IL96M From United Kingdom, joined Jun 2005, 133 posts, RR: 0 Posted (8 years 3 days 6 hours ago) and read 4304 times:
Looking at both the development plans of A and B, plus just observing the scene at airports worldwide, in most places 4-engined aircraft are becoming something of a rarity, and to fly on one you really have to do your homework when you make your reservation.
It's pretty clear the 747 Advanced is defunct (or stillborn), the 747 line will end, and now that the A380 has arrived, no new 4-engined models are being planned by anyone. Even the A380 is having major prototypical performance problems; the A340 series is either overburning or not competitive to the 777 (see other postings in this forum).
I am wondering whether with the current aircraft design topology, which is 50 years old (707), i.e. two wings stuck on a tube with engines dangling beneath, the 'evolution' of the current 'species' is converging (in terms of performance and economics) on the type of dense twinjet layouts that you see now being consolidated by both A and B.
Maybe time to look at flying wings, T-Tails, or other such configurations again...?
I don't think so. I mean look at the fleet that JL has or BA has. Can you see these companies abandoning the 747 for something else? I don`t think so.
Quoting IL96M (Thread starter): A340 series is either overburning or not competitive to the 777
OK, so tell me (I see a lot of these these days) where you got this from?
CX has tons flying, LH has tons flying, AF has tons flying. In addition; I have read in other forums about how some A346 HGW (might) be picked up by CX.
Flykal From Australia, joined Sep 2003, 441 posts, RR: 4 Reply 2, posted (8 years 3 days 5 hours ago) and read 4224 times:
Quoting IL96M (Thread starter): Maybe time to look at flying wings, T-Tails, or other such configurations again...?
What we need is a LPG powered engine that will fly at Mach 2 between SYD and LAX. Then both crew and passengers alike will be happy for the next 50 years.
One doesn't discover new lands without consenting to lose sight of the shore for a very long time
LTBEWR From United States of America, joined Jan 2004, 12365 posts, RR: 12 Reply 7, posted (8 years 3 days 3 hours ago) and read 4081 times:
Increased reliability and size of jet engines has made it possible to have longer range for 2 engine large commercial aircraft. The new ultra long range 777's and other recent models of long range a/c now allow non-stop flights of over 7000 miles (like CO's EWR-Hong Kong flights). 'ETOPS' ranges have increased by several major jumps over the last 20-25 years. Two engine aircraft are more fuel efficient than 4 engine a/c. These factors long killed off 3 engine a/c, further encouraged by the MX difficulties of the center engine.
However, large 4 engine a/c are not dead yet, nor will they be for the forseeable future. There are still locations in the world where 4 engine a/c will still be preferred including parts of the Pacific ocean, politically and physically inhospital land areas (certain areas of Russia, the Middle East, Africa and polar areas) as well as pax/customer comfort and security. I don't see some military a/c or the President of the USA in a 2 engine a/c (for longer flights) soon due to operational or security reasons.
MD80fanatic From United States of America, joined Apr 2004, 2637 posts, RR: 10 Reply 11, posted (8 years 3 days 1 hour ago) and read 3861 times:
Quoting OzarkD9S (Reply 10): ETOPS and engine reliability aside, when looking down at nothing but ocean...the concept of 4 (or 3) engines is comforting.
Just old fashioned I guess.
I'm sure at some point, when are molecules are beamed across the cosmos this hesitation will seem quaint, but not at this point...at least to me.
I agree 100%. I think ETOPS is literally flirting with disaster, all in the name of profit (which no one is making anyway). Ummm, redundancy is good and (2) of anything barely qualifies.
DfwRevolution From , joined Dec 1969, posts, RR: Reply 12, posted (8 years 3 days 1 hour ago) and read 3835 times:
>> It's pretty clear the 747 Advanced is defunct (or stillborn)
And you came to that conculsion, how? At this point, the Adv has a very good chance of proceeding to product launch
>> Even the A380 is having major prototypical performance problems;
What are you talking about? The only "major" problems have been on the production side, namely getting behind schedule and maintaining quality control. F-WOWW has been doing very well in flight testing, it's just building them in large numbers that is frustrating Airbus for the time being.
>> I think ETOPS is literally flirting with disaster, all in the name of profit (which no one is making anyway). Ummm, redundancy is good and (2) of anything barely qualifies.
I'll make the dangerous assumption that you aren't being sarcastic?
In which case, you are extremly ignorant. Would you like a flight engineer with your inflated opperating cost?
RichardPrice From , joined Dec 1969, posts, RR: Reply 13, posted (8 years 3 days ago) and read 3801 times:
Quoting IL96M (Thread starter): Even the A380 is having major prototypical performance problems;
Everything I have heard about the A380 test flights has been that the A380 has exceeded all expectations performance wise and the only problems has been passenger cabin systems related.
RichardPrice From , joined Dec 1969, posts, RR: Reply 15, posted (8 years 3 days ago) and read 3713 times:
Quoting DfwRevolution (Reply 12): In which case, you are extremly ignorant. Would you like a flight engineer with your inflated opperating cost?
Quoting Zvezda (Reply 14): Don't forget a navigator. MD80fanatic might feel safer with a navigator onboard as well.
Not saying I agree with the redundancy issue, but computers can quite satisfactorily replace a flight engineer and a navigator, but you'd have a hard time convincing me a computer can replace an engine or two
Prebennorholm From Denmark, joined Mar 2000, 6039 posts, RR: 55 Reply 16, posted (8 years 2 days 17 hours ago) and read 3501 times:
The end of the four engined Era...
That's way too early to say. Nothing is harder to predict than the future.
When we try to predict the future, then we tend to look into the past and present and extrapolate in a straight line.
It takes no more than one or two high profile ETOPS related incidents to create 300 quad orders overnight. While airlines queue up at the desert gates to retrive old 742's waiting to be beer-canned.
Imagine if the law makers in a number of influental countries - not necessarily the USA - changes ETOPS-180/-217 into ETOPS-120...
God forbid that it ever happens.
Always keep your number of landings equal to your number of take-offs, Preben Norholm
Zvezda From Lithuania, joined Aug 2004, 10511 posts, RR: 65 Reply 19, posted (8 years 2 days 9 hours ago) and read 3257 times:
Quoting B741 (Reply 18): I just have a funny feeling that 747/340 series might slowly go by the wayside.
While many rope-start JumboJets have been replaced by B747-400s, many have been replaced by B777-300s. Some have been replaced by A340-600s, but the latter was at best a mediocre seller and lately it has not been doing well against the B777-300ER.
The B747Adv might sell several hundred copies. However, the JumboJet will eventually be replaced by a clean sheet design that will almost certainly be a twin.
At the time of the WhaleJet's development, a quad made sense for such a heavy beast. However, if a WhaleJet-sized airliner were to be developed today, it would be perhaps 100,000 lbs lighter due to increased use of composites and would be a twin. If RR, GE, and PW needed to begin development of 150,000 lb engines, they could do so.
SEAPlane10 From United States of America, joined Jun 2005, 86 posts, RR: 0 Reply 20, posted (8 years 2 days 9 hours ago) and read 3246 times:
Quoting MD80fanatic (Reply 11): I agree 100%. I think ETOPS is literally flirting with disaster, all in the name of profit (which no one is making anyway). Ummm, redundancy is good and (2) of anything barely qualifies.
I think that I heard once that the probability of both engines on a twin going out is not that much higher than that of losing all four on a quad--
From my understanding, a single engine suffices to ensure a satisfactory landing at a diversion airport...
Zvezda From Lithuania, joined Aug 2004, 10511 posts, RR: 65 Reply 21, posted (8 years 2 days 5 hours ago) and read 3181 times:
Quoting SEAPlane10 (Reply 20): I think that I heard once that the probability of both engines on a twin going out is not that much higher than that of losing all four on a quad--
There are two categories of problems that lead to engine failure: those that are local to the engine and those that affect all the engines. A fan blade rupture would be an example of the first type. Fuel contamination would be an example of the second type. Bird strikes fall in between because birds often flock together. A bird strike commonly affects just one engine but can affect several or all nearly simultaneously.
The probability of both engines on an ETOPS twin failing due to a problem that would not also disable a quad are far, far lower than the chances of drowning in your bathtub.
Glom From United Kingdom, joined Apr 2005, 2803 posts, RR: 10 Reply 22, posted (8 years 2 days 1 hour ago) and read 3061 times:
Quoting MD80fanatic (Reply 11): I think ETOPS is literally flirting with disaster
You think wrong. ETOPS twins have a higher reliability than quads. Anything likely to take out both engines on a twin will take out all four engines on a quad.
Starlionblue From Hong Kong, joined Feb 2004, 15904 posts, RR: 66 Reply 23, posted (8 years 1 day 23 hours ago) and read 3001 times:
Quoting IL96M (Thread starter): . Even the A380 is having major prototypical performance problems
Really?
In any case, if you want to make a plane the size of a 744 or larger, it pretty much has to have more than 2 engines. While you could maybe make the engines even larger than the GE-90, it starts getting very expensive to develop an engine which in any case will have a small market.
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
Mrocktor From United States of America, joined Jan 2005, 1647 posts, RR: 50 Reply 24, posted (8 years 1 day 23 hours ago) and read 2990 times:
Quoting SEAPlane10 (Reply 20): I think that I heard once that the probability of both engines on a twin going out is not that much higher than that of losing all four on a quad--
From my understanding, a single engine suffices to ensure a satisfactory landing at a diversion airport...
Regards
A single engine on a twin engine aircraft suffices to ensure a satisfactory landing at a diversion airport. On a quad, losing two engines most likely means a downward glide (which may or may not permit a diversion at ETOPS distances from the alternative), losing three would certainly mean a water landing.
Quoting Glom (Reply 22): You think wrong. ETOPS twins have a higher reliability than quads. Anything likely to take out both engines on a twin will take out all four engines on a quad.
Well ETOPS twins do have a reliability requirement (in flight shutdown rate) that must be maintained (by the specific operator for the specific engine type). And you are correct, common causes (fuel system related) are the largest risk - independent loss of multiple engines being extremely remote these days.
What really makes ETOPS twins safer then other aircraft are the aditional requirements and maintenance precautions required for the fuel, electrical power, hydraulical power, flight control, environmental systems, fire protection systems. All of these systems on an ETOPS aircraft are designed (and maintained) to be capable of a long diversion flight. Not so on tri and quad jets.
The certification authorities are aware of this imbalance and there is a proposed ruling to extend all of these "extra" requirements (everything not related to the engines themselves) to aircraft with more than two engines. Needless to say, this would mean considerable work to demonstrate compliance for the A340s, 747s etc.
mrocktor
25 Wukka: The ETOPS concept / practice is only 20 years old. The US FAA was the first, in 1985. Of course it's had "major jumps" since then... it's not like it
26 Beauing: A real life example of all four engines concking out. Picture it: Alaska December 1989. Mt. Redoubt volcano is erupting and spreading an ash cloud al
27 A350: Don't forget that quads allow for large but weak and therefore ultra high bypass ratio engines. It's also no coincidence that the 787 engines are far
28 MD80fanatic: Well thanks Pleased to meet you as well. As a matter of fact I would. Might be a good choice over some ridiculous faux-missile protection system. You
30 EK156: Okay I am a bit puzzled at the title of this thread! The A 380 will soon be in operation, the B 747ADV is also going to be soon on the table.... so ho
32 Zvezda: The pilot would have wanted something above 300 knots to restart the engines without assist. A little dive might have been appropriate.
33 Mrocktor: I suppose you guys have a rather loose definition of free fall. It was just a good natured joke (thus the smiley), lighten up. You are wrong, a four e
34 Beauing: I imagine the A380 will be the last all new quad ever built for commercial aviation and I don't expect the 747A or the A380 to be big sellers.
35 Zvezda: Almost certainly correct. Depends on what one considers a big seller. I would guess 200 to 500 each.
36 Starlionblue: Maybe, but is there a point in making even larger engines at this time? Within the next 30 years, manufacturers might choose not to take engines into
37 Posti: Maybe the tube with 4 engines is on the way out, but if we take a step outside the box three and four holers may make a comeback. Many of the drawings
38 Da man: Beauing: The same thing happened to a BA 747-200 in the 80s.
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