Trimming and how it is done.

[willywonka 36]

Just go by the manuals as they are the final authority a forum is not the best place to learn about this plane unless the poster is a VERIFIED rw pilot.

Well, that's the confusing part. There's a group saying that PMDG doesn't fly like what is described in the manual, while there are a few real pilots saying it does!

[Auralumin 1]

My philosophy regarding trim is this: Trim is used to reduce pilot fatigue by reducing the need for control input once establishing stable flight. That means getting your power settings and aircraft attitude more or less settled before trimming regardless of climb, cruise, or decent. Attempting to trim while not in stable flight often results in chasing the trim and adding to the workload instead of reducing it.

[dravid kenyala 6]

Nice of all for the updates and clarifications regarding trim. Thanks a lot

[Airbusman330 300]

Well, that's the confusing part. There's a group saying that PMDG doesn't fly like what is described in the manual, while there are a few real pilots saying it does!

If the real pilots are saying its good then its good, when you think about it half of the "bugs" reported here are the result of user error or ignorance.

[3-2-1-Now 126]

Well, that's the confusing part. There's a group saying that PMDG doesn't fly like what is described in the manual, while there are a few real pilots saying it does!

 

The only real-world 777 pilot that I know of here, agrees that the FSX behavior is wrong. On a recent flight he tested the trim behavior, and he *HAD* to manually trim the real aircraft for speed changes. The sim however, will auto-trim, which is incorrect.

 

Note carefully that where the sim is wrong is with auto-trimming of speed changes. It correctly handles config changes.

 

Best regards,

Robin.

[Cowl 11]

If the real pilots are saying its good then its good, when you think about it half of the "bugs" reported here are the result of user error or ignorance.

 

There are real 777 pilots here who say it is not good. Maybe the ones who claim it is ok, have not tested thoroughly this issue and just skimmed over. There is pilot in particular, very experienced on the T7, a captain, who has carefully tested all this on the REAL airplane, and he finally stated that, as I also think, the simulation is not ok. I firmly trust what this pilot says.

 

I'm a real pilot. I do not fly or have flown the 777. I actually fly the 737 but, with my experience as a pilot and in studing FCOMs, etc, testing the handling characteristics of the PMDG 777 I can say that PMDG does not fly as per documentation regarding this issue of FBW. The first thing I do when purchase and FSX aircraft, is to hand-fly it extensively to see how it feels and behave because I love hand-flying. I inmediately felt something was not ok. I then studied the FCOMs, everything regarding FBW, handling charateristics, etc and I concluded the FBW is not correct.

 

Some others fellow simmers, very experienced and knowledgeable, and real pilots who love flight simulation just like me,  have felt the same issue themselves and agreed there is some kind of bug here.

 

And finally, you got it some posts upwards. PMDG became aware of this, they must have tested themselves, and finally concluded that we were right and fixes were to be carried out, and so they have, which I find fabulous....Don't we forget this is PMDG, and they are absolute professionals. If something is worng they do their best to fix it and for this one it seems it was wrong. In the same way if something is working ok though there are people who think it isn't, PMDG let them know why and authoritatively.

 

Cheers.

[zmak 331]

I have to ask: Where did you find connection between flight plan and trimming an aircraft?   :blink:

He wont be doing much manual trimming if he hits the autopilot at 1000ft and then does an Autoland.  you would need a flight plan for that

 

But if he fires up FSX and just does trim training he wont need a plan lol. I did make that clear in an earlier post

[hopskip 253]

Trimming only happens when the autopilot is off. If you try to trim manually with the autopilot on, the autopilot will actually turn itself off (and then the big warning sound will start till you press the Autopilot Disconnect button on the yoke/stick, or turn the autopilot back on).

 

Assuming you are manually flying your descent/glidepath/approach it's pretty simple, use the yoke (hereby called "Stick" because, whatever)

 

Getting too high? Push the stick forward.

 

Are you pushing the stick forward to maintain the attitude you want without moving? use trim so that you can release that pressure on the stick.

 

So, lets say I have let the stick go. The aircraft is pitching up which is causing it to reduce it's descent rate, (or climb) and also loose speed. I don't want it to climb, or slow down, so I push the stick forward, enough to maintain the pitch I want.

 

Now I don't like holding the stick forward all day, so I push the "trim aft (for me this is Joystick Button 3, or numpad number 7)" button enough so that I can release the stick, and keep the pitch I want at the same time.

 

pushing the trim button and moving the stick back to 'neutral' at the same rate using hand/eye co-ordination. Once the stick is released again, use the trim to make the last fine adjustment. If the adjustment gets out of hand, push/pull the stick again and start the process over.

 

Push stick first. Establish the attitude you want, then trim out the stick back to neutral.

 

It's more a feel than an adherence to numbers. You don't want to be using too much muscle to keep the status-quo. Neutral stick should = not much movement in pitch attitude. Use the trim to set up that Neutral stick.

 

If you want to change the pitch (to change your rate of decent/climb or in response to speed changing your rate of descent/climb) then pull/push the stick, and then trim the forces out once you're happy with the new pitch.

 

It's possible to use the trim without moving the stick to adjust the neutral point, but I'd only use that to "keep" the current attitude as you change speed, not to initiate a change in attitude, which should be done on the stick first.

 

If the air is turbulent, and the pitch is moving around a lot, use the stick more than the trim. You should 'feel' that there is a 'centre' somewhere around which you are yodelling the stick around in response to turbulence. Moving the trim will move that 'centre' point forward or backward in the movement range of the stick. Use the trim to put this where you want it, but be ready to move the stick forward/backward to counter the turbulence at any time. You have quicker control over the stick input than the trim, so resort to that first.

[lekijiji 15]

I'm really really impressed by the extremely relevant issues you guys arise in this forum.

Trimming in the 777 is actually not at all as trivial as some may think.

The fly by wire system in the 777 introduced some very new concepts to the trimming techniques as well.

 

The concept of "put the aircraft where you want it, then trim out the residual forces" thing, is still valid in the 777 just like in most other planes BUT on this plane the pilot needs to

 

TRIM ONLY FOR SPEED CHANGES

 

Once trimmed for a specific speed, any changes in attitude (level off; climb; turns; descends...) DO NOT REQUIRE any trim adjustments.

 

Trim System in the 777 trims at a constant rate of 10kts per second throughout the flight speed envelope SO, if you need to accelerate from say 250 to 300kts, manually push the controls down to achieve that speed and trim the plane down for 5 seconds. You should now be right in trim.

 

Trim "Blip" function.

Once your Trim Reference Speed is within 5kts from your Actual speed, a blip will synch to the Actual speed.

If at your first attempt to trim the aircraft for a 300 kts attitude, you managed to trim it at say 296, a "blip" on the trim will synchronize your Trim Reference Speed to the Actual one.

 

This is just a quick recap of another very complex system, but I hope I gave you some kind of useful explanation

[Flamin_Squirrel 71]

Trimming only happens when the autopilot is off.

tl;dr. The above is wrong though, the AP will trim when in use.

[FLEX1978 373]

He wont be doing much manual trimming if he hits the autopilot at 1000ft and then does an Autoland.  you would need a flight plan for that

 

But if he fires up FSX and just does trim training he wont need a plan lol. I did make that clear in an earlier post

hehe, since when do you need a flight plan to use the autopilot or autoland?

[martin-w 3,234]

This is so weird. Ever since the release there's a group of people saying that PMDG is wrong, and another group saying the PMDG is right... and there are real 777 pilots in both groups!

 

So now I hadn't been flying the 777 very much because I'm afraid to learn it incorrectly.

 

There is no "group of people". There was one 777 pilot that was unsure. After the confusion was addressed... he too regards the issue as present.

 

There is no debate.

 

From the moment I installed the 777 and hand flew I knew it was wrong. Precisely why I was one of the first to mention the issue, if not the first. If you know anything about the T7, and can read the relevant information available, it's clear it's wrong. Precisely why PMDG  has apparently rewritten the code.

 

As for "I'm afraid to learn it incorrectly", that doesn't apply. The real world T7 trims for speed just like any aircraft, according to real world 777 pilots on this forum. The relevant documentation confirms the same. I'm sure you have trimmed an airliner add-on before, so there's nothing revolutionary for you to learn in this respect.

[Flamin_Squirrel 71]

As a last resort you can disconnect the flight computers when you're on approach and want to hand fly. You'll lose auto-spoilers though.

[cagrikartal 8]

ive just flew with the primary flight computers disconnected and it is quite easier to fly than the computers on.

[Flamin_Squirrel 71]

ive just flew with the primary flight computers disconnected and it is quite easier to fly than the computers on.

 

Good stuff  B)