I feel like I've read in this thread by folks that are knowledgeable about c/f that it's no bueno to drill holes into/through c/f. So greater overlap is probably good, but holes drilled through is probably bad.

^^^

I was thinking along the lines of sleeves that were prepositioned and then the carbon wound in a multidirectional manner around them, as opposed to drilling (if that makes any sense :)).

He'll be here again for the 7 o'clock show, folks.

Ba-dum-bum.

http://forums.pelicanparts.com/uploa...1688332976.jpg

Today I was 'borrowing' a pair or rims of my wife's bike for my project (stealing, annexing, taking back), when I noticed....

http://forums.pelicanparts.com/uploa...1688334087.jpg

I cringed. First, because of what happened. Also, this design now has bad mojo.
I completely get this is a different application. Doesn't matter though, it made me cringe a bit. The first thing I see when I look over the bars is the front hub. I don't want a 9-11-01 hub. Dont really want a titan sub hub either. Even if the hub will never fail in a million years. Just bad mojo.

BUT THE WHEELS ARE SO SEXY STRAIGHT AND TRUE! :)

On another note- my wife 'could' be angry I stole her wheelset. If I were to pitch this as "yeah... but it's the same assembly as that submarine" it may go over better. She doesn't ride a lot, so she may never even know.

Believe it or not, but I think I'm fairly empathetic (not as much as the missus). But I can also laugh at just about anything. I had to send this one to a couple of buddies (one an ex-marine) who's motto should be "what, too soon?"

Thanks pmax, I wondered about the strength of CF under compression and about those two massive Ti end caps forcing longitudinally. I'm not qualified to read an engineering report...just seems odd to use CF in deep water. Keeping an air- or spacecraft pressurized in vacuum/near vacuum is a different set of challenges, I suspect.

I look at bike hubs a lot.
Here is another on my road bike. Similar construction. two aluminium sides encapsulating a carbon core.

http://forums.pelicanparts.com/uploa...1688337172.JPG

Now- evidently carbon sucks in compression (yeah "I knew that" :rolleyes::rolleyes:)but- in a submarine application, could the design be reversed in forces to take advantage of carbon's tensile strength?

For example. Look at this picture. Two big flanges (let's say titanium- but why?, let's say any strong non compressible metal). Now, join these two flanges would join to each other somehow under the carbon so they cannot compress toward's one another. Now, lay carbon over it all so the carbon isn't so much getting compressed, it is acting in tension around the entire assembly from the water pressure pushing in.

You heard it here first folks! I'll take 50% of the profit if you make it work :D

I also think, if weight were an issue for positive buoyancy, just make the darn thing about of metal and build in redundents, or gas filled chambers like the older designs.

There is at least one video interview with Mr. Rush where he states that the design/construction process of the Titan's composite tube included the knowledge that holes in that structure were a no-no. I doubt that the tube had any through-holes.

As stated before, the Nereus design featured a ceramic tube with Ti flanges that were glued on and Ti end caps. But this was an unmanned vessel.

Lots of engineering info on the Nereus in the public domain, included at links I already provided.

I do not know if any design elements and/or construction processes and/or materials (like adhesive) and/or testing of Titan leveraged learnings from the Nereus and/or the DeepFlight Challenger.

But I think it can be helpful to consider the possibilities.

They built a great spacecraft but an unreliable deep sea sub...I'm not an engineer, so...
I'm still baffled by the whole concern about keeping it lightweight as well

There isn't really any ambiguity about weight.

A volume large enough for 5 people with heavier materials would likely create greater dry dock logistics and cost challenges, everything else being equal.

And the heavier the vessel, the greater the power requirements, greater power = more batteries = even heavier.

The DeepFlight Challenger had a carbon fiber composite hull, was designed by an expert, and was constructed before the Titan.

Carbon fiber (CF) composites have been around for a really long time.

I vaguely remember observing testing of prototype CF CAT scanner beds way back in 1980 or so.

I cannot remember the weight specs.

A lot has been learned and tried since then.

Perhaps of interest:

https://www.compositesworld.com/articles/the-first-composite-fuselage-section-for-the-first-composite-commercial-jet

Excerpts from paper about the Nereus design (author Glenn McDonald):

"Underwater vehicles require pressure-resistant housings for components such as computers, cameras, batteries, and electronics for communications and navigation. Because housings must be strong and corrosion resistant, titanium has become the material of choice for most deep ocean work. As titanium pressure vessels (PVs) are sized for depth, wall thickness increases and weight-to-displacement (W/D) ratios increase. Thick-walled titanium housings provide no floatation at full ocean depth.

As housings get heavier, greater floatation and power requirements become necessary; everything gets bigger—more foam, larger frame, bigger vehicle, and larger ship for deployment. For most science autonomous underwater vehicles (AUVs), weight is critical, and keeping it low is an aim throughout the design. Most science AUVs rely on low-weight, high-range geometries that have a good top speed and payload capability. These factors are directly affected by the housing used, and thus the housing material selection [1].

Traditionally, ceramics have been a marginalized material for underwater pressure housings due to their susceptibility to catastrophic failure. Housing materials that yield before they fail—metals such as steel, aluminum, and titanium—have been preferred because they are much more forgiving. Metals have the ability to plastically flow to relieve the effects of stress concentrations created by features such as transitions, penetrations, and O-ring grooves. This simple ability to plastically flow can relieve point loading though local yielding. Ceramics do not share that characteristic. They are brittle in nature and will crack or chip when forces are applied to an improperly designed feature."

"In spite of the potential difficulties, the Nereus housings’ trench-depth capabilities and floatation requirements drove material selection to 96% alumina ceramic [2]. Alumina ceramic provides excellent corrosion resistance and high compressive strength in a light material that can be used to build thin-walled, buoyant housings. 6Al-4V Grade 5 titanium (Gr5 Ti) was the material choice for housing end caps and connectors, as well as joint rings and housing couplings (Fig. 2 and Fig. 3). The Gr5 Ti provides a high strength-to-weight ratio, excellent machining capability, and very good corrosion resistance.

Woods Hole Oceanographic Institution (WHOI) brought in Dr. Jerry Stachiw, noted in the field of underwater housing design, to lead the Nereus ceramic housing development. Stachiw’s years of work resulted in significant advances in many areas of ceramic housing design—strength and cycle limits, methods for joining ceramic sections, end cap shape, ceramic boss requirements. The Naval Command, Control and Ocean Surveillance Center (NCCOSC) technical reports developed through this work clearly document materials, geometries, testing, and lifespan. These reports provided a valuable path for design, construction, and testing. For further reading, please see [2]"

One can download the paper and there are references folks might find interesting.

Again, Nereus was an unmanned vessel designed to go much deeper than Titan.

And it imploded.

And I suspect that it was designed for a fixed number of dive cycles.

This seems like a good time to show Sebastien Buemi's suspension failure video. Carbon fiber front suspension wasn't quite perfected yet:

<iframe width="560" height="315" src="https://www.youtube.com/embed/ZMZJ3ZaEcIQ" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>

I just read an article that interviewed the former financial manager . She said she quit after Mr Rush offered her a lead pilot position after the lead pilot quit over safety concerns .

So as CEO you think replacing the lead pilot with someone that is a financial manager is the right move ???? Are you crazy ????

Maybe she's really good at video games?

New Yorker: An ex-OceanGate employee once sent an ominous email raising safety concerns about the doomed Titan submersible.

“I don’t want to be seen as a Tattle tale but I’m so worried he kills himself and others in the quest to boost his ego,” David Lochridge wrote about OceanGate CEO Stockton Rush.



https://www.cnn.com/2023/07/03/us/titan-sub-oceangate-employee-safety-concerns/index.html

I'm gonna bet this thread reaches 1000 posts. Not too many of those.

Or at least a little better than Rush.