This tiny submarine 2.4 miles under the sea, visiting the relics of RMS Titanic. Can it be found and the crew saved before the air runs out?

[Jameshow]

I had a summer job at 16 working for British Aerospace Military Aircraft Ltd. When being shown around we walked past a carbon fibre delta wing laid on its back edge. Apparently it had been rejected due to a very small defect identified during NDT final checks. I did get told how much it cost and it would have paid a few people's wages for a year at the time. It was for either eurofighter or more likely a prototype. Iirc it had the acronym EOP but it was a long time ago now. There were other parts there rejected too. It was outside the door of the carbon fibre production area. To get in there you had full suits on and breathing kit.

It doesn't take much for such things to be rejected apparently.

Not for Oceangate!

 

[Ming the Merciless]

Not for Oceangate!

Maybe they collected the reject stuff from the round the back

 

[PK99]

Apart from it being pretty obvious in hindsight something was liable to result in what happened, the whole thing has similarities to Comet 1 which was only resolved by constant pressurisation and depressurisation of one plane. In the absence of a twin vessel to test in a controlled situation this investigation may be more awkward and possibly not conclusive as to what failed first.

IIRC, a Comet fuselage was run on the ground through the same pressure cycles as a flying fuselage in order to test for fatigue failure. The flying one failed before the ground one. It turned out that the ground-based engineers had followed standard rig operating procedures and carried out an initial proof/over-pressure test to check the integrity of the rig sample. That overpressure test changed the metallurgy of the test sample.

 

[Deleted member 26715]

Have they found them yet?

 

[PK99]

I've signed Waivers in Canada on numerous occasions. They make clear that I accept the essential hazards of the "Adventure" but do not absolve the operator in the event that they act incompetently:

Heli-hiking in the Rockies was inherently dangerous but did not absolve them from failure to maintain the Helicopter.

Whale watching - a breaching whale landing on our Zodiac would have been covered but a poorly maintained Zodiac leaking and sinking would not.

 

[DaveReading]

I had a summer job at 16 working for British Aerospace Military Aircraft Ltd. When being shown around we walked past a carbon fibre delta wing laid on its back edge. Apparently it had been rejected due to a very small defect identified during NDT final checks. I did get told how much it cost and it would have paid a few people's wages for a year at the time. It was for either eurofighter or more likely a prototype. Iirc it had the acronym EOP but it was a long time ago now.

EAP (Experimental Aircraft Programme) - a one-off technology demonstrator, predecessor to the Eurofighter/Typhoon:

 

[Reynard]

Aside from the carbon fibre and the porthole wonder if the epoxy resin used was rated for such depths. Glues come with all sorts of wanings over temperature and water etc but surely there must be an issue on a glued joint from excessive pressure differences.

Glued joints usually fail in shear, so yes, that would be a potential issue in this case.

Unfortunately I don't know enough about adhesives to comment about them specifically, but given that even in a domestic setting we use a range of different glues to do different things, the same would apply elsewhere.

 

[Time Waster]

Not for Oceangate!

They just use inappropriate technology. We simply don't know there were flaws in the materials used only their selection for the application. It could have been to aerospace grade quality carbon fibre but not right for that application.

If I've understood the posts on here correctly the consensus is that it is only known that the wrong components and materials have been used. Not that it is known that the actual material is defective, i.e. each type of material has been made with flaws sufficient to reject it in applications it's suited for.

 

[Time Waster]

EAP (Experimental Aircraft Programme) - a one-off technology demonstrator, predecessor to the Eurofighter/Typhoon:

View attachment 697087

That's the one. Heck of a plane! Saw it being tested in the Ribble Valley. I was on a bus on a ridgeline above the valley and watched it flying low then simply did a vertical 90 degrees to gain height like a rocket! It was so manoeuvrable. It was a common sight round there. It would fly from Warton to the area near Samlesbury Aerodrome and up the valley.

I think there was a later version with modifications before the eurofighter. I think there was a later TLA. Something like EFA. I was mostly paper pushing related to Tornado with only a little of EAP and later eurofighter paperwork so didn't really pay much attention. I was only 16 getting money for a new bike and having fun afterall.

 

[Reynard]

They just use inappropriate technology. We simply don't know there were flaws in the materials used only their selection for the application. It could have been to aerospace grade quality carbon fibre but not right for that application.

If I've understood the posts on here correctly the consensus is that it is only known that the wrong components and materials have been used. Not that it is known that the actual material is defective, i.e. each type of material has been made with flaws sufficient to reject it in applications it's suited for.

Most materials have inherent defects - the only ones that don't are the theoretical ones in engineering textbooks. And, to some extent, computer modelling packages.

It's one of the reasons why it's so important to know how materials behave, how they take loading and how they fail - and then take all that into account at the design stage. It's why a Factor of Safety is included in the design work for just about anything. And it's even more important when you've something that's intended to be re-usable operating in extreme environments.

This is the problem that NASA encountered with the heat-resistant tiles on the space shuttle. For various reasons, they didn't perform to spec, were hard to make, hard to maintain, hard to replace. And it was this that caused the shuttle Columbia to break up on re-entry after some tiles failed and ionized gases got into the airframe - with inevitable results.

 

[Time Waster]

I know, what I mean is we don't know whether there were flaws sufficient to cause failure in applications the materials were designed for. If the subsea use needs a higher safety factor due to conditions / application. Conditions that might cause the various failure mechanisms in fibre/ matrix perhaps.

It's a long time since I studied composites and indeed materials so I know I'm not likely to be explaining it well. There is so much to designing with composites from fibre direction in layup through to sizing used to modify surfaces of the the fibre and so on. I'm really not going to check out my Hull and Clyne textbook to refresh myself on the basics again.

But put simply I think the design stage and in particular materials selection was probably the issue. The combination of a few materials and even components in ways that they did not suit the use and perhaps not selecting the high enough safety factors due to cost based factors.

Do you think that it is possible to use carbon fibre, titanium in such a vessel if designed in a better way than it appears this vessel was.

I also think the issue was with the boss of the company too.

 

[Reynard]

Aaaaaaaah, Hull & Clyne!

The veritable bible of composite materials theory for undergrads and postgrads everywhere.

We know that corners were cut, mainly for financial reasons. That much is clear from the information that has come out so far. IMHO, it's shockingly bad judgement from a man who supposedly had a degree in aero engineering.

Maybe with better design, a money-no-object approach and more suitable methods of manufacture, it may have been got to work, but, like the heat shield tiles on the space shuttle, it would likely still be a craft with a finite (short) lifespan. The combination of salt water and extreme pressures is not terribly forgiving, especially with a shape that is not optimized for operating under those conditions.

Innovation is good, but you've got to go about it the right way.

 

[slowmotion]

The pre-preg (so that's weave, uni-directional and mat) is supplied dry IIRC. Think sheets or rolls of paper - which is, in fact also a kind of composite, except using cellulose fibres. You need to use resin to "glue" them together in order to achieve the desired layup. Any hardeners will be in there. This is where a lay-up technician's skill shows, because it's here where any defects (wrinkles / air bubbles) have the potential to be introduced. It's careful and exacting work.

Components are then vac-bagged to help remove the air and consolidate the layers before being "cooked" in an autoclave.

Remember from my PhD days that I was supplied with a "kit" of materials to test by McLaren, but I had to send them back because neither the Mech Eng nor Materials departments had the facilities to assemble and cure the test pieces.

Thanks. It seems like it's just elevated temperature that initiates the curing process.

 

[Time Waster]

Aaaaaaaah, Hull & Clyne!

The veritable bible of composite materials theory for undergrads and postgrads everywhere.

We know that corners were cut, mainly for financial reasons. That much is clear from the information that has come out so far. IMHO, it's shockingly bad judgement from a man who supposedly had a degree in aero engineering.

Maybe with better design, a money-no-object approach and more suitable methods of manufacture, it may have been got to work, but, like the heat shield tiles on the space shuttle, it would likely still be a craft with a finite (short) lifespan. The combination of salt water and extreme pressures is not terribly forgiving, especially with a shape that is not optimized for operating under those conditions.

Innovation is good, but you've got to go about it the right way.

Found my Hull and Clyne. Little green book. Did more on steels and light alloys. Easterling, bhaddesia iirc and honeycomb were the authors of books we used a lot more than the Hull one. Another life and something I didn't follow into a career.

Wasn't it a cylindrical submarine that once held the depth record in the Mariana trench? The trieste iirc when I was a kid.

Actually it's a bathyscape and got to the bottom of the challenger trench over 10,000m down in the 60s.

 

[Bonefish Blues]

The capsule for the people was the classic metal sphere, fastened below that roughly cylindrical hull, unlike Titan, where the cylinder performed that function