificial feel in the sticks.

I don't want to re-open the debate about AF447 with you yet again. However I will say this. At least one Boeing has been lost due to pitot-static blockages and the resulting confusion with speed indications and stall warnings. Having a yoke didn't save them or add anything to the crew's awareness. In AF447 the pilot in the left seat (who was not the Captain) should have taken control with the override switch. The fact he did not is not a fault of the system. As he did not his input was summed with the other pilot's so it was having an effect on the controls. He could even have pushed it further forward and pitched the nose down.

 

Artificial feel was not the issue. The sidesticks have a heavy spring feel system. If you are pulling the stick back continuously you feel it. It's not like a flightsim joystick. The crew were very confused by the conflicting information they had due to icing. That was what caused the crash, not the flight control system.

 

I never had the intention to say that Airbusses are imprecise or uncontrollable. They must be a joy to fly in RW. All what I am saying is that the AB FBW philosophy is - although highly reliable - not 100% error free. Here the problem awareness of Airbus is still from the 20th century while Boeing has arrived in the 21st century. (Man-machine coexistence instead of displacement.)

O.K. It is a philosophical question to which a lot of answers can be found in the movie "2001: A Space Odyssey".

EDIT:

https://www.youtube.com/watch? annotation_id=annotation_895695&feature=iv&list=PL4C5804B6D1FD8B96&src_vid=Ok32VyEQYYc&v=1s-PiIbzbhw

Indeed, but you were under the misapprehension that the Airbus flies like a magic carpet. You are just as likely to lose situation awareness due to automation in a 777 as an Airbus.

 

To claim that Airbus is still in the 20th Century and Boeing is in the 21st is ludicrous. It sounds profound but has no basis in fact. You can use BS like that to win an argument.

 

Mmh. Sorry. Can not follow that. Simulating an Airbus with a (sorry, but "dead") side stick is easier than compensating for an (artificial) yoke pressure/feel that can not be felt accordingly. The trimming problems in this thread IMO seem to arise from different hardware (mechanical centering/pressure point) and null zone settings and NOT from the way PMDG simulated the 777 FBW.

That T7 FBW discussion was for sure a heavy low in the company's history. Especially from the interpersonal aspect, if you consider the dilemma with the source of "false information". So I don't see a chance for sloppy work here. Perhaps they will come out with a tool to compensate (even more) for different hardware, as I said already earlier in this thread.

A 747 or 737 also has artificial control feel, yet we can trim the PMDG 747 and 737 with no difficulty. The problem is not the presence of artificial feel in the 777, any aircraft with powered controls needs it. Please understand that. The problem is in how PMDG have implemented the speed trim reference in the simulation and split the FBW into two sub modes which are mutually exclusive.

[Orlando Younts 0]

 

 

A 747 or 737 also has artificial control feel, yet we can trim the PMDG 747 and 737 with no difficulty. The problem is not the presence of artificial feel in the 777, any aircraft with powered controls needs it. Please understand that. The problem is in how PMDG have implemented the speed trim reference in the simulation and split the FBW into two sub modes which are mutually exclusive.

 

Exactly.    With PMDG's current dual mode 777 FBW implementation, there is no pitch moment at all associated with the 'maneuver demand' mode and the sim pilot will therefore not 'feel' any pitch moment when exerting controller force.    Under this condition, the only way to trim the aircraft manually is to purposefully neutralize controls and wait for PMDG's speed stability mode to kick in, with the resultant pitch moment cluing in the sim pilot as to where the trim reference speed is set.     Basically, if you attempt to trim the PMDG 777 as you would the real aircraft, you'll end up fighting the trim relentlessly and imprecisely until you win the luck of the draw and it finally trims out on speed.     You can do it, but it's a miserable experience that represents more of an arcade game than a high fidelity simulation of a very complex aircraft.

 

What one must do is tailor their trim technique to make very subtle control inputs, along with measured, controlled trim input during pitch changes.    The idea is to keep the PMDG FBW in speed stability mode with only transient lapses into maneuver demand mode, the latter being the twilight zone where there will be no pitch moment or 'feel' generated by the PMDG FBW.      It can be done, and manual trim can be accomplished fairly precisely, but again you are having to tailor your trim technique very purposely to make the PMDG FBW behave more realistically.   Large control inputs, and/or large trim changes seem to push the PMDG FBW deep into maneuver demand mode and will almost always require you to forcefully engage the speed stability mode by again neutralizing controls.     This allows you to reacquire FBW trim reference speed pitch moment force instead of the slack force generated by maneuver demand mode, but you will end up fighting the trim once speed stability mode engages again.     

 

If you can learn to keep the PMDG FBW on the edge of the two modes, you will always have pitch moment being generated and be able to trim by feel.   It takes a lot of practice to hone, however.    

 

My impression of the current situation is that PMDG modeled the wrong 777 FBW with the RTM version (this we all understand), and only patched the C* system (via SP1b) to mimic the proper C*U system.    The proper way would have been to have completely remodeled the FBW system from the ground up instead of patching the logic that was wrong to begin with.     We are currently having to live with the resultant compromise and I'm more than a little disappointed with PMDG for this, but oh well.     Maybe a fix will come in a future patch down the road.      

[aceridgey 330]

[martin-w 3,235]

I must admit, I always use the trim ref speed on the PFD.

[Orlando Younts 0]

For added fun, try manually trimming the PMDG 777 straight and level, with or without autothrottles engaged. Mine goes into an endless phugoid oscillation by about 200 feet either side of trimmed reference speed.     I'm guessing our friends at PMDG have managed to mess this part up as well.    Yay.

 

This will be the last product I ever purchase from PMDG.    I've never experienced so much repeated frustration. The product is hopelessly flawed and either PMDG address this or they need to stop inferring they are trying to to develop real-world training aids and concentrate on marketing software to 13 year olds who will never know the difference.    

 

Heck PMDG, might as well add some rockets to the 777 and make it more appealing to your core demographic.      Would be about as realistic as the trash your selling now.   

 

The initial release of the RTM version with the wrong FBW logic, along with an entire year to issue a 'fix' which even now does not work properly is inexcusable.      There is sheer genius on the PMDG development team as evidenced by the depth of systems modeling on the 777, but there is also sheer incompetence on the part of whoever develops flight dynamics.     Unfortunately, incompetence always has a subtle way of completely undermining genius when the two are paired.   

 

The hard drive space the PMDG 777 takes up is worth more than the product that occupies it.      Easily fixed though.     :mellow:

[jcomm 5,939]

For added fun, try manually trimming the PMDG 777 straight and level, with or without autothrottles engaged. Mine goes into an endless phugoid oscillation by about 200 feet either side of trimmed reference speed.     I'm guessing our friends at PMDG have managed to mess this part up as well.    Yay.

 

This will be the last product I ever purchase from PMDG.    I've never experienced so much repeated frustration. The product is hopelessly flawed and either PMDG address this or they need to stop inferring they are trying to to develop real-world training aids and concentrate on marketing software to 13 year olds who will never know the difference.    

 

Heck PMDG, might as well add some rockets to the 777 and make it more appealing to your core demographic.      Would be about as realistic as the trash your selling now.   

 

The initial release of the RTM version with the wrong FBW logic, along with an entire year to issue a 'fix' which even now does not work properly is inexcusable.      There is sheer genius on the PMDG development team as evidenced by the depth of systems modeling on the 777, but there is also sheer incompetence on the part of whoever develops flight dynamics.     Unfortunately, incompetence always has a subtle way of completely undermining genius when the two are paired.   

 

The hard drive space the PMDG 777 takes up is worth more than the product that occupies it.      Easily fixed though.     :mellow:

 

I believe you, after reading what you wrote, will at least agree that you're being rude with your words.

 

AFAIK, a complex system like the Boeing FBW / C*U Law had never been implemented for MSFS ?  

 

I got the 777 soon after release, and although the problems with trimming were there, I confess I found the whole simulation an exceptional implementation, given the limitations of the underlaying platform, of what a 777 is IRL. Add to it all of the functionality provided for users to configure specific aircraft options, the new features added after SP1, and I really find this product an excellent one, even with it's present limitations.

 

This being said, I confess I no longer have FSX installed, nor P3D. X-Plane 10 is another platform that PMDG will embrace and, I look forward for their first product to that platform, although, again, I only use it as a scenery generator for another simulator.

 

The quality of this 777, and other previous PMDG products keep me polling this forum almost every day, because indeed I do miss my NGX, and the 777 !

 

So, admit you went probably a bit too far in they way you wrote your post Orlando, which was really not necessary, at least because it won't certainly contribute to get fixed what still needs to be fixed, right? 

 

Let's hope for upcoming patches, and for a final 777 that will be totally up to the level that PMDG has reached with all of their products ( well, less those first for the Fly! platform I really got mad at them for letting go :-(, but that was looooong ago... )

[scandinavian13 5,192]

For added fun, try manually trimming the PMDG 777 straight and level, with or without autothrottles engaged. Mine goes into an endless phugoid oscillation by about 200 feet either side of trimmed reference speed.     I'm guessing our friends at PMDG have managed to mess this part up as well.    Yay.

 

This will be the last product I ever purchase from PMDG.    I've never experienced so much repeated frustration. The product is hopelessly flawed and either PMDG address this or they need to stop inferring they are trying to to develop real-world training aids and concentrate on marketing software to 13 year olds who will never know the difference.    

 

Heck PMDG, might as well add some rockets to the 777 and make it more appealing to your core demographic.      Would be about as realistic as the trash your selling now.   

 

The initial release of the RTM version with the wrong FBW logic, along with an entire year to issue a 'fix' which even now does not work properly is inexcusable.      There is sheer genius on the PMDG development team as evidenced by the depth of systems modeling on the 777, but there is also sheer incompetence on the part of whoever develops flight dynamics.     Unfortunately, incompetence always has a subtle way of completely undermining genius when the two are paired.   

 

The hard drive space the PMDG 777 takes up is worth more than the product that occupies it.      Easily fixed though.     :mellow:

 

That's...so very mature of you.

 

...also, for what it's worth, the people who swear up and down publicly that they'll never get something again are usually the first in line for the next product.  I can't tell you how many times I heard passengers say that and then put them on a plane the next week or month.

 

If this is your last product then why stick around?  Just leave and take your vitriol and armchair knowledge with you.

 

 

 

 

 

 

All the ignorance and petulance aside, if you have critiques, you should submit tickets so that they can be evaluated and incorporated into the fixes you so desire.  This is not the avenue for asking for fixes, or providing feedback you hope will be incorporated in fixes.  If you're such an expert at the level you're inferring you are, submit a ticket and be part of the solution you claim you need.

 

Anything else is you just bleating like a small child.

[777simmer 117]

For added fun, try manually trimming the PMDG 777 straight and level, with or without autothrottles engaged. Mine goes into an endless phugoid oscillation by about 200 feet either side of trimmed reference speed.     I'm guessing our friends at PMDG have managed to mess this part up as well.    Yay.

 

This will be the last product I ever purchase from PMDG.    I've never experienced so much repeated frustration. The product is hopelessly flawed and either PMDG address this or they need to stop inferring they are trying to to develop real-world training aids and concentrate on marketing software to 13 year olds who will never know the difference.    

 

Heck PMDG, might as well add some rockets to the 777 and make it more appealing to your core demographic.      Would be about as realistic as the trash your selling now.   

 

The initial release of the RTM version with the wrong FBW logic, along with an entire year to issue a 'fix' which even now does not work properly is inexcusable.      There is sheer genius on the PMDG development team as evidenced by the depth of systems modeling on the 777, but there is also sheer incompetence on the part of whoever develops flight dynamics.     Unfortunately, incompetence always has a subtle way of completely undermining genius when the two are paired.   

 

The hard drive space the PMDG 777 takes up is worth more than the product that occupies it.      Easily fixed though.     :mellow:

I think we have established (without your help) that the PMDG777 FBW is not perfect.

 

But it is useable and with the FBW trim ref speed displayed it is easy ti trim.

No, it should not have to be like that, but if this is the end of PMDGs effort as far as the FBW system concerns then I can live with it.

The rest of the simulation is fantastic.

 

You first post actually summorised quite well what the problem with the FBW system is. You found nothing new though. This has all been posted already by quite a few others participating in this thread.

But the more people notice that the FBW behavior is not perfect the better the chances that PMDG might have another go at it.

 

Too bad that your next post had to be very rude and childish :-(

 

That is not helping at all and I would ask you to either refrain from that kind of behavior or just leave.

Any ideas that you have (or complaints) can be posted here and should then be directed directly at PMDG also.

[JRBarrett 3,074]

The initial release of the RTM version with the wrong FBW logic, along with an entire year to issue a 'fix' which even now does not work properly is inexcusable. There is sheer genius on the PMDG development team as evidenced by the depth of systems modeling on the 777, but there is also sheer incompetence on the part of whoever develops flight dynamics. Unfortunately, incompetence always has a subtle way of completely undermining genius when the two are paired.

Nice troll "Orlando". Or should I say "Bruce Arnold"?

 

Your opinions about the competency of PMDG have no more validity now did those of "Bruce" when he was trolling this same thread before wearing out his welcome at Avsim.