Tourist mini sub missing off titanic

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[VenezianBlau 87]

Where are the ballast tanks/weights?

[RNajarian]

Originally Posted by VenezianBlau 87

Where are the ballast tanks/weights?

. . . and the CO2 scrubber or the tank with 96 hours of O2 for 5 adults?

Hard to believe that AND the batteries, electronics, etc all fit in the rear cowl.

[pmax]

[otto_kretschmer]

Originally Posted by VenezianBlau 87

Where are the ballast tanks/weights?

No ballast tanks for this boat. Its too deep to use compressed air. They drop ballast to ascend.

[otto_kretschmer]

Originally Posted by RNajarian

. . . and the CO2 scrubber or the tank with 96 hours of O2 for 5 adults?

Hard to believe that AND the batteries, electronics, etc all fit in the rear cowl.

I'm taking a guess here... the batteries are outside the pressure hull and in the tail cone.

[Rawknees'Turbo]

It is amazing to me to see in the picture above how there is almost no overlap of the Ti ring and the carbon tube (maybe 10-20mm at most?) - the damn thing is essentially butt glued in place. What a joke.

[RNajarian]

Originally Posted by otto_kretschmer

No ballast tanks for this boat. Its too deep to use compressed air. They drop ballast to ascend.

Essentially littering the ocean floor needlessly?

—-comment withheld—-

[VenezianBlau 87]

Originally Posted by otto_kretschmer

No ballast tanks for this boat. Its too deep to use compressed air. They drop ballast to ascend.

Thanks Otto. On the Trieste the ballast/shot container is prominently seen below the pressure hull, but not on this thing. Carbon fiber/composites seem to work great until they fail without warning, similar to the tail of the Airbus that crashed in Queens shortly after 9/11. Allegedly hard rudder inputs broke off the CF tail.

[Mahler9th]

"It is amazing to me to see in the picture above how there is almost no overlap of the Ti ring and the carbon tube (maybe 10-20mm at most?) - the damn thing is essentially butt glued in place. What a joke. "

Others have used a similar approach.

See links at posts 448 and 449.

https://apps.dtic.mil/sti/citations/ADA273061

" Title: Adhesive Bonded Joint With Improved Cyclic Fatigue Life for Alumina- Ceramic Cylinders and Hemispheres. Fourth Generation Housings "

"A series of 20-inch-diameter monocoque cylinders of 94-percent alumina-ceramic have been pressure tested to determine their structural performance under repeated pressurizations to 9,000 psi external design pressure when their ends are encapsulated in epoxy-filled Mod 1 titanium or aluminum end caps. Naval Ocean Systems Center NOSC Type Mod 1 titanium end caps provided an order-of-magnitude improvement in cyclic fatigue life for the ceramic cylinders over previously tested Mod 0 end caps. The cyclic fatigue life of 20-inch OD by 18.63-inch ID by 30-inch L by 0.685-inch t ceramic cylinders with 0.5-inch weightdisplacement ratio, the ends of which were encapsulated with epoxy adhesive in Mod 1 titanium end caps, exceeded 400 cycles to 9,000 psi that generated inside the cylinder compressive membrane stresses of 136,000 psi magnitude in hoop and 68,000 psi in axial direction. At these stress levels, the shell of the monocoque cylinder can tolerate imperfections in the shape of spherical 0.063-inch and oblong cavities 0.063-inch by 0.187-inch located below, or on, the shell surface, provided that they are at least two inches away from the ends. The payload-carrying ability of 94-percent alumina- ceramic monocoque cylinders with above dimensions is approximately four-times larger, then, of rib-stiffened titanium cylinders with the same external dimensions and pressure rating. Ceramics, External pressure housing, Ocean engineering."

Author was considered and expert.

Other experts were involved.

Ceramic cylinder.

Not clear whether this area was what failed on Nereus.

Not clear whether Titan used some of the same or similar engineering design principals, processes, materials et cetera.

Not clear what tests were done or what, if any design parameters were extrapolations for either submersible.

Let's see what is learned by experts.

[RNajarian]

Originally Posted by otto_kretschmer

No ballast tanks for this boat. Its too deep to use compressed air. They drop ballast to ascend.

Originally Posted by RNajarian

Essentially littering the ocean floor needlessly?

—-comment withheld—-

It appears there are areas designated near the Titanic for ballast or other items to be discarded. On the map below it is called the “drop weight area.”

[fisher22]

Originally Posted by Rawknees'Turbo

It is amazing to me to see in the picture above how there is almost no overlap of the Ti ring and the carbon tube (maybe 10-20mm at most?) - the damn thing is essentially butt glued in place. What a joke.

A total joke. I bet someone argued that the joint gets stronger as pressure increases.
Utterly and completely ridiculous.

[herr_oberst]

A little animation and some more discussion on the sub. It's an interesting visual that provides a glimpse of this implosion.

[Steve Carlton]

They must have been crushed if they didn’t get to see the Titanic up close.

[Rawknees'Turbo]

Originally Posted by Mahler9th

"It is amazing to me to see in the picture above how there is almost no overlap of the Ti ring and the carbon tube (maybe 10-20mm at most?) - the damn thing is essentially butt glued in place. What a joke. "

Others have used a similar approach.

See links at posts 448 and 449.

https://apps.dtic.mil/sti/citations/ADA273061

" Title: Adhesive Bonded Joint With Improved Cyclic Fatigue Life for Alumina- Ceramic Cylinders and Hemispheres. Fourth Generation Housings "

"A series of 20-inch-diameter monocoque cylinders of 94-percent alumina-ceramic have been pressure tested to determine their structural performance under repeated pressurizations to 9,000 psi external design pressure when their ends are encapsulated in epoxy-filled Mod 1 titanium or aluminum end caps. Naval Ocean Systems Center NOSC Type Mod 1 titanium end caps provided an order-of-magnitude improvement in cyclic fatigue life for the ceramic cylinders over previously tested Mod 0 end caps. The cyclic fatigue life of 20-inch OD by 18.63-inch ID by 30-inch L by 0.685-inch t ceramic cylinders with 0.5-inch weightdisplacement ratio, the ends of which were encapsulated with epoxy adhesive in Mod 1 titanium end caps, exceeded 400 cycles to 9,000 psi that generated inside the cylinder compressive membrane stresses of 136,000 psi magnitude in hoop and 68,000 psi in axial direction. At these stress levels, the shell of the monocoque cylinder can tolerate imperfections in the shape of spherical 0.063-inch and oblong cavities 0.063-inch by 0.187-inch located below, or on, the shell surface, provided that they are at least two inches away from the ends. The payload-carrying ability of 94-percent alumina- ceramic monocoque cylinders with above dimensions is approximately four-times larger, then, of rib-stiffened titanium cylinders with the same external dimensions and pressure rating. Ceramics, External pressure housing, Ocean engineering."

Author was considered and expert.

Other experts were involved.

Ceramic cylinder.

Not clear whether this area was what failed on Nereus.

Not clear whether Titan used some of the same or similar engineering design principals, processes, materials et cetera.

Not clear what tests were done or what, if any design parameters were extrapolations for either submersible.

Let's see what is learned by experts.

I wonder why the butt-glued decision was made, possibly to simply save on the cost of the Ti pieces?

Were I building this, at a minimum I would demand an overlap that was equal to the wall thickness of the tube (5" in the case of the Titan), both inner and outer surfaces, and I would want fasteners in addition to the glue, such as precision bucked rivets that pass through metal sleeves imbedded in the carbon tube. That seems like basic, best-practices stuff to me, but who knows.

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