Why doesn't everyone have a jetpack? - Richard Browning

譯者: Camila Lin 審譯者: Thomas Tam

On April 12, 1961, Soviet cosmonaut Yuri Gagarin

1961 年 4 月 12 日， 蘇聯的太空人尤里‧加加林，

piloted a 2,400 kilogram spacecraft in humanity’s first manned space flight.

駕駛重達 2400 公斤的太空船， 成為史上首次進入太空的人。

One week later, Bell Aerosystems debuted another advancement in aviation:

一個禮拜後，貝爾航空系統推出 另一劃時代發明：

the gas-powered rocket pack.

以瓦斯為動力的火箭背包。

Capable of flying 35 meters in just 13 seconds,

這能讓人在 13 秒內 就飛出 35 公尺，

the rocket pack thrilled onlookers.

讓旁觀者都相當興奮。

But the device’s engineers were less enthused.

但設計出這個設備的工程師， 卻沒有那麼開心。

Despite years of cutting-edge work,

雖然這是超前時代的偉大設計，

they knew this short flight was all the rocket pack could muster.

但他們知道，火箭背包最多 就只能做到這種短程飛行。

So why was a massive spacecraft easier to send flying than a single pilot?

所以，為什麼讓一個飛行員升空， 比讓一架巨大太空梭升空更難？

According to Newton's laws of motion,

根據牛頓的運動定律，

the physics behind flight are actually quite simple.

飛行背後的物理學其實非常簡單。

All you need is a powerful enough upward force

你唯一需要的，

就只有一個能抵銷重力的升力。

to counteract the downward force of gravity.

And since objects with more mass experience stronger gravitational forces,

因為物體質量越大， 受到的重力就越強，

lighter objects should be easier to get off the ground.

因此較輕的物體應該更容易升空。

However, modern jet engines, our primary tool for flight,

但我們用來飛行的主要工具， 也就是現代的噴射引擎，

actually get more efficient the larger they are.

實際上，越大效率就越好。

Jet engines work by sucking in huge volumes of air,

噴射引擎的運轉， 是靠吸入巨量空氣，

and then expelling that air as quickly as possible.

接著盡可能快速地噴出氣體。

While most of this actually bypasses the inner machinery,

雖然大部分空氣都繞過內部機器，

it still contributes to a huge portion of the engine's thrust.

但它們仍然提供引擎大部分的推力。

But the air that does enter the engine’s core gets compressed

而那些進入引擎核心的空氣，

則會被壓縮機的許多葉片壓縮。

by a series of tightly packed blades.

That compressed air then enters the combustion chamber,

這些被壓縮的空氣會進入燃燒室，

where it is injected with jet fuel and ignited.

和飛機燃料混合、燃燒。

The heat causes the compressed air to rapidly expand,

高熱讓被壓縮的空氣迅速膨脹，

bursting out of the exhaust and propelling the engine forward.

從排氣管噴出，推動引擎。

As air leaves the engine it also turns a turbine embedded in the exhaust nozzle.

空氣離開引擎時， 也會啟動嵌在排氣噴嘴內的渦輪。

This turbine powers the fan and the compressor blades,

渦輪使風扇和壓縮機持續運轉，

creating a cycle that maintains thrust for as long as there’s fuel to burn.

只要還有燃料，便能繼續製造推力。

The more air an engine can take in and expel the more thrust it can produce.

引擎吸入和排放的空氣越多， 推力也就越大。

On a modern jet, the diameter of a frontal fan is larger than a truck.

一架現代噴射機的前渦輪扇， 直徑就比一部卡車還大。

And even spinning at relatively low speeds,

就算轉速相對緩慢，

these engines produce more than enough thrust to maintain the necessary speed

引擎製造的推力，

維持載客飛行器的飛行也綽綽有餘。

for flying a passenger aircraft.

But smaller engines simply can’t take in this much air.

但較小的引擎就無法容納這麼多空氣。

For most of the 20th century, engineers couldn’t produce an engine

大部分 20 世紀的時間， 工程師仍無法製造

small and light enough for an individual to wear,

理想的引擎： 輕便到能穿在身上，

yet powerful enough to lift itself alongside its pilot and fuel.

又足夠有力， 能帶駕駛和燃料一同升空。

Designs could only carry enough fuel for 30 seconds of flight,

他們的設計最多只能攜帶 支撐半分鐘的燃料量，

and when airborne, the powerful thrust in a single direction

並且在空中時， 單向的強大推力

made jetpacks difficult and dangerous to control.

讓控制噴射背包變得困難又危險。

But the new millennium brought advances in materials, manufacturing,

但隨著新千禧年到來，

我們在材料、製造、運算科技等方面， 都取得突破性進展，

and computing technology,

including systems which could manage fuel injection with incredible precision.

其中包含能以出色精確度 注入燃料的系統。

Together, these dramatically improved the fuel efficiency

這些進展大大提升了燃料效率，

and power-to-weight ratio of jet engines.

以及噴射引擎的功率重量比。

By 2016, micro-engines the size of a coffee can

2016 年，一個如咖啡罐大小、

and weighing less than 2kg

兩公斤不到的引擎，

could achieve 220 Newtons of force.

就能產生 220 牛頓力。

This was when an English engineer named Richard Browning

而這讓英國工程師理查‧勃朗寧

saw the opportunity to create a new kind of lightweight jetpack.

發現打造輕型噴射背包的機會。

In addition to a single engine strapped to the back,

除了背在背上的單顆引擎，

this so-called Jet Suit involved a pair of micro-engines on each arm

所謂的「噴射衣」也在兩臂 各配置一顆小引擎，

to split and balance the thrust.

以便分散、平衡推力。

Working with the back engine, these provided three-points of stability,

兩個小引擎和大引擎提供了三點支撐，

which some pilots describe as being akin to comfortably leaning on crutches

有些飛行員形容，

感覺就像「你舒服地倚著柺杖時， 一個朋友還從後面托著你」。

while a friend supports your back.

It may seem complicated to manage all these engines at once,

要同時控制這些引擎似乎很困難，

but many pilots master it in less than a day

但許多飛行員都在一天內就掌握訣竅，

with the help of another advanced computer system— their brain.

這都多虧了他們身上配備的 超級電腦系統：大腦。

Various brain regions and multiple sensory systems

不同的大腦部位和數個感官系統，

perfectly calibrate our sense of balance and spatial orientation,

完美地校正平衡感和空間定位，

helping pilots smoothly direct their flights.

幫助飛行員順暢飛行。

Slight movements of the arms allow operators to increase and decrease lift,

輕輕動動手臂，就能增加或減少推力，

quickly turn in mid-air, or glide forward for up to 5 minutes.

在空中迅速轉向， 或做出最長五分鐘的往前滑行。

This technology is still fairly new,

這仍是相對嶄新的技術，

and without major advances in fuel efficiency and engine technology,

而若我們仍無法在燃料效率 和引擎科技取得重大突破，

don’t expect to have a jetpack of your own any time soon.

近期仍不可能實現 人手一個噴射背包的願景。

But if reaching for the sky already got us this far,

但如果我們已經飛上天空，

who knows where we'll fly next?

那麼誰知道我們接下來 會飛到哪裡呢？