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Old 18th January 2018, 10:41   #31
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

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Originally Posted by HKap View Post
The A380 is infact one of the quietest aircrafts out there today. The 787 and the A350 are a close second followed by the A330 and the A340. The 777 and the 747 are two of the loudest twins aisle after the 767
A380 is no doubt an advanced aircraft with lots of technology innovation. I guess I should have explicitly mentioned higher 'noise' in context of about having 50 or more passengers in the aircraft economy due to folks chattering, and depending on the sector flown, that can be a big issue.
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. As far as luxury travel goes, the sheer space offered by the A380 is unmatched. However, Etihad offers exactly the same level of comfort on their 787 as their A380. Emirates with their latest purchase of 40 787s won't be any different. The problem with the 777 and the business class layout that most airlines follow is the cabin width
I mentioned my observations were not for business class. I any day prefer a 2-4-2 in economy or a 3-3-3 over 3-4-3. That's where A330 and A340 score for me compared to 787 and A350, and the jumbos. Feels less crowded on the side seats, less issues of getting up for ingress / egress etc. As you said 787 and A380 are more advanced and modern.
You're right in mentioning first class is disappearing but those single deck having it have typically much lesser seating on deck than 2 level planes.
So my preference for midsized aircraft in economy remains over the jumbo jets A380 and esp 747.

Last edited by lancer_rit : 18th January 2018 at 10:44.
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Old 18th January 2018, 11:03   #32
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

Never got a chance to sit in one, but the way this behemoth stands out amongst other planes is something that cannot be replaced.

I clearly remember skeptics expressing doubts over the feasibility of this aircraft when it was launched first. Guess they are vindicated in some sense. I have been frequenting Azerbaijan of-late and see a few Russian made Cargo planes (Antonov ?) parked which are almost the size of A380.
In my opinion the Airbus A380 got more attention than the Antonov An225, and I will always have a soft corner for Russian planes
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Old 18th January 2018, 11:09   #33
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

The biggest USP of the A380 is it's sheer space. Does it not make sense to use this on perennially crowded routes like Delhi-Bombay or Delhi-Bangalore, especially in peak hours? I believe they'll not be short of people to fill 500+ seats.
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Old 18th January 2018, 11:29   #34
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

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Originally Posted by Shreyans_Jain View Post
The biggest USP of the A380 is it's sheer space. Does it not make sense to use this on perennially crowded routes like Delhi-Bombay or Delhi-Bangalore, especially in peak hours? I believe they'll not be short of people to fill 500+ seats.
It could definitely make sense if Delhi to Mumbai were twice or thrice the distance apart.
For short haul trips, smaller planes make more sense.
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Old 18th January 2018, 14:53   #35
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

I have a feeling that smaller airplanes will dominate skies as air connectivity increases worldwide.

My brother's PhD program funded by the EU deals with making airplanes quieter and more slippery by coating them with some kind of substance. The EU seems to be betting on more planes taking off and landing, in more towns across Europe, which is why they want planes to get quieter. They saying that in future, airports will get smaller and will be bang in the middle of cities, etc. So, they're trying to find ways to minimize noise and inconvenience to people with a large number of aircraft taking off and landing daily.

If the market develops in this direction, big jets like the A380 may not have much relevance except to connect very large airports.

Cheers,

Jay

Last edited by JayPrashanth : 18th January 2018 at 14:54.
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Old 18th January 2018, 15:57   #36
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

Emirates announced the order of 36 A380 Today. It’s good hear that a380 is to stay for long.

Last edited by sooraj.naik : 18th January 2018 at 16:00.
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Old 18th January 2018, 16:00   #37
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

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Originally Posted by Jeroen View Post
yes high altitude does affect performance, but I'm not so sure there is a difference between 2- or 4-engine aircraft perse. It's not as if these airports are serviced by four engines plane only?
As you have rightly pointed, altitude does affect the engine performance, high temperature makes it worse, because of the lower air density. Due to the same reason, most of the hot and high airports like JNB, ADD etc. are payload limited, for both quads and twins. It's not that these airports are not served by twins, but the payload limitation is higher in case of twins. For twins, a single engine failure means 50% loss of the total available thrust and for a quad, it is a 25% loss.

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Originally Posted by Jeroen View Post
A twin engine aircraft is vastly overpowered, so losing one engine shouldn't be a problem at all.
Let's see some numbers, like the ones which are listed in the link that you shared. I've taken a typical example of comparable aircraft by mission (unlike the examples given in the link).

B777-200ER
MTOW - 656,000lb
Max Thrust - 2x93,700lbf=187,400lbf
Thrust to MTOW ratio - 0.286
Single engine out Thrust to MTOW ratio - 0.143

B777-300ER
MTOW - 775,000lb
Max Thrust - 2x115,300lbf= 230,600lbf
Thrust to MTOW ratio - 0.298
Single engine out Thrust to MTOW ratio - 0.149

A340-300
MTOW - 610,000lb
Max Thrust - 4x34,000lbf= 136,000lbf
Thrust to MTOW ratio - 0.223
Single engine out Thrust to MTOW ratio - 0.167

A340-600
MTOW - 840,000lb
Max Thrust - 4x61,902lbf= 247,608lbf
Thrust to MTOW ratio - 0.295
Single engine out Thrust to MTOW ratio - 0.221

You can clearly see the single engine out scenarios and the available thrust for each type (Thrust to MTOW ratio), in such a scenario. The fall in numbers are significant for a twin and not so much, for a quad. All these numbers are at sea-level and none of the engines make this much thrust at high altitude-high temperature scenarios. I've not considered factors like aerodynamic efficiency of the wing etc. into the equation. But as the numbers indicate, the loss of thrust is more in case of twins and B777-300ER uses one of the most powerful single engines available in commercial aviation today. So, the payload limitation imposed on a twin is more in case of these specific airports, than a quad, to keep a safe margin.

And, from the article which you have shared - "As you can see from the table to the right, mathematically a 747 will be able to out climb an MD-11 and B-767 with the loss of one engine. However, the B-767 will out-climb the MD-11 and B-747 with all engines running."

The same article says that - "Lightly loaded, the CRJ’s thrust-to-weight ratio is 1 to 2.4, while the Boeing 777’s is an astounding 1 to 1.7. This affords the 777 a very short takeoff distance with a steep climb-out gradient.". For me, this sentence does not make much sense, as airlines buy aircraft to lift as much passengers and luggage as possible and not to show off its performance at no load.
I'm sure that with advancements in engine technology, the industry will find alternatives for this issue, but not yet.

Quote:
Originally Posted by Jeroen View Post
do you have any real performance charts to compare?
http://www.nycaviation.com/2015/06/f...e-safety/38926
I'm not a pilot, am an enthusiast I get my information from aviation forums like airliners.net and searching through the internet. I'm quoting some of the threads, with data, below.
Hot And High Performance B773ER Vs. A346 - This one has some nice comparison numbers and as far as I know, the person quoting the numbers, zeke, is a commercial pilot with Cathay Pacific, who used to fly A340's and now A350XWB. There, he has mentioned the payload penalty for each type.
Advantages Of A Quadra-jet Over A Twin
How Does Hot/high Affect Aircraft Performance?
Is Hot & High Not an Issue Any More?
And more.
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Old 18th January 2018, 16:01   #38
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

The latest news from Emirates signals that the airline is not ending it's relation with the super jumbo just yet.
They have ordered another 36 A380s in an order worth around $16 billion, which should be enough to remove current doubts about the life of the airplane's program.
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Old 18th January 2018, 16:06   #39
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

Looks it's correct

Emirates, the world’s largest operator of wide-body aircraft, signed a $16 billion (Dh58.7bn) deal with Airbus for 36 additional A380 aircraft, ending speculation about the future of the troubled superjumbo programme.


https://www.reuters.com/article/airb...-idUSFWN1PD05J

https://www.thenational.ae/business/...irbus-1.696483

Last edited by Turbanator : 18th January 2018 at 16:07.
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Old 18th January 2018, 16:21   #40
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

I fly A380s four times a year. I selected Emirates and the specific route just to get the A380 for sure. No wonder I'm a big fan of this big boy. Lots of space and smooth ride are the USP. I'm glad Emirates placed the order. I'll continue to get to fly my favorite plane!
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Old 18th January 2018, 16:33   #41
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

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Originally Posted by troublemaker View Post
I fly A380s four times a year. I selected Emirates and the specific route just to get the A380 for sure. No wonder I'm a big fan of this big boy. Lots of space and smooth ride are the USP. I'm glad Emirates placed the order. I'll continue to get to fly my favorite plane!
I'm glad to say that even if Emirates hadn't placed the order, you could have continued to fly your favourite airplane for a majority of the foreseeable future!
The airline has invested too much in the aircraft to just retire it because the production stopped.
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Old 18th January 2018, 17:59   #42
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

And right on cue, Emirates has placed an order for 36 A380s in a deal worth $16B

https://www.emirates.com/media-centr...-us-16-billion
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Old 18th January 2018, 18:15   #43
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

I've flown the A380 six times and prefer the 787 / 777 over the A380 purely because the long boarding / disembarking time, delay in baggage retrieval; additionally on board service is very slow when the aircraft is full.

The noise level in the cabin is on par with the 777, however the 787's are considerably quieter than the A380.

Dreamliner is my first choice for now
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Old 18th January 2018, 20:15   #44
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

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Originally Posted by A350XWB View Post
. It's not that these airports are not served by twins, but the payload limitation is higher in case of twins. For twins, a single engine failure means 50% loss of the total available thrust and for a quad, it is a 25% loss.

You can clearly see the single engine out scenarios and the available thrust for each type (Thrust to MTOW ratio), in such a scenario. The fall in numbers are significant for a twin and not so much, for a quad. So, the payload limitation imposed on a twin is more in case of these specific airports, than a quad, to keep a safe margin.

.
Couple of comments.

It’s difficult comparing twin to quad performance as they are always very different planes. There are no planes available in both a twin and a quad configuration to my knowledge? So it’s always a bit of an apple to pear comparison. But lets look at it from a real life/practical perspective:

Obviously, when an engine fails on a twin you have lost 50% of your thrust. But you can’t just relate reduction of thrust to how much payload reduction is required. Twins are vastly over dimensioned to start with. It’s not how much thrust you have lost, but how much thrust remains and what performance remains.

The initial climb consist of four segments and quads are required to have better performance in these segments on a one engine out then twins!

https://aviation.stackexchange.com/q...gments-defined

There are twins around that really struggle on one engine, there are twins around that have unbelievable one engine out performance. On any plane, irrespective of how many engines, the performance after an engine out is heavily depended on your total pay load. If you were at half the max weight to start with, an engine out performance is substantially different compared to being close to your max weight.

As you mentioned, there are other considerations as well. If you loose an outboard engine on a quad you have to dial in considerable opposite lock on the rudder and ailerons to keep it going straight. Lots of drag!

The below charts are from my KLM AOM. It’s a bit dated, but the principles remain and these sort of charts are still in use in every cockpit and every dispatch/planning department. Although, these days an app might give you the numbers a little faster then tracing all these lines. When I did my pilot test on both the written (so called knowledge test) as well as the oral test we were using these kind of charts. No electronics allowed!

This one shows you how ambient temperature and field elevation affects the Maximum Take off weight with relation to climb ability.

For instance, if it’s 30oC at an airport with an elevation of 10.000 feet this chart will tell you your MTOW is 293 tonnes. At the same temperature but at sea level that would be 428 tonnes!

Days may be numbered for world’s largest passenger aircraft, the Airbus A380-747-take-off-max-weight.jpeg

Next: Is the runway long enough, taken the weather conditions into consideration as well.

The example shown here:
On the right hand side is the runway length in feet. So here we are looking at a 3000 feet long runway, with a 1% upslope, 10 knot headwind. Go the left, at 20oC, sea level, your maximum take off weight is at the intersection of the two lines, so 373 tonnes.

Days may be numbered for world’s largest passenger aircraft, the Airbus A380-747-take-off-performance.jpeg

Note that none of these performance charts mention engine out. It’s a non issue for the take off. You won’t commence a take off, with one engine out of course. It might happen during the take off run. Typically below the so called V1, the pilot would stop the plane. Everything after the take off is just climb performance.

Whereas you wouldn’t take off with a wonky out of service engine, it can be perfectly legal to take off with a braking system out of order. So there are similar tables that show,next to the normal brake energy limits you need to stay within, whether you can still come to a full stop, prior to V1 with fewer brake systems operationally.

When you plan a flight you have to ensure you can safely execute upon that flight. So you plan by using these sort of charts tools. Whether you have one, two, four or more engines if these charts tell you it’s ok, in essence you are ok. (A bit simplified, but you get the point.

On some airports there are restrictions on minimum vertical speeds. You would always plan that first with all engines running. In certain cases it could be relevant to check what an engine out scenario does. If the restriction is only for noise abaitment it’s not a problem. But if you’re taking off from a valley with high mountain tops on the left and the right, you might have to be able to reach a certain altitude to get over the next mountain in front of you and diverting is simply not an option.

I fly single engine planes. In essence there are no formal legal constraints on where I can fly based due to a possible engine out. As you can imagine on a one engine plane a one engine out scenario does not leave many options, usually!

Jeroen

Last edited by Jeroen : 18th January 2018 at 20:27.
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Old 18th January 2018, 20:22   #45
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Default Re: Days may be numbered for world’s largest passenger aircraft, the Airbus A380

Emirates just saved the legacy of A380 as earlier today CNN Money reported that it has ordered 20 new planes with an option to buy another 16. Total deal is worth about $16 billion according to the article.

There's also another interesting quote in the article that's relevant for our discussions here. "Every 15 years, air traffic doubles," he said. "You are not going to double the number of planes going to Heathrow or Frankfurt ... if people want to fly, they will need to fly in bigger aircraft."

http://money.cnn.com/2018/01/18/news...der/index.html

Last edited by Krishnan83 : 18th January 2018 at 20:25.
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