Chapter 1180: Terminal Precision Guidance
The overall design of the warhead was the task assigned to Chang Haonan on behalf of the Aviation Power Group from the very beginning.
Although this mission was neither aviation nor power, obviously no one would question his ability in the field of aerodynamic design.
Not to mention that there is also the powerful First Academy of Aerospace Science and Technology to assist.
Therefore, during this period of time, everyone's focus has been basically on other parts such as power, guidance, control and testing procedures.
It was not until the Fifth Academy interrupted that the topic was brought back to the warhead.
"Sweating to cool down..."
The heated atmosphere in the conference room calmed down a bit, and many people lowered their heads and began to think again.
The technical term proposed by Chang Haonan is not new.
The cooling fluid first flows through the porous wall and carries away heat through forced convection exchange, and then forms a dense air film on the surface of the wall to reduce the heat transfer of the high-temperature mainstream to the wall.
If liquid coolant is used in this process, it will be very similar to the sweating heat dissipation process of animals, hence the name sweat cooling.
Its characteristic is that it includes both active and passive heat exchange principles. At the same time, the surface air film formed after the cooling fluid seeps out of the porous wall has an excellent adhesion effect. Even if only the passive insulation effect is considered, it is better than simple air film cooling.
But as a price, sweat cooling requires special porous materials as carriers, and has extremely high requirements for microporous structure, thermal conductivity, processing technology and heat resistance.
Both the design difficulty and cost remain high.
"Academician Chang... isn't this a bit of an overkill?"
Li Rongwei asked in a somewhat uncertain tone:
"Transpiration cooling is generally used on rocket engine tail nozzles to withstand gas temperatures above 3500K...Our test missile is only 6-7 times the speed of sound at the end. Even if we calculate it based on the full sea level altitude, the aerodynamic heating shouldn't be to this extent, right?"
After saying this, he turned around and glanced at the representative of the Sixth Academy who specialized in this.
The latter was suddenly called out and didn't react at first, but soon nodded:
"That's true... From our experience, with current technology, the highest efficiency of sweat cooling can reach 10^9 W/m^2... Using it in a double cone, where the speed can't even reach Mach 10, is indeed a bit of a waste of talent."
"Moreover, the cooling of the nozzle is usually done directly with liquid fuel, so that the vaporized part can be burned directly. If this process is to be realized in the warhead, an additional layer of porous material heat protection layer will be needed as the base, and an additional coolant flow channel will also be needed, which will inevitably affect the overall strength of the double cone..."
From a project management perspective, the biggest risk of this type of verification missile is not how many individual new technologies are added.
After all, even if something really goes wrong, as long as you can find the specific cause, you can roll back the status if it doesn't work.
The more serious risk is that the entire system becomes increasingly complex for some reason.
Once something goes wrong, it may lead to more problems than just one.
It's like a mountain of shit code. After fixing the bug, the whole program can't run normally.
Therefore, during the meeting just a few hours ago, the only thing that increased the complexity of the system was changing the originally planned warhead counterweight to a terminal acceleration engine.
But this is still a relatively independent part. Even if the engine fails to start, it will not affect the propulsion system in front.
However, sweat cooling requires a high degree of coupling with the power system, which itself has relatively high risks. From a performance perspective, there does not seem to be such a high heat dissipation requirement.
So their concerns are justified.
But this, like the double cone, was one of the basic plans decided by Chang Haonan from the beginning, and it was obviously impossible to change it just because of two sentences:
"I understand your concerns... That's why I just said that the early air-breathing high-speed helicopters that are actually put into use in the future should still return to the traditional passive cooling route." He first gave a relatively positive answer, but then changed the subject:
"But this is a verification round after all, not intended to play a practical tactical role, so we need to be forward-looking and consider all possible situations that may arise in the future of the entire project."
"In the future, our hypersonic weapons may use infrared or visible light bands for target guidance. The biggest disadvantage of ablative heat protection design is that the ablation products will flow downstream in the gas boundary layer, causing boundary layer pollution. At the same time, they are likely to enter the window area of the visual sensor, causing the loss and attenuation of the homing information."
"In addition, at a speed of 6-7 Mach, because the thickness and strength of the ionosphere are relatively small, there is a high probability that there is no need to consider the electromagnetic shielding problem. However, for future faster flying objects, it is necessary to actively use ion flow to weaken and modify the plasma sheath wrapped around the outside of the flying object, so that radar waves of specific bands, specific phases and incident angles can pass through the shielding layer and detect the target by radar. This is similar to the requirement of sweating cooling to some extent..."
"..."
Having said that, Chang Haonan suddenly stood up, closed the PPT that was only used as the meeting background, and then opened a new document.
Above is a dizzying array of formulas.
Of course, even if everyone here is an expert, it is impossible to understand these contents immediately without any preparation.
But everyone can still understand the series of pictures sandwiched between the formulas——
Radar imaging effects of several different types of remote sensing satellites on targets such as large ships, cities, ports and airports.
Obviously, the "radar detection" mentioned by Chang Haonan is not like the early anti-ship missiles that simply received the reflected echo and then picked the largest one to shoot down.
Instead, SAR imaging is used to accurately identify targets within the search range.
It was not until this moment that everyone present suddenly realized that the goal of Academician Chang in front of them was much longer-term than they had initially thought...
At least it's not as simple as just developing a hypersonic weapon that's fast enough.
After letting everyone digest it for a while, Chang Haonan spoke again:
"Some of you here... especially those from the China Aerospace Science and Technology Corporation, may know that I was fortunate enough to participate in the development of imaging algorithms for two remote sensing satellite systems, Ziyuan-2 and Haiyang-1, a few years ago."
"After that, although the newer generation of remote sensing satellites is still under development and there is no specific launch schedule, my research team and I have not stopped researching the technology of image segmentation and target contour tracking."
"So far, we can basically find large surface ships with special contour features in the ocean background, and identify landmarks or buildings with special shapes in the land background with not very complex terrain..."
At this time, someone suddenly said:
"Like the Pentagon?"
This question was obviously a bit of a joke, but it just happened to ease the atmosphere on the spot.
A happy atmosphere suddenly filled the meeting room.
After laughing, Chang Haonan nodded:
"Although this metaphor may not be appropriate, if we only consider it from a technical perspective, it is indeed the perfect goal..."
There was another burst of laughter, a little less frequent than before.
"In fact, a more commonly used function of this algorithm may be to accurately identify the control tower, hangar and runway within an airport, or to identify the most valuable target ship in a port... In addition, if a special ground-penetrating radar is used, it is also capable of identifying bunkers or warehouses hidden underground."
He continued in a slightly bewitching tone:
"Of course, the more complex the actual situation is, the greater the amount of calculation required to identify the target. Considering that the terminal time of hypersonic weapons is very short, the current onboard computers may not be able to achieve overly precise requirements."
"But I believe that one day in the future, we will use this technology..."
