Chapter 179 - 175 Trouble with SLS_1

The CZ-10 team now, apart from being busy, hasn’t actually encountered any major issues, given that the 5-meter rocket body technology of the CZ-5 isn’t complicated and has been successful for so many years.

The connectors between the four boosters and the core stage had also withstood simulated tests, with thousands of tons of thrust acting on structures that still had to separate, which was unprecedented in China’s aerospace history.

Busy but orderly, moving ahead steadily and quickly - that was the real picture of the space agency at the moment, but NACA, on the other hand, had run into trouble.

The trouble was the SLS rocket.

The SLS rocket originated from the STS, the Space Shuttle program.

How does the Space Shuttle reach space? Its main propulsion comes from three RS-25 hydrogen-oxygen engines at the tail of the Shuttle, while it rests on an orange fuel tank with a solid rocket booster on each side.

The SLS rocket is essentially the Space Shuttle without the actual shuttle, with the engines moved under the fuel tank; it has four RS-25 engines instead of three, still strapped with two solid rocket boosters. That’s what makes an SLS rocket.

It sounds like they’re making adjustments on a mature design, which should be very small and easy, and also inexpensive, right?

Theoretically, yes, and that’s what NACA thought too.

But they overlooked one problem - the Space Shuttle hung on the side of an 8.5-meter diameter fuel tank, which was designed to primarily withstand lateral forces, without concern for vertical forces.

When the SLS rocket was officially put into manufacturing, NACA realized that if they were entirely to use the previous fuel tank, the axial strength was simply not enough, and reinforcing it based on the original design was also out of the question.

The only solution was to manufacture a new rocket body, which, though it looked the same as the original 8.5-meter "orange tank", was in fact a complete redesign.

There were no technical issues, but there was a problem with time; if they proceeded in this way, they likely wouldn’t make the planned maiden flight by the end of the year.

It just so happened that the New Yuan No. 3 rolled off the production line at this time!

After Director Claire confirmed the core stage’s strength issue, multiple review meetings were held, but none could bring the original orange tank up to standard; it was determined it had to be rebuilt.

But delaying the launch was out of the question. A December 2016 launch was already later than China’s freshly built CZ-10, and a further delay would turn it into a laughingstock.

In the end, Director Claire and the engineers, after a long discussion, decided to use more of the budget to increase efficiency and adopt non-stop manufacturing using three or even four shifts – not only had to ensure that the new rocket body was built within two months but also had to launch before December.

This meant that, including the test model, they had to manufacture the workload of two SLS rockets in the remaining five months.

The estimated manufacturing cost of the first SLS rocket was expected to increase from 400 million US dollars to 800 million US dollars, but since the funding was sufficiently ample, Claire didn’t hesitate to approve it.

News about the SLS defects had been tightly under wraps, with very little known to the outside world; currently, everyone’s attention was on the New Yuan No. 3 rocket, scheduled for launch on June 25.

In the space agency’s several research institutes, the First Institute watched New Yuan No. 3 quietly carrying out the initial design for the CZ-9, while the Sixth Institute had already started preliminary research on the YF135; only the Fifth Institute had a different style.

There were now an additional stack of plans on the space agency Big Shot’s desk.

Everything from a ten-thousand-ton class space power station to deep-space crafts was included, and the most exaggerated was something they titled the "Super Heavenly Court," an enormous space station.

The "Heavenly Court" was fittingly named - a massive centrifugal space station with a rotation radius of 240 meters, spinning at 1.5 rotations per minute to generate 0.6G of gravity, making it much more spectacular than the March.

Unlike the March, the chambers of the "Heavenly Court" are a series of interconnected ring sections. The Heavenly Court has two such rings, with a rectangular cross-section; the inner ring has a radius of 47 meters and generates 0.12G gravity, suitable for use as a microgravity laboratory.

The overall mass reaches 9,000 tons; when fully loaded and operational, it exceeds 10,000 tons and is expected to be completed with 50 launches of the New Yuan No. 3 rockets...

After flipping through pages for quite a while, he finally saw something practical: A massive lunar base of 100 tons to be sent to the Moon, capable of accommodating 10 people for extended stays.

Aside from this one, discard all the rest.

...

"Liquid oxygen kerosene... Why don’t you use methane engines? They don’t even produce soot, and New Yuan’s high-thrust methane engine technology is quite capable!"

Tang Weitian, who had just completed his first four-day pre-training session for the astronauts, also arrived at Qiongzhou and looked with awe at the colossal New Yuan No. 3 rocket, which seemed too large to fit even the assembly building.

New Yuan’s three series of heavy/super-heavy rockets: New Yuan-2A with methane engines, New Yuan No. 3 with kerosene engines, and New Yuan No. 4 with hydrogen-oxygen engines.

Technologically speaking, these are three different approaches, and actually, these three different thrust level engines could be simplified into a single line of engines with three thrust segments.

Running three lines simultaneously, that’s no ordinary boldness.

Lin Ju did understand why, though. These three engines could indeed be integrated into one, but each line has its advantages. The choice depends on the use case; after all, with all the technology available, there’s no risk of the conventional enterprise’s research and development failure.

The M220 Liquid Oxygen Methane Engine, relying on the dual cryogenic fuels, can easily use a common bulk tank, reducing the rocket’s dead weight. Methane burns cleanly, making engine cleanup easy, and the fuel isn’t expensive. It’s suitable for the New Yuan-2 series, which has a particularly high frequency of launch missions.

The K380 kerosene engine can’t use a common bulk tank due to the properties of its fuel, and after each reuse, the engine’s carbon deposits have to be scrupulously cleaned, but it has a higher specific impulse. For a super heavy-lift rocket like New Yuan No. 3, the extra cost of cleaning isn’t significant compared to the payload capacity it gains. This is why it achieves a payload fraction of 4.2%, while the old CZ-5 was only at 2.9%!

The latest iteration of New Yuan No. 4, an ultra super-heavy rocket, is even more extravagant, with its core stage requiring 39 H240 liquid oxygen-liquid hydrogen engines, boasting the highest specific impulse advantage and about a 5% payload fraction!

After explaining the reasons, Tang Weitian could only nod with a grave expression.

Developing three lines of engines with such superior performance concurrently is unprecedented worldwide.

During the space race last century, NACA favored the highly efficient hydrogen-oxygen engines, which were expensive but performed excellently. The Space Shuttle program, rather than being about recovering the launch vehicles, was more about salvaging the three extremely costly RS25 hydrogen-oxygen engines at the tail of the shuttle.

One engine cost 50 million US dollars, and that was 50 million US dollars from the last century!

The Union, benefiting from its abundant oil resources, used high-quality sulfur-free kerosene and vigorously developed high-performance liquid oxygen-kerosene engines.

NACA once tried to develop liquid oxygen-kerosene engines, but they faced difficulties separating sulfur compounds and the impurities in kerosene that led to unstable combustion. Despite many attempts at purification, they were unsuccessful, whereas the Union directly selected high-quality kerosene, provoking envy, jealousy, and resentment in America.

China, starting later and with insufficient technological capabilities, began by replicating the Union’s YF1 engines and developed the YF20/21 series of engines, which became the mainstay of the last century and even to this day. The engines, employed by the CZ-2, CZ-3, and CZ-4 rockets, use unsymmetrical dimethylhydrazine and nitrogen tetroxide as fuel.

Late last century, China also copied the Union’s RD120 liquid oxygen kerosene engine, branching off into the YF100 engine line.

Private enterprises, with Blue Origin and SpaceX at the forefront, have bet on liquid oxygen and methane engines.

New Yuan Aeronautics’ Power: I want them all.

This staggering technical strength and confidence deeply shocked Tang Weitian.