Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Indian startup 3D prints rocket engine in 72 hours

spectrum.ieee.org

Post reply on HN
Print view View original

121–130 of 288 posts

Re: Indian startup 3D prints rocket engine in 72 hours

#121

Post by toss1 »

ETH_start wrote: post #107
rvnx wrote: post #73

Earlier quoted context omitted.

If it would be a Tesla, just enough time for the auto-pilot to disengage and claim it was the fault of the user.

Tesla autopilot is not supposed to be unmonitored, so any accidents under its control are entirely the fault of the driver. If a driver disengaged 0.1s before impact, they were derelict in their driving.

This is true, but it also falsifies Tesla's naming, promotion, abd advertising of the capability as "Full Self-Driving".

("Self-Driving" alone could be reasonable in certain contexts, but insisting on "Full Self-Driving" is a flat-out lie in plain language. Saying " Alan is fully capable of driving the car." means that he requires zero monitoring and/or intervention; same for the "Fully..." phrase.)

Re: Indian startup 3D prints rocket engine in 72 hours

#122

Post by shepherdjerred »

ETH_start wrote: post #107
rvnx wrote: post #73

Earlier quoted context omitted.

If it would be a Tesla, just enough time for the auto-pilot to disengage and claim it was the fault of the user.

Tesla autopilot is not supposed to be unmonitored, so any accidents under its control are entirely the fault of the driver. If a driver disengaged 0.1s before impact, they were derelict in their driving.

You're completely right, but unfortunately people place too much trust in it.

Re: Indian startup 3D prints rocket engine in 72 hours

#123

Post by wongarsu »

jfyi wrote: post #113
krisoft wrote: post #87

Earlier quoted context omitted.

> 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 ha…

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.

Re: Indian startup 3D prints rocket engine in 72 hours

#124

Post by OutOfHere »

constantcrying wrote: post #117
OutOfHere wrote: post #112

Earlier quoted context omitted.

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.

Re: Indian startup 3D prints rocket engine in 72 hours

#126

Post by stainablesteel »

constantcrying wrote: post #97
stainablesteel wrote: post #85

Earlier quoted context omitted.

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

Re: Indian startup 3D prints rocket engine in 72 hours

#127

Post by NortySpock »

Etheryte wrote: post #26

> The machine also automatically outputs a report that details any deviations during printing, removing the need for postfabrication qualification. Anyone who's previously worked with 3D printing knows that this simply does not pass any kind of a sniff test. Both preventing and detecting internal defects is one of the, if not the hardest problem in 3D printing. There are many large companies trying to find ways to re…

To steelman the argument, maybe they meant "the monitoring system is good enough at catching defects that if none are reported, the engine will probably pass an all-up hotfire test of the engine".

Of course you could do a water or air-pressure leak test on the plumbing pretty easily, and you would likely do that on the first 30 engines...

But if you have confidence in your build process, maybe the juice isn't worth the squeeze on (say) a direct contact ultrasound void check on every square millimeter of the part.

It's all about "how expensive is it to run the test" vs "what is the likelihood the test catches an issue" vs "what's the cost of failing while everyone is watching?"

Same reason SpaceX went from dry-dress-rehersals to wet-dress-rehearsals to separate-static-fire-before-launch to hold-down-for-three-seconds-before-launch... The hold-down -before-launch is an integration test that covers everything the previous tests do, so eventually you can start removing redundant tests.

Re: Indian startup 3D prints rocket engine in 72 hours

#128

Post by la64710 »

Etheryte wrote: post #26

> The machine also automatically outputs a report that details any deviations during printing, removing the need for postfabrication qualification. Anyone who's previously worked with 3D printing knows that this simply does not pass any kind of a sniff test. Both preventing and detecting internal defects is one of the, if not the hardest problem in 3D printing. There are many large companies trying to find ways to re…

Yes and innovation curve tends to go down in large companies because of barriers which a startup is not bounded by. This is how future big companies are created.

Re: Indian startup 3D prints rocket engine in 72 hours

#130

Post by chasd00 »

troyvit wrote: post #105
teitoklien wrote: post #46

Earlier quoted context omitted.

World isnt some amazing la la land, I hope people who break laws to immigrate to America, will continue having the same sympathies towards you, when they become majority, and start dominating over you with their culture. It feels bad to say this, but to build a good well integrated state, integration is key, you cannot integrate people into a society, if you cannot even control the immigration rate. You can't just le…

> I hope people who break laws to immigrate to America, will continue having the same sympathies towards you, when they become majority, and start dominating over you with their culture. I don't know how many folks around me broke the law to immigrate to America, but whether or not they broke the law to come here they faced a lot of racism, classism, and suspicion. I've been in the same area for about 20 years, and i…

If you don't mind sharing, i'm curious to know where you live. I live in North central Oak Cliff which is a large, predominantly hispanic, area consisting of multiple neighborhood just SSW of downtown Dallas. In my neighborhood there's a local Mercado that i can walk to for small things, i speak enough Spanish to manage but I'm eyed with suspicion from when i go in to when i leave. My wife is a HS teacher with about 25% of her students being undocumented. They use a bus service in Oak Cliff to freely move back and forth to Mexico, i'm not sure how that works but that's what they use.

My son's middle school is a DISD public magnet in a wealthy area called Preston Hollow. The middle school is probably 85-90% hispanic and despite my kids being 1/2 Mexican they have faced enough racism and abuse that my wife and I have had multiple meetings with the administration to address it. African American kids face it even worse. One other anecdote, when my kids were in elementary some of their calsses were taught in Spanish because my kids and one other were the only ones who spoke English. The teachers, who barely spoke English themselves, got in trouble for that. Ironically, if you want true diversity in Dallas schools you have to pay/be admitted to the elite private schools.

All this to say, in my experience, neighborhoods consisting of mostly undocumented immigrants and cities welcoming of undocumented immigrants aren't that great... unless you're an undocumented immigrant.

Post reply on HN