Brian Malone
Industrial
hpaircraft what are some of the techniques used?
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Tourist submersible visiting the Titanic is missing Part 2 68
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TugboatEng
Marine/Ocean
In my sketch above, I recommended removing the outer ring at the glue joint. This allows the adhesive to flow outwards to removing any voids as it does.
Some other options may include machining a caulking groove into a surface and pumping the adhesive in.
Some other options may include machining a caulking groove into a surface and pumping the adhesive in.
Brian Malone
Industrial
TugboatEng - yes, the outer lip of the interface rings did form a 'void/bubble trap. Perhaps the intent was some form of edge capture for limiting bell-mouthing of the cylindrical ends due to compression of the hull body. But since there were the stepped diameter/hub features adjacent any edge capture just increased load concentration at the diameter transition corners. And the hub features were machine-cut - were the inner corners machined sharp or filetted?
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- #185
GregLocock
Automotive
Yes, the red triangle , but with a more sophisticated taper than that, feathering down to nothing. The guy who taught me the practical aspects of CF used to build monocoque motogp motorbike frames.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
A video with some tidbits that I hadn't seen before, including some photos near the end:
Somebody up there mentioned rhino liner- that sounds like truck bed liner or something, so I just assumed that was humor. But no, there's a video clip somewhere of Stockton saying that's what they used. I'm not familiar with the product, so can't comment on the appropriateness of it.
Somebody up there mentioned rhino liner- that sounds like truck bed liner or something, so I just assumed that was humor. But no, there's a video clip somewhere of Stockton saying that's what they used. I'm not familiar with the product, so can't comment on the appropriateness of it.
TugboatEng
Marine/Ocean
Don't fall for the sensationalism. Rhino liner wasn't a structural component of the hull and PlayStation controllers didn't cause the collapse. Being able to incorporate commercially available components into a design is an engineering talent, not a fault.
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- #188
GregLocock
Automotive
I agree, but the controller is not designed for a wet and salty environment. OK, they may well have a spare in a dry-bag, but the same goes for the receiving end of the electronics.
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Greg Locock
New here? Try reading these, they might help FAQ731-376
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
TugBoatEng said:
If Rhino Liner has been tested for permeability under 5000 psi of long term saltwater exposure I'll eat my hat. For a composite hull, especially one with machined end grain directly exposed to full test pressure, protection and sealing against water ingress would be a very important component of the engineering of the hull. The playstation controller had already failed previously, with very dangerous consequences, and provided zero redundancy.
Being able to incorporate commercially available products into a design is a virtue when the selected products are appropriate for their intended service conditions, and don't represent a safety compromise.
Neither of those conditions is true in this case. Both examples serve to provide us significant evidence that the engineering of the complete package was half ass.
TugboatEng
Marine/Ocean
Sorry, I'm a bit jaded when it comes to marine hardware. Marine grade does not imply satisfactory duty. Here is a recent example from the best supplier of that equipment. I guess companies with specific products suffer from small engineering teams that may be strong overall but lack knowledge in specific areas. I have some interesting pictures to post of watertight hatches on my boats that I will share tomorrow.
If the sub can surface without the "PlayStation" controller I don't see the issue with using one.
To complicate the story, there isn't really a marine grade. Some items get DMV approval which gives an environmental tolerance rating. None of
If the sub can surface without the "PlayStation" controller I don't see the issue with using one.
To complicate the story, there isn't really a marine grade. Some items get DMV approval which gives an environmental tolerance rating. None of
TugBoatEng said:
No one said anything about 'marine grade' whatever. The pictures you have of hatches on your boat are meaningless. This sub was not a tugboat.
They used a bunch of completely untested solutions for the problems they were trying to solve. If you're designing a trash can, that's not good engineering, period. In an application involving a major duty to engineer for life safety, especially for paying clients, it is literally criminal negligence.
If this had happened while Rush was on the support ship and 5 other people had been killed, he would be spending a very significant amount of time in prison. Implying that any of these decisions were good is absolutely asinine.
TugBoatEng said:
The sub can't surface if it's fouled on wreckage. If the sub loses attitude and/or directional control, even momentarily, near a shipwreck at 3800m deep and fighting the powerful currents that exist at that depth, there is a high risk that the sub becomes fouled and is either damaged or cannot surface.
Maintaining directional and attitude control at all times is as important for a deep sea submersible intended to explore shipwrecks as it is for an airplane. They went down there using a system that had already demonstrated low reliability through previous failures, and had zero redundancy, and after the previous systematic failure they made zero changes to the system.
Implying that there was any sliver of good engineering here is wild.
TugboatEng
Marine/Ocean
The sub wasn't supposed to enter the wreckage. That should eliminate the fouling risk.
My hatch pictures were meant to demonstrate some often misunderstood material limitations. I wasn't trying to explain anything about the wreck, just that the marine industry is plagued with misapplied materials.
The tugboat industry in general is plagued with bad engineering. I am unfortunate that I have to deal with so many problems that I never get to be proficient in them I just have to keep moving on to the next and that's what funds my paycheck. I come here to try to learn better ways to do things.
My hatch pictures were meant to demonstrate some often misunderstood material limitations. I wasn't trying to explain anything about the wreck, just that the marine industry is plagued with misapplied materials.
The tugboat industry in general is plagued with bad engineering. I am unfortunate that I have to deal with so many problems that I never get to be proficient in them I just have to keep moving on to the next and that's what funds my paycheck. I come here to try to learn better ways to do things.
TugboatEng said:
The sub was most definitely intended to operate in close proximity to the wreckage. It had a viewport for looking at the wreckage, which you can't do from 300m away.
Lose control in the middle of a tour with your billionaire clients and the risk that a current pushes the sub into the wreck and it becomes damaged or fouled is very real. Rush either ignored this risk, or didn't care because somehow using a game controller represented 'innovation', and he was a member of the Silicon Valley culture that values innovation, even false innovation, above all else including good first principles engineering.
TugboatEng said:
We aren't talking about the 'marine industry'. We're talking about one guy, who despite a pretty big pile of highly qualified advice made a bunch of awful choices which resulted in the negligent homicide of four people and his own death. Humans know how to build ultra-deep sea submersibles. There are kind of lots of them that do this stuff without issue. He ignored them out of a killer combination of ego and ignorance, and you're now inexplicably defending the choices he made. The sub is not one of your diesel tugs. Your 'well on my tugboat...' logic that you use in every scenario on this forum does not apply.
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- #194
TugboatEng
Marine/Ocean
Who said I was defending? I was complaining about an industry plagued with poor choices that I struggle to manage. It's frustrating to deal with the low quality equipment but when I see complaints of using consumer grade equipment I understand that may be an upgrade in some instances. We used to use synchros for our azimuthing controllers but have moved to pots. Now we aren't much better than the consumer level electronics. The pot systems have proven reliable over 15 years but the synchro systems have been flawless for 30 years. Good thing as there is no support for the synchro systems.
The newest thing are magnetic rotation sensors. There is one that uses a chip that is operated by moving a magnetic domain so it doesn't require power to maintain the location -and- if the item is moved with the power off, the magnet still moves the domain so it still keeps count within the range. It has 6(?) turn capability.
For sure synchos are less popular now that there are so many A/D converters and digital CPUs, but Analog Devices is making synchro ICs for someone. The controls guys I worked with preferred resolvers for sub-milliradian accuracy and lack of wear failures though those were plenty expensive. Using synchros as direct motion controllers certainly is gone.
What used to take a dozen 8x10 inch circuit boards stuffed with discrete transistors or simple ICs can now be had for $4 and fit on a fingernail. When it cost $20,000 (a new house) spending $500 (newish car) on a decent housing was a no-brainer. That $4 chip still requires a similar level of protection and the cost for low volumes has kept the price about the same, but the bean counters don't see that the failure cost was never $20k and isn't $4, it's millions of dollars when whatever should be controlled no longer is.
For sure synchos are less popular now that there are so many A/D converters and digital CPUs, but Analog Devices is making synchro ICs for someone. The controls guys I worked with preferred resolvers for sub-milliradian accuracy and lack of wear failures though those were plenty expensive. Using synchros as direct motion controllers certainly is gone.
What used to take a dozen 8x10 inch circuit boards stuffed with discrete transistors or simple ICs can now be had for $4 and fit on a fingernail. When it cost $20,000 (a new house) spending $500 (newish car) on a decent housing was a no-brainer. That $4 chip still requires a similar level of protection and the cost for low volumes has kept the price about the same, but the bean counters don't see that the failure cost was never $20k and isn't $4, it's millions of dollars when whatever should be controlled no longer is.
I understand that on one trip one of the thrusters was wired backwards and not tested.
The error did not become apparent until they started trying to maneuver at depth.
That thruster was not used when descending and had not been function checked on the surface.
The controller was working but they had to fugure out how to use it with one thruster reversed.
Was there a game controller failure that I am not aware of?
PS; I'm not defending the controller.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
The error did not become apparent until they started trying to maneuver at depth.
That thruster was not used when descending and had not been function checked on the surface.
The controller was working but they had to fugure out how to use it with one thruster reversed.
Was there a game controller failure that I am not aware of?
PS; I'm not defending the controller.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
My understanding was that the controller to motor wiring was reversed on one thruster. Apparently reversing a jumper at the controller "fixed" that problem, although the real problem from my perspective was nobody realized that problem existed until it was in the water. If any control were reversed on my ultralight airplane, I would have discovered it during preflight check. There it must have been like ... splash. Not really a controller, or motor problem at all. That was only a symptom of the true problem.
--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
There have been a large number of cases where ailerons were reversed, up to and including the A320. People check to see if they move; not all check to see if they move correctly, not even licensed aircraft mechanics.
The write-ups indicate it had just been mounted and they installed it pointing in the wrong direction.
In this article are several photos - note that the orientation of the starboard fore/aft thruster changes from the motor being forward to the motor being aft. The port motor is forward of the duct.
It's entirely possible someone programmed the motor direction to match one configuration and Rush changed his mind. The thrusters appear to be clamped on the rim and easily placed in either orientation with sufficient length of cable. On the top it appears they sometimes just doubled up excess cable length.
In later versions the thrusters go into pods and the motors are placed to the rear of the duct/sub.
Here's another - starboard motor to the rear At the 15 second mark of this video the starboard motor is to the front:
The write-ups indicate it had just been mounted and they installed it pointing in the wrong direction.
In this article are several photos - note that the orientation of the starboard fore/aft thruster changes from the motor being forward to the motor being aft. The port motor is forward of the duct.
It's entirely possible someone programmed the motor direction to match one configuration and Rush changed his mind. The thrusters appear to be clamped on the rim and easily placed in either orientation with sufficient length of cable. On the top it appears they sometimes just doubled up excess cable length.
In later versions the thrusters go into pods and the motors are placed to the rear of the duct/sub.
Here's another - starboard motor to the rear At the 15 second mark of this video the starboard motor is to the front:
Lou Scannon
Automotive
Checking control freedom and correct action is nothing more than proper pre-flight procedure.
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
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