777x woes
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krismiler
My simple brain thinks had some calculations been done in relation to C of G and balance, the design could have/should have been done so that software was NOT needed to address angle of attack and control issues.I appreciate things like the fuel load and payload will affect the balance, but with modern computing surely this could have been done at design?
My simple brain thinks had some calculations been done in relation to C of G and balance, the design could have/should have been done so that software was NOT needed to address angle of attack and control issues.I appreciate things like the fuel load and payload will affect the balance, but with modern computing surely this could have been done at design?
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"My simple brain thinks had some calculations been done in relation to C of G and balance, the design could have/should have been done so that software was NOT needed to address angle of attack and control issues.I appreciate things like the fuel load and payload will affect the balance, but with modern computing surely this could have been done at design?"
That's a bit like saying that in order to produce the 777X, Boeing shouldn't have used the 777 as a basis ...
You might have a point.
"My simple brain thinks had some calculations been done in relation to C of G and balance, the design could have/should have been done so that software was NOT needed to address angle of attack and control issues.I appreciate things like the fuel load and payload will affect the balance, but with modern computing surely this could have been done at design?"
That's a bit like saying that in order to produce the 777X, Boeing shouldn't have used the 777 as a basis ...
You might have a point.
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They used the same fuselage for everything from the 707 through to the 757 (obviously not the 747), but the wing config and/or engine placement were all different; the larger engines on the 757 meant longer landing gear too. They didn't get it wrong till the Max.
With the Max am I correct in saying the gear is the same as the classic, but the geared engines created the issues due to the pylons being different? Maybe TD Racer could comments, as he usually has great insight into those sort of things?
With the Max am I correct in saying the gear is the same as the classic, but the geared engines created the issues due to the pylons being different? Maybe TD Racer could comments, as he usually has great insight into those sort of things?
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Technical issues aside, where is the market for the 777X? We've just started to emerge from the global pandemic and pax volumes are not there; there will be an indeterminate period where volumes will rise but no-one knows if volumes will reach previous levels let alone surpass them.
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"With the Max am I correct in saying the gear is the same as the classic, but the geared engines created the issues due to the pylons being different?"
You will find this is a great site for all 737 technical queries: The Boeing 737 Technical Site - Home Page (b737.org.uk)
In answer to your specific questions, while the Max's NLG is longer than that of the NG, the MLG is the same (other than the levered gear on the Max 10). The 737 doesn't have geared engines - you may be thinking of the P&W GTFs offered on the A320neo family.
"With the Max am I correct in saying the gear is the same as the classic, but the geared engines created the issues due to the pylons being different?"
You will find this is a great site for all 737 technical queries: The Boeing 737 Technical Site - Home Page (b737.org.uk)
In answer to your specific questions, while the Max's NLG is longer than that of the NG, the MLG is the same (other than the levered gear on the Max 10). The 737 doesn't have geared engines - you may be thinking of the P&W GTFs offered on the A320neo family.
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TD,
Thanks for the correction, my minuscule brain was thinking of something else.
Regarding the work it does, I haven't directly stated that I don't like it
Thanks for the correction, my minuscule brain was thinking of something else.
Regarding the work it does, I haven't directly stated that I don't like it
Last edited by 568; 1st Jul 2021 at 17:14. Reason: text
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I know I can never match the knowledge of tdracer on this subject, but might not the numerous Airbus uncommanded pitch issues make everyone more leery of certification without resolving any issue encountered? I refer most to QF72 and shortly after QF71. Despite many reviews of the systems verifying they were fail safe, only altitude saved the passengers of QA72 from meeting the same fate of the 2 MAX. Those incidents were in 2008 so would not everyone be much more sensitive to any indication the computers are assuming control? I know this is an anti-Boeing thread, but wouldn't one think the FAA and EASA will learn for everyone's issues?
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Those all had different type ratings. Boeing is trying to make the 777X a derivative type that will require as little additional crew training as possible. I assume that means similar handling qualities and cockpit as the 777(classics?)
The same happened with the Max which is where it all went wrong.
Those all had different type ratings. Boeing is trying to make the 777X a derivative type that will require as little additional crew training as possible. I assume that means similar handling qualities and cockpit as the 777(classics?)
The same happened with the Max which is where it all went wrong.
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The obvious difference being that MAX was yet another iteration of a 50 year old design, something that can't be said for the 777X, which is based on much, much newer platform, that has also seen a fairly successful variant (787) developed in the meanwhile, which also shares the type rating.
Comparisons to the 737 MAX are not really relevant to this (aside from creating additional scrutiny by the FAA). The 777 has always been a FBW aircraft, so s/w control of pitch was baked into the design from the very beginning. Flight Control software for FBW is always DAL A (Design Assurance Level) - which means flight critical (most FADEC s/w falls in the same category) - that isn't a guarantee that it's perfect, but it's as good as we know how to make it.
By comparison, MCAS was (originally) DAL C - which is not considered flight critical and is allowed to lack redundancy. That being said, the MCAS software didn't 'fail' - it performed exactly as designed. It was the design that was flawed and didn't adequately account for a bad AOA sensor.
Countless aircraft have been stretched over the years - nearly every Boeing model from the 707 to the 787 has been stretched - the exceptions being the 720 and both versions of the 717 (the KC-135, and what started out as the MD-95), and most have been re-engined at least once. Similarly, most Airbus aircraft models have been stretched. It's a well understood process and the 777X is not fundamentally different than what Airbus did with the A321neo - just on a larger scale.
I'm sure the Flight Control software is getting tweaked on the 777X to insure it behaves much the same as the original 777 - just as I'm sure Airbus tweaked the A320neo to behave as much as possible like original A320. There is nothing new or novel about this.
What I find worrisome about all this is that the 777X should be a straight forward development program - but it's not panning that way.
By comparison, MCAS was (originally) DAL C - which is not considered flight critical and is allowed to lack redundancy. That being said, the MCAS software didn't 'fail' - it performed exactly as designed. It was the design that was flawed and didn't adequately account for a bad AOA sensor.
Countless aircraft have been stretched over the years - nearly every Boeing model from the 707 to the 787 has been stretched - the exceptions being the 720 and both versions of the 717 (the KC-135, and what started out as the MD-95), and most have been re-engined at least once. Similarly, most Airbus aircraft models have been stretched. It's a well understood process and the 777X is not fundamentally different than what Airbus did with the A321neo - just on a larger scale.
I'm sure the Flight Control software is getting tweaked on the 777X to insure it behaves much the same as the original 777 - just as I'm sure Airbus tweaked the A320neo to behave as much as possible like original A320. There is nothing new or novel about this.
What I find worrisome about all this is that the 777X should be a straight forward development program - but it's not panning that way.
