Chapter 168 Resonance
In the aerospace field, liquid fuels are more commonly used, while solid fuels are generally reserved for ejection systems.
This is primarily related to the distinct characteristics of the two fuel types. Liquid fuels are relatively inexpensive, offer high specific impulse, and allow for precise control of power output, though their engine structures are correspondingly complex.
Solid fuels, on the other hand, are convenient to store and dense in mass, enabling rockets or missiles to undergo long-term storage, concealment, and mobile transport prior to launch, accompanied by a simpler engine structure.
Specific impulse represents the propulsion efficiency of a rocket. Measured in seconds, it defines the duration for which one kilogram of fuel can produce one kilogram of thrust.
Between these two options, the advantages of one inevitably constitute the disadvantages of the other.
While liquid fuels are renowned for high specific impulse, the highest recorded specific impulse currently comes from liquid oxygen, reaching only 457. Domestically, the Long March series commonly relies on dinitrogen tetroxide paired with unsymmetrical dimethylhydrazine, which typically yields a specific impulse of around 348.
Although solid fuels fall somewhat short in specific impulse and thrust, they deliver greater absolute thrust, facilitate rapid launch procedures, and involve lower costs. In today's increasingly expansive micro-satellite market—where routine launches are frequent in China—these advantages make solid fuels extremely appealing for the deployment of small spacecraft.
From the very beginning, Wu Tong determined that a solid-fuel engine would be more suitable. However, while solid-fuel engines offer the highest cost-effectiveness and greater thrust, achieving her anticipated results required optimizing certain limitations of conventional solid fuels. In other words, it necessitated designing and developing an entirely new high-energy solid fuel unlike anything currently available on the market.
CO, $H_2$, $C_2H_2$, $CH_4$, $C_2H_4$, $CH_3CH_2OH$, $N_2H_4$
...A succession of chemical symbols flowed from Wu Tong's pen, crystallizing on the draft paper in her hand.
Most fuels currently used in solid rocket motors are advanced borosilanes, paired with oxidizers such as dinitrogen tetroxide ($N_2O_4$), liquid oxygen ($O_2$), or hydrogen peroxide ($H_2O_2$).
Liquid oxygen can serve as fuel; alcohol and methane can serve as fuel; what about nitrogen...? It accounts for roughly four-fifths of the atmosphere—does it hold any utility?
$N$, $N_2$... $N_{16}$... $N_{18}$... All-nitrogen molecules. A trending sector of high-energy materials flashed through Wu Tong's mind. All-nitrogen ionic salts?
Theoretically, all-nitrogen substances possess extraordinarily high energy, frequently reaching the range of 100,000 to 1,000,000 joules per gram—an energy level equivalent to ten or even a hundred times that of traditional TNT explosives.
Her absolute intuition told her that this accidental spark of inspiration was a delightful and unexpected harvest.
$N_{18}$, $N_{24}$... These two complement each other and point the way forward, offering a path to synthesize a passivated high-energy material suitable for explosives. Its destructive power should be roughly tenfold that of ordinary TNT, while the $N_{18}$ base possesses unique properties of its own.
Without paying attention, had she inadvertently conjured something dangerous? The fleeting distraction was quickly dismissed by Wu Tong, who was deeply immersed in her work. After all, this substance had more than just a single application.
The other application was the very reason Wu Tong conceptualized it in the first place: it could be used to manufacture solid rocket and missile fuel.
Nitrogen is chemically inactive; under directional storage conditions, all-nitrogen compounds exhibit relatively stable performance and can generate immense power in small quantities. This means that utilizing this new substance as a fuel would yield a high specific impulse and a lightweight volume, while remaining inexpensive once the preparation technology matures, resulting in exceptional cost-effectiveness...
Listing her criteria, this material possessed the combined advantages of both solid and liquid fuels while successfully avoiding the drawbacks of conventional solid fuels, making it supremely suited for launching rockets into the heavens.
How should it be prepared and applied?
Filtration? Precipitation? Vapor deposition?
Wu Tong suddenly recalled the insights gained from her previous derivation of covalent bonding effects.
Could poly-oxygen reduction serve as a viable preparation method through reduction pathways?
It seemed to strike at a core principle, bearing a striking conceptual parallelism. Ideas swept across Wu Tong's mind like a prairie fire; in an instant, inspiration struck, and her train of thought expanded completely.
Silica, silicon monoxide (SiO), silicon dioxide ($SiO_2$)...
As chemical formulas were listed one by one, her absolute intuition identified the optimal choice as $SiO_6$, hexasilicon dioxide.
Through a specialized covalent bonding effect, these atoms could be assembled into a special hexagonal molecule, more appropriately termed polyhedral silicon oxide.
The data transformed into a deductive model beneath Wu Tong's hands, filling in the decision-making variables one by one. Wu Tong confirmed that hexasilicon dioxide best met the current demands for synthesizing all-nitrogen compounds.
How should this specialized silicon oxide be prepared and utilized to achieve the desired separation effect? With this question posed, currently known materials swept through her mind in a tempestuous storm.
Ultimately, among the available material preparation methods, Wu Tong finalized the manufacturing direction, jotting down another series of molecular formulas on her draft paper and sketching out the atomic structure of the target material.
The hybrid-bonded carbon atoms were densely packed into a single-layer two-dimensional honeycomb crystal lattice—a typical hexagonal structure possessing a remarkable honeycomb architectural aesthetic.
Graphene-$(CH)_n$-COOH-COOH-HOOC-HO...
Graphene, a revolutionary new material of the future, represented another highly trending frontier topic in the physico-chemical community. By employing a vapor deposition process, specialized hexasicon dioxide would be combined with graphene thin films to form a specialized filtration membrane.
She would also need to construct specialized equipment, complete with nitrogen gas delivery pipelines, filtration units, and a vacuum pump. The entire preparation process required a pressure differential, a cleanroom environment exceeding a cleanliness rating of 100,000, and total darkness...
Condition by condition, the preparation requirements were deduced and confirmed by Wu Tong, and the manufacturing process standards gradually took shape.
Having established the foundational infrastructure for preparation, Wu Tong proceeded to deduce the manufacturing processes themselves. Drawing upon the categories and subcategories envisioned for the materials, she applied the method of elimination to its absolute limit through rigorous iterative filtering and deduction. Mathematical models assisted in deriving the directional data required to achieve the corresponding outcomes under specialized conditions...
By integrating these various capabilities, Wu Tong successfully filtered out the precise process parameters needed for preparation.
Pressurization, pressurization parameters, vacuum pressure differentials, specific currents and voltages, coupled with the specialized electrical effect applied to the hexasilicon dioxide—through this unique effect, the synthesis from gas to solid phase...
Step by step, an epoch-making new high-energy molecular material chain took shape under Wu Tong's pen.
As the final procedural step fell into place, Wu Tong gradually emerged from her state of absolute, single-minded immersion in deep research.
At that very moment, looking at the creation resting beside her, a belated realization dawned upon her: it appeared that what she had conjured this time was somewhat extraordinary!
This sudden burst of inspiration seemed to have yielded an unbelievable reactive material chain.
Originally, her sole intention had been to research a better solid fuel to serve as the power source for her newly designed scramjet dual-pulse ramjet engine.
Yet as her research progressed step by step, a sudden flash of inspiration resonated with the specialized molecular formula she had previously derived through covalent bonding effects, leading her to discover an entirely novel and specialized all-nitrogen compound, $N_{18}$.
This specialized all-nitrogen compound belongs to a unique allotrope of nitrogen.