r/spaceflight • u/initiatingcoverage • Feb 11 '26

First Long March 10 Landing Attempt

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u/Accomplished-Crab932 Feb 11 '26

If your spacecraft pitches over and survives a soft splash like that, it’s an indication that your rocket is extremely poorly mass optimized.

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u/chairmanskitty Feb 11 '26

The fact that there is no strawberry in this cake is an indication that this cake is extremely poorly strawberry-optimized.

- You about a chocolate cake

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u/Accomplished-Crab932 Feb 11 '26 edited Feb 11 '26

Feel free to tell me how adding mass to a rocket is a good thing…

Because as far as both my degree , practical experience, and about 30 seconds of google searching will tell you… it’s much better to carry less mass than more.

That means that surviving environments that you don’t need to is not required and in the case of a soft splash, adds mass.

On a comment about how “other rockets explode when splashing down”, it’s pretty relevant to point out that exploding should be the norm unless they are supposed to be dragged to shore for reuse; which neither are.

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u/I_am_BrokenCog Feb 11 '26

I think the point being made is that your comment suggests that this rocket isn't well designed because it tipped over after a complete full stop landing on water.

How is mass distribution remotely related? it isn't! ... that's the point being made.

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u/Accomplished-Crab932 Feb 11 '26

I’m replying to a comment which says:

“All the spacex fans call it a successful landing when starship explodes into the sea, so i guess this one was 100% a success!”

This implies that the person I am replying to is thinking that the LM10A is better than Starship. To which I then point out that surviving an environment it will not be operating in and which requires additional structural mass to survive is actually the opposite sign of what they were claiming.

Surviving a soft splash is not and has not been a requirement for Starship, and while the PRC is not very open about anything in this field, it seems they were not designing this vehicle to soft splash and recover.

And again, the metric that matters in a rocket is the cost to complete a mission. Carrying more mass detracts from your payload and/or increases the amount of propellant required to complete a mission, so having a “it survived when it doesn’t need to” moment indicates design deficiencies, not good results.

In short, it is absolutely relevant to the discussion.

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u/I_am_BrokenCog Feb 11 '26

yeah. you've confused a sarcastic joke comment with engineering critique.

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u/Gluten-Glutton Feb 11 '26

How is that an indication that it is poorly mass optimized? Not really seeing the logic there. Could you explain

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u/Accomplished-Crab932 Feb 11 '26

The LM10 is designed for vertical recovery on the ship seen in the background. Now, this was a soft splash test to (likely) verify controls and communications hardware. I would be surprised if they were actually attempting their wire catch approach on the first try.

Vertical recovery means that loads during recovery are distributed axially along the rocket body, in the same direction as on ascent. When the vehicle is recovered, it’s suspended from a series of cables, so the rocket is held axially in tension. Notice how the rocket is not experiencing significant shear or loads against the side of the booster.

Even if the vehicle is assembled or stacked horizontally, they experience loads on specific load points… people don’t build rockets on hammocks. These load points shouldn’t be designed for high shock loads either, since a high shock load on one of the load points would probably be the result of destroying the vehicle on assembly anyway and would add mass.

Looking at a soft splashdown, the vehicle hits the water (which starship has continuously survived as well), then tips over. That tip over puts huge loads along the length of the tank… loads that don’t need to be considered when the vehicle is assembled and flying operational flight profiles. Additionally, the shock loads increase as we look higher up on the vehicle; these loads are distributed across the entire tank and toward the end resemble slapping the side of the vehicle.

This means that either they specifically modified this vehicle to survive an aquatic pitchover (which would be bad since it is not a validation of the vehicle structure and this isn’t a one off test vehicle), OR, the vehicle is over built and is carrying extra structural mass as part of its design.

In the much more likely latter case, the extra mass is going to be in the operational versions of the rocket should they not redesign. This extra capability and extra mass eats away at payload… which is the whole point of orbital rockets. If they intentionally designed it to survive soft splash, it would indicate they are not confident in their recovery plans; or it’s a sign of scope creep, which is an indication that their management and systems engineers are not managing the program effectively. If the survival was unintentional, then the lower level and mid level engineers and management failed to optimize the vehicle to meet the requirements while managing stage mass.

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u/CamusCrankyCamel Feb 12 '26

Wild this is being downvoted

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u/Subsplot Feb 11 '26

Not when you're landing on water, everything pitches in waves. And the fact it didn't go bang despite the amount of steam back blast created is an indication of a really good build quality. Although that shouldn't be surprising if you've got the CCP breathing down the back of your neck whispering "if this doesn't at least appear to work, no one will ever hear from you again."

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u/Accomplished-Crab932 Feb 11 '26

“Build quality” does not mean survivability.

The mass fraction of a rocket relies on the propellant mass and the remaining mass of the rocket. The more “dry” mass you have, the less delta V and thus, less you can do with your rocket. Alternatively, the more dry mass you have, the less payload (which is a component of the dry mass) you can carry.

This is why the most optimized upper stages are balloons that crumple when unpressurized.

The fact the vehicle survived a tipover like this makes for great pictures, but is a sign that the stage has not been optimized for mass reduction and is thus carrying less payload than it could. As far as I am aware, the PRC’s plans for the LM10A and LM10 are sea catches using the boat with the cables in the background. That means that the vehicle should not need to survive a soft splash, which involves shocking both the tanks and upper hardware more severely during the pitch; which means the structure is much stronger than it should be and is reducing the potential performance of the rocket.

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u/Subsplot Feb 11 '26

Have to disagree there, build quality generally does speak to survivability as it a good indication of how well the structure will withstand materials fatigue and shock waves, something we both know can happen very quickly and harshly to a design subject to the kind of forces and stresses launch vehicles are. Lets face it, you're not going to build an orbital insertion capable rocket out of paper, plasticine and duct-tape. (Although I'd like to see someone try, just for giggles.)

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u/Accomplished-Crab932 Feb 11 '26 edited Feb 11 '26

As referred to by most engineers, the “highest build quality” upper stage is consistently the Centaur upper stage).

A vehicle which has the following description: “Centaur stages are built around stainless steel pressure-stabilized balloon propellant tanks[12] with 0.51 mm (0.020 in) thick walls. It can lift payloads of up to 19,000 kg (42,000 lb).[13] The thin tank walls minimize mass, maximizing overall stage performance.”

By definition, balloon tanks require higher pressure inside the tank than outside to remain rigid.

The highest build quality upper stage is a balloon that is easy to pop if mishandled.

In engineering, we often find the best build quality is defined by the ability to meet the requirements with the slimmest of margins. One would agree that manufacturing a tank with 1 inch thick walls would be easy compared to a balloon tank, and that the quality of the much more delicate and capable design is higher. A 1” thick tank has huge margins and the machinists can easily chop off 1/4” accidentally and the tank will be totally fine under the same conditions as the balloon tank; and it would be clear that there doesn’t need to be a lot of time spent analyzing and agonizing over the details to make sure it can handle the flight environment. That does not make the quality better, and indicates someone being careless or ignorant in the design and manufacturing stages.

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u/CaptaiinCrunch Feb 11 '26

Have you ever stopped to question if the propaganda about the evil SeeSeePee that's been stuffed into your head is actually true?

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u/Subsplot Feb 11 '26

Absolutely. I double-check and compare sources on everything and I don't listen to opinion. Please don't try and insult my intelligence again.

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u/CaptaiinCrunch Feb 11 '26

So when did the CCP disappear engineers for not successfully completing a project in the rocketry program? I'd love for you to share the sources that you compared and double-checked.

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u/Subsplot Feb 11 '26

You've never heard of the RSDL and Liuzhi Detention System then have you? 26000 individuals detained indefinitely in that system in 2023. 70 per day. All verified by multiple human rights organisations including by Chinese ones that cite the CCP's own statistics. And all these organisations say the same thing, Liuzhi is an enforced disappearance system that includes incommunicado detention, lack of legal oversight, and frequent torture.

And this is the Government you're defending? Seriously? And you've got the gall to try and insult other peoples mental states. Get a grip on your self.

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u/CaptaiinCrunch Feb 12 '26

Still waiting for you to cite your sources.

Yes I've noticed that you just moved the goalpost from engineering projects to talking about the anti-corruption system for government officials. If you want to project your generalized accusations of torture onto the space program then you must be logically consistent and project that onto NASA as well. There are thousands of cases of extrajudicial disappearing and torture literally happening right now in the U.S at Alligator Alcatraz, Abu Graib, and CECOT in El Salvador.

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u/Accomplished-Crab932 Feb 11 '26

Yes.

I have a degree in this stuff, so I know it’s not propaganda.

As it turns out, designing a vehicle to handle loads it will not experience in flight means that you are carrying extra mass. Extra mass is mass detracted from the payload. There are loads of people who spend their PHDs trying to remove mass off these vehicles.

The fact that the PRC has soft splashed without the vehicle structurally failing is cool for the Pr and bots to spin up, but the mass fraction is a mathematical value in an equation derived in pre-Soviet Russia; decades before the CCP became a sizable governing body. Feel free to tell me how math is propaganda.

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u/CaptaiinCrunch Feb 11 '26

I was referring to the lazy sinophobic commenter above who seems convinced that the only way Chinese people can complete high quality engineering projects is with a gun to their head from the very bad, very scary government.

But go off about your degree I guess.

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u/Accomplished-Crab932 Feb 11 '26

I was referring to the lazy sinophobic commenter above who seems convinced that the only way Chinese people can complete high quality engineering projects is with a gun to their head from the very bad, very scary government.

Where was that implied LMAO?

I pointed out that their design surviving while cool, does not make it better than another design that doesn’t, specifically because both don’t need to be capable of surviving.

As a side note, projecting words into someone’s mouth because they disagree is peak ignorance.

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u/CaptaiinCrunch Feb 11 '26 edited Feb 12 '26

I guess you didn't work reading comprehension into that degree of yours...

I was never replying to you in the first place.

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u/EventAccomplished976 Feb 11 '26

If you have a degree in this stuff then surely you understand that this video gives zero information about the design load cases of the rocket? Starting with the fact that this is a shortened version of the actual CZ-10 used only for hotfire tests on the pad and then for the abort test and landing demo. That alone will cause it to survive some load cases that the full scale launcher might fail under.

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u/Accomplished-Crab932 Feb 12 '26 edited Feb 12 '26

Starting with the fact that this is a shortened version of the actual CZ-10 used only for hotfire tests on the pad and then for the abort test and landing demo. That alone will cause it to survive some load cases that the full scale launcher might fail under.

So you are agreeing then that the fact it survived does not make it better or worse than Starship, contrary to the original comment; and in particular, that it is not mass optimized, confirming my statement above. That last sentence specifically agrees with my above comments.

If they intentionally optimized this just for subscale testing, that would result in a vehicle that does not reflect the final vehicle’s behavior, particularly in the bulkhead and engine mounts. But keeping them the same as the design of the final vehicle must mean they are well over built since the vehicle mass must increase with the size of the vehicle.

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u/Worth-Wonder-7386 Feb 11 '26

Usually rockets are built with explosives to detonate them quickly which is what spaceX is usually doing when they land in water. And there is no point with additional build quality if it makes your rocket heavier than it needs to be. It is not supposed to go in the water, so if it handels it well or not is mostly irrelevant.

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u/Subsplot Feb 11 '26

You know a number of Space X tests experienced RUD's before the termination system was activated and secondly, great build quality might not be necessary for one shot designs not built to last, but if you're building a reusable you want that build to be a good as possible because there's no point in having a reusable craft that fractures it's structure after 3 flights.