FBW Yoke Sensitiviy
Ok chaps,
We already know that 777 first came as the FBW Narrow Body A/C with a yoke. But I was never get used to idea using the FBW without the auto-trimming, especially with a yoke. You have a feeling of depth, bank, pitch and even the wind when using a HYD yoke(maybe not as the manual reversion but still), as when the control surface move, it moves the actuator, puts pressure and moves the yoke. At point of larger G, it becomes harder to move so it can point the limits to pilot. Thus you can have the correct trim on yoke. Airbus I suppose does this making restrictions on banking, even with non-A/P "hand flying". Trim is done automatically while in Normal and Alternate laws. Correct me if it's not exact. But does the T7 also features that?? "Simulating" the way yoke acts in a HYD/Mechanical system, and allowing pilot to trim as its done in the "classical" way. Not just the T7, also the B748, and B787. Also another little question, Airbus uses autothrust and there is no react on levers(as far as I know), Boeing does it in the autothrottle way and levers move. T7 has which one? |
The B777 trim switch is only used for speed changes. There is no need to trim for turns, configuration changes, or power changes. The thrust levers move in response to autothrottle power changes just as if you were hand flying. All Boeing autothrottle systems are like that. A lot of pilots prefer this as it gives them another cue as to what the autoflight system is doing.
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The 777 works. You can debate FBW vs hydraulics, A vs B, but the 777 is a great flying airplane where the FBW is an invisible system. It just works. No mode shifts that catch you out. It just works.
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Westnest,
FBW vs Cables and pulleys makes no difference to the yoke feel it's exactly the same, both are completely artificial. Under the floor is a mechanical set up just the same as any Boeing yoke which at some point connects to springs to provide artificially feel and some additional hydraulic/electromechanical resistance when required. The trick with FBW is to make sure the 1cm, 1 inch or whatever amount of movement under the floor translates to the corresponding hydraulic actuator movement and resulting flight control movement and pitch/roll rate plus provide the visual yoke movement feedback. As stated FBW can take advantage of the fact that the lack of mechanical connections between yoke and actuators means the flight controls can be commanded to move without having to feedback to the yoke and therefore remove the requirement to trim as it's being done behind the scenes with no feedback. |
Since when is the B777 a narrowbody :confused:
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Originally Posted by misd-agin
The 777 works. You can debate FBW vs hydraulics, A vs B, but the 777 is a great flying airplane where the FBW is an invisible system.It just works. No mode shifts that catch you out. It just works
Did Russian pilots in Kazan had working invisible licenses too ? |
What 777 crash due to FBW are you referring to?
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Since when is the B777 a narrowbody :confused: AF Flight 296 was one of the famous FBW incidents, though it wasn't about the control surfaces or the airframe. The thrust levers was just a decoration instead of controlling the fuel flow, or the Captain Michel Asseline was trying to commit suicide with his passengers on board. What if 777's overintelligent computers disagree with the pilots commands just as in the AF296? If everything is simply is on the computer's determination, that would make no sense to try a yoke to be tweaked as its feeling like a hydraulic yoke. Because in fact aircraft decides on its own pitch and bank angle. So 777 has a bit less strict FBW system than what found in buses? |
Aren't thrust levers "just a decoration" on any FADEC-equipped aircraft?
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What if 777's overintelligent computers disagree with the pilots commands just as in the AF296? |
Isn't QF72 one of the famous incidents where a FBW system disagreed with the pilots? Probably a better example than AF296.
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Once again Habsheim is mentioned.
I will reply here. |
Aren't thrust levers "just a decoration" on any FADEC-equipped aircraft? |
"....therefore remove the requirement to trim as it's being done behind the scenes with no feedback"
Hasn't this created a few problems lately when the aircraft has significant amounts of trim in that the aircrew will only be aware of if they specifically look for it? Is this not confusing when modes change or the AP drops out? :confused: |
Aren't thrust levers "just a decoration" on any FADEC-equipped aircraft?
Perhaps on Airbus, but not on Boeing. On ALL Boeing FADEC-equipped, the thrust command is directly linked to the throttle position. Baring some sort of mechanical failure that would prevent the engine from responding, on a Boeing if you set the throttle at idle, you'll get idle. Set the throttle at part power, and you'll get part power, set high power, well, you know... On Boeing, there is no aircraft computer between the throttle and the FADEC - it's a basic design philosophy. |
Originally Posted by misd-agin
(Post 8194137)
The 777 works. You can debate FBW vs hydraulics, A vs B, but the 777 is a great flying airplane where the FBW is an invisible system. It just works. No mode shifts that catch you out. It just works.
Originally Posted by SMOC
(Post 8194198)
FBW vs Cables and pulleys makes no difference to the yoke feel it's exactly the same, both are completely artificial. Under the floor is a mechanical set up just the same as any Boeing yoke which at some point connects to springs to provide artificially feel and some additional hydraulic/electromechanical resistance when required.
The only difference FBW makes on the B777 and B787 is that the artificial resistance is software-controlled as opposed to mechanical.
Originally Posted by roulishollandais
(Post 8196361)
I don't share your non scientific concept of invisibility for a control system who just works....until the failure and crash ! Your invisible banker never puts his money on your acount !
Thus far there have been no accidents on the line put down to errors in FBW implementation - none.
Originally Posted by tdracer
(Post 8208950)
On ALL Boeing FADEC-equipped, the thrust command is directly linked to the throttle position.
On Boeing, there is no aircraft computer between the throttle and the FADEC - it's a basic design philosophy.
Originally Posted by SMOC
(Post 8197677)
What are you talking about, AF296 crashed because TOGA thrust was applied to late, the plane didn't climb over the trees because it was already at max alpha for the slow fly-by and the engines took around 4 sec (which was normal) to get to any decent amount of thrust...
Originally Posted by Mac the Knife
(Post 8208344)
"....therefore remove the requirement to trim as it's being done behind the scenes with no feedback"
Hasn't this created a few problems lately when the aircraft has significant amounts of trim in that the aircrew will only be aware of if they specifically look for it? Is this not confusing when modes change or the AP drops out? |
Same with Airbus. The FMGC can order thrust to assist control inputs, but it augments the original settings rather than overriding them. |
Hey guys, a bit of an old thread but here goes .
Artificial feel unit simulates the air pressure loads on the yoke so the pilot does not end up over controlling the aircraft ,as powered flying controls are not back driven . Does this apply to FBW as well ? ( A320 ) because from my understanding the FBW systems have flight envelop protections so there is no fear of over controlling the aircraft . you can have a simple spring centered yoke/stick and call it a day . If that indeed is the case then how is it handled when the protections are lost ? SO in short , does the A320 have an artificial feel unit or q feel ? I am sure the 737 has this . |
FBW Airbus types (as in A32x/A330/A340/A380) have passive spring feel in the sidesticks in all modes. As far as I can tell it's not an issue and hasn't been now for around 25 years.
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No mode shifts that catch you out. It just works. |
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