China's Space Program Thread II

iewgnem

Senior Member
Registered Member
There is not much stopping SpaceX from developing a more conventional, expendable second stage -- i.e.: to aim for reusability only for the first stage of Starship (Super Heavy), which in turn will enhance the useful payload to orbit in terms of mass and volume.

Putting it another way, the excess focus and critique of Starship (second stage) should not obscure the more real and significant potential in the first stage/Super Heavy, and the current course of development allows the US and SpaceX significant ability to pivot and integrate a more conventional second stage to Super Heavy.
Two things are stopping SpaceX from developing a conventional expendable upper stage:
1. Elon's ego
2. Time

When a pivot involve building an entirely new rocket thats not a pivot, thats admiting the old design failed and trying again. Remember they went stainless steel to avoid having to develop 10m aluminum welding and structure tech, its not trivial to start from scratch.

Elon posted that Starship V2 can do 35 tons to LEO when its velocity altitude chart clearly shows it cant make orbit, which overwhelmingly suggest 35 ton is Starship v2's theoretical expendable LEO payload, which also align with their payload claims on F9 and FH both of which advertise theoretical expendable numbers.

35 ton expendable to LEO on 5000 ton takeoff mass is absolutely atrous.
 

gelgoog

Lieutenant General
Registered Member
If dollar per kg to orbit is sufficiently low the launch capacity can be used up. The simple way is to add propellants to satellites to give them extra delta-V to maneuver.
Useless ever since ion propulsion started becoming standard.

Starship’s second stage is directly integrated with the function of its space application. In essence, this means custom-building a rocket’s second stage for a specific space application. Anyone with a deep understanding of engineering research will naturally recognize the dreadful implications of such a customized rocket approach.
I do not think that is so bad. But Elon should have started with an expendable upper stage that is for sure.

Putting it another way, the excess focus and critique of Starship (second stage) should not obscure the more real and significant potential in the first stage/Super Heavy, and the current course of development allows the US and SpaceX significant ability to pivot and integrate a more conventional second stage to Super Heavy.
The Superheavy has too many engines which I suspect will make it unreliable. Assuming you could even find the payloads to make it economically viable which is highly doubtful.

That is certainly a significant capability. However the cost structure is no different than a Falcon-9, in fact the LEO cost per kg would be worse because such a super heavy will never reach the launch tempo of Falcon-9 as the market demand isn't there.
And this is the sore point. The Superheavy is just a gigantic waste of resources.

There is no reason why the Falcon 9 could not have been improved instead to further reduce turnaround time. Or at least a rocket around that size.
 

enroger

Senior Member
Registered Member
There is no reason why the Falcon 9 could not have been improved instead to further reduce turnaround time. Or at least a rocket around that size.

A better idea is to develop a reusable upper stage on F9 and see if upper stage reusability is worthwhile, and even if it shave 50% off payload capacity they can still get plenty of contract with it.

I think full reusability is definitely worth it, just not starship size and probably not built with stainless steel.
 

madhusudan.tim

New Member
Registered Member
Allegedly they tried designing a reusable upper stage for Falcon 9 and figured out the payload was really low.
Please, Log in or Register to view URLs content!
Wishcasting……..Why not build neutron style launchers? Consider a 5 meter diameter stainless 1st stage, common bulkhead, autogenous pressurization with gaseous methane, and 9 powerful 120 tonne class engines. Carbon fibre based fairing which opens like space shuttle at around 100 km altitude and 3 kmph speed. You would require a significantly smaller second stage given the smaller delta V requirement for the LEO, removal of fairing, and lighter weight of the second stage structure, and higher isp of methalox based second stage engine.

The problems, higher thermal load on the landing stage. But, I think the strakes or fins like that on the ZQ-3 can come to play; prolong the reentry angle and reduce the speed more gradually reducing the peak thermal load. Also if the frontal area can be made higher without significantly increasing the weight, it should be doable. Falcon heavy center core was recovered in 2019 after reaching similar speeds.

Only thing expendable would be the tiny second stage and second stage engine. Mass produced stainless tank should lower the cost to thousands of dollars, 3d printing should reduce the cost of the second stage engine to thousands. A 5m diameter frontal area of a rocket should give more aerobraking so that reentry burn might not be needed as well.
 

Jason_

Junior Member
Registered Member
The fundamental concept behind Starship is flawed (as evidenced by its v3->v4->vX… iterative cycle), and Elon Musk’s aerospace capabilities and understanding are deficient.

His paradigm is, in fact, a regression for the aerospace industry—a throwback to an older era—and is meaningless from a macro-level perspective.

The current Starship follows a specialized-purpose rocket philosophy, whereas the industry has long since adopted a general-purpose rocket design approach. Starship’s second stage is directly integrated with the function of its space application. In essence, this means custom-building a rocket’s second stage for a specific space application. Anyone with a deep understanding of engineering research will naturally recognize the dreadful implications of such a customized rocket approach.

China suffered from this problem for decades (the CZ-2 and CZ-3 series were, frankly, specialized-purpose rockets; only with the CZ-5, CZ-6, CZ-7, and CZ-8 did China enter the era of general-purpose rockets). The United States, on the other hand, largely moved away from the custom-rocket mindset starting in the 1980s, which is why it achieved such a high degree of standardization.

Today, Musk’s Starship is essentially a bespoke, in-house system (unlike Falcon 9) that forces payloads to adapt to its design, completely integrating the payload with the Starship second stage. It is evident that he has not yet solved the problem of deploying individual, independent payloads, as Starship cannot deliver oversized or exceptionally large payloads.

The maximum standard payload Starship can deploy in a single go is, at best, four bundled 5-6 ton class satellites (limited by its 6x8 meter payload bay door). A single mission could deploy two batches of these, totaling eight satellites (approximately 50 tons, which would fully utilize the payload bay’s volume), and only to Low Earth Orbit (LEO).

This vehicle is less practical than even the Falcon 9. Let SpaceX continue down this path. In 10 to 15 years, when Americans look back, they will regret it, much like the current situation with China’s electric vehicle industry.
Are you fking serious?

Starship's 9m diameter fairing is the largest in the world by far. It is better at delivering oversized or exceptionally large payload than any rocket developed to date. And so what if payloads are forced to adapt to its design when a fully reusable Starship has two orders of magnitude lower cost per kg to orbit? (And as if payload today are not already forced to be adapted to much less capable launch vehicles.) Currently, SpaceX delivers >90% of all payloads to orbit. Whatever SpaceX does IS THE SPACE LAUNCH INDUSTRY STANDARD.
1761420215284.pngDismissing Starship and SpaceX is like Jai Hinds dismissing J-20. Stop this cringe nonsense.
 

iewgnem

Senior Member
Registered Member
Are you fking serious?

Starship's 9m diameter fairing is the largest in the world by far. It is better at delivering oversized or exceptionally large payload than any rocket developed to date. And so what if payloads are forced to adapt to its design when a fully reusable Starship has two orders of magnitude lower cost per kg to orbit? (And as if payload today are not already forced to be adapted to much less capable launch vehicles.) Currently, SpaceX delivers >90% of all payloads to orbit. Whatever SpaceX does IS THE SPACE LAUNCH INDUSTRY STANDARD.
View attachment 163241Dismissing Starship and SpaceX is like Jai Hinds dismissing J-20. Stop this cringe nonsense.
You might want to hold off on Starship payload volume, because the only way to fix its inability to reach orbit is to shrink payload bay volume in exchange for fuel, whuch they are already doing with v2 and v3

Remember, Starship's fairing is steel...
 

nativechicken

Junior Member
Registered Member
Are you fking serious?

Starship's 9m diameter fairing is the largest in the world by far. It is better at delivering oversized or exceptionally large payload than any rocket developed to date. And so what if payloads are forced to adapt to its design when a fully reusable Starship has two orders of magnitude lower cost per kg to orbit? (And as if payload today are not already forced to be adapted to much less capable launch vehicles.) Currently, SpaceX delivers >90% of all payloads to orbit. Whatever SpaceX does IS THE SPACE LAUNCH INDUSTRY STANDARD.
View attachment 163241Dismissing Starship and SpaceX is like Jai Hinds dismissing J-20. Stop this cringe nonsense.
You are fundamentally ignorant of the technology. Starship’s payload bay is an enclosed design (and what you call a fairing is actually the internal volume of the spacecraft itself). The larger the volume, the more constrained the payload deployment is, as this is limited by the dimensions of the payload bay door.

The real problem with Starship right now is that this storage space is integrated with and inseparable from the second stage. For any payload to be deployed, it must exit through a door. Considering the need for reusability, the current design for the door has a maximum area of approximately 8x6 meters or 8x7 meters. An 8-meter height is roughly the minimum length required to deploy a heavy geosynchronous satellite (which are >6m long).

Furthermore, as a heavy-lift launch vehicle, Starship’s payload bay volume is actually the smallest in its class.

The SLS Block 2 (130t to LEO) has a payload bay volume of 1,800 m³.
The CZ-9 (150t to LEO) is projected to have a payload bay volume of 2,100-2,400 m³, and could even reach 2,800-3,000 m³ for LEO missions.
Let me also tell you this: even the improved Starship, the original v3 version with a height of over 150 meters, would only have a payload bay volume of 1,200-1,400 m³. The latest v4, with a height of only 142 meters, will likely have a volume of just 1,100-1,200 m³. Other variants have even smaller payload bays than the v1/v2 versions.

In my eyes, Starship is essentially the worst heavy-lift rocket design ever conceived. You don’t understand the requirements of rocket design, which is why you can’t see that Starship is a deformed piece of junk with grotesquely imbalanced metrics. But most of the professionals in China and the U.S. who truly understand aerospace design get it. It’s just that these experts are routinely attacked (by Musk’s fans who use Falcon 9 as a weapon), so they mostly keep quiet now.

If you truly understood spacecraft, you would know that a good design is a synthesis of multiple parameters. Starship only excels in one metric: one-time payload capacity. It also has a good metric for reusability (low cost). All other spacecraft metrics are abysmal to an absurd degree. For example, if there were a metric for payload deployment capability, all currently visible versions of Starship are inferior to Falcon 9. And that is frankly ridiculous.

This is why I say it’s a specialized-purpose rocket, not a general-purpose one. You clearly don’t understand the problems China encountered with the CZ-2/CZ-3 series, where adapting one type of rocket for one class of payload was incredibly inefficient. Just look at Starship now: isn’t it a case where one class of payload requires a specific variant of the rocket?

If you still don’t understand this, I don’t care to elaborate further. I’ll just say that Western de-industrialization has gone on for so long that you’ve forgotten how to evaluate engineering and assess risk. Meanwhile, those of us in China can only chuckle to ourselves while reading the Chinese translations of various Western textbooks from the industrial peak of the 1960s-90s that fill our libraries.
 

nativechicken

Junior Member
Registered Member
Are you fking serious?

Starship's 9m diameter fairing is the largest in the world by far. It is better at delivering oversized or exceptionally large payload than any rocket developed to date. And so what if payloads are forced to adapt to its design when a fully reusable Starship has two orders of magnitude lower cost per kg to orbit? (And as if payload today are not already forced to be adapted to much less capable launch vehicles.) Currently, SpaceX delivers >90% of all payloads to orbit. Whatever SpaceX does IS THE SPACE LAUNCH INDUSTRY STANDARD.
View attachment 163241Dismissing Starship and SpaceX is like Jai Hinds dismissing J-20. Stop this cringe nonsense.
Let me add one more thing: the data in that image is wildly inaccurate. For instance, the larger Falcon Heavy fairing—that was never actually built. The current Falcon Heavy fairing is 10 meters tall, exactly the same as the one on Falcon 9. They’ve been trying to develop a 15-20 meter fairing for years but have never been able to solve the associated problems.

In reality, the issue isn’t the size of the fairing itself. It’s that the rocket’s length-to-diameter ratio (the ratio of its length to its diameter) has already reached its limit on the Falcon 9 platform. Its length cannot be increased.

Why? You would need a thorough understanding of rocket structural mechanics to grasp the reason.

Also, the Starship payload bay height in that image is complete nonsense. The usable height inside Starship’s payload bay is 18 meters, with the total external height at most 21 meters (due to a fuel tank in the nose section).

Furthermore, the volume for SLS Block 2 is also wrong. If you check the news, you’ll find that the maximum payload bay volume for SLS Block 2 is 1,800 m³.
 
Top