After verifying the practicality of the space shuttle, the design and construction of the second space shuttle was also put on the agenda.

Compared with the Cold War between the red and blue sides in the last century, whether it is the space shuttle designed and manufactured by the Red Soviet Union or the United States, the advantages of the Xinghai are really too great, and it is not an exaggeration to say that it is a leapfrog qualitative change.

However, despite this, the weight of the cargo carried by the Xinghai itself, or the amount of materials that can be carried to climb the gravity well, is still limited.

Judging from the current experimental and test data of Xinghai's multiple unmanned flights, Xinghai can carry a maximum of nearly 50 tons, and the accurate data should be 48.75 tons of materials climbing gravity wells into outer space.

This data is a certain shrinkage and error compared with the previous calculation of more than 60 tons by joint simulations of aerospace engines and miniaturized fusion reactors.

However, this is a normal situation, after all, the previous simulation data is based on supercomputing and various conditions are basically perfect. In fact, the design of the Xinghai was not perfect, whether it was the wing or the hydrodynamic balance, it needed to be optimized and adjusted step by step after experimentation.

Nearly 50 tons of low-earth orbit transfer capacity, for the development of astronautics, this load is not small, but it is not very large.

After all, if the payload of a traditional chemical fuel launch vehicle, such as the Long March 9 or the BRF of Space-X, starts with a few hundred tons of low-earth orbit transfer loads.

On the one hand, the purpose of designing and manufacturing the second space shuttle is to fill the vacancy of the Xinghai Research Institute's payload in the aerospace field and increase the space transportation capacity.

If the two space shuttles carry out manned landing on the moon or the construction of a lunar surface base, their ability to transport materials is not 50 tons + 50 tons, but much greater than 50 + 50.

With the size and size of the cargo compartment of the space shuttle, and without the infection of gravity and air resistance in outer space, Xinghai can carry hundreds of tons of supplies to the moon at a time.

In this case, it is possible to make the two shuttles work together. The first one will carry supplies into the sky first, adjust its orbit after entering low-earth orbit, and then the second space shuttle will carry supplies to replenish it.

It works in a similar way to the docking of a space station and a space supply ship.

This was one of the main reasons for the design and construction of the second space shuttle.

And another important reason is 'Interstellar Rescue'!

"The Martian" and "Gravity" must be familiar with these space movies, which are about interstellar rescue.

In the field of modern aerospace, since it can go to space, it is natural to take into account the occurrence of disasters and accidents in which astronauts are trapped in outer space, and all major spacefaring countries also have corresponding methods of 'space rescue' or 'space rescue'.

However, due to the limitations of various technologies, it is too difficult to implement.

The Xinghai, which uses electric propulsion, is different. Compared with the traditional spacecraft that has no power and endurance after entering outer space, it can complete space flight at the fastest speed, and has full orbit adjustment ability in outer space.

The new generation of electric propulsion space shuttle, which uses small fusion reactors + aerospace engines as a function and power system, is not a problem at all in terms of power and endurance.

It can adjust the orbit again and again to return to the spacecraft in question and complete the rescue work, even if the rescue and docking failures have been repeated countless times.

On the other side, in the Xinghai Research Institute.

After handing over all the space-related work to Weng Yunzong, Xu Chuan returned to his office, thinking about how to solve the problem of high temperatures and thermal barriers faced by the space shuttle when it returned to the atmosphere.

This is a world-class puzzle that has existed since the space competition between the two sides in the last century, or since the development of the first spacecraft into space.

In the decades of development, although researchers and scholars in the field of aerospace have thought of countless solutions, they have never been able to solve this problem.

Of course, there are corresponding improvement ideas and methods.

The most famous of these is the shock wave theory proposed by Professor Henry Allen, a physicist at the NACA space agency (the predecessor of NASA).

In 1951, Henry Allen, in a confidential internal study, discovered that the front end of a spacecraft with a high-speed re-entry creates a strong compressive effect on the air.

That is, when the shuttle returns, the head of the aircraft will form an umbrella-shaped shock cone in the atmosphere in front of it, and the density of the air at the front of the shock wave will increase dramatically, and finally it will act like a moving wall in front of the spacecraft, and the spacecraft will move forward in the wake of the shock cone.

To put it simply, it can be understood that the highest temperature of the space shuttle on the return trip is not the shuttle itself, but the 'shock cone' generated at the head of the shuttle.

And 'pneumatic heating' is also mainly caused by compression and friction between the static air at the front and front of the shock wave.

According to this theory, Henry Allen believed that if the surface of the spacecraft was kept at a certain distance from the shock front of the shock wave, the frictional temperature of the spacecraft surface could be greatly reduced.

With this idea, Henry Allen designed a blunt spacecraft head, and through experiments and final demonstrations, it was determined that this theory was effective.

This is the reason why the heads of spacecraft, space shuttles, and intercontinental missiles currently being studied by various countries all use blunt-tipped cones.

Because the blunt head of the spacecraft can effectively launch a wide and strong shock wave in the bow during deceleration and keep the wave front away from the bow and its surroundings, like the wave pushed by the bow of a flat-headed barge ship.

These days, Xu Chuan has been searching through relevant materials and papers, thinking about how to further improve Professor Henry Allen's shock cone theory.

Compared with traditional materials and technologies such as heat insulation, heat dissipation, and heat resistance, the shock cone theory is his most optimistic route at present.

This is determined by the extremely high speed of the space shuttle.

In daily life and in the physics that most people have learned, if you want to reduce the aerodynamic drag to reduce the aerodynamic heating, then the volume of the object should be as small as possible.

Because when the volume of the object becomes smaller, the friction area with the air will also decrease. Therefore, in areas where speed and efficiency are emphasized, the smallest possible object design is often chosen.

However, on spacecraft, this theory is invalid, especially during re-entry, when the extremely high speed of the spacecraft heats up the aerodynamic heating too quickly, and the sharp head has little effect on reducing the aerothermal heating.

The head cone, on the other hand, is subjected to a highly concentrated heat load in time and space, has no time to dissipate heat at all, and will quickly burn out.

Traditional heat-resistant materials or thermal insulation, heat dissipation, and thermal conduction technologies can only slightly delay the timing of burning, but they cannot fundamentally change the outcome of burning.

The shock cone route is more suitable for extremely high-speed space shuttles.

In the office, Xu Chuan pondered theories related to shock cones.

Although Professor Henry Allen's shock cone theory has brought some optimization to the blunt head of spacecraft, this problem still exists, and the core mathematical theory has not been solved.

Behind the desk, after thinking for a while, he pulled out a stack of scratch paper from the drawer, pondered for a while, and then scratched the ballpoint pen in his hand.

【∑i=1·/xi(H(φ)φxi)= 0】

This is the equation for the 'supersonic turbulence problem'.

To put it simply, when a flying body flies in the air at supersonic speed, a shock wave is usually generated in front of the flying body. From the point of view of relative motion, it can also be understood that when a supersonic air flow passes over a fixed object, a shock wave will be formed in front of the object due to the obstruction of the object.

That is, the shock cone of the head of the spacecraft mentioned earlier, the formation of this shock cone will greatly change the state of the air flow, and thus change the situation of the force on the object.

The study of the position of the shock surface and the flow field after the wave is blocked by a fixed object is called the 'supersonic flow' problem.

If it is expressed mathematically, the Euler equation or the Navier-Stokes equation is usually used to describe the flow in aerodynamics.

It is a hyperbolic equation in the supersonic region and an elliptical equation in the subsonic region.

The study of this equation is crucial for the development of modern high-speed flight technology and the solution of the equation system of the supersonic turbulence problem.

Unfortunately, since the distribution of fluid velocity in the flow field is unknown, the line of change from hyperbolic to elliptical equations is also unknown, plus the equation of fluid motion is nonlinear

The accumulation of various complex factors has led mathematicians to study this system of equations, and when dealing with mathematical analysis, they will involve nonlinearity, hybrid, free boundary, global solution, and so on, which are generally considered to be the most difficult factors in the theory of partial differential equations.

Therefore, for the supersonic flow of blunt-headed objects, due to the inevitable deformation of the equation, there is a lack of results that have been rigorously proven by mathematical theories, whether it is about the existence, stability of the solution, or the structure of the solution.

Although its difficulty is not as high as that of the NS equation and Euler's equation, the lack of research progress in the mathematical community is enough to prove its difficulty.

Staring at the formula on the scratch paper, Xu Chuan fell into deep thought.

In order to derive the problem of supersonic circulation of blunt-headed objects, according to his mathematical intuition, the best way to deal with it is not to deal with it directly.

It is a system of partial differential equations evolved from Euler's equation and the NS equation, and if it is to be solved, it is best to decompose it further in his current mathematical intuition.

Of course, he is not the only one who has this kind of thinking, many mathematicians are doing it, but everyone's understanding and perspective are also different.

After thinking for a while, Xu Chuan continued to write, turning the three-dimensional inviscous-free compressible constant flow equation into a boundary value problem with a fixed boundary, and further transforming.

Then: given the curve i:x h(z),y=g(z) in three-dimensional space oxyz and given the wing surface with i as the leading edge, ∑y=ψ(x,z)."

"When the incoming stream is supersonic it produces a shock wave S+:y=p attached to the leading edge, and when only the local solution near the origin is discussed, there is μ·f/x-υ+ω·f/z=0, and y=f(x,y)"

The ballpoint pen in his hand kept falling on the white manuscript paper, and Xu Chuan was immersed in it, constantly expanding his thinking.

Although he usually instructs and teaches his students and keeps him active in mathematics in NTU, he honestly hasn't had such a focused and in-depth thinking in mathematics for a long time.

Originally, Xu Chuan thought that it would take him a few days to fully recover his sense of mathematics, but unexpectedly, when the first line of the equation was written, the thoughts that had been hidden in his mind for a long time became active again.

It's like muscle memory, no, it might be more appropriate to describe it as instinct as it is portrayed in DNA, and when he breaks down and deduces the supersonic flow of a blunt object, the mathematics in his mind comes alive like flowing water.

The transformation, decomposition, twisting, and processing of each item are as natural and fluid as breathing.

As the long time passed, little by little, when the last line of calculations fell on the manuscript paper, the desk was already covered with the calculation paper of the finished formulas.

Putting down the ballpoint pen in his hand, Xu Chuan looked at the equation he had deduced.

【||(Un+2-Un+1，φm+2-φm+1）||E〃N-1(T)≤CT||（Un+1-Um，φm+1-φm）||】

When T is sufficient, {(Um,φm is limited to the solution of (7)-(9) in E〃N-1, and then the existence of the local solution is obtained from the original standard.

Since N can be arbitrarily large in the theorem proof, the solution is C∞ and smooth!

A phased work on the supersonic circulation of blunt-headed objects was completed in his hands.

The whole process is incredibly smooth, as if a clear stream is flowing smoothly like jade.

Even he felt a little surprised by this.

After all, he hadn't focused on mathematical research for quite some time.

And if you put down anything for a while, it will definitely take time to get back to the state, that's for sure.

Just like ordinary people playing games, if you haven't played a game for a long time, then when you pick it up again, your state will deteriorate and your level will decrease.

For a scholar, when they spend too long in their field of expertise, their skills will gradually weaken.

This is also the reason why the vast majority of researchers or scholars are not idle.

Even many of them have entered their old age, such as his mentors, Professor Deligne and Professor Witten, are still studying academics because they can't bear the knowledge they once mastered to pass through their minds.

However, in today's mathematical reasoning, Xu Chuan felt as if he had directly skipped the process of recovery training, and the thoughts in his mind kept supporting him to move forward.

Even if the NS equation has been solved before, he still can't believe that he can make a phased result for the supersonic flow of blunt objects so smoothly.