[SOLVED] 777 trim broken

[KL-666]

Someone in all their wisdom has added auto trim to the 777, but removed manual trim, wrongly believing it is unnecessary. Well, let me show you pilots use it all the time in manual flight.

Guess what this guy is doing moving his thumb on the yoke.

https://www.youtube.com/watch?v=hCV4sNNPSTA

Currently i use the latest 777 from Hyde's git, which should be rather the same as the one in fgmembers.

Kind regards, Vincent

[IAHM-COL]

The thing that is concerning me is that no-one but Hyde has been working on that plane

https://github.com/FGMEMBERS/777/commits/master

I don't know for sure what's going on, but I would give him a couple of days to figure out. At this point he may just be in the middle of the development rounds.

[Octal450]

The problem is in FG the trim cannot be manipulated by the pilot. In real life, Autotrim turns off, when the autopilot is disengaged. See, the autopilot does not use only the trim, and not only the elevator. It uses the elevator, and then uses the trim to hold the change. When the AP is off, it only trims, if the pilot is pushing or pulling his yoke in the same direction alot, or manually is trimmed.

Regards,

[KL-666]

The problem is in FG the trim cannot be manipulated by the pilot.

Errr, i have manipulated trim always, when there was no auto trim. So maybe you say that manual trim and auto trim can not go together in fg?

@Israel
I pm-ed Hyde on the other forum to get his attention to this (i do not post there). So, we'll see what comes from it. We already exchanged some thoughts.

Kind regards, Vincent

[jwocky]

Well, most planes don't have autotrim in FG, thus, the problem rarely occurs. And manual trim appears also to be a bit out of fashion by what I saw lately. Aside of that, it appears, that there is a lot of pumping around fuel in some planes in rl and that is part of the trim, we also lack.
So, maybe, if someone explains what is needed, en detail please, we can find a solution. Not for the 777 though, that is Hyde's baby and if he wants something, he is man enough to open his mouth and otherwise able enough to deal with it.

[Octal450]

@KL-666, I mean NOW you can't, I know before you could.

[KL-666]

And manual trim appears also to be a bit out of fashion by what I saw lately

Whoever told you that, is dead wrong. You probably did not watch the film i put in the first post here.

Specifically with speed change and configuration change (selecting flaps) in manual flight, manual trim is necessary to relieve the yoke faster than auto trim would do. The reason that auto trim reacts slow is because not every control input should immediately change trim.

Changing the CoG with fuel is another matter. In cruise the auto trim gets the aircraft always in trim with any CoG. But with less pitch the plane flies more fuel efficient, so the CoG is changed that the plane is in trim with a lower pitch.

I do not have any documents with the exact factory programming of auto trim. If anyone has (maybe even for the 777), then please let us know. To Hyde i wrote what it approximately should be like from a pilots perspective. He is going to look into that.

Let me recap what i think is best for an fg plane, without the reference speed thing.

Auto trim:

When there is elevator deflection, then after a few seconds delay (3-5), slowly adjust the stabilizer until there is no elevator deflection anymore. It should have the delay and slowness, because you do not want trim to change with every small steering movement. Only when it is sure that the pilot wants to stay in the position he is steering in, trim should go there.

Manual trim:

Immediately move the stabilizer. And maybe use a longer delay before auto trim starts messing the choice of the pilot up again (maybe 10 seconds). There has been a deliberate choice of the pilot, so that should be respected longer i think.

Kind regards, Vincent

[Octal450]

@KL-666
That sounds right, now just let Hyde know of that!

[Hyde]

Give me some time. I'm thinking how to implement this.

[IAHM-COL]

thanks for the note, Hyde