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Indian startup 3D prints rocket engine in 72 hours

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

#151

Post by serf »

dotnet00 wrote: post #145
skybrian wrote: post #132

Earlier quoted context omitted.

I’m curious about why that is. Naively, it seems like printing layer by layer would allow for a lot of inspection. Maybe even photograph each layer as you go? And then test and go back to see what kinds of defects were apparent in the photos.

It's just that it's very easy for deviations from what the sensors see to occur. In traditional 3d printing, this can be stuff like a sensor switch wearing out, maybe physically moving slightly, being temperature sensitive, maybe the frame has changed shape slightly due to heat, moving the sensor a little, maybe something in the microcontroller happened to cause a slight delay in reading the sensor, or looseness deve…

>It's just that it's very easy for deviations from what the sensors see to occur.

right, but this is a problem in any modern precision machining, and it has been (mostly) conquered to a degree that we can produce very precise things in an almost entirely automated fashion.

>If material is missing somewhere, you could have the machine go back and add it

laser sintering is easier to audit than a normal fdm style print in a lot of ways if you care to take the time to do it. The process can be paused fairly easy with the right machine and right environment, the product can be weighed mid-process, it can have all sorts of vision and laser metrology done to the product midway through production; whatever -- and the mid print failure rate is astronomically lower than extrusion based methods.

it doesn't seem that unbelievable to me.

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

#152

Post by throwitaway222 »

sandworm101 wrote: post #142
NortySpock wrote: post #127

Earlier quoted context omitted.

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 t…

>> maybe the juice isn't worth the squeeze In rockets/aerospace, where the failure of any one of a thousand different parts means instant disintegration, checks are always worth the squeeze. Everyone talks about building rockets on the cheap and accepting a slightly-higher failure rate, but in reality that doesn't work. Even a tiny increase in component fault rates translates to total mission failure once multiplied…

Well, if you build it robust enough, you can test less. Not saying testing is worthless, but sometimes a one-piece that used to be 45 pieces held together by rivets is just, much much more resilient.

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

#153

Post by ETH_start »

abduhl wrote: post #114
ETH_start wrote: post #107

Earlier quoted context omitted.

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.

OSHA has a nice pamphlet regarding hazard identification and hazard controls. The least effective method of protecting workers is to put the risk on the worker to protect themselves. Your view has a similar vibe to "well they weren't wearing their hard hat and so it's their fault," a view that has been rejected across the board for safety in favor of the view that even letting the situation get to that point is a fai…

Driver control IS making the driver responsible, by definition. Tesla is legally required to put the driver in control.

This is a driver assist program. There is no way such a program, that is subordinate to the driver and depends on the driver being in control, can protect the driver from not doing their part, and driving.

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

#154

Post by ETH_start »

toss1 wrote: post #121
ETH_start wrote: post #107

Earlier quoted context omitted.

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.)

What the name implies if interpreted without any context pales in comparison to the repeated and explicit instructions and warnings given to the driver that clarify that the driver should always be in control.

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

#156

Post by jes5199 »

sandworm101 wrote: post #142
NortySpock wrote: post #127

Earlier quoted context omitted.

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 t…

>> maybe the juice isn't worth the squeeze In rockets/aerospace, where the failure of any one of a thousand different parts means instant disintegration, checks are always worth the squeeze. Everyone talks about building rockets on the cheap and accepting a slightly-higher failure rate, but in reality that doesn't work. Even a tiny increase in component fault rates translates to total mission failure once multiplied…

this might be 20th-century thinking. if you can build enough copies of a rocket cheap enough, maybe disintegrating a bunch of them isn't a showstopper

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

#157

Post by lesuorac »

jes5199 wrote: post #156
sandworm101 wrote: post #142

Earlier quoted context omitted.

>> maybe the juice isn't worth the squeeze In rockets/aerospace, where the failure of any one of a thousand different parts means instant disintegration, checks are always worth the squeeze. Everyone talks about building rockets on the cheap and accepting a slightly-higher failure rate, but in reality that doesn't work. Even a tiny increase in component fault rates translates to total mission failure once multiplied…

this might be 20th-century thinking. if you can build enough copies of a rocket cheap enough, maybe disintegrating a bunch of them isn't a showstopper

Who pays when the payload disintegrates?

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

#158

Post by nordsieck »

jes5199 wrote: post #156
sandworm101 wrote: post #142

Earlier quoted context omitted.

>> maybe the juice isn't worth the squeeze In rockets/aerospace, where the failure of any one of a thousand different parts means instant disintegration, checks are always worth the squeeze. Everyone talks about building rockets on the cheap and accepting a slightly-higher failure rate, but in reality that doesn't work. Even a tiny increase in component fault rates translates to total mission failure once multiplied…

this might be 20th-century thinking. if you can build enough copies of a rocket cheap enough, maybe disintegrating a bunch of them isn't a showstopper

> if you can build enough copies of a rocket cheap enough, maybe disintegrating a bunch of them isn't a showstopper

The problem with that idea is that you won't be legally allowed to launch again until you root cause and fix the failure, which can take months (or years if you're Blue Origin). Also, your insurance rates tend to go up a lot when your rockets blow up regularly, which tends to push customers away.

In practice it doesn't work.

Notes: Astra said they were going to pursue this strategy. It was not well received by potential customers and they basically had to walk it back.

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

#159

Post by locococo »

jes5199 wrote: post #156
sandworm101 wrote: post #142

Earlier quoted context omitted.

>> maybe the juice isn't worth the squeeze In rockets/aerospace, where the failure of any one of a thousand different parts means instant disintegration, checks are always worth the squeeze. Everyone talks about building rockets on the cheap and accepting a slightly-higher failure rate, but in reality that doesn't work. Even a tiny increase in component fault rates translates to total mission failure once multiplied…

this might be 20th-century thinking. if you can build enough copies of a rocket cheap enough, maybe disintegrating a bunch of them isn't a showstopper

from the rocket perspective, sure, but not so much from the perspective of your cargo.

In many cases the cargo is more precious than the rocket so you need reliable rockets.

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

#160

Post by lowkeyoptimist »

abduhl wrote: post #114
ETH_start wrote: post #107

Earlier quoted context omitted.

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.

OSHA has a nice pamphlet regarding hazard identification and hazard controls. The least effective method of protecting workers is to put the risk on the worker to protect themselves. Your view has a similar vibe to "well they weren't wearing their hard hat and so it's their fault," a view that has been rejected across the board for safety in favor of the view that even letting the situation get to that point is a fai…

If a driver is using any driver assistance feature they need to be paying attention all the time. Not only is it stated in all vehicle manuals, it is the intelligent way to use the features given that automated driving is still far from perfect.

Your analogy makes no sense given that the risk is always on the driver whether there are driver assistance features or not.

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