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  • Okay, I say the wordAirplaneand what do you imagine? I know, a very funny movie

  • with really bad jokes, yeah, but let’s try harder. Okay. “Big, white, a rounded nose,

  • relatively small tires, two oddly angled wings with their tips curling up, normally late

  • taking off. Oh, and you always get on board through the left side!” Yep, spot on! But

  • WHY is all that so? Well let me tell ya.

  • - Commercial aircraft usually have their wings angled backward - that's why they're also

  • called swept wings. This shape helps planes be as fast as they are. The air moves over

  • a wing at a higher speed than under it. This creates shockwaves that would otherwise slow

  • the plane down. But these unique swept wings miraculously (kidding - it's just physics)

  • reduce the airflow speed above the wing. There are no more shockwaves, and the plane can

  • reach incredible speeds.

  • - Besides being angled toward the rear, many plane wings also have curved tips. Those are

  • called winglets. When a plane is flying, there’s a pressure difference between the wing's lower

  • and upper surface. This difference is big enough to produce wingtip vortices (they're

  • something like mini-tornadoes, which sounds pretty dangerous to me). Wingtip vortices

  • lead to slower speeds, more fuel consumption, higher CO2 emission, and safety issues. If

  • another plane is following one that's creating such vortices, it can lose stability and end

  • up in an emergency situation! Luckily, engineers invented winglets to separate the two regions

  • with different pressure, preventing those vortices from appearing.

  • - Ok, but why is the entire wing tilted upward instead of being perfectly parallel with the

  • ground? This upward angle is crucial for the airplane's stability. That stability is at

  • risk when a jet comes across some obstacle, like a bump from turbulence, that can make

  • it roll to either side. When that happens, the more upward wing gets less lift and naturally

  • goes down. The wing that rolled downward becomes more parallel to the ground and generates

  • more liftmaking it go up. And voila! The plane levels out on its own, all thanks

  • to the wings' upward tilt.

  • - Let’s delve deeper into that oh-so-important liftafter all, it’s one of the forces

  • that help a plane stay in the air and move forward. The angle the oncoming air meets

  • the wing at is known as the angle of attack. The lift greatly depends on this angle. Take

  • a wing and start tilting it upward (like when a plane is taking off) - and you'll see that

  • the lift is getting better! But only until a certain point. If you tilt the wing too

  • much, the lift will get weaker or disappear altogether! Then the plane will stall in the

  • air and eventually fall. If the wings are tilted down, the lift decreases. You can notice

  • it when a plane is pitching down before landing. Long story short: aircraft wings are an engineering

  • marvel!

  • - Another thing you may spot if you're watching an airplane about to touch the ground is that

  • its landing gear is a bit tilted. On some planes, the rear set of the wheels touches

  • the ground firstlike stepping with your heel. The tilt serves several purposes: to

  • soften the landing and absorb the touchdown shock, to level the plane and prevent it from

  • pitching forward, and to let the gear fit properly in the gear well.

  • - And since I've started talking about those wheels, you ever notice how small they are

  • for such a massive machine? Well, if you made airplane wheels bigger, it would add extra

  • load, and aircraft would waste more fuel carrying them. And the more fuel a plane consumes,

  • the more money an airline loses. That's why manufacturers have a tough task: they need

  • to make airplane wheels and tires as small, sturdy, and safe as possible, and theyve

  • accomplished that!

  • - Airplane tires are also famous for being super inflated: the pressure inside is 6 times

  • greater than what’s in your car's tires and 4 times bigger than a person can withstand!

  • Surprisingly, thanks to this pressure (as well as the material they're made of), airplane

  • tires don't burst under the immense weight of a landing aircraft.

  • - If you're flying at night, you may see flashing lights on your airplane's wings. The light

  • on the left wingtip is red, and the one on the right is green. I know you can’t see

  • both lights from where youre stuck back in the middle of the economy section, so trust

  • me on this one. That lighting scheme helps pilots figure out the direction of oncoming

  • planes in the dark and avoid a collision. The green and red lights on commercial aircraft

  • must be on from sunset to sunrise.

  • - Most airliners have nicely rounded noses, but there are jets with pointy onesso

  • what decides it? Your aircraft's nose shape simply means that you aren't going to travel

  • faster than the speed of sound. During the flight, a plane's blunt nose pushes the air

  • in front of the jet, allowing it to roll over the airplane's body more freely and without

  • any serious resistance. The faster a plane is, the sharper its nose will be since they

  • need to cut through the air without meeting too much resistance. That's why almost all

  • supersonic aircraft (ones that travel faster than the speed of sound) have pointy noses.

  • Just like the pointy-nosed witches on broomsticks. Yes, they can go supersonic too. Didn’t

  • know that, did you? Then why not build commercial airplanes with

  • pointed noseswon't it make t hem faster? Nope! If a plane's speed is subsonic (lower

  • than the speed of sound), the blunt nose causes less drag - that's one of the forces that

  • keeps aircraft in the air but, at the same time, slows them down. Plus, pointed noses

  • are longer than blunt ones, so they may prevent pilots from seeing the runway clearly.

  • - Commercial airplanes have doors on both sides, but in most cases, you board on the

  • left. For one thing, it's a tradition. Earlier, airports were organized in such a way that

  • a plane had to taxi up to the terminal building and discharge passengers there. Pilots sat

  • on the left side and needed to see where they were going to put the plane's door right in

  • front of the terminal entrance. If they misjudged the distance, they could hit the wing against

  • the building. These days, left-side boarding is more of a safety concern. The right side

  • is used for fueling the plane and loading and unloading baggage and cargo. If passengers

  • were also entering aircraft from the right side, it would mess up the whole process and

  • probably lead to accidents. Boarding from the left side may also have something to do

  • with ship design. A ship's left side is a port side where people get on and off. Airplane

  • and jetway manufacturers mightve just followed this maritime practice.

  • - Modern commercial planes have at least 6 entrances (or exits): 2 in the front of the

  • passenger cabin, 2 in the back, and 2 emergency exits over the wings. C’mon, you remember

  • that talk they give up right before takeoff? Then why don't airlines save time by letting

  • people in through all the entrances at once? Ok, maybe not the wing ones, but what about

  • the other 4? Well, you can't use the right side because of the whole baggage and fueling

  • thing I just mentioned. So, now were down to a front and rear door on the left. Some

  • airlines do use both for boarding and deplaning. But those are mostly low-cost carriers that

  • bring passengers to planes by buses and use mobile stairways. But if people board an aircraft

  • through a jetway, using both doors won't work. Jetways only reach the front left entrance.

  • To reach the rear ones, they’d have to go around the wing. In other words, jetways would

  • have to be longer, which equals not only more money spent but also more terminal space taken,

  • which is already tight. And finally, the rear and opposite-side doors are sometimes used

  • to load food and drinks and take out the trash. If passengers were boarding through them,

  • it wouldn't buy any additional timeit’d actually slow everything down.

  • - But returning to buses and mobile stairs: why them, why not good oljet bridges that

  • can protect you from the elements every single time? Some airports are just too busy and

  • don't have enough gates. It's either using buses and mobile stairs or waiting for hours

  • for an available gate. Plus, if you're flying with a low-cost airline, itll try to save

  • as much money as possible (after all, it's low-cost for a reason!). Since jetways and

  • parking right near the gate cost a lot, budget carriers prefer much more distant parking

  • places, mobile bridges, and buses.

  • That’s it. Gotta fly!

  • Hey, if you learned something new today, feel free to give the video a like and share it

  • with a friend! And here are some other videos I think you'll enjoy. Just click to the left

  • or right, and stay on the Bright Side of life!

Okay, I say the wordAirplaneand what do you imagine? I know, a very funny movie

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為什麼你從左邊登機 (Why You Board the Plane from the Left)

  • 7 1
    林宜悉 發佈於 2021 年 01 月 14 日
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