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Has everyone suddenly forgotten how to build airplanes?

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Has everyone suddenly forgotten how to build airplanes?

Old 12th Sep 2019, 19:39
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Has everyone suddenly forgotten how to build airplanes?

A320neo ans A321neo experiencing CoG issues?

https://simpleflying.com/lufthansa-a320-cog-economy/

Following concerns regarding the center of gravity issues with the A321neo, the European Union Aviation Safety Agency (EASA) has uncovered a similar problem with the A320neo
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Old 12th Sep 2019, 23:56
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Originally Posted by Mark in CA View Post
A320neo ans A321neo experiencing CoG issues?
Probably not the case that the world has forgotten how to build. Information flows faster today than previously, and is less fettered or filtered. Issues that arise are now aired in various arenas including online news, chat rooms, and social media.

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Old 13th Sep 2019, 01:10
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I don't know, but I flew the 757 since it first came out of the factory. I don't recall any issues with the design.
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Old 13th Sep 2019, 01:36
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It's worth noting that all that happens with the neo is that it behaves like a normal aeroplane under a specific set of circumstances, and all the pilot has to do is fly it like a normal aeroplane. It is vastly different from the MAX issue.
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Old 13th Sep 2019, 01:50
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Salute!
Prolly a flight control law that needs some work.

As the bus model(s) in question go, they do not have to meet the same control column pressure WRT AoA requirement that the 737Max does (no direct or indirect control surface posiiton/force feedback required for the FBW bus) They also do not have a stick vibrator like the Boeing stick shaker for stall warning, just "bells and whistles".

Besides using direct AoA values for the control laws, we also have gains due to CAS ( Q, or dynamic pressure) and some rate variables. So unless there are serious aero pitch moment problems that the existing control surfaces cannot overcome, this should be a quick fix,and an effective one.

EDIT: The AoA limiter ( they call it "protection") should have some degree of "rate" or pitch onset to prevent overshoots, but we would have to see the curves/plots and time constants for all the variables to gain a good understanding..

This problem appears to be an overshoot one, does it not? So maybe the rate variable could use some attention, as well as the gains in effect got TOGA scenarios.. END EDIT

Gums opines...

Last edited by gums; 13th Sep 2019 at 04:26. Reason: added rate stuff
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Old 13th Sep 2019, 03:07
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it behaves like a normal aeroplane under a specific set of circumstances, and all the pilot has to do is fly it like a normal aeroplane
And therein lies the problem.

As the systems have improved, the point at which they fail keeps getting deeper and deeper into the areas that make the aircraft unnecessarily hard to fly. At some point, as they keep progressing, the 'system' will hand over a larger and larger bag of shit each time.

Airbus has had the effect of weakening pilot skills because they've automated a lot of the day to day stuff...but at the same time, when it all goes tits-up, you'll need those very same weakened skills.

Just a thought.....
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Old 13th Sep 2019, 05:57
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The problem is essentially mitigated if the rear row of seats is unoccupied. That’s not a fundamental aeronautical design issue, it is a 'Well, head office insist on another row up back' issue.
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Old 13th Sep 2019, 06:29
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Originally Posted by gums View Post
As the bus model(s) in question go, they do not have to meet the same control column pressure WRT AoA requirement that the 737Max does (no direct or indirect control surface posiiton/force feedback required for the FBW bus) ..
It's an interesting point - how come Airbus gets away with this exemption just because the stick is on the side, while Boeing are required to create perfectly progressive stick feedback force, all the way to the extremes of the envelope, and in trying to meet the requirement, create MCAS? Progressive pitch force is a major design headache, from single engine homebuilts, right through to airliners. Meanwhile there have been several Airbus incidents, arguably attributable to the lack of stick force feedback.
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Old 13th Sep 2019, 07:23
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Why are we allowing electronics to make planes safe to fly? Should they not be designed to be "stable" in normal flight conditions without computer intervention, with override only happening when something very unusual happens?
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Old 13th Sep 2019, 08:04
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Originally Posted by robdean View Post
The problem is essentially mitigated if the rear row of seats is unoccupied. Thatís not a fundamental aeronautical design issue
Sounds like a pretty good description of one to me.

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Old 13th Sep 2019, 08:10
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That's what happens with the modular approach airplane families are designed today. Stretch them, make them heavier, install more powerful engines and change the cabin interior and onboard installations (tanks) to upset weight and balance - But keep the wings and rudders the size they were before.
No surprise you end up with some surprises at the corners of the flight envelope. On computer controlled aircraft those things can be modified more elegant than on old style (MAX) mechanical controlled airplanes.
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Old 13th Sep 2019, 08:18
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Engineers have not forgotten how to build airplanes. It is just that today, it is the CEOs, accountants, and marketing people who are driving the design process from the top down. In the past it was the engineers saying what could be done and the upper management marketed and sold what the engineers could build.
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Old 13th Sep 2019, 08:25
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Originally Posted by Atlas Shrugged View Post
And therein lies the problem.

As the systems have improved, the point at which they fail keeps getting deeper and deeper into the areas that make the aircraft unnecessarily hard to fly. At some point, as they keep progressing, the 'system' will hand over a larger and larger bag of shit each time.

Airbus has had the effect of weakening pilot skills because they've automated a lot of the day to day stuff...but at the same time, when it all goes tits-up, you'll need those very same weakened skills.

Just a thought.....
As I understand it, this happens when flying manually so you arenít being ďhandedĒ anything, you already have it, you just need to push the stick forward a bit.
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Old 13th Sep 2019, 11:26
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Has everyone suddenly forgotten how to build airplanes?
Also applies to many other facets of engineering while they pay corporate flunkies a mega salary to do top level designs that an eight year old could do in five minutes.
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Old 13th Sep 2019, 11:37
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Although they may look like airplanes, they are really giant computers. That said, it doesn't hurt to all step back and remember that the recent era of the aviation industry is safer now statistically that it ever was. That is not an argument against continuing to improve.
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Old 13th Sep 2019, 12:03
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As is ever the case we pilots love to debate niff naff and trivia. Airliners may be giant computers but airlines buy them to MAKE MONEY! Airlines are run by accountants whose sole purpose is to MAKE MONEY! Safety is not in the ledger. When have you ever heard of an accountant being held responsible for anything safety related in ANY industry? Industry are under intense pressure to produce these aircraft quickly and cheaply. This isn’t a “rocket science” problem. A few high profile corporate manslaugter convictions when accidents happen will soon focus the mind, before these slippery corporate types slither away to take charge of a nuclear power station project or the next space shuttle.

As a pilot I don’t give a rip how many computers or widgets the manufacturer has incorporated into the design. I don’t care whether it’s a Boeing or an Airbus. I just want the hunk of metal to be a quality product and safe. And I want to be properly instructed to fly it. I’d personally be willing to take a lower salary to be sure of those things. Sadly the thing we senior pilots seem far to preoccupied with is MAKING MONEY!........... and round and round we go!

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Old 13th Sep 2019, 13:01
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Originally Posted by NEDude View Post
Engineers have not forgotten how to build airplanes. It is just that today, it is the CEOs, accountants, and marketing people who are driving the design process from the top down. In the past it was the engineers saying what could be done and the upper management marketed and sold what the engineers could build.
See I cant agree with that. Commercial pressure has been there since day one, and sales/marketing have exerted pressure on the designers to build what they perceive the market desires from the get go.

Take the 777, in which the market had a seat at the table. It makes no sense for it to work any other way, it just requires engineers to be clear about what can or cant be done
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Old 13th Sep 2019, 13:01
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Originally Posted by svhar View Post
I don't know, but I flew the 757 since it first came out of the factory. I don't recall any issues with the design.
Wasn't that circa 1983?

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Old 13th Sep 2019, 13:15
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"The problem is essentially mitigated if the rear row of seats is unoccupied. Thatís not a fundamental aeronautical design issue

Originally Posted by DaveReidUK View Post
Sounds like a pretty good description of one to me.
Rarely does the designer specify where each row of seats are placed or baggage stowed. They tend to specify the pressure bulkheads fore and aft and then provide info for an operator to use the plane.

I believe we have talked about not sitting in the last row on our own flights on some planes
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Old 13th Sep 2019, 14:09
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Originally Posted by lomapaseo View Post
Rarely does the designer specify where each row of seats are placed or baggage stowed. They tend to specify the pressure bulkheads fore and aft and then provide info for an operator to use the plane.
Yes, that's true.

But the designer will have determined the C of G envelope within which the airlines can configure the cabin and operate the aircraft. For a regulator to step in and retrospectively impose a more limited C of G range indicates that something hasn't gone according to plan.

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