But all in all we are impressively close to the real thing :-)

Great to read from a real 777 pilot. Do enjoy reading your posts on the 777.

 

 

Can't you?

 

I wasn't the one complaining about the FBW, was I?  :wink:

I love complex aircraft sims and I fly the 737 NGX all the time, but I'm really scared to purchase the 777 right now.     It just doesn't seem like FSX is truly capable of fully modeling FBW systems properly from what I'm reading in this thread.     If a real B777 pilot is still saying the FBW trim is not working completely right after all of this time, I just don't hold out any more hope.    

 

Maybe the 747v2 won't have to deal with these kinds of issues as it's a more conventional aircraft.      Think I'll hold out until that is released.    

 

 

Signed,

 

Arnold Bruce

Arnold, I respect your caution but am compelled to say that, should you take a pass on the 777 as a result of this discussion, then you'll be missing out on a great simulation. It really does fly well, particularly after the latest service pack, and I interpret the comments here, all by folks who are actually flying this wonderful beast in FSX, as enthusiastic critiques from knowledgeable sorts who can't help themselves but delve into the finer points of the simulation.

 

But maybe I'm wrong...

I wasn't the one complaining about the FBW, was I? :wink:

Of course not but you implied the FBW wasn't able to fly the 777 as per the FCOM when it clearly can. That's why I quoted you.

I was backing up the performance of the sim. Rob's observations back it up as well. I was simply noting that the FCTM can't be used as an absolute. Just because it's in the manuals doesn't mean that it can escape the laws of actuality. That's not to say that the plane won't behave like the FCTM claims, but in the end, physics wins. There's a reason there's a difference between the EST and ACT columns on flight plans: no matter what the books, or the fancy flight planning software says, the real world is a highly variable place. Sure, the FBW might eliminate a lot of the back pressure required, but I wouldn't be surprised if you still have to hold in a little on the roll in (as is supported by the pilot in the thread).

Kyle, adjusting pitch initially, as Rob said, is one thing. Maintaining back pressure in the turn, which you suggested might be necessary is quite another. The latter is what people are expecting to see, more or less. And, more or less that is what the 777 is giving them. Just like Airbus FBW it isn't perfect and there are overshoots and wobbles. I suspect the problem here is some people are expecting it to be exact the entire time, and that isn't the case. Another problem is trying it with a joystick controller. It's not easy to separate pitch and roll inputs perfectly, unlike with a yoke.

 

Also, FBW is a closed loop system, just like an autopilot, and it can eliminate completely the pitch input required of the pilot in level coordinated turn. It's not like a mechanical system which might be misrigged. There is a pitch input of course, but it's provided by the FBW, the pilot doesn't feel it. If course if there's any turbulence, etc then it won't do this perfectly. That's why whenever I've checked this out I've selected "Clear Skies" theme.

 

Let me make this clear, I'm agreeing with you in the main. The only thing I disagree with you on is the idea that it isn't going to work as per the FCOM in practice for reasons of physics and the laws of the universe.

I'm holiday for one day and the thread goes sour. Tut Tut gentlemen! :-P

 

Now, can people do an experiment for your OP.

 

Settle the aeroplane at a constant altitude and speed 240knots (use ap to stabilise under the above conditions if you want and then obviously disconnect).

 

Then add a small amount of back pressure and select trim nose down (increasing trim ref speed) heavily. Relax your joystick in neutral and wait one second, does the aircraft suddenly pitch?

 

Post your results please,

 

Cheers guys!

 

Alex

I'm holiday for one day and the thread goes sour. Tut Tut gentlemen! :-P

 

Now, can people do an experiment for your OP.

 

Settle the aeroplane at a constant altitude and speed 240knots (use ap to stabilise under the above conditions if you want and then obviously disconnect).

 

Then add a small amount of back pressure and select trim nose down (increasing trim ref speed) heavily. Relax your joystick in neutral and wait one second, does the aircraft suddenly pitch?

 

Post your results please,

 

Cheers guys!

 

Alex

Hi Alex,

 

I tried your experiment a couple of times, but I didn't get any sudden pitch changes when I released the column, just a smooth pitch down. I was flying the -300ER but I don't think the airframe will make a difference.

 

Cheers

 

Kevin

Hi Alex,

 

I tried your experiment a couple of times, but I didn't get any sudden pitch changes when I released the column, just a smooth pitch down. I was flying the -300ER but I don't think the airframe will make a difference.

 

Cheers

 

Kevin

 

Same experience here, Kevin, and I tried this with both the 777F and the 300ER.

I am still getting this issue. 

 

Shall I make a video?

 

Alex

I am still getting this issue.

 

Shall I make a video?

 

Alex

By all means. Videos and pics are the best way to make sure we are all talking about and looking at the same thing.

I'm holiday for one day and the thread goes sour. Tut Tut gentlemen! :-P

Now, can people do an experiment for your OP.

Settle the aeroplane at a constant altitude and speed 240knots (use ap to stabilise under the above conditions if you want and then obviously disconnect).

Then add a small amount of back pressure and select trim nose down (increasing trim ref speed) heavily. Relax your joystick in neutral and wait one second, does the aircraft suddenly pitch?

Post your results please,

Cheers guys!

Alex

Just one thing......

In your post above you wanted people to try pulling up and then trimming nose down.

But you can only trim in the same direction as you are moving the elevator (in the real 777).

This was simulated correctly in the first version of the PMDG777.

I have not checked in SP1b yet, but if trimming in the opposite direction is now possible then you discovered something that got broke in SP1b. You should also submit a ticket to PMDG in that case.

 

The info about opposite trimming not being possible is a little hidden, but I finally found something in the manuals. See the last paragraph under STABLIZER SHUTDOWN on page 9.20.13 of PMDG777_FCOMv2.pdf.

 

So if you make a video of the example you gave us......and if the PMDG777 is simulated correctly in SP1b, then we should see no STAB trimming taking place when you pull up but trim nose down.

By all means. Videos and pics are the best way to make sure we are all talking about and looking at the same thing.

Just one thing......

In your post above you wanted people to try pulling up and then trimming nose down.

But you can only trim in the same direction as you are moving the elevator (in the real 777).

This was simulated correctly in the first version of the PMDG777.

I have not checked in SP1b yet, but if trimming in the opposite direction is now possible then you discovered something that got broke in SP1b. You should also submit a ticket to PMDG in that case.

 

The info about opposite trimming not being possible is a little hidden, but I finally found something in the manuals. See the last paragraph under STABLIZER SHUTDOWN on page 9.20.13 of PMDG777_FCOMv2.pdf.

 

So if you make a video of the example you gave us......and if the PMDG777 is simulated correctly in SP1b, then we should see no STAB trimming taking place when you pull up but trim nose down.

 

I'll look into it Rob, thank you so much for your time and effort, I'll get back to you

The PMDG 777 pitch trim has never worked properly from the very beginning of the release of the RTM version, and at the current SP1b juncture it still does not behave like the real aircraft.      Aceridgey, I am seeing all of the same issues you are reporting;  you are far from alone with your experience.     Pitch trim is unpredictable, inconsistent, and hopelessly imprecise.   

 

PMDG need to be upfront and acknowledge this ongoing issue,  and also be completely honest about their ability to address it.     As it stands, using the 'cheat' trim reference speed indicator on the ADI is the only way to consistently achieve any kind of precise manual trim.    It should not be this way, and if PMDG cannot fix it, they need to state such.    

 

Signed,

 

Arnold Bruce

 

Trim can't work the same way as the real 777, because you don't have force-feedback yokes that "feel" heavy (trying to pull the pitch axis of the yoke toward the trimmed position) that get 'lighter' the more you trim (trying to pull the pitch axis of the yoke toward the position it is already in).

The "Trimmed position" of a flightsim joystick or yoke is its "middle" position. So to trim out the forces you would either need a really expensive million dollar yoke system with biasies and hydraulics and springs and stuff.

 

Or you need to push the yoke back to its neutral position as you roll the trim.

 

In the real jet you hold the yoke (against the force trying to move it) in the position you need to maintain pitch, then trim the thing till the yoke stops trying to move on its own out of the position it is already in.

 

So if PMDG fix it so it works exactly like the real 777 works, then we will all need to trade in our Saiteks and get Boeing yokes worth more than the average house.

Trim can't work the same way as the real 777, because you don't have force-feedback yokes that "feel" heavy (trying to pull the pitch axis of the yoke toward the trimmed position) that get 'lighter' the more you trim (trying to pull the pitch axis of the yoke toward the position it is already in).

 

The "Trimmed position" of a flightsim joystick or yoke is its "middle" position. So to trim out the forces you would either need a really expensive million dollar yoke system with biasies and hydraulics and springs and stuff.

 

Or you need to push the yoke back to its neutral position as you roll the trim.

 

In the real jet you hold the yoke (against the force trying to move it) in the position you need to maintain pitch, then trim the thing till the yoke stops trying to move on its own out of the position it is already in.

 

So if PMDG fix it so it works exactly like the real 777 works, then we will all need to trade in our Saiteks and get Boeing yokes worth more than the average house.

What you describe isn't unique to the 777. All aircraft are like this. Artificial feel forces in the real aircraft are not the problem. Most large airliners have such systems. Apart from it being able to trim opposite to column input I don't see much significantly wrong with the current 777 trim simulation in SP1b. Some users are clearly still having problems but I don't think that is to do with the simulation but with the hardware being used and set up inside and outside the 777.