I can't figure out the technique either. I get the whole trimmed for speed thing, but I can't fly the flight path I want.

 

I checked several sources now (all real-world) and the wording is such that it strongly implies the system will auto-trim to maintain flight path.

 

It is C*U law (C Star U), meaning it will maintain the FLIGHT PATH automatically (Airbus style via auto-trim), and in the trimmed condition, will maintain speed (so increase in thrust will result in climb in order to maintain speed).

 

Thus, if you fly manually, and stabilize the speed at e.g. 250 kts when levelling off, when you let go of the stick (return to neutral), it will trim for 250 kts and level flight (assuming you maintain good speed control). It seems this is not quite how the sim is operating however.

 

Best regards,

Robin.

I do think you understand how it works but just to make it clear...

 

The 777 autotrim tries to maintain path.

It is not locked on a path like following a GS and it is not as...how do you say this....rigid? as Airbus. It only TRIES to help you compensate for things but its not like you can let go of the yoke and do nothing while extending flaps or so and expect the plane to keep its altitude.

It just reduces the effect of pitch up after adding thrust, requirement for pulling on the yoke while turned, etc etc.

 

"it will trim for 250 kts" hmmm,....

 

IT wil do nothing.

It does not automatically trim to the speed you are at!

You will have to trim the yoke forces away (just like Cessna)

If you dont and let go of the yoke (to neutral) it will pitch up or down to reach the PFC trim reference speed that is still set.

 

If you were climbing/descending already with 250kt and then level off, yes.

The airplane (PFC speed) was 250kt during climb and will remain 250kt after level off.

Again, just like a Cessna.

 

I am just confirming things here...not saying you got it wrong.

That is correct.

 

You know what....maybe you are having a similar problem as the person in another thread.

He could not trim because the PMDG777 is made so realistic that just like the real aircraft it will not allow trim imputs nose down while you are pulling on the yoke (and vice versa).

You can only trim in the direction you are pushing or pulling the yoke.

 

Sounds logic......but maybe when you let go of the yoke it is not perfectly centered!

The yoke could then send an ever so small pitch up signal while you are trying to trim down.

 

Try increasing the dead band of the pitch axis!

 

 

Don't think that's the issue for me  Rob.

Don't think that's the issue for me Rob.

Ok it was just an idea.

 

Instead of reinstalling Fsuipc, why dont you try without it at first and setup controllers via FSX menu.

Also some guys with throttle problems had to make FSUIPC see the axis....but not calibrate it within FSUIPC.

Can you try that for pitch/roll/bank as well?

 

Here:

http://forum.avsim.net/topic/419504-throttle-problems/

 

There seem to be only a few (you guys) reporting this.

So since so many use FSUIPC, does it work correctly for them?

Or did they post their problems at the FSUIPC forum?

Maybe check there as well.

 

 

The second point of course, is the weird way you can "not trim" and just maintain level flight with the elevators

 

I certainly notice an 'auto-trimming' effect on the elevator.   Like @T1492 said, I've never needed to use trim once in flight (only on the ground before flight) as the aircraft certainly appears to autotrim.

 

I must admit that - knowing that it's a FBW aircraft - I just assumed this was realistic.   But then from the different posts on this thread I can't decide whether we've landed on the 'autotrimming' effect being realistic or not? :lol:

 

I have to say, I do enjoy this effect, and I would be surprised if PMDG had got something so fundamental, wrong.

Ok it was just an idea.

 

Instead of reinstalling Fsuipc, why dont you try without it at first and setup controllers via FSX menu.

Also some guys with throttle problems had to make FSUIPC see the axis....but not calibrate it within FSUIPC.

Can you try that for pitch/roll/bank as well?

 

Here:

http://forum.avsim.net/topic/419504-throttle-problems/

 

There seem to be only a few (you guys) reporting this.

So since so many use FSUIPC, does it work correctly for them?

Or did they post their problems at the FSUIPC forum?

Maybe check there as well.

 

 

I only use FSUIPC for wind smoothing. Don't use it for controllers. I use FSX for controller. 

 

Works great for pitch roll... just trim is the issue.

 

 

I must admit that - knowing that it's a FBW aircraft - I just assumed this was realistic.   But then from the different posts on this thread I can't decide whether we've landed on the 'autotrimming' effect being realistic or not? :lol:

 

 

 

No, none of us can find any evidence that it's realistic.

 

The T7 only trims out config changes, like flap deployment or thrust increases, not speed changes. We should still need to trim for speed changes.

Hi everyone...

 

I would very very much appreciate if someone from the PMDG staff and/ore some real 777 pilot should say something about this issue.

 

I'm also experiencing this sort of airbus-like auto-trim behaviour, wich I think doesn´t match with what the FCOM is telling about the FBW normal law behaviour.

 

I mean, for example, I take-off without using AFDS, ie, handflying, no autothrottle and no autopilot at all. With the pitch trim adjusted on ground for my weight and CG location, say 2.5 anu in this case. I rotate and go airborne....I stablish 15º nose-up. After a few seconds maintaing 15º, if release de control column, the aircraft is in trim by magic...

 

If now I increase pitch attitude to say 20º nose-up, just the same...after a few seconds maintaining 20º, if I let go the control column to neutral steadily, the aircraft is again more or less in trim by bagic and will maintain that attitude and correspondig airspeed.....and all of this without having made any trimming by myself.

 

I think this is NOT normal....and if I'am/we're doing something wrong, I would appreciate someone would give us an authoritative explanation about this one.

 

Thank you very much in advance.

Anyone using PFC Cirrus 2 Rs232 setup?

I mean, for example, I take-off without using AFDS, ie, handflying, no autothrottle and no autopilot at all. With the pitch trim adjusted on ground for my weight and CG location, say 2.5 anu in this case. I rotate and go airborne....I stablish 15º nose-up. After a few seconds maintaing 15º, if release de control column, the aircraft is in trim by magic...

 

If now I increase pitch attitude to say 20º nose-up, just the same...after a few seconds maintaining 20º, if I let go the control column to neutral steadily, the aircraft is again more or less in trim by bagic and will maintain that attitude and correspondig airspeed.....and all of this without having made any trimming by myself.

Ok hard to check all this because I still dont have the plane......Day after tomorrow I will though.

 

But to your first remark:

The goal of calculating the T.O. trim value is that after you rotate to 15degrees this trim should pretty close to what you need to maintain V2+15. So no magic there if no trimming is needed. Its suppossed to be like that.

 

To your second remark:

Ok you are handflying (AT + AP off) and you increase pitch from 15 to 20 degrees you would loose airspeed. If you let go of the yoke the nose should drop down.

However, if ofcourse you are adding thrust to keep the airspeed from reducing while pitching to 20 degrees....then yes, you are still trimmed and you dont need to retrim.

(you added thrust to keep the airplane at the trimmed airspeed but at an increased pitch attitude)

Don't think that's the issue for me  Rob.

I am just giving ideas here ok, but do you have the realistic sliders all at max?

I have to say I am not sure about this yet myself. Been trying to understand it by flying it and have to say I don't yet. I have experienced most of the issues brought up in this thread. 

 

Tomorrow I will be doing some reading on this myself to see if it seems correct or not and I will also try not mapping through FSUIPC.

 

Regards.

Whoa - I'm generally surprised by all of this. I think she's easier and nicer to hand fly than anything else I've ever experienced in FSX. Whether its "realistic" or not can only be judged if you've flown the real thing.

Ok hard to check all this because I still dont have the plane......Day after tomorrow I will though.

 

But to your first remark:

The goal of calculating the T.O. trim value is that after you rotate to 15degrees this trim should pretty close to what you need to maintain V2+15. So no magic there if no trimming is needed. Its suppossed to be like that.

 

To your second remark:

Ok you are handflying (AT + AP off) and you increase pitch from 15 to 20 degrees you would loose airspeed. If you let go of the yoke the nose should drop down.

However, if ofcourse you are adding thrust to keep the airspeed from reducing while pitching to 20 degrees....then yes, you are still trimmed and you dont need to retrim.

(you added thrust to keep the airplane at the trimmed airspeed but at an increased pitch attitude)

I am just giving ideas here ok, but do you have the realistic sliders all at max?

Hi 777simmer.

 

I'm an airline pilot currently flying the 737 and you really got me with the initial trim being  to be in trim for V2+15...I forgot all about that time ago...I just pitch for my speed and apply trim as necessary to relief pressure on the column

 

With regard to my handflying example, may be I expressed myself worng. I'm trying to explain it better now.

 

Just imagine the PMDG 777, with our intial trim set for our weight and CG, we have already taken-off.

I'm handflying the airplane, already in climb thurst. I've just retrated the flaps and I'm at aprox. 210 kts accelerating for my goal 250 kts. I just manage my pitch in order to attain and maintain 250 kts and at the moment I have not touched the trim.

 

Suppose that I know have attained 250 kts with pitch (I do NOT touch thurst; it is in CLB thrust). Well, imagine that the pitch attitude that is giving me 250 kts it 15º nose up. Well, what I wanted to say was, that if I now release back pressure on the control column, letting it go to neutral and still NOT touching the trim at all, I find to my surprise that the aircraft is in trim by magic at 250 kts 15º nose up...

 

No suppose I apply back pressure in order to lift the nose up to 20º, still on climb thrust, willing to accept the new speed at 20º. Imagine that now at 20º nose up, my speed has dropped to 230 kts. Well, if I let go the control column to neutral, again, the aircraft is in trim at this new attitude and speed, and I haven't touched thrust and have not touched the trim at all. The aircraft auto-trims itself, just like an Airbus does, but as far as I know, and as per the FCOM, this is not the way a 777 should behave....and I've been seeing on the forum this evening in several threads that a lot of people is noticing and very confused with this issue.

 

I hope I've expressed myself clearly this time.

 

Thanks for answering  777simmer.

I just finished a flight without touching the trim except for takeoff trim. I hand flew it up to 8000ft and disabled AP 2000ft on approach. It did autotrim. Wheather it was realistic or not, it was easy as said above.

I just finished a flight without touching the trim except for takeoff trim. I hand flew it up to 8000ft and disabled AP 2000ft on approach. It did autotrim. Wheather it was realistic or not, it was easy as said above.

A lot different from my perspective I have noticed it is a heavier airplane (not unexpected) which reminds me of the level d 767. I also love the auto trim reminds me of the airbus but while I'm flying a Boeing. :lol:

Just imagine the PMDG 777, with our intial trim set for our weight and CG, we have already taken-off.

I'm handflying the airplane, already in climb thurst. I've just retrated the flaps and I'm at aprox. 210 kts accelerating for my goal 250 kts. I just manage my pitch in order to attain and maintain 250 kts and at the moment I have not touched the trim.

 

Suppose that I know have attained 250 kts with pitch (I do NOT touch thurst; it is in CLB thrust). Well, imagine that the pitch attitude that is giving me 250 kts it 15º nose up. Well, what I wanted to say was, that if I now release back pressure on the control column, letting it go to neutral and still NOT touching the trim at all, I No suppose I apply back pressure in order to lift the nose up to 20º, still on climb thrust, willing to accept the new speed at 20º. Imagine that now at 20º nose up, my speed has dropped to 230 kts. Well, if I let go the control column to neutral, again, the aircraft is in trim at this new attitude and speed, and I haven't touched thrust and have not touched the trim at all. The aircraft auto-trims itself, just like an Airbus does, but as far as I know, and as per the FCOM, this is not the way a 777 should behave....and I've been seeing on the forum this evening in several threads that a lot of people is noticing and very confused with this issue.

 

 

Ok, yes that is what the others have described as well.....and it is way off!

That is so wrong that IF this is true (and I will find out tomorrow) that this is the biggest bug of them all, and I will regret having bought an Airbus Boeing only moments after purchase :-(

 

Leaves problems like more OOM sensitive than the NGX and lower fps than the NGX as distant second and third place problems!

 

I cant imagine that after having spend time in real 777 simulators and having real 777 pilots on their team, PMDG felt this how the aircraft behaves?

 

I hope someone from the BETA team or the support team can comment on this!

 

 

Just to make sure.....you guys have al Realism sliders set to max correct (I doubt lower sliders will make the 777 fly like an airbus, but you never know)?

 

Regards, and stand by for my first flight experiences tomorrow.

Really glad more of you are noticing the "presumed" issues that I first posted about.

 

To be honest, [and no I'm not a real 777 pilot] it seems very unrealistic to me, and not at all akin to the documentation and research I have done on T7 trimming.

 

Despite the weird auto trimming effect, the trim in general is VERY difficult to get to grips with, it makes hand flying a chore. Oscillating up and down, chasing the trim is the inevitable result.

 

I suspect those not complaining about this, are mostly flying of autopilot, and not disengaging the autopilot until the last few hundred feet before touchdown.

 

 

The aircraft auto-trims itself, just like an Airbus does, but as far as I know, and as per the FCOM, this is not the way a 777 should behave

Absolutely Carlos, that's what I've been saying all along, since day one.

 

I hate to criticise PMDG because they are a superb developer, but it baffles me how the trim function could have been interpreted this way. And I don't understand at all how the beta team didn't query this.

 

If I am wrong, and my opinions are as a result of my ignorance, then I wholeheartedly apologise to PMDG. But I don't for a second believe Boeing would have made the aircraft very difficult to hand fly.