Can you solve the airplane riddle

你能解开飞机之谜吗

来源视频

Professor Fukano, the famous eccentric scientist and adventurer, has embarked on a new challenge: flying around the world nonstop in a plane of his own design. 

Able to travel consistently at the incredible speed of one longitude around the equator per minute, the plane would take six hours to circle the world. 

There’s just one problem: the plane can only hold 180 kiloliters of fuel, only enough for exactly half the journey. 

著名的古怪科学家和探险家Fukano教授，开始了一项新的挑战：用他自己设计的飞机进行一次环绕世界的无停靠飞行。

这架飞机能够持续以每分钟飞过每一经度的高速沿着赤道飞行，只需要6小时就可以环绕世界一周。

只有一个问题需要克服：飞机只能携带18万升的燃料，这个量只够完成一半旅程。

Let’s be honest.

The professor probably could have designed the plane to hold more fuel, but where’s the fun in that? 

Instead, he’s devised a slightly more elaborate solution: building three identical planes for the mission.

所以还是现实点吧。

教授或许可以设计一种能携带更多燃料的飞机，但那就没意思了。

相反，他想出了一种更复杂的解决方案：为这项任务建造三架一模一样的飞机。

In addition to the speed, the professor’s equipped them with a few other incredible features.

Each of the planes can turn on a dime and instantly transfer any amount of its fuel to any of the others in midair without slowing down, provided they’re next to each other. 

The professor will pilot the first plane, while his two assistants Fugori and Orokana will pilot each of the others. 

However, only one airport, located on the equator, has granted permission for the experiment, making it the starting point, the finish line, and the only spot where the planes can land, take off, or refuel on the ground.

How should the three planes coordinate so the professor can fly continuously for the whole trip and achieve his dream without anyone running out of fuel and crashing?

除了高速之外，教授还给它们装备了其他绝妙的功能。

每一个飞机能够在很小的空间里转弯并立刻把任意量的燃料转移到空中的其他飞机内且不需要减速，只要他们相邻而飞。

教授驾驶第一架飞机，他的两个助手Fugori和Orokana分别驾驶另外两架飞机。

然而，只有一个赤道上的机场许可了这项实验，它成为了起点、终点，以及飞机降落、起飞和地面加油的唯一地点。

这三架飞机应该如何配合，才能使教授在每一架飞机都不会耗尽燃料或坠毁的情况下持续飞行完全程以实现他的梦想呢？

Pause here if you want to figure it out for yourself.

Answer in 3, 2, 1

According to the professor’s calculations, they should be able to pull it off by a hair. 

The key is to maximize the support each assistant provides, not wasting a single kiloliter of fuel. 

It also helps us to think symmetrically so they can make shorter trips in either direction while setting the professor up for a long unsupported stretch in the middle.

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答案：3 2 1

根据教授的计算，他们应该可以勉强完成这个任务，关键就在于把每个助手的力量最大化，不浪费每一升燃料。

对称地思考这段旅程可以帮助我们理解，他们可以从起点的两个方向进行短途飞行，同时让教授从中途开始进行无供给的长途飞行。

Here’s the solution: All three planes take off at noon flying west, each fully loaded with 180 kiloliters. 

After 45 minutes, or one-eighth of the way around, each plane has 135 kiloliters left. 

Orkana gives 45 to the professor and 45 to Fugori, fully refueling them both. 

With her remaining 45 Orokana returns to the airport and heads to the lounge for a well-deserved break. 

45 minutes later, with one-quarter of the trip complete, the professor and Fugori are both at 135 kiloliters again.

Fugori transfers 45 into the professor’s tank, leaving himself with the 90 he needs to return.

解决方案是这样的：三架飞机都在正午起飞向西飞行，每架飞机装在18万升燃料。

45分钟后，也就是1/8的行程后，每架飞机剩13.5万升燃料。

Orkana给教授和Fugori 分别输送了4.5万升，使他们的飞机加满油。

Orkana用她余下的4.5万升返回机场，并到休息室好好休息一番。

45分钟后，1/4的行程飞完，教授和Fugori的燃料又都剩下13.5万升。

Fugori给教授传输了4.5万升，给自己留下9万升用来返回机场。

Professor Fukano stretches and puts on his favorite album. 

He’ll alone for a while. 

In the meantime, Orokana has been anxiously awaiting Fugori’s return, her plane fully refueled and ready to go. 

As soon as his plane touches the ground, she takes off, this time flying east. 

At this point, exactly 180 minutes have passed and the professor is at the halfway point of his journey with 90 kiloliters of fuel left.

Fukano教授可以伸伸懒腰听听音乐了。

他要自己度过接下来的一段时间。

与此同时，Orokana正焦急地等Fugori回来，她的飞机已经加满油并准备出发了。

Fugori的飞机降落的同时，她立刻起飞，这次向东飞行。

到目前为止，已经过去了180分钟，教授正好完成了一半的旅程，还剩下9万升燃料。

For the next 90 minutes, the professor and Orokana’s planes fly towards each other, meeting at the three-quarter mark.

Just as the professor’s fuel is about to run out, he sees Orokana’s plane. 

She gives him 45 kiloliters of her remaining 90, leaving them with 45 each. 

But that’s just half of what they need to make it to the airport. Fortunately, this is exactly when Fugori, having refueled, takes off.

45 minutes later, just as the other two planes are about to run empty, he meets them at the 315 degree point and transfers 45 kiloliters of fuel to each, leaving 45 to himself.

在接下来的90分钟内，教授和Orokana的飞机相对而飞，在行程的四分之三处相遇。

就当教授的燃料将要耗尽时，他看到了Orokana的飞机。

她从余下的9万升燃料中给了教授4.5万升，让两架飞机都有4.5万升。

但这只够完成接下来的半程。幸运的是，这时Fugori已经加好油起飞了。

45分钟后，就在另两架飞机燃料要耗尽时，Fugori在315度处遇见了他们并给他们分别传输了4.5万升，给自己留下了4.5万升。

All three planes land at the airport just as their fuel gauges reach zero.

As the reporters and photographers cheer, the professor promises his planes will soon be available for commercial flights, just as soon as they figure out how to keep their inflight meals from spilling everywhere.

三架飞机在机场降落时，燃料正好耗尽。

记者和摄影师们开始欢呼，教授承诺他的飞机很快会作为商用航班投入使用，只需等他们研究出怎么样在飞机上用餐才不会撒得到处都是，就是时候了！

特别感谢@ 221A_Baker_St 投稿整理的近两期文档