Set sail?! ”

Pang Xuelin got up from the bed all of a sudden, picked up his mobile phone according to the memory instilled in him by the system, and dialed Shen Yuan's phone.

"Answer the phone, answer the phone!"

Pang Xuelin was a little anxious in his heart.

Although he knew that the chances of saving the crew of Sunset Six were slim - not to mention that he didn't know where Sunset Six was sailing now, Pang Xuelin was not at all sure how to persuade Shen Yuan to give up the mission of Sunset Six.

In his impression, his teacher was persistent and stubborn by nature, and once he made a decision, no one could make him change his decision.

But Pang Xuelin always has to try.

Not only for the girl who will be trapped in the center of the earth, but also for his own mission.

If Sunset Six can return early, I don't know if there is a way to make that tragedy happen.

Toot-toot-toot-

The beep on the phone was unusually long.

It rang a dozen times before the phone was picked up.

"What's the matter?"

On the other end of the phone, Shen Yuan's slightly tired and majestic voice rang.

"Teacher, I'm Pang Xuelin, is Sunset 6 setting sail now? Where are you going? ”

"Sunset 6 has been on sail for more than ten hours, and it is now in the position of the mantle about 2,500 kilometers underground......"

Pang Xuelin was shocked and said, "Teacher, let Sunset Six return quickly, if you don't return, it's too late!" ”

"What's wrong? Why let Sunset Six return? ”

Pang Xuelin pondered for a moment, and quickly organized the language: "Teacher, Sunset 6 is very dangerous, I checked the route planning of Sunset 6 this time, and found that in the mantle of this route, it is very likely that there is a crack leading to the core, and the high-pressure liquid iron-nickel in the core is full of this crack, so that on the route of Sunset 6, the discontinuity of Gutenberg at the junction of the mantle and the core extends upwards for nearly 1,000 kilometers, and Sunset 6 does not have the ability to navigate in the core of the earth with high-pressure liquid iron-nickel as the core, once it enters this rift, The ship will most likely sink into the core of the earth and never get out again! ”

Shen Yuan's voice suddenly became serious: "Are you sure? ”

"Pretty sure!"

Pang Xuelin cut the railway.

As soon as the voice fell, a shrill alarm sounded on the other end of the phone, and there were faint exclamations from others.

Shen Yuan said: "Something happened on my side, let's not talk about it first." ”

The phone was hung up.

Pang Xuelin frowned, he had a faint bad premonition.

Sure enough, half an hour later, the bad premonition became a reality.

Shen Yuan called, and he on the other end of the phone looked a little anxious: "Xuelin, the danger you said has become a reality, Sunset Six did fall into a gap filled with high-pressure liquid iron and nickel. I need you to come to Turpan to discuss the rescue plan for Sunset Six, and tell us how you managed to figure out this rift that extends from the core to the mantle. I have already sent a plane and it is expected to arrive in the capital within an hour, you wait patiently in your dormitory, someone will pick you up when the time comes. ”

"Okay."

Pang Xuelin said in a deep voice.

Hanging up the phone, Pang Xuelin shook his head helplessly.

He knew that the system wasn't that good, giving him a chance to stop the accident before the ship had an accident.

But no matter what, now that Sunset Six has entered the center of the earth, how to rescue it next is the most important thing.

At the end of "Earth Cannon", humans are unable to accurately locate Sunset Six, and decades later, they are still unable to rescue Sunset Six from the depths of the earth's core.

"Just because they can't do it doesn't mean I can't!"

Pang Xuelin clenched his fists, and his eyes flashed with an inexplicable light.

Half an hour later, there was a knock on the door, and two soldiers appeared in front of Pang Xuelin.

"You're Dr. Pang Xuelin, right?"

"It's me, you are?"

"Oh, it's Academician Shen who sent us to pick you up, and he needs you to go to the Turpan base immediately."

"Wait a minute!"

Pang Xuelin took the luggage that had been prepared and followed the two soldiers out of the door.

This era is very different from the city of Beijing in his memory.

Although the core area maintains the style of the historical ancient city, in the new city, hundreds of thousands of kilometers of high-rise buildings are lined up one after another, reaching into the sky, and the most surprising thing for Pang Xuelin is that the high-rise buildings are connected to each other through overpasses and overpasses, forming a unique 3D three-dimensional city style.

Along the way, he can also occasionally see some pedestrians in solo flight suits passing through, filling the landscape of the future city.

It took less than 20 minutes for Pang Xuelin and the two soldiers to arrive at a military airport in the flying car.

What appeared in front of Pang Xuelin was a manned aircraft with a wave-riding body shape, nearly 30 meters long, more than 10 meters wide, and 6 meters high.

"Waverider manned aircraft!"

Pang Xuelin muttered to himself.

The so-called wave-riding body has to start with the shock wave.

A shock wave is a strong perturbation wave.

At the shock wave, the pressure, temperature, and density of the air increase abruptly from pre-shock to post-shock wave, and the air velocity decreases.

In general, shock waves are common in situations such as supersonic vehicles, explosions, bullet shots, etc., and can be directly observed using a schlieren instrument.

Due to the step-like abrupt change in gas density before and after the shock wave, a very obvious dark pattern will be produced on the Schlieren at the shock wave.

Of course, although the shock wave is intermittent from a macroscopic point of view, the shock wave itself still has a certain thickness, generally in the order of several molecules' average free path.

Generally speaking, people divide shockwaves into positive shocks and oblique shocks according to their shape.

The positive shock wave assumes that there is an infinitely long cylinder in which the air is at rest.

A piston is housed in the cylinder. When the piston accelerates from stationary to the right, the gas on the right surface of the piston will in turn produce a disturbance wave and propagate to the right.

When the piston continues to accelerate, the wave velocity of the subsequent wave is greater than that of the previous wave, so the latter wave will definitely catch up with the previous wave. A positive shock wave is formed when an infinite number of perturbation waves are superimposed to form a compression wave of a perpendicular plane.

When a cone moves at supersonic speed, the perturbation emanating from the object is superimposed to form a wave front, i.e., oblique shock, because its velocity exceeds the speed of sound.

The Mach wave formed by a supersonic moving object is an ideal case of oblique shock waves.

The faster the object moves, the smaller the angle of the shock wave formed.

When the velocity of an object does not exceed the speed of sound, the perturbation emitted by the object cannot be superimposed on a wavefront and cannot form a shock wave.

In general, normal oblique shocks are appendage shocks. And when the turning angle of the air flow is too large, δ will produce a detached shock wave.

Most of the front-end of the detached shock wave exists in the form of a positive shock wave, which will bring a large shock wave resistance to the object.

Under normal circumstances, hypersonic vehicles use possession shock waves to reduce shock wave resistance; The spacecraft return capsule will use the blunt head to generate a detached shock wave, and use the drag of the detached shock wave to convert kinetic energy into heat energy more quickly, so as to achieve deceleration after re-entry.

The heat energy is absorbed and carried away by the ablation layer that covers the bottom.

The concept of waverider is the idea of using shock wave pressure to improve the lift-to-drag ratio of the aircraft in the aerodynamic design of hypersonic aircraft.

Therefore, the lower surface of the waverider body will be designed in the form of a flat bottom to leave room for the airflow after the shock wave of high pressure; The upper part is normally designed into various streamlined types according to different needs.

In this way, the aircraft can use the pressure from below as its own lift, improving the lift-to-drag ratio. Because it obtains lift on the shock wave generated by its own flight by "riding", it is named "wave riding body".

In the real world, this kind of aircraft is only used in ballistic missile warheads and other fields, and it is still a high-precision product.

But in this era, waverider vehicles have clearly been used on a large scale.

No wonder Shen Yuan said that he would send a plane from Turpan to the capital within an hour.

Pang Xuelin said secretly in his heart.