It's sleek flying wing design makes it practically invisible to radar and incredibly fuel efficient, allowing it to penetrate even the most sophisticated of enemy defenses.

它光滑的飛翼設計使它幾乎不會被雷達發現，而且令人難以置信地省油，使其能夠穿越哪怕是最先進的敵方防禦系統。

But how did this incredible aircraft come into existence, and what technological advancements made it possible?

但這個前所未有的飛機到底是如何打造出來的？背後有哪些科技的進展使其成為可能？

The rise of stealth aircraft can be tracked back to World War One, when the Germans attempted to use transparent canvas to make their planes difficult to spot.

匿蹤飛機的興起最早可以追溯到第一次世界大戰，當時德國人試圖使用透明帆布來使他們的飛機難以被發現。

That plan backfired, as the glossy canvas made the aircraft even more visible in sunlight.

結果這一計劃適得其反，因為有光澤的帆布反而使飛機在陽光下更加顯眼。

The demand for stealth aircraft, as we think of them today, rose with the advancement of practical radar technology in the late 1930s.

而人們對於如今我們所知的匿蹤飛機的需求，則是從雷達在 1930 年代末期開始能實際運用時開始的。

The technology formed the backbone of Britain's early warning system during the Battle of Britain, saving uncountable lives from German bombing runs.

這個科技成為了不列顛戰役時英國早期預警系統的骨幹，從德軍的轟炸下拯救了無數生命。

Let's see how the technology works.

讓我們看看這個科技是如何運作的吧。

Radar works by sending short pulses of electromagnetic energy in the form of radio waves outwards,

雷達的工作原理是以無線電波的形式向外發送短脈衝的電磁能，

the antenna then switches to receiver mode and waits to detect the reflections of these radio waves off distant objects.

接著天線會切換到接收模式，等待偵測這些無線電波碰撞到遠方物體並反彈回來。

The radar now receives a blip on the screen called a radar cross-section, and it's size changes with the magnitude of radio waves returning to the antenna.

雷達接著會將訊號轉為螢幕上稱為雷達截面積的一個小點，而它的面積大小會隨著傳回到天線的無線電波強度而有所變化。

The Radar Cross-Section is a measure of how detectable an object is with radar.

雷達截面積是判斷一個物體能否被雷達偵測到的數值。

The size of the object is just one factor, which can be mitigated with clever engineering.

物體本身的大小只是其中一個因素，而這點也能藉由精心策畫的工程設計來規避。

The B-2 has a 52 m wingspan, yet it has been reported to have the same radar cross-section as a large bird.

B-2 的翼展長度為 52 公尺，但據說它的雷達截面積與一隻大鳥相當。

So how does the B-2 manage to achieve this incredible feat?

那麼，B-2 是如何做到這難以置信的創舉的？

The core concept behind the B-2 is reflection.

B-2 背後的核心概念是雷達波反射。

It was designed to reflect the radio waves away from the source, so that they never get the chance to be detected.

它被設計為能夠將雷達波反射到發射來源之外的地方，讓這些雷達波不會被天線偵測到。

What is amazing is that every surface of the B-2 has been designed with this in mind.

最令人驚奇的，莫過於 B-2 上的每一個表面都依據了這樣的原則設計。

The aircraft was designed with the aid of computational models and a supercomputer, which resulted in an incredibly complex curved shape.

整架飛機的設計過程由多個計算模型與一台超級電腦輔助，造就了它那極為複雜的曲線外型。

This technology was not available during the development of the F-117 Nighthawk, resulting in its much simpler faceted flat panels.

在 F-117 「夜鷹」的開發過程中，這樣的科技還沒有發展成熟，因此該戰機的外觀因此以更加單純的多面體平板構成。

The B-2's radar cross section is further reduced by its streamlined flying wing design, with its highly reflective engines embedded within the aircraft where radar cannot see it.

B-2 的雷達截面積還因為它流線型的飛翼設計而近一步降低，而容易反射雷達波的引擎則被裝進了機體內部，讓雷達波無法照射到。

Even the engines air intakes and exhaust vents are located on top of the plane to ensure they cannot be detected by ground based devices.

就連引擎的進氣口與排氣口都被裝設在飛機的上方，藉此確保它們不會被地面的裝置偵測到。

But the flying wing has some unique flying characteristics that took many years for Northtrop to perfect.

但飛翼設計所帶來的獨特飛行方式則讓諾斯諾普花了許多年才得以完善。

One of the most notable is the lack of a tail rudder to control the yaw.

其中最引人注目的便是缺乏控制偏航的尾舵。

The B-2 instead uses a split rudders, on the tips of the left and right wing.

B-2 使用的是分體式方向舵，其位於左翼和右翼的尖端。

They act as airbrakes to slow either side of the wing, and cause a yawing motion.

它們就像空氣煞車一樣在將兩翼中的其中之一減速，藉此來達成偏航動作。

But, when in use, the split rudders can increase the radar cross section of the plane.

然而在使用時，分體式方向舵卻也會增加飛機的雷達反射面積。

So the B-2 can also use differential thrusting of its left and right engines to allow it be controlled when stealth is a priority.

因此在以維持匿蹤為優先的狀況時， B-2 也能藉由調整左右引擎的推力來調整方向。

Beyond the shape, the B-2 is also made with advanced composite materials capable of absorbing and dissipating incoming radio energy

除了外形之外，B-2 還採用了先進的複合材料，能夠吸收並消散迎面而來的無線電波。

The exact composition of the B-2 is classified, but we know that the skin is made from a carbon fiber reinforced plastic,

打造出 B-2 的具體原料仍是機密，但我們知道它的外皮是由經碳纖維強化的塑膠所包覆，

while the leading edge of the B-2 is likely painted with a paint which contains small particles of iron, which absorb electromagnetic energy and converts it to heat.

而 B-2 的最外層塗裝則有可能是一種含有微小鐵分子的噴漆，能吸收電磁能並將其轉化為熱能。

With these technologies combined the B-2 barely even registers on radar screens.

在這些技術的結合下，B-2 幾乎沒有出現在雷達螢幕上過。

What is even more terrifying to think about is the fact the Nazi 's had created a very similar plane all the way back in 1944.

而令人細思極恐的是，納粹在 1944 年時就曾經打造過一架非常類似的飛機。

The Horten 229 incorporated many of the same principles as the B-2, long before the stealth technology that made the B-2 possible was fully understood.

早在用在 B-2 上的匿蹤科技被完全發展出來以前，霍頓 229 就採用了許多與 B-2 相同的原則。

Today, we can only imagine what the impact this plane would have had, if it was ready before the wars end.

如今我們只能想像要是這架飛機在戰爭結束之前發展完成的話，將可能帶來怎麼樣的影響。

Thanks for watching! And welcome to all my new subscribers.

感謝收看！同時也歡迎新訂閱的觀眾們。

I told myself I would not set up a Patreon account until I hit 10,000 subscribers, and I blew through that goal with my previous video.

我之前告訴自己，直到頻道達到一萬名訂閱數之前我不會辦 Patreon 的帳號，而我在上個影片順利達成了這個目標。

So the link for that is below, along with my Instagram, Facebook and Twitter accounts. I'm really excited for my next video, so be sure to subscribe and watch it when it comes out.

所以 Patreon 的連結就在下面了，隨附的還有我的 Instagram、Facebook 與 Twiteer 帳號。我對下一部影片感到非常興奮，所以記得要訂閱並在影片推出的時候過去看看。