[GTO]

Image shot by Stratos - related thread.

The jumbo jet, for many years the workhorse of modern air travel, could be close to running out of runway.

Last year, there were zero orders placed by commercial airlines for new Boeing 747s or Airbus A380s, reflecting a fundamental shift in the industry toward smaller, twin-engine planes. Smaller planes cost less to fly than the stately, four-engine jumbos, which can carry as many as 525 passengers.

Source & full Reuters Article

[M5_fan]

This is also because passengers prefer convenience. They want point to point flights rather than hub to hub flights. And it doesn't make sense for airlines to buy a jumbo jet and then run it point to point as in most sectors, the seats won't fill up.

[rrsteer]

Does that mean Boeing's strategy worked out much better than Airbus'?

As far as I remember Boeing had invested on a strategy which banked on smaller planes to be used on shorter routes (Dreamliner 787).

While Airbus put its money on large planes - A380 - and the future of aviation deviating towards larger planes and longer routes.

[D33-PAC]

Originally Posted by rrsteer

Does that mean Boeing's strategy worked out much better than Airbus'?

Without a doubt. I keep seeing articles on how much of a failure the A380 is. Without middle eastern buyers with serious state money backing them, the A380 would have no customers. Emirates is a godsend for Airbus.

Other than a handful of companies everyone is running away from the A380.

It's not just airplanes i see it everywhere else. Even in F1 we went to V6 turboes, and even in the shipping industry over the top sized ships are simply out of the question.

I don't think we've ever lived in such an efficiency and green oriented world before. In the engineering world I see things getting smaller, lighter, and just more cost-effective and efficient. The era of big is over IMHO, as far as the material world of engineering is concerned.

[Doge]

But its been around for years! The 747 is easily the most successful Jumbo jet ever and has made a lot of money for Boeing. It also may be the most widely recognized aircraft ever. A380 on the other hand is a disaster if it was not for emirates.

[SmartCat]

Recently, I was looking at the financials of Jet Airways. They had a revenue of Rs. 17,000 crores in FY14 and fuel expenses of Rs. 8,000 crores. Fuel costs for this particular airline works out to be an eye-popping 50% of revenues.

It's pretty obvious why airlines go for smaller twin engined fuel efficient aircraft - because even 10% or 15% fuel savings - can significantly improve balance sheets of airlines.

Also, airlines have an average passenger load factor - or passenger occupancy per trip - of 80%. Having a 400 seat aircraft might not help increase revenues. Having smaller aircraft can help increase passenger occupancy rate.

[mail4ajo]

I dont prefer to travel in the 747s anymore as most of them have been in service for years. In long haul routes, the more swanky B777 and the dreamliner are more comfortable, have better entertainment options and give you a more cozy feeling.

I arrive more fresh after a 11 hour journey in a dreamliner or A380 compared to B747s primarily due to the air conditioning system, I believe.

[vivtho]

Originally Posted by GTO

The jumbo jet, for many years the workhorse of modern air travel, could be close to running out of runway.

Last year, there were zero orders placed by commercial airlines for new Boeing 747s or Airbus A380s, reflecting a fundamental shift in the industry toward smaller, twin-engine planes. Smaller planes cost less to fly than the stately, four-engine jumbos, which can carry as many as 525 passengers.

The 4-engined airliners rose in prominence mainly due to ETOPS-90 rules which limited twin-engined airliners to routes that always had a emergency airport available within 90 minutes of flying time (in case one engine quit). With the increasing reliability of turbofan engines, newer twin-engined airliners are certified to the ETOPS-180 standard (which allow a margin of 180 minutes).
This has allowed airlines to operate them on long over-water routes that were previously barred to them. A twin-engined airliner does save some fuel compared to a 4-engined one. However, to airlines the chief savings come in drastically reduced maintenance and inventory costs.

The 747 is still in production, but only in its cargo variant. Cargo airlines (despite not being bound by ETOPS regulations) need the power of 4-engines to take off with a full load and still carry the fuel required for their long-range point-to-point routes.

Originally Posted by rrsteer

Does that mean Boeing's strategy worked out much better than Airbus'?

As far as I remember Boeing had invested on a strategy which banked on smaller planes to be used on shorter routes (Dreamliner 787).

While Airbus put its money on large planes - A380 - and the future of aviation deviating towards larger planes and longer routes.

Actually both manufacturers hedged their bets very well. Boeing did take the position that the way of the future was in fast mid-sized airliners that could provide point-to-point service. It started development of the Sonic Cruiser which cruised faster (Mach 0.98 compared to Mach 0.7-0.8) than other airliners). However this plan fell by the wayside primarily due to a lack of airline interest. Airlines were more interested in a new aircraft that could offer a big reduction in cost per seat-mile. An additional factor in the lack of airline interest was that airlines had spent billions over the past 50 years refining the hub-and-spoke model. A point to point model would have disrupted that and brought in new costs (e.g. aircraft would have to be parked and serviced at locations where the airline didn't have long-term discounted agreements). Boeing wound-up the Sonic Cruiser concept in the early 2000's.

Airbus placed their bets on the opposite end of the spectrum - building the biggest aircraft. They hoped to achieve lower seat-mile costs by offering more seats per aircraft. The result was the A380. Despite being a technological achievement, the A380 hasn't sold as well mainly due to 2 factors - not all airports have been upgraded to handle it and because it's frankly too big for most routes. The second factor is the reason why even economy seats on the A380 are so spacious - they couldn't sell more seats if they'd installed them (the A380 is certified to carry up to 800 passengers but is normally fitted with just 550 seats).

Boeing decided to use technology to reduce seat-mile costs and the result was the 787 (initially called the 7E7). This airliner introduced composite structures, electrical motors (replacing heavy and maintenance intensive hydraulics) (these features were previously seen only on smaller military aircraft) coupled with new-generation fuel-efficient engines. Airbus was initially dismissive of the 787 ... until the orders started rolling in after which they started the crash development of their response - the A350.

[SmartCat]

Originally Posted by vivtho

The 4-engined airliners rose in prominence mainly due to ETOPS-90 rules which limited twin-engined airliners to routes that always had a emergency airport available within 90 minutes of flying time (in case one engine quit). With the increasing reliability of turbofan engines, newer twin-engined airliners are certified to the ETOPS-180 standard (which allow a margin of 180 minutes).

Good point there.

Modern engines are not only reliable, but also very powerful. All twin engined aircraft can - not just fly or land - but also takeoff safely with just one engine. So if there is a bird hit or a technical issue shuts down an engine while taking off, the pilot can still manage to safely put the bird in the sky. By stepping on the gas pedal hard, I presume!

[Akshay1234]

Originally Posted by vivtho

The 4-engined airliners rose in prominence mainly due to ETOPS-90 rules which limited twin-engined airliners to routes that always had a emergency airport available within 90 minutes of flying time (in case one engine quit). With the increasing reliability of turbofan engines, newer twin-engined airliners are certified to the ETOPS-180 standard (which allow a margin of 180 minutes).
This has allowed airlines to operate them on long over-water routes that were previously barred to them. A twin-engined airliner does save some fuel compared to a 4-engined one. However, to airlines the chief savings come in drastically reduced maintenance and inventory costs.

The 747 is still in production, but only in its cargo variant. Cargo airlines (despite not being bound by ETOPS regulations) need the power of 4-engines to take off with a full load and still carry the fuel required for their long-range point-to-point routes.

But what about 2 engined planes that do much longer routes? I can't imagine some planes running over the Atlanta or Pacific on some routes are always within 180 minutes of airports which can support them?

Also what about the 747-8? Isn't that still being made, even though they don't have fresh orders for it?

Originally Posted by smartcat

Good point there.

Modern engines are not only reliable, but also very powerful. All twin engined aircraft can - not just fly or land - but also takeoff safely with just one engine. So if there is a bird hit or a technical issue shuts down an engine while taking off, the pilot can still manage to safely put the bird in the sky. By stepping on the gas pedal hard, I presume!

Can they take off on a single engine? with a full load?


Anyway since this thread is about 747s, I've had the privilege of flying these beasts a few times. Ever since I was a child the 'Jumbo Jet' used to fascinate me just like cars. Each time we would fly out of the country I would hope it would be a jumbo, and a few times it was. More recently I've managed to fly the upper deck on the 747, which is like nothing else. Only 8 seats, which makes it so private. And the engines are a distant hum, its really something like flying private I would imagine.

[V.Narayan]

The Boeing 747 is indeed one of the most graceful birds to take to the skies. Happily we will behold its beautiful lines for at least 15 to 20 years and more. Fact is that as jet engines get larger it is more fuel efficient to be powered by two giant turbofans rather than four slightly less powerful turbofans. Even if all other parameters are the same two engines create less drag than four. With ETOPS 180 there is no need for 4 engines except if they are the largest four available mated to the largest airframe to carry more passengers than any other machine and noticeably drop the passenger-mile costs (does that sound like the A380 )

The Boeing 777 carries (in a 3 class cabin) about 375 passengers on the back of 188,000 lbs engine thrust 2 GE engines generating a maximum of 94,000lbf (called pound force). The venerable Boeing 747 carries around 410 passengers on the back of 4 GE engines delivering a total thrust of 248,000lbf. 10% more passengers for 30% greater engine power. This lies at the heart of the economics. Of course things are not that simple and the ratio at cruising speeds will be different but directionally it is the same. In the guise of the freighter maybe the 747-8 will survive but it is a wobbly may. With a production run of 46 years the 747 has earned its place in the hearts of aviation buffs.

Aircraft demand supply is notoriously difficult to estimate mainly because it is driven by factors that are unpredictable. In 1966 when design work was in full swing Boeing estimated that 200 was the best global demand for the 747 passenger version because soon (or so it was thought) the world will only be flying supersonic and bulbous kites like the 747 will be relegated to freighter duties. At the time the prototype flew the order book was a healthy 178! But then the economic crises of 1970 and the first oil crises of 1973 caused the orders to stall and sputter with only 108 more aircraft being ordered in the first 7 years from 1970 to 1976 both included. And Boeing had some real cause for concern because traffic on most routes could not sustain the carrying capacity of a 747....airports were not expanded or runways lengthened/strengthened to tak e a 747....airport terminals at many otherwise important airports could not handle 400 passengers disgorging at a time. The same script is playing again for the A380. After 1977 ie its 9th year in service that the fortunes turned and the 747 only looked up.


Now coming to the A380. Traffic demands on trunk routes will in my view eventually grow to need an aircraft that carries 600+ passengers at a go. Some routes which may not be topline trunks today will become so in 10 years. In India less than 3% of the population has ever flown in an aircraft. In USA this number was surpassed in the mid-1950s. China will be a little better off but directionally similar in terms of future potential. These aircrafts are designed keeping in mind the need to serve and fly for 50 years out. Yes Airbus is facing a bleak order book right now and the global economic uncertainties are worrisome but tomorrow's traffic potential out of Asia will need a jet the size of an A380. So tough times are ahead but we have not seen off the A380 yet. Airlines (other than Emirates apparently) are looking to re-configure their A380 cabins to accommodate more seats and toss out the bars and lounges and other space grabbers. So sardine days will continue. The technical issues on wing structures the A380 is facing are actually more concerning than filling the demand.

The Boeing 747 was designed by Joe Sutter who also designed the 737 which to date has had the largest production run of any civil jet plane. 8471 Boeing 737s have been delivered to date and a further 4244 are in the order backlog! Sutter is 94 now. Photo below of Joe Sutter in February 1969 against the prototype 747. What a man.

[SmartCat]

Originally Posted by akshay1234

Can they take off on a single engine? with a full load?

Absolutely.

https://www.youtube.com/watch?v=UBdajN4tHKs

[vivtho]

Originally Posted by akshay1234

But what about 2 engined planes that do much longer routes? I can't imagine some planes running over the Atlanta or Pacific on some routes are always within 180 minutes of airports which can support them?

180 minutes margin allows the aircraft to service more than 90% of the long-haul routes. Flying for 180 minutes equates to a distance more than 1000-1200 km. The Northern Atlantic great-circle (the shortest distance between two points on the globe) routes have diversion airports that allow even ETOPS-90 aircraft to fly them. The Southern Atlantic routes can't follow the exact great-circle route but a close approximation to keep airports in the Azores, Western Africa and Eastern South America. As for the Pacific, it's not so empty as it seems. During WW2, the US built airports on virtually every island chain in the Pacific to support their campaign against Japan. Most of them are now civilian airports whose primary purpose is to support such emergency diversions.

Originally Posted by akshay1234

Also what about the 747-8? Isn't that still being made, even though they don't have fresh orders for it?

The 747-8 comes in a freighter version the 747-8F which is in production ... mainly to cargo operators who are looking for a newer wide-body aircraft to replace their earlier 747 models.

Originally Posted by akshay1234

Can they take off on a single engine? with a full load?

They can't take off from a standing start, but once they have enough speed they are designed to take off even if one engine fails. In fact, every civilian airliner is tested to ensure that once the aircraft reaches a certain speed (i.e. it is going fast enough that it can't stop before the end of the runway) it should have enough power to continue the take off, circle and return on the power of a single engine.

[Ricci]

Originally Posted by mail4ajo

I arrive more fresh after a 11 hour journey in a dreamliner or A380 compared to B747s primarily due to the air conditioning system, I believe.

That is partly due to cabin pressurization, seating dimensions, and insulation. The recent jets maintain a higher cabin pressure (equivalent to 6000 feet or so if I remember correctly), early jets were as high as 11,000 feet equivalent. Plus over the years, planes like 777 and A330/340 made some progress towards bigger seats , although now airlines are back to squeezing as many pax per jet owing to more powerful engines and reducing luggage allowance to manage. You remember the ads in late 90s or early 200s about the Airbus, about how quiet and comfortable the A340 was, and how you were never more than 1 seat away from the aisle ?

Originally Posted by vivtho

The 4-engined airliners rose in prominence mainly due to ETOPS-90 rules which limited twin-engined airliners to routes that always had a emergency airport available within 90 minutes of flying time (in case one engine quit). With the increasing reliability of turbofan engines, newer twin-engined airliners are certified to the ETOPS-180 standard (which allow a margin of 180 minutes).
A twin-engined airliner does save some fuel compared to a 4-engined one. However, to airlines the chief savings come in drastically reduced maintenance and inventory costs.

Cargo airlines (despite not being bound by ETOPS regulations) need the power of 4-engines to take off with a full load and still carry the fuel required for their long-range point-to-point routes.

I'm not sure of worldwide regulations, but the FAA apparently has a requirement that a jet should be able to continue to climb and clear obstacles after failure of 1 engine immediately after lift off. Since any jet has a certain requirement of thrust in order to remain airborne , that thrust must be met with 1 engine on a twin , but 3 engines on a quad-jet. That means, 1 engine is 100% of a jet's minimum thrust on take-off requirement on a twin, but on a quad one engine is 33% of the minimum. In other words, a twin jet has more excess power available, and I think this is borne out by the steeper climb angle twin jets have after take off as compared to the 4-engined jets. Realisitically speaking, even a single engine on a 4 engine jet is likely to be better than the 33% minimum thrust must make, but suffice to say a twin jet has more leeway built in, which corresponds to more spare thrust when all engines are working optimally.

[V.Narayan]

Some Boeing 747 trivia for your entertainment...

• A typical long haul 747 flight carries 5500 kgs of food and drinks - next time you fly make sure you enjoy your full share
• The paint on a 747 weighs about 300 kgs
• The 747's wing tips are designed to flex 26 feet
• The tail fin of a 747-400 carries ~12,000 litres of fuel
• There are 6 million parts in a 747-200 of which 1.5 million are rivets
• Early 747s were equipped to carry a fifth engine (a spare) on the right wing. This was used to transport a much needed spare engine to a sister ship stranded up the line

"Good evening ladies & gentlemen; this is your captain speaking. We have a small problem. All four engines have stopped. We are doing our damndest best to get them going again. I trust you are not in too much distress" - A typically British understatement by British Airways Captain Eric Moody during a flight from Kuala Lumpur to Perth in June 1982. The aircraft had flown through ash cloud thrown up by a simmering volcano. Eventually all four engines re-started and the flight landed safely at Jakarta.

Photo below of a NASA Space Shuttle Carrier - a modified Boeing 747. The shuttle carrier Boeings (2 of them) were used to ferry the space shuttles from their landing sites (on return from space) to the Kennedy Space Centre in Florida and to and from the production centres and the Kennedy launch site. Theoretical evaluation was done to see if the space shuttle could be launched off the back of a Boeing 747, get it up to a high enough altitude to fire off into low orbit on its own engines. But studies proved it would be a tough call.

I shudder at the complexities of the aerodynamics of this combination and salute the pilots who flew it.