75

Whenever you see titanium being used on aircraft, look for heat sources. The metallic alternative aluminum is usually lighter and much cheaper. In most commercial aircraft the APU (Auxiliary Power Unit) is in the tail, behind the rear pressure bulkhead and the empennage. (modified from aerospaceweb.org) The APU is a small turbine and its exhaust gases are ...


55

Well, it does look pretty, doesn't it? Boeing wanted to reduce the noise generated because of jet blast of the engines. Many airports around the world are implementing new noise regulations. As mentioned by Boeing: To combat the sound of jet-blast from the rear of the engine, Boeing, General Electric, and NASA developed serrated edges called chevrons ...


46

I think both answers are correct, but I would like to spend some time describing the phenomena that chevrons try to reduce so that I can complement the answers already provided. So, what is happening in an engine? We have a hot gas at high speed leaving the engine core, and another gas at higher speed than the external air but much slower than the core, on ...


39

No. Firstly, as a comment noted, the takeoff was hardly "near vertical", the camera angle makes it look so. The takeoff angle in the video certainly is much steeper than a normal one, but Airbus aircraft are more than capable of doing the same - in fact an A350 did very much the same thing at the Paris Air Show. The notion that an Airbus doesn't let the ...


28

Norwegian’s heat issues stem from an unusually high passenger capacity aboard the Boeing 787-8 jetliners that the carrier uses on its Las Vegas routes. Most airlines operate the plane with an average of 200 seats, but Norwegian puts 291 seats for sale on the 787-8 aircraft to keep costs down as part of its low-cost model. Given the weight of those ...


28

It is because of the carbon fibre. This is the same reason that the 787 has bigger passenger windows. Here you can find a link explaining the polarized windows on the 787. Because of its higher tensile strength, you can have bigger windows. Windows are considered weak points in the fuselage where there is no structural reinforcement. This means that the ...


24

From here: The amount of flex is really a product of the material. The wing requires a specified ultimate strength; with metal, that translates into a given amount of flex. This can be varied within limits, but it is really the material, its stiffness to yield point ratio, and its fatigue properties, that control how much flex you are going to end up with....


24

I found this 16-year old thread on airliners.net. The Boeing 777 has the same system, and at the time it was unique in that. (You can watch it here.) When takeoff power is applied, hydraulic power is removed from the flaperons, as not to stress the actuators for an extended duration, which causes them to drop due to gravity. They are then slowly lifted by ...


24

Those are the thrust reversers, which cause the engines to produce thrust "backwards" to help slow the aircraft during the landing. You can see a close-up video of 787 thrust reversers in operation, including a look at the panels at the back of the engine which block the normal flow of air. We also have a question How do thrust reversers work on a jet ...


23

The wings of the Boeing 787 are so flexible because its carbon fiber material can be stretched more, and the high aspect ratio of 11 will magnify this effect. In flight, all you will feel is less shaking due to gusts, because the wing will dampen load changes more effectively. On the ground, the wing might have less tip clearance, because less in-built ...


23

It's very likely that the 787 would have less problems with turbulence than the DC-8 did. The wings of the Boeing 787 are more flexible than the DC-8, and that flexibility will damp the immediate impact of turbulence. More important, the Boeing 787 has a gust alleviation system that reacts to turbulence by counteracting the induced accelerations using the ...


22

The wings of the Boeing 787 are so flexible because its carbon fiber material can be stretched more, and the high aspect ratio of 11 will magnify this effect. In flight the consequences are: Less shaking due to gusts, because the wing will dampen load changes more effectively. Delayed aileron response, because the lift change due to aileron deflection will ...


22

According to this document by Boeing: Altitude: How High Is Just Right? Today's airplanes are pressurized to a typical cabin altitude of 6,500 to 7,000 feet (1,981 – 2,133 m), with a maximum certification altitude of 8,000 feet (2,438 m). Because the advanced composite materials that make up the 787’s fuselage do not fatigue, the 787 can be ...


22

A gust alleviation system is a control system fitted to some Fly-by-wire (FBW) aircraft that reduces the effect of gust loads on the aircraft by deflecting control surfaces such as ailerons, rudder and elevators. The system works by measuring the upward acceleration of the aircraft and comparing that with the acceleration commanded by the (auto)pilot. A ...


22

Actually, there were similar tricks used on Boeing aircraft before to reduce jet noise. The Rolls-Royce Conway (as used on the Boeing 707) had a scalloped exhaust which improved jet mixing and reduced exhaust noise. Since the Conway was also the first operational bypass engine, the lower exhaust speed of this design helped to reduce noise already. At the ...


22

The 787 is among the safest airliners currently flying. At the time of writing, it has been involved in zero hull loss incidents and there have been zero fatalities due to incidents. While you can find numerous incidents including those you mention there have been exactly zero total losses and no loss of life on board (due to the aircraft itself - its ...


21

Contrails are created due to variances in the pressure of the air, coupled with the amount of moisture in that air. When the 2 engines of the B787 blast their exhaust out, the high pressure of the exhaust temporarily causes the moisture to condense. Two contrails are visible. However, as the pressure waves from the 2 exhaust trails propagate through the ...


20

Aircrews seldom have to power off an aircraft completely (also known as a cold and dark cockpit). Airliners usually stay powered on at the gate. This is known as a "short turn-around": engines are stopped, the APU is stopped, but electrical power and air conditioning is still supplied by ground equipment. This has the advantage of minimizing turn-around ...


20

You have not defined your benchmark/reference value, but a three-year-old article suggests this was possible depending on definition even at a very early stage for some airlines: ANA earlier this month was the first to reveal that its aircraft were producing around 21% lower fuel burn on international flights compared to the 767-300ER that the 787 is ...


19

Fascinating question. Not being an expert in contrail aerodynamics I'm forced to speculate, but I'm guessing the apparent three trails is caused by the spreading of the trails by wingtip vortexes. I find similar examples called hybrid contrails. Here's one animation of a four-engine A340 from that article: I think if you ignore the trails from the outer ...


18

The cockpit is clean and uncluttered thanks to the absence of the large circuit breaker panels that we’re used to in traditional types. Almost all circuit breakers are ‘virtual’ and are accessed via the forward Multi-Functional Display (MFD). — flight.org The 787 and its contemporaries have moved away from physical CB's and use virtual CB's instead. ...


17

The rules on visibility from the cockpit have been updated. There are rules and regulations imposed on the view from the cockpit, for very good reasons - collision avoidance for instance. During approach, the pilots must be able to see the runway while on the glide slope, at any COG location. From Torenbeek: The angle of view forward and downward must be ...


15

Wikipedia's B787 article states that: According to data from launch customer All Nippon Airways, the 787 surpassed the promised 20% fuel burn reduction compared to that of the Boeing 767. This newer (8 months old) article states that: Air Canada and Japan Airlines are on the way to achieve it.


15

There have been issues with the 787 giving "nuisance" messages after starting up. One solution would be to start the process earlier, to leave time to deal with them. Another is to just never shut it down. However, the plane does need to be shut down sometimes for regular maintenance. A Boeing spokesperson said: No airplane in the fleet experienced that ...


15

Usually an APU provides electricity and bleed-air, just like the aircraft engines do. An all-electric APU only provides electricity. This can be done in the Boeing 787 because of the bleedless architecture where systems that would normally require hydraulic or pneumatic pressure are fully electrified.


14

According to Boeing (via airliners.net), it takes 53 minutes to load 55,800 US gallons with two fuel trucks operating at 35 psi delivery pressure. The total fuel capacity of the 787-8 is 33,340 US gal, so fueling from empty to full should take about 31.6 minutes with two trucks.


13

It may surprise you to know that the 6000 feet cabin pressure wasn't even a new feature when the Boeing 787 released! The Aérospatiale-BAC Concorde, the world's first and last profitable supersonic airliner maintained its cabin pressure at 6000 feet AMSL. From Wikipedia: Airliner cabins were usually maintained at a pressure equivalent to 6,000–8,000 feet ...


13

The reason is twofold: The materials used and the high aspect ratio. The 747-8 primarily uses advance aluminum alloys, while the 787 uses carbon composites. The carbon composites flex more compared to the aluminum alloys. This can be achieved because the carbon fibers are anisotropic and their properties can be tailored in each direction. The yield ...


11

As the other answers say, ANA is happy with the 787 surpassing the 20% fuel savings. But that does not mean for any given trip a 787-8 burns 20% less fuel than a 767-300ER. Which makes your point about Air India valid, here's why: It's not a fair comparison. The ANA 767-300ER on transpacific routes is not in its natural habitat, i.e., it can fly the mission,...


11

The Boeing 787 is special due to its high count of composite parts. When aluminium comes in contact with graphite fiber, contact corrosion will damage the aluminium whereas titanium will be unaffected due to its higher position in the electrochemical series. 15% of the initial 787s empty weight consists of titanium, a fraction much higher than in other ...


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