Chapter 524 - 513 Underwater Eject_1

Qiongzhou.

At the nearest beach to a land-based launch site, Xinyuan Company had built a towable floating launch platform, surrounded by two semi-submersible ships.

The cranes on the semi-submersible ships lifted a super-long container with a black external steel structure, measuring 5 meters in diameter, and moved it above the "口"-shaped floating launch platform, gently lowering it until its tail was just above sea level.

The workers on the floating platform took some time to pull out several metal cables from beneath the water’s surface at the center and tied them to the steel frame on the upper part of the container; these metal cables were connected to the ballast that had sunk to the bottom and could be retracted or extended by underwater motors.

Next, the crane began to release its hooks, letting the container fall, guided by the four metal cables surrounding it. The workers on the floating platform tactfully stepped back to avoid the tightly stretched cables from suddenly snapping.

Sealed inside the super-long container was a rocket, with a retractable fixation structure inside to keep it centered.

This was an experimental test rocket, fitted with an H280 liquid oxygen-hydrogen engine onto the naked body of a Core Stage One of a New Yuan No. 5 base model rocket.

It was now simulating the sea launch scenario of the New Yuan No. 4 (CZ-18) rocket:

Since it was impossible for any land-based launch pad to handle the thrust impact of the New Yuan No. 4 rocket, it opted for a semi-submerged launch mode, similar to the PPT rocket "Sea Dragon".

When the rocket was transported out from the inland waterways, it was completely encased by a giant steel container with a cross-section of 26 x 26 meters and length of 260 meters. The inner walls of the container also had large areas of curved soft support boards pressing against the rocket, ensuring that the inter-stage and booster connection mechanisms were not subjected to any force. The container was akin to a portable assembly building, with its own weight nearing two thousand tons.

Before the launch, a specially extended semi-submersible ship would arrive at the designated launch area with the horizontally positioned, fully assembled giant container. It would then start to release the locking structures of the steel framework attached to the front of the container, let out some of the steel cables fixing the rear steel frame, and begin to ballast the ship to submerge until the entire container floated.

The location for the rocket launch was not chosen at random but was a fixed sea area. It required the construction of a 150,000-ton undersea cement base by pouring cement on the seafloor in a relatively calm nearshore water body. This only cost eighty to ninety million and could be completed within a month—the requirement was just a large lump of cement.

The special semi-submersible could sink to 50 meters. As it began to submerge, the super assembly container would touch the water’s surface, floating up. Due to the 39 engines installed in the rear of the rocket and the four solid boosters weighing over 5,000 tons, the overall center of gravity was skewed towards the rear and floated upwards at an angle. Although a significant portion emerged from the water, because it was supported by the container’s internal structure, the rocket itself did not bear any lateral load and there was no need to worry about radial forces.

At this point, four heavy-lift vessels equipped with large cranes would be nearby, connecting the external steel framework of the container with steel cables from four directions using multiple boats and divers.

As the semi-submersible continued to submerge, the steel cables at the rear of the container began to tighten, reducing the tilt angle. At the same time, the four lifting vessels coordinated efforts to pull the entire container upright. Approximately 30 meters of the 260-meter-high container was submerged, maintaining a vertical position through cables at the bottom and around the sides.

Now, it was crucial for the fuel ship to promptly refuel the rocket. Once the first and second stage fuels were fully filled, the container and rocket’s weight would cause about 50 meters to sink into the water, with the majority still exposed.

Then, underwater operators would transfer the hundreds of steel cables from the underwater semi-submersible to the rear of the container, and then the semi-submersible would leave from underwater. The cables at the seabed would start pulling, causing the container to slowly sink until all but the load-bearing part was submerged.

The buoyancy of the submerged part of the container was 120,000 tons, while the weight of the rocket, steel structure, and cement base together was approximately 167,000 tons, enough to counteract the buoyancy.

At this point, the lifting vessels would detach their cables and leave along with the fueling ship, arriving at the sea region 10 kilometers away after about 50 minutes, waiting for the launch.

At launch, the top cover and the casing that were exposed above the sea were dismantled, and then 30,000 tons of seawater were injected into the assembly container through the drainage holes in the submerged part of the outer walls, causing the water level inside the container to rise to 95 meters. The buoyancy acting on the rocket reached 25,000 tons, which was the maximum force that the rocket’s structural constraints could withstand.

After that, under the influence of several explosive bolts, the four oversized watertight doors on the sides of the super assembly container were blown out in less than a second, allowing a massive amount of seawater to instantly rush into the container housing the rocket, while the limiting mechanisms were simultaneously released.

The New Yuan No. 4 rocket had the potential to generate over 60,000 tons of buoyancy. If the rocket lost control during water injection, it would be propelled out of the water by the buoyancy, just like a ping pong ball springs up when you release it after pushing it underwater.

The rocket’s own buoyancy was enough for it to leap out of the sea surface. As it was mere meters from popping out of the assembly container, whose sea surface part had already been dismantled, the four boosters and Core Stage One rapidly ignited, producing enough thrust to prevent the rocket from falling due to gravity.

The entire launch process of the New Yuan No. 4 rocket, along with the preparations and operational methods, was exceedingly complex, requiring over 1,000 maritime workers and a total ship displacement of tens of thousands of tons. These preparatory support tasks alone would cost hundreds of millions.

The location had already been chosen, in an uninhabited area in Qiongzhou with water depths deemed suitable, and preparations were underway to pour the underwater cement base.

The assembly container itself was equivalent to a crude pressure hull of a giant submarine. Fortunately, the technical requirements were not high, requiring only special steel. The construction progress in Huludao had already reached one-third, and in one more month, it would be completed and transported to a tributary of the Yangtze River near Xinyuan.

Most of the necessary auxiliary vessels were also essentially available. China was not short of special operations vessels, which could easily be mobilized.

This extremely complex launch system was considered the best solution the base could think of. When it was reported to the Aerospace Development Committee in August, it took the veteran space officials by surprise, but upon careful study, they realized that was the only way to do it; otherwise, the super rocket simply couldn’t be launched.

When they learned that such a crazy super rocket was already in the process of manufacturing a prototype and the assembly containers were being custom-ordered from manufacturers in Huludao, the Aerospace Development Committee passed a resolution to officially include it in the Long March sequence, designating the engine with the YF-94 number, and then they started the launch preparations with full effort, given that there were less than four months left until the first launch!

Meanwhile, Joan conducted a verification test immediately, to check the engine and the launch method.

The inexperienced team spent most of the day completing all the preparatory work. Guo Shen, who was supervising on-site, checked all the systems once more and then issued the launch command.

The rocket, bound in steel cables underwater, began to fill with water from beneath as the surface part of the shipping container was dismantled. A few seconds later, as the ocean floor shook, a burst of water splashed up, and the seawater poured in furiously.

At that moment, the chemical reaction containers at the aft of the rocket became active, generating a large amount of nitrogen to evacuate the seawater from the engine pipes and the combustion chamber.

When the container’s locking claws that fixed the test rocket in place were released, the rocket immediately popped out under the effect of buoyancy. As more than half the rocket emerged, the engines submerged in water ignited successfully in one go. The high-temperature exhaust gases immediately vaporized the surrounding seawater, creating a spectacular mist rising dozens of meters and shrouding everything.

Soon, a rapidly ascending ball of fire appeared within the mist, propelling the test rocket out of the water vapor that had spread hundreds of meters, flying towards the sky.

Ten minutes later, the test rocket reappeared above the launch area’s sea surface, splashing back into the ocean in a vertical position.

The rocket’s multiple RCS quickly activated, ejecting gas and causing the rocket to flop over, lying down and floating on the sea before it fully leaped out of the water again.

Underwater launch, above-water recovery, a success.