how to hand fly with C*U law aircraft

[willywonka 36]

"I know what you did!!! I...Hey I saw it. You went over to the clone stamp tool, didn't you?!? Wrong! St...Put it down! We're gonna go...we're gonna go do it. That's bush league and we're gonna do it this way..."

 

 

 

(Oddly enough, you actually learn some stuff in these videos.)

I love the Donny series! I even thought about doing some of those for FSX, but can't imagine that it'd be well received ^_^

[Tabs 2,790]

Hi,

 

I have the Warthog, and before it, the SideWinder 1 from way back! That stick lasted me 10 years.

 

I do have a T.16000 stick I can try to se if it makes any difference, but I can't see why it should.

 

To those apparently NOT having the problem of the FBW system waiting for the stick to be centered before applying the trim, can you please try this?

 

* Set the trim reference speed to 320 kts, but fly at 210 kts

* To fly straight and level will require a lot of back pressure (I think you will have sufficient elevator authority to do this)

* Holding straight and level with the control column only (stick back), hold it there and trim nose up

* As you trim, do ***** NOT ***** move the stick to center! Hold it where it was the entire time

 

Does the aircraft pitch up? For me, it does NOT.

 

Video of the flight control page as you perform this test would be perfect, then I can compare here.

 

Best regards,

Robin.

 

Ok, so here's the story:

 

I was able to reproduce what Robin described here two days ago. The reason I hadn't seen it prior is that all my testing was done with the opposite scenario - trim reference speed below actual airspeed. (this was definitely a big mistake on my part to assume that the other direction worked too without testing it) After some investigation, it turned out that there was an error in the FBW code for this opposite situation where the trim reference speed was higher than the actual airspeed. This was resulting in behavior that was not at all what we intended - the control loading was barely taking effect, trimming wasn't resulting in pitching unless the controls were neutral etc. I verified in tonight's test version that this is now functioning as it should and you all should see a large improvement in being able to trim "by feel" as a result in SP1b once it's out.

[martin-w 3,234]

Great news.

 

Thanks for the update Ryan.

[James Bennett 52]

Excellent news.

[777simmer 117]

Fantastic, thx for the info :-)

[UAE77W 16]

Thanks for the info Ryan.

 

Quick question: I'm at 3000ft (MCP ALT window 3000ft), A/P engaged, A/T on speed set to 250 in MCP window, and Heading Hold mode.

 

Now I tried to do everything the EVA Air pilot on youtube told me.

So A/T at 250 still on, A/P disengage and MCP ALT window to 4000ft. So I pulled my joystick very slightly to reach an V/S of 1000ft and once reaching or at VS of 900ft I put it back to neutral, like he showed me in the video.

 

My Problem: The -300ER doesn't hold the V/S. Every few seconds the V/S decreases. In the video the -300ER (or all 777s) holds the V/S of 1000ft. I'm not touching the trim switches, like in the video.

 

 

Is this a bug and fixed in SP1b, or just my error or did I misunderstood something in the video?

- One more question: Is it normal to use forward pressure after rotation to hold F/D pitch? FBW Ref speed was set to V2+20 and A/T did a perfect job to hold V2+20 (around 185kts). In the NGX I trimmed for pitch (I know this is not the NGX)  but after 30sec. my T7 still wanted to pitch up (around 20 deg. F/D pitch was at 15 deg.) A/P was disengaged only A/T on and N1 CLB Thrust.

[willywonka 36]

 

 

My Problem: The -300ER doesn't hold the V/S. Every few seconds the V/S decreases. In the video the -300ER (or all 777s) holds the V/S of 1000ft. I'm not touching the trim switches, like in the video.

My setup holds the climb with the yoke at neutral. Check your null zones.

 

 

 

One more question: Is it normal to use forward pressure after rotation to hold F/D pitch?

If I understand the string of events correctly, this will be fixed with SP1b. 

[MauB 74]

Great news! Thank ou Ryan!

[UAE77W 16]

My setup holds the climb with the yoke at neutral. Check your null zones.

 

 

 

If I understand the string of events correctly, this will be fixed with SP1b. 

 

 

Thanks, I'll check that.

[sosuflyer 30]

Ok, so here's the story:

 

I was able to reproduce what Robin described here two days ago. The reason I hadn't seen it prior is that all my testing was done with the opposite scenario - trim reference speed below actual airspeed. (this was definitely a big mistake on my part to assume that the other direction worked too without testing it) After some investigation, it turned out that there was an error in the FBW code for this opposite situation where the trim reference speed was higher than the actual airspeed. This was resulting in behavior that was not at all what we intended - the control loading was barely taking effect, trimming wasn't resulting in pitching unless the controls were neutral etc. I verified in tonight's test version that this is now functioning as it should and you all should see a large improvement in being able to trim "by feel" as a result in SP1b once it's out.

That's awesome Ryan! Thanks to you and the team for listening to the feedback and working hard on fixes.

[cmbaviator 5]

My setup holds the climb with the yoke at neutral. Check your null zones.

 

 

 

If I understand the string of events correctly, this will be fixed with SP1b. 

 

I have the same issue

 

V/S seems decreasing even  in trim.

 

My nullzone in FSUIPC is -3500 / 3500 is that not enough ?

 

Defaut null zone in the MCDU

[willywonka 36]

I have the same issue

 

V/S seems decreasing even  in trim.

 

My nullzone in FSUIPC is -3500 / 3500 is that not enough ?

 

Defaut null zone in the MCDU

At this point, it's best to wait for SP1b and retest your setup :mellow:

[777simmer 117]

One more question: Is it normal to use forward pressure after rotation to hold F/D pitch? FBW Ref speed was set to V2+20 and A/T did a perfect job to hold V2+20 (around 185kts). In the NGX I trimmed for pitch (I know this is not the NGX)  but after 30sec. my T7 still wanted to pitch up (around 20 deg. F/D pitch was at 15 deg.) A/P was disengaged only A/T on and N1 CLB Thrust.

No fwd pressure is not normal.

 

You shuld set your STAB trim setting at the value indicated in the FMC.

I am not sure yet realistic this number is simukated (have to do more flights) but so far it seems to be around 2.75 units for every take off in the PMDG777.

But one thing you must understand is that during take off and climb, the AT is not holding speed. It is just at full T.O. thrust or Clb thrust.

YOU must hold the speed with your pitch attitude!

And you must re-trim if the nose does not stay where you want it.

Make sure Magenta Bug speed = FBW trim speed

 

As for your other problem, the PMDG777 seems to be a little less stable when it comes to holding attitude than the real thing.

It is doing pretty good though, but with AT engaged, only if you have the FBW trim ref speed set EXACTLY at you magenta speed bug (target)!

Target bug speed = FBW trim ref speed.....

otherwise you will never be in trim and pitch will be unstable (as in it will not stay where you want it to stay).

But even in the real thing you have to adjust and readjust every now and then (maybe every 5-10sec I would guess) to keep a steady vs of 700ft/min.

So the video is nice in showing how stable the real 777 is, and it is...., but I can show you a video where I would be readjusting again just the same.

 

Like I said, a little more stability in the PMDG777 would be nice it seems (seems because I really would need to do way more test flights with it to be 100% sure) but the 777 is a Boeing, and Boeings need to be actively flown....constantly!

[UAE77W 16]

Thank you very much Rob. I really appreciate your comment.

 

No fwd pressure is not normal.

You shuld set your STAB trim setting at the value indicated in the FMC.
I am not sure yet realistic this number is simukated (have to do more flights) but so far it seems to be around 2.75 units for every take off in the PMDG777.
But one thing you must understand is that during take off and climb, the AT is not holding speed. It is just at full T.O. thrust or Clb thrust.
YOU must hold the speed with your pitch attitude!
And you must re-trim if the nose does not stay where you want it.
Make sure Magenta Bug speed = FBW trim speed

 

Yep, Stab trim is set at the value indicated in the FMC. I haven't got any units around 2.75 yet. Most units were at around 4.50 to 5.25.

ZFW is mostly around 203T to 215T.

I'll try your suggestions in a test tomorrow.

 

To my other problem. I don't know how the real T7 behaves but does the 777 trim automatically to hold the pitch in general (like in an Airbus) or not?

You said you have to adjust and readjust the trim to keep a steady vs. So the 777 should not trim automatically either for speed and pitch?

But why does the pilot do not have to trim to keep his target vs of 1000ft/min? That's confusing me a little.

 

In my next test it'll be normal to adjust trim to keep a steady vs, right? I think a video would be really appreciated from all of us here.

[kevinh 409]

To my other problem. I don't know how the real T7 behaves but does the 777 trim automatically to hold the pitch in general (like in an Airbus) or not?

 

You said you have to adjust and readjust the trim to keep a steady vs. So the 777 should not trim automatically either for speed and pitch?

 

But why does the pilot do not have to trim to keep his target vs of 1000ft/min? That's confusing me a little.

In any aircraft if you are trimmed and then pitch up to a new angle (a different VS), thrust must increase to maintain airspeed. In a non-FBW aircraft the thrust change will affect trim and need to be adjusted for. In the 777 the FBW compensates for the trim change due to thrust, there is no need for the pilot to adjust it.

 

The only thing you need to trim for is an airspeed change.