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Fiedman
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A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 11:54 am

I pose this question to everyone, after production of the Airbus A380 and the Boeing 747 comes to an end will we ever see another four engine airliner?
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BREECH
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 12:06 pm

Impossible to predict. It depends not on technical aspect but on political. If tomorrow someone decides to start a major "safety" campaign saying that two-engined planes are dangerous for transoceanic flights (which they inherently are), the entire picture can change. OR an engine manufacturer can develop an engine that will be smaller but much cheaper to service. Lots of variables. Nothing is impossible.
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AVFCdownunder
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 12:19 pm

I can't see any manufacturer taking the plunge by developing another 4-engine product. Given the amount of trans-continental flights with two-engined aircraft that pass without incident, it would take something cataclysmic for safety to become an issue. Engines are becoming increasingly more reliable and fuel efficient, what would be the need to revert back rather than look forward?
 
Noshow
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 12:21 pm

With blended wing bodies and their improved drag some four engine sized airplanes could do with only three or two big engines. So quads might be out. However future electrical concepts could go back to many smaller engines or just e-fans elsewhere.
 
DALCE
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 12:26 pm

I do see a certain future for 4-engined airliners albeit in a slightly different manner. Hybrid-powered aircraft will pop up some day and i can see them take off with regular jetengines of some sort and then switch over to electric powered cruise and descent. This may take a while, but I really see this happening someday in the future.
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gunnerman
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 12:42 pm

The 365-seat 777-300ER does most of what a 747-400 does but much cheaper. The forthcoming 414-seat 777-9 should be in production by 2020. With both Airbus and Boeing struggling to sell their quad jets, the future is big twin jets unless a radical airframe design is done.
 
thijs1984
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 12:48 pm

Maybe only after the next "revolution" in aircraft engines, which is predicted to be hydrogen powered engines. the first engines of the new generation could be smaller / have less power / be less reliable and it could require 3 or 4 engines for the same size of aircraft.
 
morrisond
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 1:48 pm

DALCE wrote:
I do see a certain future for 4-engined airliners albeit in a slightly different manner. Hybrid-powered aircraft will pop up some day and i can see them take off with regular jetengines of some sort and then switch over to electric powered cruise and descent. This may take a while, but I really see this happening someday in the future.


Please understand that I am just asking a question - I am not being critical - just trying to understand.

Wouldn't it be better to have the Electrics help with things like taxi and climb out? Then you can use much smaller more efficient turbines for Cruise?

For example - a 787 Sized plane with a 35K GTF and electric fans to supplement that can produce 40-45K of Thrust?

You would need the batteries to supply maybe 1 -1.5 HR of power for an 4,000NM+ Flight, versus batteries sized to last 8 hours?

I'm just wondering what would be more efficient.
 
mjoelnir
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 2:12 pm

I do not think we will see new 4 engined airliners designed like the 4 engined airplanes of today. But regarding new designs it could change. If somebody finds a good way to use 4 engines at takeoff but only 2 at cruise for example.
Two engines build like engines today with 2 more APU like engines working on electrical driven shrouded fan at takeoff and climb. Only the two engines driving both themselves and the shrouded fan at cruise. Perhaps that would result in a lighter drive or less drag in cruise.
The two engines could be smaller as the shrouded fans would work as a bigger bypass and you could also reduce the whole power need as you would only have to speculate at loosing 25% power at takeoff. The Fans could be placed to reduce drag, like the NASA idea. It would also work for three engines.
There could be a lot of changes with electrical drives and other design changes.
 
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NameOmitted
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 2:34 pm

Keep in mind, we just saw China launch a new large flying boat. Politics still lead to beat aircraft.

If a Russian-Chinese joint venture crates a large aircraft that is now powered by imported Western engines, it could well take 4 of them.
 
Aither
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 2:37 pm

Why not ? the 4 engines is the optimum choice for a double decker (2 engines per deck). We're not talking about A340 here...
Never trust the obvious
 
morrisond
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 2:50 pm

mjoelnir wrote:
I do not think we will see new 4 engined airliners designed like the 4 engined airplanes of today. But regarding new designs it could change. If somebody finds a good way to use 4 engines at takeoff but only 2 at cruise for example.
Two engines build like engines today with 2 more APU like engines working on electrical driven shrouded fan at takeoff and climb. Only the two engines driving both themselves and the shrouded fan at cruise. Perhaps that would result in a lighter drive or less drag in cruise.
The two engines could be smaller as the shrouded fans would work as a bigger bypass and you could also reduce the whole power need as you would only have to speculate at loosing 25% power at takeoff. The Fans could be placed to reduce drag, like the NASA idea. It would also work for three engines.
There could be a lot of changes with electrical drives and other design changes.


Just expanding this out - a Three Engine 787 Sized Plane with 35K GTF's under the wings and an Electric fan in the tail for Takeoff and climb to cruise. Doors could open in both sides (Picture Torpedo Tube doors) of the tail to feed the fan air. It would supply 40-45K of thrust. You wouldn't need an APU as you would have the batteries.

No idea on the math - but an Electric motor should be a lot lighter than The difference between two 80K engines and two 35K engines - weight you could use for the batteries. Plus the plane would then need less fuel as the Engines would be more efficient.
 
mmo
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 2:56 pm

BREECH wrote:
Impossible to predict. It depends not on technical aspect but on political. If tomorrow someone decides to start a major "safety" campaign saying that two-engined planes are dangerous for transoceanic flights (which they inherently are), the entire picture can change. OR an engine manufacturer can develop an engine that will be smaller but much cheaper to service. Lots of variables. Nothing is impossible.



Care to explain your justification about the safety of twins being "inherently" dangerous? Would to see some factual justification.....
If we weren't all crazy we'd all go insane!
 
nehalem
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 2:58 pm

BREECH wrote:
Impossible to predict. It depends not on technical aspect but on political. If tomorrow someone decides to start a major "safety" campaign saying that two-engined planes are dangerous for transoceanic flights (which they inherently are), the entire picture can change. OR an engine manufacturer can develop an engine that will be smaller but much cheaper to service. Lots of variables. Nothing is impossible.

I don't think such as safety campaign would be effective. Two-engined planes have been flying transoceanic flights for decades. Has there ever been a crash of a 2 engine plane flying over the ocean that would have been avoided had it had 4 engines?
 
BREECH
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 3:31 pm

mmo wrote:
Care to explain your justification about the safety of twins being "inherently" dangerous? Would to see some factual justification.....

You are over water and six hours away from the nearest airport and suddenly half of your engines shut down. Factual justification - Amelia Earhart.
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BREECH
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 3:43 pm

NameOmitted wrote:
Keep in mind, we just saw China launch a new large flying boat. Politics still lead to beat aircraft

Come again! Where? When? Show me!!!!!!!!!!!!!!!!
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MSPbrandon
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 3:46 pm

BREECH wrote:
mmo wrote:
Care to explain your justification about the safety of twins being "inherently" dangerous? Would to see some factual justification.....

You are over water and six hours away from the nearest airport and suddenly half of your engines shut down. Factual justification - Amelia Earhart.


I see your point, but comparing Earhart with a Modern 777 or A350 is a bit of a stretch, IMO.
 
BREECH
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 3:53 pm

MSPbrandon wrote:
I see your point, but comparing Earhart with a Modern 777 or A350 is a bit of a stretch, IMO.

True. With her landing speed she actually had a chance of a successful ditching. My point is this. If something hasn't happened before, it doesn't mean that it can't happen at all. I believe that ETOPS has been WAY over-commercialized at the expense of common sense and safety. And I pray to God that we won't have to pay a heavy price for it.
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nehalem
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 3:54 pm

BREECH wrote:
MSPbrandon wrote:
I see your point, but comparing Earhart with a Modern 777 or A350 is a bit of a stretch, IMO.

True. With her landing speed she actually had a chance of a successful ditching. My point is this. If something hasn't happened before, it doesn't mean that it can't happen at all. I believe that ETOPS has been WAY over-commercialized at the expense of common sense and safety. And I pray to God that we won't have to pay a heavy price for it.


If something hasn't happened in over 30 years I think common sense would argue that its silly to spend billions of dollars to avoid the risk.
 
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NameOmitted
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 3:57 pm

BREECH wrote:
NameOmitted wrote:
Keep in mind, we just saw China launch a new large flying boat. Politics still lead to beat aircraft

Come again! Where? When? Show me!!!!!!!!!!!!!!!!

Hey, look! It's even a 4 engine craft! (and when I wrote "beat" I meant neat. I'll blame my phone)


[code][/code]
 
BREECH
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 4:12 pm

NameOmitted wrote:
Hey, look! It's even a 4 engine craft! (and when I wrote "beat" I meant neat. I'll blame my phone)

WOW! That looks like Beriev, though.
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Revo1059
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 4:23 pm

BREECH wrote:
mmo wrote:
Care to explain your justification about the safety of twins being "inherently" dangerous? Would to see some factual justification.....

You are over water and six hours away from the nearest airport and suddenly half of your engines shut down. Factual justification - Amelia Earhart.


..and that plane with 1 engine can still fly and maintain altitude as it's required to be able to do.

When is the last time a twin had engine failures that doomed it vs if it had been a quad?
Last edited by Revo1059 on Fri Jan 12, 2018 4:27 pm, edited 1 time in total.
 
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lightsaber
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 4:24 pm

Keep posts on topic. Off topic political posts will result in a ban. Non-av discussions should be in non-av.
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767333ER
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 4:35 pm

Revo1059 wrote:
BREECH wrote:
mmo wrote:
Care to explain your justification about the safety of twins being "inherently" dangerous? Would to see some factual justification.....

You are over water and six hours away from the nearest airport and suddenly half of your engines shut down. Factual justification - Amelia Earhart.


..and that plane with 1 engine can still fly and maintain altitude as it's required to be able to do.

When is the last time a twin had engine failures that doomed it vs if it had been a quad?

:checkmark:
And with that fact based argument the discussion is over. Twins are not inherently dangerous and won't as long as they are designed how they have been.
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dtw2hyd
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 4:35 pm

There may not be 4 engined aircrafts, but we may actually see more than four electric motor fans powered by two engines/generators.

I am not sure why battery weight is an issue. It will never leave the ground if batteries have to power the motors.

Seimens achieved 5KW power per Kilogram. BAe146 Technology Demonstrator replacing one engine with a 2MW electric motor(400 Kgs)

4xALF502(628Kgs) = 2512 Kgs
4x2MW Electric Fan(400Kgs) = 1600 Kgs.
Leaves 912Kg for power generation.

Is it possible to achieve?
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Jayafe
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 4:37 pm

767333ER wrote:
:checkmark:
And with that fact based argument the discussion is over. Twins are not inherently dangerous and won't as long as they are designed how they have been.


Quad are inherently safer than twins. In case of failure, the twin has 1 engine left. The quad would still have 3. Please, check your maths.
 
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767333ER
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 4:43 pm

Jayafe wrote:
767333ER wrote:
:checkmark:
And with that fact based argument the discussion is over. Twins are not inherently dangerous and won't as long as they are designed how they have been.


Quad are inherently safer than twins. In case of failure, the twin has 1 engine left. The quad would still have 3. Please, check your maths.

And twins are required to be able to maintain altitude and speed on one engine so in other words you only need one engine to keep the plane in the air once it is in the air. Please check your facts and understand the design requirements of twins.
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Jayafe
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 4:44 pm

767333ER wrote:
Jayafe wrote:
767333ER wrote:
:checkmark:
And with that fact based argument the discussion is over. Twins are not inherently dangerous and won't as long as they are designed how they have been.


Quad are inherently safer than twins. In case of failure, the twin has 1 engine left. The quad would still have 3. Please, check your maths.

And twins are required to be able to maintain altitude and speed on one engine so in other words you only need one engine to keep the plane in the air once it is in the air. Please check your facts and understand the design requirements of twins.


My facts look pretty good, but your maths still look quite poor.
No one is saying that twins are dangerous, ilegal or can't fly. The actual fact that you seem to ignore is that in case of failure it's better to have 3 more than 1 more. Got it now? :)
 
caetravlr
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 4:45 pm

I am no aerospace engineer, but while we may not see any more large commercial tube and wing aircraft with 4 engines hanging from the wings, there may be other applications where 4 engines makes sense. With any type of design where there engines are contained within the body of the aircraft, it might make sense to have 4 smaller engines vs. 2 larger ones for aerodynamic reasons. It all depends on the overall economics of a new design.
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Polot
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 4:47 pm

Jayafe wrote:
767333ER wrote:
:checkmark:
And with that fact based argument the discussion is over. Twins are not inherently dangerous and won't as long as they are designed how they have been.


Quad are inherently safer than twins. In case of failure, the twin has 1 engine left. The quad would still have 3. Please, check your maths.

That doesn't make them inherently safer, as twins are designed to fly with 1 engine, and quads 3. That doesn't mean a quad has a greater "buffer" and can necessary safely fly with 2 engines or 1 in case there are additional engine failures.
 
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United787
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 4:50 pm

I thought quads are inherently more dangerous than twins because with 4 engines, you have double the chances of a catastrophic uncontained engine failure that damages something else on the plane. That scenario is more likely (and has happened QF A380) than a twin losing both engines. So when you do the real math... the risk is greater in a quad... but still very low. I know there are more qualified people that can expand on this.
 
GalaxyFlyer
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 5:35 pm

The only real advantage to the quad is loss of an engine does NOT REQUIRE a diversion as soon as possible or practical. The quad can lose one engine and, if two engine out performance allows, can continue. Note: “can continue”; doesn’t have to continue but is legally and operationally possible. With so few experienced in quad operations, the default case has come down to divert.

Now, it’s true the 747 and A380 have more potential redundancies in the systems with an engine out. But, modern systems, especially flight controls, have multiple back-ups. The A380 advanced a lot of that technology in distributed power; EHAs at the surfaces; etc.

GF
 
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SQ22
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Re: A380 B747 The last of the four engine airliners?

Fri Jan 12, 2018 7:59 pm

The initial question has been answered an this thread will be closed now.

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