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mrvoyager

Pitch Autotrim

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I would like to know if there is a way I could increase the level of autotrim activity in both 777 versions. I am not very good at manually adjusting and maintaining the elevator levels during turns so I would like more of an airbus feeling to the pitch adjustment. I know it has some pitch autotrim thou.

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The "FBW" of the T7 does maintain the pitch during turns. So you should need very slight corrections with elevators while in turn.

But for autotrim to work in the sim properly, I have noticed at least in my sim that the yoke must be centered.

There is a setting in the simulation option of the FMC to set the deadzone % for the yoke so that the FBW maintains the trim to speed.

Also, you can display the speed setting of the trim in the option of the FMC. It is a "cheat" but in my case it is very useful as I have some difficulties to set correctly the trim while moving the yoke.

The response from the trim function of the FBW are effective only when my yoke is almost centered in the % I have set in the options.

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The "FBW" of the T7 does maintain the pitch during turns. So you should need very slight corrections with elevators while in turn.

But for autotrim to work in the sim properly, I have noticed at least in my sim that the yoke must be centered.

There is a setting in the simulation option of the FMC to set the deadzone % for the yoke so that the FBW maintains the trim to speed.

Also, you can display the speed setting of the trim in the option of the FMC. It is a "cheat" but in my case it is very useful as I have some difficulties to set correctly the trim while moving the yoke.

The response from the trim function of the FBW are effective only when my yoke is almost centered in the % I have set in the options.

What do you mean by maintaining the joke centered? How would you do this while turning? 

I just noticed that you can stimulate the autotrim by letting go of the joke after holding it back while making a turn. So before I would start a turn and pull on the elevators to maintain altitude but the autotrim would not simply raise the pitch to maintain the angle, unless I then let go of the joke a bit, so when the pitch angle goes down, only then the autotrim would move enough, but usually I have to raise the ailerons a second time so that the autotrim corrects again, so its kind of a lazy autotrim where I would have to kind of shake the airplane a few times so the flightpath is not very smooth at times, but other than that it works well. I just wished there was an option where the autotrim would be airbus like, where when you made a turn the vertical speed would be stable. I guess this is what you mean by getting the joke to be centered. What is your setting for the FMC deadzone?

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What do you mean by maintaining the joke centered? How would you do this while turning?

 

I mean only centered for the pitch (I have B737 yoke so the roll is controlled by a "wheel").

 

Regarding the option to have the FBW working like an Airbus... well, no it's a Boeing! And PMDG wouldn't give option to feel flying their Boeing anything else like a Boeing!

You have a deep ultra-realistic simulation of a T7, not a basic tasteless aircraft like other developers do!  :P

 

My settings are 5% for the deadzone.

I believe they are some limitations with fsx however that prevent a full level-d FBW rendering, which is why the auto-trim seems to work only in that deadzone.

But somebody from PMDG would need to confirm that.

There are dozens of topics in the forum regarding FBW and I'm too lazy to read them all again to find out what has been said on the matter. :ph34r:

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Regarding the option to have the FBW working like an Airbus... well, no it's a Boeing!

 

I enjoyed that.  I've never flown a Airbus and don't have any opinion of their products; however, the B77L handling is just like most any airplane.  A little back pressure in a turn is due to physics and not the physical differences between airplanes.  As the lift vector is tilted to provide lateral acceleration the vector must be increased to make up for the decrease of the vertical component. This works the same in the B777 as the Cessna 150 (although the Cessna requires the pilot to understand the use of rudder too LOL). Boeing has used control laws in the flight control systems to tame a thousand tigers hiding in the aerodynamics of this jumbo, but only to tame and not remove.  Also, PMDG has done a good job of adding a touch of control movement to answer to the lack of any feedback in most of our game controllers.

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I mean only centered for the pitch (I have B737 yoke so the roll is controlled by a "wheel").

 

Regarding the option to have the FBW working like an Airbus... well, no it's a Boeing! And PMDG wouldn't give option to feel flying their Boeing anything else like a Boeing!

You have a deep ultra-realistic simulation of a T7, not a basic tasteless aircraft like other developers do!  :P

 

My settings are 5% for the deadzone.

I believe they are some limitations with fsx however that prevent a full level-d FBW rendering, which is why the auto-trim seems to work only in that deadzone.

But somebody from PMDG would need to confirm that.

There are dozens of topics in the forum regarding FBW and I'm too lazy to read them all again to find out what has been said on the matter. :ph34r:

Oh so you mean the joke has to be centered before trimming the pitch? That's odd, I guess this is not the case for the real 777.

 

I have the areosoft airbus and I like it a bit, mostly the clinical look of the cockpit and just how easy it is to control, very responsive autotrims, but that's about it, its not as well made as the pmdg simulation.

 

I guess the joke about the airbus saying retard when landing is because the plane is so easy to handfly that its like it was made for retarded pilots and even the airplane itself knows it hah.

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Oh so you mean the joke has to be centered before trimming the pitch? That's odd, I guess this is not the case for the real 777.

 

I actually mean that the autotrim becomes really effective when I release the yoke to the center position after having set the trim setting to the actual speed. But if the bird is out of trim, I can feel it anyway even when the yoke is not centered.

But sometimes, I don't feel the change in trim setting if I don't release the yoke.

 

 

 

I guess the joke about the airbus saying retard when landing is because the plane is so easy to handfly that its like it was made for retarded pilots and even the airplane itself knows it hah.

 

Some retarded pilots may forget to retard the thrust levers during flare...  :P

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I guess the joke about the airbus saying retard when landing is because the plane is so easy to handfly that its like it was made for retarded pilots and even the airplane itself knows it hah.

 

Well, preflighting an Airbus is pretty much entering FMS data and pressing all the buttons with white lights. It's so simple you can train a monkey to do it,

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I actually mean that the autotrim becomes really effective when I release the yoke to the center position after having set the trim setting to the actual speed. But if the bird is out of trim, I can feel it anyway even when the yoke is not centered.
But sometimes, I don't feel the change in trim setting if I don't release the yoke.
 

 

Right, but I now have a question, are you supposed to constantly hold some elevator pressure when making turns? This is what I am getting, that the autotrim never fully corrects the elevators to hold altitude during turns, it doesn't compensate for g-force and power thrust changes.

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No, if my trim setting is correct and the aircraft stable in pitch before starting the turn, then I almost don't need to correct for the pitch during the turn if I do it smoothly. Sudden and brisk changes in roll may introduce some variation in pitch.

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No, if my trim setting is correct and the aircraft stable in pitch before starting the turn, then I almost don't need to correct for the pitch during the turn if I do it smoothly. Sudden and brisk changes in roll may introduce some variation in pitch.

This is what I expected but its not happening. I remember when I first tried the er with the sp1 the autotrim was more responsive. Right now, when I make a turn, the vertical speed will start to go down unless I pull the stick. After I pull the stick I must keep it there, otherwise it will start to fall again. Also the autotrim feels unstable, it will start to go up and down along the way so I have to be compensating for this, specially as the thrust starts to change.

 

I have another question, is the fbw marker on the speed tape a separate measure from the manual trim setting? I know the trim changes the fbw level thou, but I think they might be separate values.

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No, if my trim setting is correct and the aircraft stable in pitch before starting the turn, then I almost don't need to correct for the pitch during the turn if I do it smoothly. Sudden and brisk changes in roll may introduce some variation in pitch.

Also, I found that I just prefer the ngx because I feel that since it doesn't have this weird autotrim behavior by not having autotrim at all, I can actually fly it much better with smooth trim adjustments. I which I could deactivate the pitch autotrim for the 777.

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This is what I expected but its not happening

 

Full names in the PMDG forums please.

 

There's no way to tell if both you and Romain are not saying the same thing because your description is pretty vague.  When you say "when I make a turn the vertical speed will start to go down" please describe what you're experiencing. Include a few very important things like IAS, bank angle and what do you mean by vertical speed going down?  I think you mean the IVSI indicates a descent, how much? 100 fpm or 1000 fpm?  Sure makes a difference how these three factors affect turn performance.

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Full names in the PMDG forums please.

 

There's no way to tell if both you and Romain are not saying the same thing because your description is pretty vague.  When you say "when I make a turn the vertical speed will start to go down" please describe what you're experiencing. Include a few very important things like IAS, bank angle and what do you mean by vertical speed going down?  I think you mean the IVSI indicates a descent, how much? 100 fpm or 1000 fpm?  Sure makes a difference how these three factors affect turn performance.

I have my name, do I have to also include my last name?

 

What I simply mean is that when I make a turn, the vertical speed goes down, say from 0 to -500 when banking to 15 degrees unless I raise the ailerons. The autotrim is not enough to keep the plane on the 0 vertical speed level. The other thing is that there is an interaction, sometimes conflicting, between what I am trying to do with the pitch and trim and the autotrim activity, so the flight path is not very stable. With the ngx, I make a turn, raise the elevators a bit, and with good precision I can trim it to stay level.

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I have my name, do I have to also include my last name?

 

Yes sir, that is what full name means.  Numerous pinned posts by PMDG explain this policy.

 

Okay so 15 deg bank is a less than standard rate turn unless you're pretty slow and 0 -500 fpm descent would be expected unless you corrected with back pressure (nose up pitch correction).  My advice to anyone trying to figure out so-called autotrim (I really don't like that terminology) is to ignore it.  Just fly the airplane like a Cessna, in which you are required to nose up in a turn.  The optional indicator on the speed tape is more of a convenience for simulator controllers without force feedback than a real performance indicator.  The reason I don't like the term autotrim is because you don't find it in the Boeing documents.  However, PMDG did include a very thorough explanation of their implementation in the Introduction starting on page 0.00.164. That should answer to some of your concerns.

 

As mentioned earlier, I find flying the B777 very natural, easy and predictable, but I only have a few thousand hours in smaller aircraft and no simulated Airbus time.

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Okay so 15 deg bank is a less than standard rate turn unless you're pretty slow and 0 -500 fpm descent would be expected unless you corrected with back pressure (nose up pitch correction). My advice to anyone trying to figure out so-called autotrim (I really don't like that terminology) is to ignore it. Just fly the airplane like a Cessna, in which you are required to nose up in a turn.

Your advice about ignoring the autotrim system and flying the 777 like a Cessna is very sound. I do the same myself. The point being made was that even up to 30 deg bank the real 777 FBW will maintain the vertical flightpath so no pitch correction should be necessary. Assuming you are stabilised before starting to turn of course. So the natural tendency for the nose to drop doesn't happen. Beyond 30 deg bank it is allowed to.

 

If you make a pitch input inadvertently while applying wheel input then the aircraft will respond of course. Also if there are gusts or turbulence then it won't maintain altitude perfectly either.

 

As long as you keep the aircraft trimmed correctly for the current airspeed then it works well. Display the PMDG optional trim reference speed bug if it helps. Fly with small inputs. The FBW simulation isn't ideal but it works well enough if you respect its limitations.

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