Qiongzhou.

On the beach closest to the land launch station, Xinyuan built a floating launch pad that could be towed, surrounded by two semi-submersible ships.

The crane on the semi-submersible ship lifted a 5-meter-diameter black extra-long container with a steel structure attached to it, moved it to the top of the floating launch pad in the shape of a "mouth", found the right position, and slowly lowered it until the tail was just above sea level.

Workers on the floating launch pad took a moment to pull out a few metal ropes from under the exposed sea in the middle and tie them to the steel frame in the upper half of the container, which were attached to the counterweights that had sunk to the bottom and could be retracted by the underwater motors.

Then the crane began to release the hook, so that the container was pulled down by the four metal ropes around it, and the workers on the floating platform tacitly stepped back to prevent the straight steel rope from suddenly bouncing off.

The inside of the extra-long container is sealed with a rocket, and there is a retractable fixed structure inside that remains in the center.

This is an experimental test rocket, with an H280 liquid oxygen liquid hydrogen engine mounted on the core of the Xinyuan-5 basic rocket.

It now simulates the sea launch of the Xinyuan-4 (Long March-18) rocket:

Since it is impossible for any land launch pad to undertake the thrust impact of the Xinyuan-4 rocket, it has chosen a semi-underwater launch mode similar to that of the PPT rocket "Sea Dragon".

When the rocket is transported out of the inland river, the rocket body has a cross-section of 26 * 26 meters, and the splicing super-large steel final packing box with a length of 260 meters is completely wrapped, and there is a large area of arc-shaped soft supporting plate on the inner wall of the final packing box to resist the rocket, ensuring that the interstage and booster connection mechanism of the rocket body are completely free from force, which is equivalent to a movable assembly building, with a self-weight of nearly 2,000 tons.

Before preparing for launch, a specially designed and lengthened semi-submersible ship will arrive at the predetermined launch area with a recumbent, assembled oversized final packing box, and then begin to release the steel frame attached to the head of the final packing box, release a part of the steel cable that holds the steel frame at the tail end, and then begin to fill the hull with water and sink until the entire final container is completely floating.

The place where the rocket is launched is not to be found randomly, but to fix the sea area, and it is necessary to enclose a piece of cement to the seabed in a relatively calm shore area to make a submarine cement base weighing 150,000 tons, which only costs eighty or ninety million yuan, and can be done in a month, anyway, all that is needed is a big cement mound.

The special semi-submersible ship can sink 50 meters, and when it begins to sink, the super final packing box will touch the water surface and float up, and because of the 39 engines installed at the tail of the rocket and four solid boosters weighing more than 5,000 tons, the overall center of gravity is inclined to float upwards backwards, although there are many parts that are exposed to the water, but because it is supported by the structure in the final packing box, the rocket itself is not subject to lateral load, and there is no need to worry about radial force.

At this time, there will be four 10,000-ton cargo ships with large cranes installed in the vicinity, and the outer steel frame of the final packing box will be connected with steel cables in four directions by multiple small boats and divers.

As the semi-submersible ship continues to sink, the steel cable at the tail of the final packing box begins to straighten, so that the tail pulls down to make the tilt angle smaller, and at the same time, the four crane ships cooperate with the operation to pull and assist in erecting the entire general packing box, and about 30 meters of the 260-meter-high total packing box is immersed in water, and the steel cable at the bottom and around it maintains a vertical attitude.

At this time, the fuel ship has to hurry over to refuel the rocket, and when the first and second stage of the rocket are all refueled, the final packing box and the rocket will sink into the water with a length of 50 meters because of its own weight, and most of it is still exposed.

Then the underwater operator will transfer hundreds of steel cables from the cement base to the tail of the final packing box from the underwater semi-submersible ship, and then the semi-submersible ship leaves underwater, and the steel cable begins to pull under the action of the underwater motor, so that the final packing box slowly sinks until the rest are submerged except for the load part exposed to the water surface.

The buoyancy of the submerged part of the general packing box is 120,000 tons, and the rocket, steel structure, and cement base together weigh about 167,000 tons, which is enough to resist these buoyancy.

At this point, the crane detached the cables, left with the bunkering vessel, and arrived almost 10 kilometres away in about 50 minutes, where it awaited launch.

At the time of launch, the top end cover and the box exposed to the sea surface are removed, and then the water discharge hole of the submerged part of the outer wall of the final packing box will first inject 30,000 tons of seawater into the box to make the water level in the final box rise to 95 meters, and the buoyancy of the rocket reaches 25,000 tons, which is the maximum force that the rocket body can withstand the limiting mechanism.

After that, the oversized waterproof doors on the four sides of the super final container flew out to one side in less than 1 second under the action of multiple explosive bolts, and at the same time, a huge amount of seawater instantly poured into the box containing the rocket, and the limiting mechanism was disconnected at the same time.

The volume of the Xinyuan-4 rocket can bring more than 60,000 tons of buoyancy, and when the water is filled, the rocket that loses control will accelerate directly under the buoyancy and jump out of the sea, just like if you press a ping-pong ball into the water with your hand and bounce up when you let go.

The rocket itself is buoyant enough to leap out of the sea level, and when it is almost a few meters away from the final packing box that has been dismantled from the sea surface, the four booster and core stages quickly ignite, generating enough thrust before falling due to gravity.

The launch process, preparation, and operation of the entire Xinyuan-4 rocket are extremely complex, requiring more than 1,000 offshore operators and a total displacement of 10,000 tons of ships, and the auxiliary work of these preparations will cost hundreds of millions of yuan.

The site has been chosen, and a suitable depth of water has been found in a no-man's land area in Qiongzhou, and the underwater cement base is being poured.

The final packing box itself is equivalent to the pressure-resistant hull of a simple giant submarine, but fortunately, the technical requirements are not high, only special steel is needed, and the construction progress of Huludao has reached one-third, and it can be completed and sent to the Yangtze River tributary near Xinyuan in another month.

The rest of the auxiliary ships are basically ready-made, and there is no shortage of special operation ships in China, which can be easily mobilized.

This extremely complex launch system is already the best solution that the base can think of, and when it was reported to the Aviation Development Commission in August, the old astronauts were taken aback, but a closer study found that this was the only way to do it, otherwise the super rocket would not have been launched at all.

When it was learned that such a frenzied super rocket had begun to manufacture sample arrows and find a Huludao manufacturer to customize the final packing box, the Aviation Development Committee passed a resolution to "turn it into a positive one" for the Long March sequence, and the engine was also given the number of YF-94, and then began to prepare for the launch with all its might, after all, it was less than four months before the first launch!

At the same time, Qiongzhou immediately carried out verification tests to test the engine and the launch method.

It took the inexperienced team more than half a day to complete all the preparations, and Guo Shen, who was supervising the scene, checked that all the systems were in good condition again and gave the launch order.

Trapped in the water by a steel cable, the container that had been dismantled from the surface of the water began to pour water from underwater, and after a few seconds, a large splash of water was made as the bottom of the water vibrated and the sea water rushed in frantically.

At this time, the chemical reaction vessel at the tail of the rocket body begins to activate, producing a large amount of nitrogen to empty the engine lines and seawater in the combustion chamber.

When the limit jaw of the test rocket in the container is released, the rocket immediately pops out under the action of buoyancy, and the engine soaked in the water is successfully ignited when most of the arrow body stretches out, and the high-temperature gas makes the surrounding seawater immediately vaporize to produce a spectacular water mist, up to dozens of meters and envelop everything.

Immediately, a rapidly rising flame appeared in the mist, pushing the test rocket to rush out of the mist, which had spread for hundreds of meters, and flew into the sky.

Ten minutes later, the test rocket reappeared over the launch area and splashed vertically into the sea.

Multiple RCS around the rocket body immediately activated the ejection of gas, causing the rocket to fall sideways and float in the sea before it could fully jump out of the sea again.

Underwater launch, water recovery, one success.

(End of chapter)