Apparently no one here really knows what it is... this thread contains seven pages lol!

According to a A330/A340 FCOM

So, if there is no input on the stick:

 

. The aircraft maintains the flight path, even in case of speed changes

 

. In case of configuration changes or thrust variations, the aircraft compensates

for the pitching moment effects

 

. In turbulence, small deviations occur on the flight path. However, the aircraft

tends to regain a steady condition

 

Oh okay, "maintains flight path." So in light of that I now understand what CoolP meant when he said the plane will "pitch up." If you retard the throttles, of course it will, because it must do so to maintain the flight path. I've spent to many hours flying the PMDG md-11 which is in a perpetual state of Attitude Hold, not Flight Path Hold, and so it will basically let the plane drop out from under you if you aren't careful with the throttles. I guess my concerns then about this lack of speed trimming in an Airbus are renderred moot if the plane will keep a constant velocity vector--a little bit different and far more convenient than the md-11 LSAS paradigm that always plagues me to death when working the throttles! Cool.

In large aircraft mechanical connections are not much use at all, ever try flying a 737 with dual hydraulic failure in mechnical backup mode, those cables are going to be next to useless, the controls are heavy as ****. And every other large jet out there doesn't even have mechnical backup, if hydraulics are lost, those wires don't mean squat.

 

 

I'm not entirely sure, but I think that you do have to trim the 777 for speed. I'm sure some of the folks at PMDG could answer that for you though.

 

Regards,

Ró.

 

Concerning the 777 :

"An established flight path remains unchanged unless the pilot changes it through a

column input, or if the airspeed changes and the speed stability function takes effect.

TRIMMING is required only for AIRSPEED changes and not for configuration changes"

 

This is the conclusion of Chapter 11.8.1 'PITCH Control' of this very good explanation

of the 777 FBW:

http://www.davi.ws/a...book_Cap_11.pdf

 

Guy

I've found some old papers (1968) which described the thinking behind and 'need' for fly-by-wire setups. Since not only military aspects get mentioned but also general benefits, it's a nice read. For example, if one ever wondered how e.g. weight savings or just a reduced complexity affect an aircraft's control system, two schematics deliver a bit food for thought.

On another occasion, here's the list of the initial design of the A320. So whenever you hear someone saying 'powerful computers', you will just recall this. ^_^

ELAC: 3 Motorola 68000

SEC: 2 Intel 80C86

FAC: 2 Intel 80C286

Well that's certainly much simpler...

From an engineering point of view, not always!

^_^ Leaked maintenance doc. Wait!

:lol: Seems about right... ^_^

Ooh Ró you should know better :lol:

And Coolp for future reference instead of wd40 or speedtape as far as an airbus is concerned switch it off then on again,generally works a treat just ask Ró

Just ask Ró

Yup, she's just one big 'ol computer... ^_^

 

Ooh Ró you should know better :lol:

In which regard are we talking about here? :huh: ^_^

In which regard are we talking about here?

 

Engineers are your best friend , and our flow charts are much more complicated

 

We have lots of different tape :Big Grin:

I don't know, that diagram sums up my 4 years studying applied engineering in university pretty well... :rolleyes: B) ^_^ :blush:

At least the WD40 part anyways....

Q: Which fly by wire a/c celebrated its 50th anniversary last year?

Mercury Atlas 6 space capsule? :huh:

Good guess, Rónán.

 

Since we were on that engineering viewpoint. What's the most common cause of errors on a modern setup in normal line ops? I could imagine 'simple' problems on e.g. contact sections to trigger a lot. To be precise, a lot of random stuff, which is hard to come by.

 

And who was the guy cross-wiring that side stick once? :wacko: Stop doing that! http://www.aviationt...rols_12796.html