SWComposites
Aerospace
Reverse_Bias - where did you see it was 5 layers?
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Tourist submersible visting the Titanic is missing 101
- Thread starter JohnRBaker
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According the article linked by GregLocock:
"Spencer opted for a layup strategy that combines alternating placement of prepreg carbon fiber/epoxy unidirectional fabrics in the axial direction, with wet winding of carbon fiber/epoxy in the hoop direction, for a total of 480 plies."
"Spencer opted for a layup strategy that combines alternating placement of prepreg carbon fiber/epoxy unidirectional fabrics in the axial direction, with wet winding of carbon fiber/epoxy in the hoop direction, for a total of 480 plies."
Brian Malone
Industrial
My previous feeling that Stockton Rush was not blatantly shirking safety concerns appears to have been wrong. I have seen enough history that is indicating though Mr Rush was a skilled engineer, pilot, and technologist he apparently also ignored/discounted obvious signs the structure of Titan was being over stressed. This NYT article quotes another submersible expert, Karl Stanley as hearing loud cracking sounds while on a dive piloted by Stockton Rush. In later communication with Stockton, the concerns about the integrity of the composite cylindrical hull were brushed aside.
As SWComposite discussed in previous posts, buckling behavior would have to have been very carefully considered in the design analysis. The links provided definitely illustrate thin shell designs can be fraught with gotchas and should not be lightly dismissed. Specialized analysis/FEA modeling would be required.
I do wonder if the 'certification/classing' process would have been beneficial for identifying any latent flaw in the Titan design being it is an adhesive bonded structure with its two major material interfaces at the titanium to carbon fiber cylinder connections. Obviously, this failure was a fatigue based failure. Would the cert/class process have applied enough cycles on the structure to have identified the true risk? And thus change the OceanGate engineering team's belief they had a 2.25 safety factor? I have seen many comments saying the vehicle should have been certified - anyone have an understanding of how the certifying process is done to capture time-based failure modes?
Another wonder: the 2.25 safety factor seems low for such a life-critical system. Anyone have a feel for what is standard in the submersible industry? Pressure vessel/boiler standards may make for a too heavy vehicle to work with buoyancy considerations.
As SWComposite discussed in previous posts, buckling behavior would have to have been very carefully considered in the design analysis. The links provided definitely illustrate thin shell designs can be fraught with gotchas and should not be lightly dismissed. Specialized analysis/FEA modeling would be required.
I do wonder if the 'certification/classing' process would have been beneficial for identifying any latent flaw in the Titan design being it is an adhesive bonded structure with its two major material interfaces at the titanium to carbon fiber cylinder connections. Obviously, this failure was a fatigue based failure. Would the cert/class process have applied enough cycles on the structure to have identified the true risk? And thus change the OceanGate engineering team's belief they had a 2.25 safety factor? I have seen many comments saying the vehicle should have been certified - anyone have an understanding of how the certifying process is done to capture time-based failure modes?
Another wonder: the 2.25 safety factor seems low for such a life-critical system. Anyone have a feel for what is standard in the submersible industry? Pressure vessel/boiler standards may make for a too heavy vehicle to work with buoyancy considerations.
Still have to be able to find nuclear submarines
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
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Brian Malone
Industrial
Apparently the support team on the ship had an understanding early on a catastrophic failure had occurred. I just saw an interview with James Cameron, who states the Titan had a pinger system that was active during the mission and when that went silent he says those in the know knew the vehicle had been structurally compromised to a level that had disconnected the electronics from the vehicle batteries, etc. Losing the text comms would be one thing but the loss of text and pinging was ominous.
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The more I read and learn about the company, the clearer it becomes that the root cause was arrogance and ego. The lack of testing, backup systems, basic location services, "40-year old white guys," etc. were all driven by a vision that was flawed, but the man in charge brooked no dissent that would damage or affect his vision. It's an unfortunate story, which will be unfortunately not learned by the ones that should learn it because their arrogance and ego blinds them to anything that affects their visions, and so on and so on.
"40-year old white guys" because the founder made a point of not hiring such persons in favor of younger, inexperienced engineers, since they would be less likely to say, "No, this isn't going to work this way." The company did fire one engineer who said that more (> zero) testing was necessary to ensure safety. It's clear that the safety was only pair a minimal of lip service at this company, despite advertising to the contrary. Safety, and many other things, start at the top, and while "go fast and break things" does produce innovations, such innovations often come at a cost, and people potentially die as a result.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
"40-year old white guys" because the founder made a point of not hiring such persons in favor of younger, inexperienced engineers, since they would be less likely to say, "No, this isn't going to work this way." The company did fire one engineer who said that more (> zero) testing was necessary to ensure safety. It's clear that the safety was only pair a minimal of lip service at this company, despite advertising to the contrary. Safety, and many other things, start at the top, and while "go fast and break things" does produce innovations, such innovations often come at a cost, and people potentially die as a result.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
Brian Malone
Industrial
Stockton Rush was definitely a driven individual - his education qualifications, work history, and accomplishments all clearly speak to that. I think his "50 year old white guy" comments were hyperbole/sound bites to grab attention - he himself was 61 years old and white. I suspect those comments are red herrings. I would be surprised if the OceanGate team is anymore diverse than average for a company located in the Pacific Northwest and chances are the staff was chosen based on the qualifications and not color. But I'll hop off that soap box - that line of concern is a distraction from the engineering aspects of the Titan.
Definitely, pushing new materials and processes into a high-risk endeavor is well, risky. Mr. Rush had a vision of changing the design envelope of submersibles - and yes, it appears he tried to commercialize his vision too quickly. It is one thing to risk your own life in an experimental vehicle, but quite another item to risk the lives of others if the technology truly is not fully understood.
Definitely, pushing new materials and processes into a high-risk endeavor is well, risky. Mr. Rush had a vision of changing the design envelope of submersibles - and yes, it appears he tried to commercialize his vision too quickly. It is one thing to risk your own life in an experimental vehicle, but quite another item to risk the lives of others if the technology truly is not fully understood.
Brian Malone
Industrial
IRStuff I am not discounting your observation there is a risk of hiring young inexperienced engineers to stack the team with 'yes men' - but that is a generalization. There are young engineers who are risk averse because of their lack of experience and there are older engineers who are risk averse because they have become set in their ways. There is no truism on this which is 100%. The judgement is always clear in hindsight. I have worked with very bright engineers of all ages that all had their own levels of design agressiveness (or lack of). Some were at times reckless and others often were infuriating stuck with 'anaIysis paralysis'. I recently worked with a group of older engineers who were pushing the use of newer technologies that had many on the design team saying 'hey let us just use the older tried and true tech' - but these guys were aggressive possibly because of their age and experience - and they were pushing on the edge of knowledge of a fatigue-based failure mode.
Mr. Lochridge's concerns have been confirmed in hindsight but had the Titan not suffered a catastrophic failure and the composite pressure vessel design had continued to work flawlessly we would be seeing articles touting Stockton Rush as one who boldly went to the edge and prevailed.
Mr. Lochridge's concerns have been confirmed in hindsight but had the Titan not suffered a catastrophic failure and the composite pressure vessel design had continued to work flawlessly we would be seeing articles touting Stockton Rush as one who boldly went to the edge and prevailed.
LittleInch
Petroleum
I was wondering how they knew where the sub was as they had to guide it. No one really commented on it or asked how did they know where the thing was. Comms is different to not hearing the pinger. The pinger though should have had its own battery supply or maybe it did and hence when it died they knew something pretty catastrophic had probably happened.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
Murph 9000
Computer
I'm not absolutely positive, but I think I saw/heard one of the many articles saying it had an inertial navigation system. As long as that was properly initialised at the start of the dive, that could be quite accurate over the expected 8 to 12 hours of each dive. Inertial nav is mature tech these days, and no longer requires spinning gyros and the associated problems such as gimbal lock.
![[ponder]](/data/assets/smilies/ponder.gif "[ponder] [ponder]")
I wonder if the inertial guidance system was borrowed from a childs toy. Possibly the system from a small toy quadro-copter.
As for a broken view port and water hammer:
Water hammer is associated with the inertia of the fluid in a rigid section of piping.
The geometry of the sub, relative to the viwe port seems to be more similar to a snubber used to mitigate water hammer.
But, I may be wrong.
I am waiting to see if the view port was broken and if so, how.
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Ohm's law
Not just a good idea;
It's the LAW!
That doesn't square with the submersible being unable to find the Titanic when comms with the mother ship were lost, as described on some previous expeditions.
As for a broken view port and water hammer:
Water hammer is associated with the inertia of the fluid in a rigid section of piping.
The geometry of the sub, relative to the viwe port seems to be more similar to a snubber used to mitigate water hammer.
But, I may be wrong.
I am waiting to see if the view port was broken and if so, how.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
LittleInch
Petroleum
Maybe it did but I also saw an interview where they said the text messages told them where to go " Titanic is 150 m away on your starboard side". Which implies to me that the surface ship had some sort of knowledge about their position in real time. But no one said what that system was or why when they lost contact they couldn't use it. Complete implosion clearly but it remained unexplained.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
SWComposites
Aerospace
dik - commercial aircraft generally use a 1.5 FoS, with a few special load cases with higher or lower FoS. And the critical load cases are extreme maneuvers or events.
Waross-
I feel the same way. You don't have to know what you're talking about to be a critic. I'm still discounting the innuendo, and unsubstantiated allegations to see what happened. Right now for me this just highlights the fact that with innovation also comes risk.
I remember the story about a long time ago when a couple of bicycle mechanics built this crazy contraption out of wood and fabric. They clearly had no idea of what they were doing.... right?
Brad Waybright
The more you know, the more you know you don't know.
I feel the same way. You don't have to know what you're talking about to be a critic. I'm still discounting the innuendo, and unsubstantiated allegations to see what happened. Right now for me this just highlights the fact that with innovation also comes risk.
I remember the story about a long time ago when a couple of bicycle mechanics built this crazy contraption out of wood and fabric. They clearly had no idea of what they were doing.... right?
Brad Waybright
The more you know, the more you know you don't know.
LI, an article I read, don't remember which, said the Titan had a transponder of some type on board.
I assumed this would allow the support ship to know Titan's location, similar to radar transponders for aircraft.
The problem with sloppy work is that the supply FAR EXCEEDS the demand
I assumed this would allow the support ship to know Titan's location, similar to radar transponders for aircraft.
The problem with sloppy work is that the supply FAR EXCEEDS the demand
Cool_Controls
Electrical
List of inventors killed by their own invention
Link
Link
Reverse_Bias
Electrical
The James Cameron interview on Anderson Cooper explains a lot, everyone should probably watch the entire thing before posting.
They lost Navigation and communication signals at the same time, which implies that the implosion happened within 1 navigation pulse cycle of the last communication. I would assume that's less than a second. Hopefully they make the Navigation data public at some point.
Here's another quote from Cameron about carbon composites. I think it shows OceanGate was indeed a very bold experiment that should never have been made commercial.
They lost Navigation and communication signals at the same time, which implies that the implosion happened within 1 navigation pulse cycle of the last communication. I would assume that's less than a second. Hopefully they make the Navigation data public at some point.
Here's another quote from Cameron about carbon composites. I think it shows OceanGate was indeed a very bold experiment that should never have been made commercial.
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