Jump to content
Sign in to follow this  
Werner747

Handling dynamics with redesigned FBW Sytems

Recommended Posts

Well I just brought the B77L in for a landing after a 12 hour flight from KORD - RJAA, marginal weather to.   The aircraft really does handle the turbulence so much better!   It really feels heavy and solid to fly now and the FBW trim function on the PFD, was incredibly helpful, really allowed me to trim the aircraft very precisely!

 

I am really, really impressed with the SP1 stuff - I don't have ASN yet so I could not play around with the WXR, but apart from that, really cool stuff!   Oh and the extra features with the FMC requests - awesome!

 

How are you guys and girls experiencing the new FBW system and the other perks?

 

Kind regards

Share this post


Link to post
Share on other sites

Will test out the FBW tomorrow on a flight to Helsinki, the Data Uplink feature is superb and the WXR is fantastic, cant wait to handfly her and trim a lot more than I used to..


spacer.png

MSI Codex 5 10SC-262UK Desktop PC - Intel Core i7-10700, RTX 2060 Graphics, 16GB RAM, 2TB HDD, 256GB SSD.

Share this post


Link to post
Share on other sites

Hi Werner,

My first 'official' participation here in a topic :).

From my part, I have some difficulties getting warm with the FBW system. I think I've read the manual where the FBW is explained 15 times, did research on the Internet how this system works... but don't get it right.

I recalibrated my Yoke (Saitek), deleted FSUIPC.ini, played with Slope, Deadzones and the new FBW column settings in the FMC. Either I smash my beloved 777 on the runway with 600 - 800 ft/min. or I float above the runway, but a good landing wasn't archieved within 30 tries today :(.

On my approach it happens that when I established my path and the yoke gets in neutral position, the 777 pitches up to catch the trimmed ref speed (if I'm too fast), causing a loss in V/S. When I'm a bit too slow and Yoke gets neutral it pitches down increasing the V/S. I'm constantly fighting the airplane with the Yoke :lol:. If I watch my Bluerays of Justplanes or Pilotseye where a 777 is on approach, they make small inputs, not even looking at the trim button.

I think I do something really wrong or misunderstood the FBW completely, that's for sure. 

 

Even when I takeoff I don't understand the logic behind the FBW. I activated the Trim Reference Speed bug to understand how this works. As my 777 climbed and the new commanded speed shifted from 210 to 250 knots. I tried to trim the aircraft conventionally. But somehow I never get the Trim Speed matched with the speed I want (250 knots for example). Maybe I'm too muched focused on the FD. I know that I need to trim down to set the new ref speed but the FD commands pitch up (so I pull the Yoke back) and then all of the sudden (when I trimmed down) jumps from 10° nose up to 5°. It's really confusing for me.

 

Maybe here's someone who have mastered this or does this for a living and can give me some tips and advice, I'm always willing to learn (and will read some parts of the FCOM later on). I want to get this system mastered ....... some day ;).

 

Nevertheless, the other stuff PMDG implemented is awesome. The weather radar works like a breeze and I was searching for the thunderstorms to test it  :lol:. It was really really immersive to avoid the thunderstorm cells with HDG SEL mode and not with guesswork as happened in the past. Great addition!

 

Have a nice evening.

Ben

 

Share this post


Link to post
Share on other sites

I will have to trust the folks at PMDG that this update made the FBW dynamics more realistic, as I never took the wheel on the real deal. But as a simmer, I have to say the response is much closer to other non-FBW Boeing aircraft, as I think Boeing intended when producing the real FBW for the 777. I takes some trimming (unlike the Airbus logic) and it handles smoothly responding to pilot inputs. I also noticed the awesome improvements over turbulence, really quite different now.

Share this post


Link to post
Share on other sites

Hi Werner,

Either I smash my beloved 777 on the runway with 600 - 800 ft/min. or I float above the runway, but a good landing wasn't archieved within 30 tries today :(.

 

On my approach it happens that when I established my path and the yoke gets in neutral position, the 777 pitches up to catch the trimmed ref speed (if I'm too fast), causing a loss in V/S. When I'm a bit too slow and Yoke gets neutral it pitches down increasing the V/S. I'm constantly fighting the airplane with the Yoke :lol:. If I watch my Bluerays of Justplanes or Pilotseye where a 777 is on approach, they make small inputs, not even looking at the trim button.

I think I do something really wrong or misunderstood the FBW completely, that's for sure.

 

Even when I takeoff I don't understand the logic behind the FBW.

I have not been able to test SP1 yet. Maybe I can download it tomorrow.

 

But, first....don't worry too much about these landings.

I find it quite hard to judge just how much too pull on the yoke for the perfect flare as well.

It is easier in real life because of all the visual clues/peripheral view you have and are missing in FSX.

The only tip I can give is dont pull too much. pull just a little bit (pitch change from about 2 degrees to 4 degrees from around 30ft to touchdown)......or monitor the Auto Land system a few times

 

If I understand things correctly it is possible to display the trim reference speed?

Maybe that was possible before SP1 as well......but for heaven's sake, dont display that!!

You will be going nuts chasing that speed.

If you can trim a Cessna, then you can trim the 777......it is done 100% the same!

 

For any flight path you are trying to maintain (level/a descend/a climb).

Are you pushing on the yoke to keep the nose (pitch) where you want it?.........trim down one second

Now let go....Need to push down again?.........one more second of down trim.

Almost there, just slightly off, just a slight nod down required here and there?........just a quick hit of the trim down switch should do the trick!

(If you are now pulling to keep the nose (pitch) where you want it then you trimmed down too much)

 

Are you pulling on the yoke to keep the nose (pitch where you want it?........trim up a second

ditto

ditto

 

Try the above with FD off......you do not want any distractions, but you can use the AT.

Just maintain 5000ft or so at various airspeeds and retrim the plane.

 

Then, once you can do that, try a 500ft/min climb or descend. Keep the nose (pitch) at a value that maintains 500ft/min climb or descend. Use the throttles (or AT) to maintain the desired speed.

Pitch controls flight path.......thrust controls speed.....this is important!

Then change the speed (you can use the AT if you want)......now keep that nose at a pitch value that miantains 500ft/min (pitch controls flight path)......and trim up or down untill you can let go of the yoke and the nose stays where you want it, still maintaining 500ft/min!

 

There IS no logic you need to understand to trim this airplane other than basic pitch vs power flying!

In fact the less you read and study up about it, the more likely it is that you will automatically do the right thing....it is that easy and natural.........well, it should be (like I said, I have not tested it yet)......... (unless you come from an airbus maybe).

I swear....give this thing to a C172 pilot, tell him to trim the thing and he will!


Rob Robson

Share this post


Link to post
Share on other sites

Gents,

 

The basic idea for this FBW system as conceived by Boeing is that a normal trimmed airplane (without FBW) will hold a specific speed. Ergo you add thrust it climbs, you remove thrust it descends. Hence the term trim reference speed.

 

Now you can very very simply view the FBW system as a level change autopilot mode (or FLCH if you like), with the target airspeed being set by the trim buttons on the yoke (instead of the MCP speed dial in the case of the automatic flight system). That's all there is to it basically.

 

Say the aircraft is trimmed for level flight...Now if you remove thrust the plane will descend to "chase" the speed. If you add thrust the plane will climb to chase speed, exactly like the FLCH AP mode with thrust controlled by you (why don't you try FLCH with manual thrust control to see what it does...)

 

The difference is that by design the system is very "loose" in order to mimic a normal plane's behaviour. It will under shoot the target and overshoot the target (compared with FLCH which on a commanded 50 knot acceleration barely goes 0.5 knots over the target). We had FBW response times, commanded correction pitch rates and another 1000 details measured directly from the real thing.

 

PS. The above behaviour occurs when your controls are centred.


====================================

E M V

Precision Manuals Development Group

====================================

Share this post


Link to post
Share on other sites

 

Now you can very very simply view the FBW system as a level change autopilot mode (or FLCH if you like), with the target airspeed being set by the trim buttons on the yoke (instead of the MCP speed dial in the case of the automatic flight system). That's all there is to it basically.

 

Although I understand what you are trying to say.....I am afraid this is just going to create more confusion.

 

It trims like a Cessna.....plain and simple :-)

 

(The rest of the info was good though).


Rob Robson

Share this post


Link to post
Share on other sites

It trims like a Cessna.....plain and simple :-)

 

AHAHAHA ! OK that works too. Assume it is not there and you fly a big Cessna with a small stab (hence some ups and downs when you chase speed)


====================================

E M V

Precision Manuals Development Group

====================================

Share this post


Link to post
Share on other sites

 

 


Even when I takeoff I don't understand the logic behind the FBW. I activated the Trim Reference Speed bug to understand how this works. As my 777 climbed and the new commanded speed shifted from 210 to 250 knots. I tried to trim the aircraft conventionally. But somehow I never get the Trim Speed matched with the speed I want (250 knots for example). Maybe I'm too muched focused on the FD. I know that I need to trim down to set the new ref speed but the FD commands pitch up (so I pull the Yoke back) and then all of the sudden (when I trimmed down) jumps from 10° nose up to 5°. It's really confusing for me.

 

Hi, Ben,

 

Is it possible your trim buttons are causing too much change in pitch trim?  Take a look at the pitch trim indicator on the pedestal and see if it changes very fast when you press your trim buttons.  Also check the same problem with your yoke and elevators -- how fast does the elevator position change when you pull or push your yoke?  Look in external view.

 

Mike


 

                    bUmq4nJ.jpg?2

 

Share this post


Link to post
Share on other sites

Hey people,

 

@777simmer:

Thank you very much for your explanation and advice. I'll do this practices as you said to get the hang of it. Don't worry the FBW Reference Speed I had only activated in the very beginning to get a basic understanding of the FBW mechanism.

Regarding the landing, I'm not a professional but I can say that I don't have the problems with landing. My problem was, that as soon as my controls where centered, the airplane tries to catch the Ref. Speed wich is - as you all explained - perfectly normal. And these corrections cause my V/S to go rapidly down or too much up causing an unstable approach. And this is the point (I think) where I do the mistakes and mess up the landings. But practise makes perfect.

 

@emvaos:

Thanks for your explanation and the comparison with FLCH mode. I understand.

Watched some videos again, these showed that every pilot controls the thrust as well, not relying on the A/T. They sometimes pull and push the yoke, but they control the thrust all the time. Maybe I should set the Autothrust Override mode to always and also work more with thrust. Because when I simply go with the FDs and pitch too my V/S needed for the 3° slope; as soon as the Yoke gets centered, the FBW catches the trim speed 'ruining' my flightpath  ^_^. So I'll will try thrust as well.

 

@Mike:

It's really hard to judge. The elevators and ailerons look 'normal' to me, no overreacting or such. In FSUIPC I set the Slope for both to 0 and the Nullzones as well. In the FMC options I set both FBW nullzones to 2%.

For the buttons I use LINDA.

The drim buttons are set as follows:

On Press: Elevator Trim dnfast / upfast

On Repeat: Elevator Trim dnfast /upfast

 

I'm curious what you guys have set there, maybe I did something wrong with this settings and didn't know it!?

Lets see. Now I'll go learn a bit trimming  :lol:.

 

See you later  :dance:

 

 

 

 

 

 

Share this post


Link to post
Share on other sites

What i expirience that sometime the nose is luffing up and down. You can force this, if you make an RNAV/VNAV approach and set the altitude after VNAV path neutral point and the plane is over the VNAV. The plane don't know what to do and start luffing. Its funny ride for the pilots and the passengers backwards. :) But you can forget your approach at this point.

 

In my speed Tape is activated FBW Trim Speed in blue vector. If i trimm this vector don't go smooth up and down. It's jumping extremely. I don't know if this is right or not. Are my trim settings for my yoke wrong?

 

Would be nice to get some feedback. If somebody want, i can make a video of it.

Share this post


Link to post
Share on other sites

I have not been able to test SP1 yet. Maybe I can download it tomorrow.

 

But, first....don't worry too much about these landings.

I find it quite hard to judge just how much too pull on the yoke for the perfect flare as well.

Hi Rob.

 

For some reason I'm not getting any touchdown sounds. Each landing is like a greaser. I would expect some kind of a rumble when I touch down. Didn't prior to SP1 and not now.

 

I'm sure you will confirm, that the 777 when it touches down isn't dead silent?

 

maybe it's my sound settings. Will check later.

 

As for the trim, I haven't had a chance to test it properly yet. But the one second blip trim didn't seem to function on a brief test flight. Could be wrong.

 

 

 

https://www.youtube.com/watch?v=kae_wDCGex0&index=3&list=PL5caETAZRBN6mPhNASIlMg2bkWH2DbtIz

 

Here's a short video i came across demonstrating the trim for reference speed function.

 

 

Kind regards,

That's a nice video. We can compare directly to the sim.

Share this post


Link to post
Share on other sites

Sure you can both feel and hear the real 777 touchdow.

Less so if it is a greaser ofcource.

 

Have not done a landing yet in the PMDG SP1.....will let you know.

 

 

As it stand right now, I am all over the sky with the way trim works now :-(

I did a take off, retracted the flaps and accelerated to clean speed.

No trim was required almost the whole time (which is not as in real life) untill about 10kt prior to reaching clean speed.

The nose suddenly went up and even full elevator down pressure could not bring the nose down! (also not realistic).

Trim down then rectified the situation.....but boy what a messy take off :-(

 

I already deleted the FSUIPC.ini once......but will do so again, and I will try a flight with basic FSX controller settings (so with FSUIPC off!).

 

It could be my FSUIPC settings.....so no judgement yet, + I also still have to read the new manual (there is something new about controller dead zones in the FMC settings).


Rob Robson

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
×
×
  • Create New...