Search found 91 matches

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by IADFCO
Fri Jun 14, 2019 4:36 am
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

the airlines need this ungrounded. this isn't about just boineg. they have 5000 orders. European airlines too. expecting to make money. it will be ungrounded in a few months. there wasn't anything that wrong with it. I mean, boeing haters, as there is a love for wild speculation and what ifs, what ...

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by IADFCO
Tue Jun 11, 2019 4:30 pm
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

It's about the lift the MAX's nacelles generate at high angle of attack due to complex airflow between nacelle, pylon and wing, rather than "engine too big". In my opinion it is mostly the position not so the size of it. [...] It's quite likely that's a wing airflow issue at high AoA, bes...

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by IADFCO
Fri Jun 07, 2019 4:38 am
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

For me the big unknown is the post-stall behavior of the wing--there is zero factual information about that. When the aerodynamic effects of the nacelle started being discussed I thought: why didn't they try to stall the nacelle before MCAS had to kick in? You could do it with fixed or active spoile...

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by IADFCO
Sun Jun 02, 2019 10:31 pm
Forum: Civil Aviation
Topic: KLM investing in TU Delft's Flying-V concept
Replies: 29
Views: 4791

Re: KLM investing in TU Delft's Flying-V concept

Waterbomber2 and MartijnNL have spoken: the concept looks terrible and it won't work. The moderators might as well lock this thread. Until then, I'm sure they have read carefully the detailed technical documentation on the project available by following the links on the web site, which includes deta...

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by IADFCO
Mon May 27, 2019 11:54 pm
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

furthermore, MCAS 2.0 will turn itself off *by design* after activating once. So, after the "protection" is needed once, it will not be available again (not clear for how long). I think you're incorrect on how MCAS 2.0 will function. - MCAS 2.0 will activate once when both AoA vanes excee...

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by IADFCO
Sun May 26, 2019 3:55 pm
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Boeing should just tell the airline pilots how exactly the MAX behaves in slow flight and how to handle it in manual flight without MCAS in order to fly out of it manually. If pilots would know they could be prepared and handle it themselves. No MCAS needed anymore. Maybe the FAA can even give it a...

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by IADFCO
Wed May 22, 2019 10:47 pm
Forum: Technical/Operations
Topic: Do the MAX 7 and 10 require MCAS?
Replies: 35
Views: 3717

Re: Do the MAX 7 and 10 require MCAS?

The problem is that none of the information about what MCAS is supposed to do, and what happens if it's turned off, none of it, is based on objective facts. Has anybody seen a plot that shows how pitching moment changes with stick force, for example? I'm not talking about good guesses, qualitative g...

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by IADFCO
Tue May 21, 2019 4:46 pm
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

In your discussion of the pilots' responsibility in the two MAX crashes, you may want to keep this in mind: https://en.wikipedia.org/wiki/Amygdala_hijack https://apstraining.com/the-biology-of-an-aircraft-upset-event-and-loss-of-control/ from the second link: "The term “amygdala hijack”, coined...

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by IADFCO
Mon May 20, 2019 6:24 pm
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

[...] Avoiding a stall in the situation like you described above is more difficult but not some insurmountable task like you are trying to make it. You still have all the warnings and it's not like you will go from flying to full stall in a split second - you will really have to screw up for a good...

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by IADFCO
Thu May 16, 2019 1:15 pm
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

[...] MCAS V2 - properly implemented shouldn't really need training as the outcome would be so benign and the counteraction so simple (return trim to normal and hit cutout switches) that it should not require SIM time. [...] Maybe, maybe not. With the modified MCAS, apparently now a MAX can fly MCA...

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by IADFCO
Mon May 13, 2019 2:19 am
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

I have just sent a comment to the FAA, and I encourage all of you who feel that the current draft is missing something to do the same. I believe that these comments will become part of the public record. I am reposting here the link: https://www.faa.gov/aircraft/draft_docs/fsb/ all the necessary inf...

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by IADFCO
Fri May 10, 2019 2:58 pm
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

@jh380, @planecane: many thanks for the link -- you saved me who knows how much time on the phone trying to get that information from the FAA. After reading the proposed changes, my reaction has been: is that all? IMHO, one key missing item is what happens when MCAS is deactivated, and what level of...

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by IADFCO
Fri May 10, 2019 3:32 am
Forum: Technical/Operations
Topic: Direct mode charachteristics and currency
Replies: 12
Views: 1990

Re: Direct mode charachteristics and currency

Many thanks to all of you who answered my question (#4). Very interesting answers, I learned a lot.

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by IADFCO
Fri May 10, 2019 3:30 am
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

According to AW&ST, https://aviationweek.com/commercial-aviation/alpa-simulator-time-not-needed-un-ground-737-max (free registration required): "The public has until May 15 to comment on the draft FSB report. Approving it will be a key step in getting the MAX fleet back in the air, along wi...

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by IADFCO
Wed May 08, 2019 5:16 am
Forum: Technical/Operations
Topic: Direct mode charachteristics and currency
Replies: 12
Views: 1990

Re: Direct mode charachteristics and currency

I realize it's probably never done, but if you wanted to go intentionally from Normal to Alternate to Direct Law in actual flight (not in a simulator), could you do it, i.e., is there a switch that a pilot could use?

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by IADFCO
Wed May 08, 2019 5:02 am
Forum: Civil Aviation
Topic: Something wrong with Boeing's safety culture?
Replies: 270
Views: 30059

Re: Something wrong with Boeing's safety culture?

@777Jet: thanks for the link -- it worked here in the US.

Both as a person and as an aerospace engineer working in flight dynamics and control, I found it very hard to watch. 350 people are not supposed to die that way.

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by IADFCO
Tue May 07, 2019 3:56 pm
Forum: Travel, Polls & Preferences
Topic: 44% say wont take MAX for a year?
Replies: 96
Views: 7707

Re: 44% say wont take MAX for a year?

The fact that most "civilians" can't tell the difference between a MAX and an NG (I agree) may actually work in reverse: all 737 will be MAXes and therefore potential death traps (in the "civilians" minds).

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by IADFCO
Mon May 06, 2019 3:52 pm
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

I can think of several designs that in my opinion were worse than the Max and MCAS. I would say the Electra because the wings just fell off; the Comet because the whole airplane just fell apart; the Concorde because a little FOD caused it to burst into flames. The thing about it is that the Electra...

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by IADFCO
Sun May 05, 2019 4:21 am
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Very personal opinion, of course, but a self-imposed limit of one or two postings per thread per day sure would be nice...

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by IADFCO
Sat May 04, 2019 11:06 pm
Forum: Civil Aviation
Topic: Alitalia bankruptcy and selling process discussion thread
Replies: 908
Views: 222610

Re: Alitalia bankruptcy and selling process discussion thread

Last Thursday Alitalia started its year-round IAD-FCO service, *finally* giving a minimum of competition to the seasonal UA flight, so it cannot go bankrupt until *I* say so.

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by IADFCO
Sat May 04, 2019 6:31 pm
Forum: Civil Aviation
Topic: Boeing 737MAX Grounded Worldwide Q2 2019
Replies: 3027
Views: 297517

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Before the grounding is lifted, I think it's very important to have a good understanding of what happens when MCAS is deactived. If I understand correctly, in case of "AoA disagree" MCAS will now deactivate. So, following a sensor failure, e.g., a bird strike, a MAX might be in a flaps up,...

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by IADFCO
Mon Apr 29, 2019 2:06 pm
Forum: Civil Aviation
Topic: B737MAX Grounded Worldwide Q1 2019
Replies: 6472
Views: 709595

Re: B737MAX Grounded Worldwide

More thinking about how to justify such oversize facility. One wing off model is probably on par with 75% model cost-wise -but when I think about per-hour costs involved for something like that... Instrumentation may still be better than what you can get flying... maybe.. In the 80' x 120' Ames tun...

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by IADFCO
Mon Apr 29, 2019 5:36 am
Forum: Technical/Operations
Topic: Vortex drag-induced drag
Replies: 5
Views: 1114

Re: Vortex drag-induced drag

Not 100% rigorous, but close enough for A.net purposes -- Think of the wingtip vortex and its effects (downwash) as starting from the leading edge, i.e., from the "present" using your type of description, and extending from there to the trailing edge and beyond (i.e., the past).

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by IADFCO
Mon Apr 29, 2019 4:59 am
Forum: Civil Aviation
Topic: B737MAX Grounded Worldwide Q1 2019
Replies: 6472
Views: 709595

Re: B737MAX Grounded Worldwide

Would it make sense to have part of a plane, as opposed to scaled model? Say chop off one wing - even half of it - and look at the flow over the other. Force on supports will be different, of course, but wing flow likely will be there. Using production, or even test plane may be problematic, of cou...

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by IADFCO
Sat Apr 27, 2019 2:57 pm
Forum: Civil Aviation
Topic: B737MAX Grounded Worldwide Q1 2019
Replies: 6472
Views: 709595

Re: B737MAX Grounded Worldwide

It's pretty clear by now morrisond and OldAeroGuy are either engaged in astroturfing or self identify with Boeing to the point there is no point to argue with them. Claiming certification requirements for flight control and aerodynamic behaviour are not relevant to the question whether a plane is s...

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by IADFCO
Fri Apr 26, 2019 1:41 pm
Forum: Civil Aviation
Topic: B737MAX Grounded Worldwide Q1 2019
Replies: 6472
Views: 709595

Re: B737MAX Grounded Worldwide

Well the bizarre thing is MCAS isn't really needed to make the MAX safe - it's just needed MCAS to meet a specific regulation that the MAX was barely over on. I don't think anyone can conceive that an MAX without MCAS would be unsafe and lead to crashes as even the worst trained pilots would recogn...

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by IADFCO
Fri Apr 26, 2019 2:58 am
Forum: Travel, Polls & Preferences
Topic: JetBlue uses facial recognition as boarding pass
Replies: 16
Views: 1771

Re: JetBlue uses facial recognition as boarding pass

However, now JetBlue (or whoever) has your picture matched with your name (so this improves the reliability of the training algorithm, and also updates it if you don't travel frequently). They can go and sell this information to Google, Facebook, Amazon, whomever, can't they? Or maybe the other way ...

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by IADFCO
Fri Apr 26, 2019 2:39 am
Forum: Civil Aviation
Topic: B737MAX Grounded Worldwide Q1 2019
Replies: 6472
Views: 709595

Re: B737MAX Grounded Worldwide

I second what kalvado wrote, and add this: to this day we don't have a precise picture of the problem that MCAS is trying to address when in normal operation, let alone what may happen when it's malfunctioning. Sure, even just in this thread we have thousands of posts with pretty good ideas and a ge...

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by IADFCO
Mon Apr 22, 2019 3:25 am
Forum: Civil Aviation
Topic: B737MAX Grounded Worldwide Q1 2019
Replies: 6472
Views: 709595

Re: B737MAX Grounded Worldwide

Replying to @kalvado, but trying to save some space by not quoting everything... I was thinking exactly about the difference between straight flight and turns. Both the reports on pilots testing the fixes in the simulator, and on the flight tests in preparation for a request to the FAA to lift the g...

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by IADFCO
Sat Apr 20, 2019 5:41 pm
Forum: Technical/Operations
Topic: 737 MAX MCAS Fix Is In
Replies: 48
Views: 4837

Re: 737 MAX MCAS Fix Is In

Presently, one would have to have their head up their ass not to know how and why the MCAS works. In my opinion that dead horse is beaten and that training mistake is solved. So ... solve the engineering mistake of why it happened and both sides of the issue are solved. I would not be so sure. Qual...

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by IADFCO
Fri Apr 19, 2019 4:33 pm
Forum: Technical/Operations
Topic: 737 MAX MCAS Fix Is In
Replies: 48
Views: 4837

Re: 737 MAX MCAS Fix Is In

I am not sure what they mean by "chain of event cannot be programmed". If a new set of control logic is loaded into a sim, same problem should not be possible any more; that is the nature of a fix. Getting two sets of logic to reproduce previous problem is meaningless, as pilots would hav...

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by IADFCO
Fri Apr 19, 2019 3:51 am
Forum: Civil Aviation
Topic: B737MAX Grounded Worldwide Q1 2019
Replies: 6472
Views: 709595

Re: B737MAX Grounded Worldwide

Regardless of whether or not simulator time is required, wouldn't there be an issue of simulator fidelity? A simulator is as good as the equations of motion coded into it, and especially the flight conditions for which MCAS was designed (a high speed, high-g turn, near stall, right?) are not the eas...

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by IADFCO
Fri Apr 12, 2019 7:15 pm
Forum: Civil Aviation
Topic: B737MAX Grounded Worldwide Q1 2019
Replies: 6472
Views: 709595

Re: B737MAX Grounded Worldwide

The airflow that creates the additional lift at high AoA would have to be partially diverted under the wing. To achieve this the fin would have to be big (along the whole nacelle due to engine placement on the wing). Turning an upward flow down is what we call "lift". :-) You are right th...

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by IADFCO
Mon Apr 08, 2019 6:36 pm
Forum: Technical/Operations
Topic: MAX nacelle, AOA, center of lift, and C/G
Replies: 193
Views: 13915

Re: MAX nacelle, AOA, center of lift, and C/G

Taller gear would be a real problem in terms of space. Just look at what they had to do for the MAX 10 to fit the gear in the wheel well, with the lever action etc. Keep in mind that even the MAX 10 landing gear only provides additional height on rotation, not all the time. It would be easier (in m...

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by IADFCO
Fri Mar 29, 2019 2:19 am
Forum: Technical/Operations
Topic: MAX nacelle, AOA, center of lift, and C/G
Replies: 193
Views: 13915

Re: MAX nacelle, AOA, center of lift, and C/G

How about something on the aerodynamics of annular wings. Lift, drag, & pitching moment vs alpha up through stall would be a good start. In addition to Fletcher's chestnut, another NASA pub.. https://apps.dtic.mil/dtic/tr/fulltext/u2/a098191.pdf That paper describes phenomena that occur at much...

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by IADFCO
Thu Mar 28, 2019 10:07 pm
Forum: Technical/Operations
Topic: MAX nacelle, AOA, center of lift, and C/G
Replies: 193
Views: 13915

Re: MAX nacelle, AOA, center of lift, and C/G

Agreed. Boeing has the data, but the data about the MAX nacelle, AOA, center of lift, and C/G.are not public. The C/L moves when the AOA exceeds the critical AOA in the NG or any other frame. https://aviation.stackexchange.com/questions/27476/when-approaching-stall-why-does-the-center-of-pressure-m...

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by IADFCO
Thu Mar 28, 2019 6:46 pm
Forum: Technical/Operations
Topic: MAX nacelle, AOA, center of lift, and C/G
Replies: 193
Views: 13915

Re: MAX nacelle, AOA, center of lift, and C/G

I agree that only Boeing has all the necessary data. Maybe not even Boeing, if we believe the anonymous insider reports mentioned, for example, by the New York Times, which suggest that there was heavy pressure to complete the MAX quickly, and that corners were cut. For example, if flow separation (...

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by IADFCO
Mon Mar 25, 2019 3:35 am
Forum: Technical/Operations
Topic: MAX certification: new systemic issues identified
Replies: 109
Views: 10988

Re: MAX certification: new systemic issues identified

The cm(alpha) curve for which OldAeroGuy posted a link is exactly the type of chart that would greatly help assess the root cause of the problem (although I am not sure I understand it: if the bare airframe reaches Cm limits due to stall, how can any kind of augmentation increase it?). It would be i...

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by IADFCO
Sat Mar 23, 2019 1:16 pm
Forum: Civil Aviation
Topic: B737MAX Grounded Worldwide Q1 2019
Replies: 6472
Views: 709595

Re: B737MAX Grounded Worldwide

Re: fixes. If the root cause of the problem is really the destabilizing pitching moment generated by the aerodynamic lift of the nacelles, they could try to disrupt the flow at high AoA so that the nacelle stalls before the rest of the aircraft does. This could perhaps take the form of spoilers arou...

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by IADFCO
Fri Mar 22, 2019 3:49 am
Forum: Civil Aviation
Topic: Virgin Atlantic and Alitalia new expansions
Replies: 113
Views: 20107

Re: Virgin Atlantic and Alitalia new expansions

AZ will start IAD-FCO in May, year round, five times a week. I have heard the first commercial today on the radio here in the Washington DC area. I don't think that this new service has been discussed in this thread yet, but it has in a couple of others. If they don't start it or cancel it after a f...

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by IADFCO
Wed Mar 20, 2019 9:18 pm
Forum: Civil Aviation
Topic: B737MAX Grounded Worldwide Q1 2019
Replies: 6472
Views: 709595

Re: B737MAX Grounded Worldwide

AFAIK the max10 MLG change was to allow the plane to rotate and avoid a tailscrape without needing another extra mile of runway and another 100knots speed etc etc as the Max10 is "too long". it wont affect the actual height above ground of the bottom of the engine nacelle It appears that ...

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by IADFCO
Wed Mar 20, 2019 12:15 am
Forum: Civil Aviation
Topic: B737MAX Grounded Worldwide Q1 2019
Replies: 6472
Views: 709595

Re: B737MAX Grounded Worldwide

Fix the root cause of all these problems, and increase the length of the @#%@& MLG. I know it's not trivial and I know it's not cheap. Find a location where it doesn't affect the wing box structurally, design a fairing that doesn't increase drag too much, reroute what needs to be rerouted, fire...

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by IADFCO
Mon Mar 18, 2019 4:08 pm
Forum: Civil Aviation
Topic: B737MAX Grounded Worldwide Q1 2019
Replies: 6472
Views: 709595

Re: B737MAX Grounded Worldwide

Fix the root cause of all these problems, and increase the length of the @#%@& MLG. I know it's not trivial and I know it's not cheap. Find a location where it doesn't affect the wing box structurally, design a fairing that doesn't increase drag too much, reroute what needs to be rerouted, fire ...

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by IADFCO
Sat Mar 16, 2019 1:31 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5474
Views: 712970

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

In post #2411 GalaxyFlyer has a PPW quote about the MAX that caught my eye: "it's another dynamically unstable aircraft". Really? In my corner of the world wings rotate, so in the fixed wing world I'm just an interested bystander. Is the MAX really dynamically unstable, i.e., with eigenval...

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by IADFCO
Thu Mar 14, 2019 6:34 pm
Forum: Technical/Operations
Topic: From 737 'Jurassic' to 737 'Classic' before MCAS
Replies: 22
Views: 2938

Re: From 737 'Jurassic' to 737 'Classic' before MCAS

It's not clear to me whether the MAX flight control system modifications, including the MCAS, were driven by the desire to claim that there were no differences in the handling compared with the NG, or to address intrinsic problems of the aircraft. In other words, if Boeing had accepted the fact that...

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by IADFCO
Mon Mar 11, 2019 8:13 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5474
Views: 712970

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

May I make a suggestion to the moderators? Years ago, when there were these very long and frequently updated threads, usually to discuss a crash, a thread would be closed after a certain number of pages, and given a number N. Then, a new one would be opened with a number N+1, and a brief summary of ...

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by IADFCO
Sat Mar 02, 2019 10:58 pm
Forum: Civil Aviation
Topic: 'She flies! Concorde flies at last!' - First flight of Concorde 50 years ago today!
Replies: 26
Views: 5039

Re: 'She flies! Concorde flies at last!' - First flight of Concorde 50 years ago today!

Yes, great post and links! Thank you! I remember it at around 1:20pm every day flying over my place of work in the Washington DC suburbs, having just taken off from Dulles and on its way to the Chesapeake Bay and the Atlantic Ocean, much much louder than any other airliner, and already so much highe...

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by IADFCO
Tue Feb 26, 2019 6:27 pm
Forum: Civil Aviation
Topic: BA492 Unstable Go-Around at GIB / Diverted to AGP
Replies: 114
Views: 24088

Re: BA492 Unstable Go-Around at GIB / Diverted to AGP

Following up on mm320cap post: large pilot input to correct = high roll attitude feedback gain = lower (or negative) closed loop stability margin = textbook PIO. But what would have happened if the pilot had not tried to correct the roll attitude perturbation? Would the flight control system have fl...

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by IADFCO
Tue Feb 26, 2019 2:05 pm
Forum: Civil Aviation
Topic: BA492 Unstable Go-Around at GIB / Diverted to AGP
Replies: 114
Views: 24088

Re: BA492 Unstable Go-Around at GIB / Diverted to AGP

Following up on the PIO comments... Strictly speaking, to have PIOs you must have a pilot in the loop. So, letting go of the controls by definition stops the PIOs because there is no longer a "P". Then it's up to the flight control system to keep you wings level. Do airlines train pilots t...

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