The military-industrial scientific research system of the academic master.

Chapter 1345 Don’t really come up with the Nan Tianmen plan?

After hearing Chang Haonan's answer, Xing Muchun lowered his head and pondered for a while, then he sighed softly:

"Well... the times nowadays are indeed different from those in our time."

The former will not completely deny the value of the other party's work:
“I can definitely continue to include this section in future reports…it’s more interesting and comprehensive than the simple summary of fund use given to me by the finance department.”

This sentence is not entirely intended to provide emotional value.

As the project leader, Chang Haonan can no longer focus solely on technical matters as he did in his early years.

Organization, personnel, administration, funding...

Although each of these parts has a dedicated person in charge, it is impossible for him to just sit there and do nothing.

Although they are both charts and numbers, for Chang Haonan, wind tunnel test data and flow field calculation equations are simpler and easier to understand than financial accounting conditions.

The statistical data provided by Xing Muchun certainly cannot replace the conclusions in any professional field, but it can at least add a perspective to look at the problem.

"..."

The two discussed the current research and development progress for some time.

Afterwards, Chang Haonan put the report aside and took out a few pages of A4 paper filled with writing from the drawer.

"One more thing."

He turned the paper around and placed it in front of Xing Muchun:
"Based on this month's research on combined waveriders, I have some new ideas at the theoretical level."

Almost like a conditioned reflex, Xing Muchun's upper body left the seat back.

However, he did not immediately look at what Chang Haonan wrote on the paper.

He knew very well that even if he could understand it, it would not be possible in just a few minutes or hours.

So, the key is to listen to what the other person says.

Sure enough, Chang Haonan explained:
"The proof may be a bit complicated, but to sum it up, the three-dimensional supersonic flow equation can be approximated by the axisymmetric flow equation within the second-order accuracy range. As long as the axis of the axisymmetric flow is located in the tangent plane of the streamline passing through the point, the local three-dimensional flow can be described by the local two-dimensional axisymmetric flow."

Even after a round of explanation, this part still seems a bit abstract.

Fortunately, in the past few years, Xing Muchun has also strengthened his theoretical level and at least captured the key words.

"It means that the reference flow field on the tangent surface is no longer limited to the same type of axisymmetric flow field, but can be customized to design some detailed features according to specific requirements... such as the sweep angle of the leading edge line, or the reverse angle on the lower surface?"

If this is true, it will greatly liberate the design freedom, and it will no longer be possible to cut ready-made surfaces from different rotating bodies as in the past.

Its significance to the design of hypersonic aircraft is no less than directly stepping into the wing-body fusion era from the Flyer One.

Chang Haonan nodded:

“In fact, we can get even more specific and even identify part of the design process.”

He organized his words a little, and then continued:

"The three-dimensional flow field is divided into several tangent planes by a given shock wave curve. The flow in each tangent plane is determined only by a specific tangent cone in the plane. The shock wave angles of the conical flows in each tangent plane are kept equal to ensure the same shock wave intensity and the spanwise continuity of the flow field..."

"The base radius of each tangent cone can be different, which is determined by the curvature radius of the shock wave curve and the incoming flow parameters: if the curvature radius is a finite value, it is a three-dimensional conical flow, otherwise it is a two-dimensional wedge flow. This method can reversely design the reference flow field and the waverider shape according to the customized shock wave shape..."

"..."

Compared with the pure mathematics parts on the previous papers, these contents that are closer to the engineering field are obviously more to Xing Muchun's taste.

Although it is impossible for two people with paper and pen to really replace supercomputers, there is no problem in giving some qualitative analysis conclusions based on experience.

After listening to Chang Haonan's explanation, he quickly reacted:

"Specific to our design, by designing the curvature of the shock wave profile of the lip cross section to change continuously along the span direction, we can achieve a continuous transition of the tangent plane reference flow field from the inward contraction shock wave reference flow field to the outward compression shock wave reference flow field along the span direction... Ideally, we can even make the outer side of the forebody compress the shock surface outward and the inner side contract the shock surface inward..." However, halfway through the analysis, his voice became smaller and smaller, and finally stopped completely.

Xing Muchun stretched out his hand and gestured on the table for a while before he raised his head again and said in a somewhat uncertain tone:
"But the combined waverider designed in this way seems to be closer to a...parallel structure?"

"All I can say is that in form it is closer to two waveriders connected in parallel."

Chang Haonan drew a simple diagram on paper:

"But if we really want to strictly classify it, whether this scheme can be regarded as a combined waverider is another matter."

Xing Muchun stared at the contents on the paper for a while:

"Indeed, it is designed as a whole after all, and it looks more..."

He pondered for a long time but still couldn't find a suitable adjective.

However, Chang Haonan did not have these concerns and directly completed a cloze test:
“Be more coordinated.”

There's really nothing wrong with that.

Compared with the current plan of connecting the high-speed waverider and the low-speed waverider through a transition section, the concept map on paper is obviously more in line with the concept of "aircraft" understood by normal people.

"really."

Xing Muchun also expressed his agreement with this.

But then he seemed to think of something:
"Could it be possible... that you want to change our design plan again?"

There was a lot of horror in his tone.

It's just the finishing touch, and it would be unbearable if I have to start all over again.

"don’t worry."

Chang Haonan quickly waved his hands and said comfortingly:

"Firstly, we cannot make any major changes at this stage. Secondly, the biggest difficulty in hypersonic flight control lies in longitudinal stability control, and the current series combination scheme has the best static stability among all designs. Other subsequent concepts will have to wait until this test is completed and the feasibility is re-verified before they can be formally considered."

Xing Muchun finally breathed a sigh of relief after hearing this:

"Huh...that's good."

In fact, the former has another reason that is not directly stated.

The greatest significance of this tangent flow field design lies not in the upper surface and outer contour, but in the ability to flexibly customize the lower surface, that is, the compression surface.

In other words, the ability to uniformly compress airflow will most likely no longer be exclusive to ossified cone waveriders.

If the tangent cone waverider and the inward-contracting air inlets on both sides can be integrated into an integrated design through geometric fusion, an almost consistent incoming flow compression effect can be achieved, providing sufficient air intake conditions for the scramjet engine.

It also has a higher cruise lift-to-drag ratio, fully meeting most of the requirements as an aircraft.

The only flaw is probably that the already limited internal volume is further compressed. After arranging the passenger/cargo compartments and various control systems, the space left for fuel is probably very limited.

Fortunately, the near-space vehicle itself also flies at the edge of the atmosphere using a jumping orbit. The engine only needs to work for a short time within an appropriate range, so it does not need to carry a large amount of fuel to achieve long-term high-speed flight.

In fact, at this point, the definition of the final product is already very close to the "White Emperor" aerospace fighter in the science fiction universe of the previous life——

Although it cannot actually enter space, it can operate at suborbital altitudes for a long time and achieve autonomous takeoff and landing.

Chang Haonan was of course aware that in his previous life, at least until his rebirth, there had never been such a project.

But because of this, it is inevitable to make some associations:
"Is this Nan Tian Men Project really going to be implemented by me?"

(End of this chapter)