Diagram of Titan's pressure hull/chamber courtesy Washington Post.
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One path (A) of thinking about Titan's implosion (into bits) is that it happened instantly, before it hit the seafloor. This is discussed below. Another path of thinking is Titan imploded following a distortion of hitting the seafloor. Either way this may have resulted in the one loud sound picked up be the US Navy.
It could be that at each end of Titan's pressure hull/chamber, the Titanium hemispheres you can see above, were generally able to withstand pressure down to 4,000 meters.
1. Except for the Titanium front hemisphere's porthole (of glass or plastic?) which was only rated as being safe to "1,300 meters" - quite a physical gamble even before the first of Titan's several dives to around 4,000 meters.
Usual materials for a pressure hull are Steel Alloys and more rarely Titanium which are suitable because they are partly malleable/flexible, so able to slightly contract, under pressure of water, as a sub descends and slightly expand to their original shape as the sub returns to the surface.
Submarines using steel in particular, have been tested for over 100 years, with each submarine undergoing hundreds of contraction and expansion cycles. This simply didn't happen to Titan's mix of pressure hull materials. Titan's pressure hull weaknesses may have accumulated over its few previous cycles.
2. As well as the porthole the major weakness of Titan was the mid-section cylinder of around 130mm of carbon fiber, basically a type of plastic. Unlike steel or Titanium, carbon fiber for submarines/submersibles only has a short track record. Titan's carbon fiber was little tested, therefore little understood. It was inflexible hence tending to crack or tear rather than shrinking slowly (like metals).
3. The use of two radically different materials (Titanium and Carbon Fiber) in the one pressure hull may, in itself, have led to differing, incompatible, rates of contraction and expansion, leading to ultimate destruction.
4. Another fault, if the diagram above is accurate, are relatively sharp inward-facing "corners" of the pressure hull where the Titanium hemispheres meet the edges of the carbon fiber cylinder. Corners should be avoided where pressure is concerned (even outward facing corners of the Comet airliners' square windows 60 years ago caused metal fatigue under pressure in another direction, leading to destruction).
So the inward facing corners of the pressure hull may have caused metal and carbon fatigue and/or a "spike" (also in relation to 3.) of highly pressurized water between those two materials.
See my subsequent alternate theory of June 29, 2023 "B. Collision With Seafloor Destroyed Titan?"
4 comments:
Correction of comment on 6/26/2023 6:58 PM
Hi Pete
Based on design concept of SHINKAI 6500,theJapanese deep (6500m) submerge research vehicle, crushing depth of 6000m (= depth of the Titanic 3800m x 1.5 + 300m) must be achieved at least to achieve safe diving for Titan [1].
[1] Crushing depth of SHINKAI 6500 is based on “Rules for the survey and construction of steel ships” by Nippon Kaiji Kyokai, where crushing depth (m) is maximum diving depth (m) x 1.5 +300 (m)
Regards
Thanks Anonymous at 6/26/2023 8:13 PM
Thanks very much for your corrected comment on crush depths.
Here is additional information on Depth Ratings for other countries, particularly the US https://en.wikipedia.org/wiki/Submarine_depth_ratings
Regards Pete
Hi Pete,
I've always had an interest in DSVs, and the 'industrial dogma' that Stockton Rush belittled in his interviews is actually known practices from over 70 years of practical experience.
I found it highly interesting to compare the Titan's construction to that of DSV Limiting Factor, the only submersible rated for unlimited use.
Titan's hull was created 6 years ago, by winding a carbon fibre strand around a trunk (https://youtu.be/Vi4J1LDS504) and then gluing it to titanium endcaps (https://youtu.be/WK99kBS1AfE)
Limiting Factor's pressure hull was created from 90mm forged and milled titanium that was then pressure tested to 14,000 msw/20,000 psi - which is 20% more than full ocean depth pressure - so it's certified for unlimited operation. https://youtu.be/pb5j9oeZCm0
Hi Shawn
It is poetically fitting that Rush went down with his "ship". This is after Rush is on record saying https://en.wikipedia.org/wiki/Stockton_Rush#Personality_and_personal_life :
"You know, at some point, safety just is pure waste. I mean if you just want to be safe, don't get out of bed, don't get in your car, don't do anything. At some point, you're going to take some risk, and it really is a risk/reward question. I think I can do this just as safely by breaking the rules."
And 4 other people perished.
If Rush had gone to the trouble of building his own Limiting Factor submersible https://en.wikipedia.org/wiki/DSV_Limiting_Factor completely of Titanium it would have been safer, but perhaps not as profitable...
He got those killed to sign a no-fault waiver. But I wonder if his company will pay back, even a small portion of the $millions in USN, Coastguard and commercial search costs?
Regards Pete
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