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> Besides, the question I have is why 3D printing?

Rocket nozzles are heat limited. You could get more trust out of them only if the nozzle would not melt. So you do a lot of tricks to cool it. One of those many tricks is that you circulate your rocket fuel as a coolant in the wall of the nozzle. This requires an intricate web of many tiny pipes which form the wall of the nozzle.

Typically these are constructed by hand by brazing together many many pipes. That takes forever. In contrast additive methods seem to perform well in this application.

This is standard stuff nowadays. Everyone seems to be doing it. I'm not sure what is your objection. If you don't believe me listen to Tony Bruno: https://youtu.be/Bh7Xf3Ox7K8?si=YVDIDq1bvKeCuvY9&t=1509

> This plainly is not true

Which particular part are you objecting to?

> I'm not sure what is your objection.

I am. It is that it's an Indian company. How dare these brown people do something cutting-edge in science or engineering!

My guess is failing to read between the lines and taking marketing too seriously.

"Removing the need for postfabrication qualification" doesn't mean "perfectly detects errors" it means "detects errors within our business specs and we expect it to be profitable within that margin".

In a typical rocket the payload is the most expensive thing, followed by the engines, and then the rest of the rocket and the fuel. Shaving costs off the engines is well worth it, but not if it sacrifices reliability.

Maybe they have a model in mind where it works. If you use dozens of engines like SpaceX's Starship you can tolerate more engine issues. Of maybe they want to launch really cheap payloads on inexpensive rockets. But in the parameters of traditional rocket design, QA on your engines is one of the last things you want to save money on.

Eh sounds like lying to me. Maybe it sounds like marketing to people who develop software “we can iterate no worries” but I think rocket science has a higher bar for safety.

Reminds me of that failing nuclear startup that tried “fake it until you make it” with the US government.

3d printing rocket engines makes a lot of sense. The engines of Rocket Lab's Electron rocket are 3d printed, Aerojet Rocketdyne's AR1 engines have 3d printed fuel injectors, SpaceX's SuperDraco thrusters (the ones in the Dragon 2 capsules) are 3d printed. Complex geometries with lots of liquid channels make rocket engines difficult to machine, so overcoming the issues with 3d printing heat-resistant parts is well worth it.

But skipping qualification testing is indeed a weird reason. I doubt you can skip test fires.

Everyone has a test environment, not everyone has a production environment.

> Besides, the question I have is why 3D printing?

My understanding is that there's interesting things in the aerospace industry that are very difficult or sometimes impossible to machine from a single part in a conventional subtractive machining process. GE is doing it as well for the LEAP engines: https://3dprintingindustry.com/news/ge-aerospace-to-scale-th...

As an easy example, imagine a single-piece rocket nozzle with internal channels for delivering fuel and oxidizer. Pretty much impossible to machine and not that big of a deal* to do with additive manufacturing.

* Your mileage may vary, talk to your doctor for details. :)

What part is not true?

https://www.youtube.com/watch?v=kz165f1g8-E

I'm sure that there are lots of problems with this approach, but it is not as obvious as your comment makes it out to be.

The part which is not true is: "removing the need for postfabrication qualification"

Makes sense, thank you

Yeah, that's just not true - it _eases_ post-fabrication qualification, but Agnikul does indeed qualify their nozzles (among other means, by static firing them in a test rig).

SpaceX has been printing the Draco and Super Draco engines for the Dragon capsule for many years. It’s a proven technology at this point.

With 3D printing you can create geometries that are simply not possible with any other manufacturing processes.

The issue is not 3D printing. The issue is deluding yourself by thinking that somehow 3D printing is magical and you get to skip qual. You don’t.

Integrating all the plumbing in to the structure is a lot easier to achieve with 3d printing.

relativity space does this as well, they have youtube videos on what they do

They don't do qualification of their hardware? Why would you put that on YouTube?

i dont know about that part, but they 3d print

i don't honestly believe there's anyone building a rocket like this that isn't concerned about the rockets success

Why are they saying they don't need QA then?

Sure, you can use whatever appropriate manufacturing processes you want. But none of them can replace QA.

i dont believe relativity space has said this, and i dont speak on their behalf

i have no idea what they do, im not in this industry

At the very least, 3D printing allows nearly full automation without having to create expensive custom production lines.

It worked. The engine flew. Mission success. Is that not qualification enough? As long as nobody is put in danger.

"When you don't have any real criticism, just make stuff up! Keep people down at all costs."

P.S. Nick checks out.

How is gross negligence on QA not a "real criticism"?

You hardly enough know anything about the project to make an assumption about the absence of QA. If you were an employee there, and you had specific concerns, that would be worth something. You made it up because you had no real point.

>You hardly enough know anything about the project to make an assumption about the absence of QA.

I take their claims at face value. Either they are for some weird reason lying about not doing QA or they are extremely negligent in their manufacturing. Granted, I can not exclude the first option, but to be honest that might make the company look even worse.

They're not shipping people into space with this tech yet. As such, even if QA were missing, which we don't really know much about, the need for QA is way less than you make it out to be. It's not a big deal if a cargo rocket blows up, and so far it hasn't even blown up. Together, this is why your line of comments is unqualified.

I sincerely hope you are never involved in any aerospace projects.

Like I said originally, when you run out of arguments, not that you ever had one really, you resort to forms of attacks that are not substantiated by any logic. You don't know me or what I would do if I were or were not involved in aerospace. Maybe you want to go taunt Elon Musk for how many rockets his company has blown up.

If you don't understand that rocket hardware needs QA, please stop talking about the subject. It is like a software engineer who believes that software should be shipped without any testing.

>You don't know me or what I would do if I were or were not involved in aerospace

True. I still hope that you are never involved in any aerospace or remotely safety critical project.

I hope you are not involved in anything at all, as you look to be a fairly toxic person to be around who will put others down at all costs.

Also, like I said, you have no idea of the emphasis I place on safety when the situation and funding merit it.

> Maybe you want to go taunt Elon Musk for how many rockets his company has blown up.

We know that Elon's SpaceX has many machines inspecting 3D printed (and other) parts, as per the SpaceX factory tours on YouTube. https://youtu.be/xahiWQQKw7Y?si=UGZ1u9xTil5iYoBi&t=71

Also, SpaceX blows up very few (none?) operational rockets. They only tend to blow up in novel ways while testing new technology.

Bear in mind that the SpaceX Raptor is a cutting edge engine - full flow staged combustion is hard.

As far as I know none of the Raptors have failed in flight, it’s always been various issues with the fuel delivery to the engines.