Using off the shelf components is probably the best thing they did. You don't want to reinvent the wheel if you can help it. I don't know why the game controller is a sticking point for most of social media. It's funny to think of a vehicle being piloted by one, but they really are designed to be used for thousands of hours. Game controllers have been used in all sorts of military applications.
The issue as far as I have read is that the hull was made of carbon fibre. There hasn't been any submersible that has reached those depths before made of that material. The effect continued pressurization/depressurization had on the carbon fibre wasn't understood. Composite materials are so much more complicated to model and understand. There was no non-destructive testing to see what effect the repeated cycles had on the hull, no way of knowing whether cracks could form beneath the surface. The failure mode at depth is catastrophic, there's no room for error. Someone pointed all this out to them and was fired https://newrepublic.com/post/173802/missing-titanic-sub-face....
In response to them knowing the sub wasn't fit for purpose they opted to install a "real time health monitoring system" which acoustically checked the integrity of the hull. But it's pointless. By the time any acoustic monitoring system picked something up it would be too late, because carbon fibre just shatters into a million pieces. It's not like Steel where it can gradually fatigue, it's crack BOOM dead.
Using carbon fibre for the hull is like rolling your own crypto. Maybe you can get it to work but unless you properly scrutinize it there is most likely fundamental flaws in your implementation and it's just better to use tried and true methods. In the sub world that tried and true method is just thick steel.
> Using off the shelf components is probably the best thing they did
No. Not really. It's a horrible idea. It's irresponsible. It's negligent.
Consumer grade components are not designed for the kind of reliability and failure tolerance requirements these kinds of applications have to face every mission. A simple example of this would be no conformal coating anywhere to prevent failures due to condensation on the circuit board. Also, tin whiskers due to RoHS solder. No redundancy or failure tolerance in any portion of the design. It isn't enough to say "we have extra game controllers". That's not how you build reliable failure-tolerant systems where people's lives depend on things working perfectly 99.9999% of the time.
Also, it is a fallacy to say that millions of people use these controllers. The most obvious problem with this statement is that we have zero data on failure rates and failure modes. And, of course, nobody dies. As a parallel example, you would be hard-pressed to find toy controllers on medical equipment, even in situations where there might be time to deal with failures.
> the hull was made of carbon fibre <snip> In the sub world that tried and true method is just thick steel.
Yup. Fundamental principle: Carbon fiber is best used under tension, not compression. Not a good choice for a life-support compartment under incredible external pressure. One way I think of it is: In compression you are mostly relying on the epoxy to keep things together. Without epoxy carbon fiber will support as much compression as a common string. Zero.
I agree the electronics could be better, but from what I am understanding, even if the electronics completely failed, they could mechanically safely return to the surface.
The carbon fiber seems to be the critical nail in the coffin.
> they could mechanically safely return to the surface
That's what it sounds like.
> The carbon fiber seems to be the critical nail in the coffin.
If the CF vessel failed it would have instantaneous and violent beyond comprehension. What little reliable info is out there seems to indicate that's what happened.
The carbon fibre is interesting angle because I have seen in the last 5-10 years a change in fire fighters, under water rescue services and military to go from using steel cylinders for breathing gas (300 bar) to a composite of aluminum and carbon fibre with the same pressure of 300 bar. The benefit being targeted is the reduction in weight. Those tanks do get tested regularly but those tests might just be as pointless as in this case. If they explode they will do so with a shattering boom.
I wonder if this event will cause some changes, or if it is an expensive step in figuring out how to properly test this material.
I think the behavior of the material is probably more understood when it's internal pressure vessel. I think in general that's a much more understood problem and carbon fibre probably is perfectly fine for that sort of vessel. Similar to how a thin aluminum can of beer can be pressurized quite high, but it'll quickly buckle when poked on the outside.
The issue as far as I have read is that the hull was made of carbon fibre. There hasn't been any submersible that has reached those depths before made of that material. The effect continued pressurization/depressurization had on the carbon fibre wasn't understood. Composite materials are so much more complicated to model and understand. There was no non-destructive testing to see what effect the repeated cycles had on the hull, no way of knowing whether cracks could form beneath the surface. The failure mode at depth is catastrophic, there's no room for error. Someone pointed all this out to them and was fired https://newrepublic.com/post/173802/missing-titanic-sub-face....
https://edition.cnn.com/2023/06/21/us/titan-sub-safety-ocean...
In response to them knowing the sub wasn't fit for purpose they opted to install a "real time health monitoring system" which acoustically checked the integrity of the hull. But it's pointless. By the time any acoustic monitoring system picked something up it would be too late, because carbon fibre just shatters into a million pieces. It's not like Steel where it can gradually fatigue, it's crack BOOM dead.
Using carbon fibre for the hull is like rolling your own crypto. Maybe you can get it to work but unless you properly scrutinize it there is most likely fundamental flaws in your implementation and it's just better to use tried and true methods. In the sub world that tried and true method is just thick steel.