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Tourist submarine exploring Titanic wreckage disappears in Atlantic Ocean

Donk said:
Who says you have to autoclave it? (Also who says they didn't) Don't get me wrong there's benefits to doing so but vacuum and heat aren't essential to achieve a full cure if the correct resin is used .
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That's why I'm asking. No information I've found so far that details what and how. The 'winding' and 'bonding' videos look kinda sketchy for an item with this intended use case.
 
Donk said:
Who says you have to autoclave it? (Also who says they didn't) Don't get me wrong there's benefits to doing so but vacuum and heat aren't essential to achieve a full cure if the correct resin is used .
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At the McDonnell Douglas research facility I worked at in San Diego, we had a racquetball court-size (but longer) autoclave.

We made F-18 and F-15 nose cones/wing components/and tail components for testing.
 
CDA 455 II said:
Ah; you're saying they took discounted time-expired raw material and made it themselves?
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I am but I'm also saying that if they were raw rovings it isn't necessarily as bad as it initially sounds as they may have still been in perfectly useable condition.
 
plym49.2 said:
That's why I'm asking. No information I've found so far that details what and how. The 'winding' and 'bonding' videos look kinda sketchy for an item with this intended use case.
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It looks pretty standard from what I've seen of winding pressure vessels in the past.

Another thing to consider is that for aircraft in particular weight is an issue so the processes used for their composite structures are going to be the best available to achieve the perfect resin to cloth ratio and minimise fabrication defects to prevent the need for over engineering to achieve their required safety factor. An item that's not weight limited like a boat or in this case a sub could be over engineered to make up from inferior processes but I'd argue that in the case of these ultra DSVs that construction and engineering standards should be well proven and of the highest quality available.
 
So if CF has a usable shelf life- all cars with CF components become essentially useless after ten or so years?
 
Just sucks alot of companies will no longer get carbon prepreg from Boeing for a dirt cheap price when the prepreg still works well for non-critical applications or rough testing. Just means more waste to the landfill instead of being used.


I've used alot of expired prepreg at work to build prototypes or test out an idea that doesnt support spending 5-10k on a roll of prepreg. Usually I call up some coworkers over at the composite shop at work to see what they have expiring to build up prototypes. I'll still have the ability since its just a work place transfer. Right now I'm sitting on 6 rolls of material that is expired but as worked well for our stuff.
 
Duc said:
Just sucks alot of companies will no longer get carbon prepreg from Boeing for a dirt cheap price when the prepreg still works well for non-critical applications or rough testing. Just means more waste to the landfill instead of being used.


I've used alot of expired prepreg at work to build prototypes or test out an idea that doesnt support spending 5-10k on a roll of prepreg. Usually I call up some coworkers over at the composite shop at work to see what they have expiring to build up prototypes. I'll still have the ability since its just a work place transfer. Right now I'm sitting on 6 rolls of material that is expired but as worked well for our stuff.
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In today's social environment; I'm surprised they even sold them the material.

Then again; this is the same company that sold an updated/upgraded aircraft (737 MAX) and didn't bother to emphasize a key safety point on said aircraft resulting in killing hundreds of people.
 
Cameron made the point that with so many different materials, CF, Ti, Plex, etc., the expansion, or in this case contraction rates would be different. I can see how that might lead to some bonded components becoming un-bonded, and smush.

Reminds me of the mid-run 911 engines. Magnesium block, aluminum barrels and heads, and steel studs, great now you've got three components trying to stay together with different expansion rates. They switched to Dilivar for the studs which kinda worked, but eventually ditched the mag case for Al.
 
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Roc Doc said:
Cameron made the point that with so many different materials, CF, Ti, Plex, etc., the expansion, or in this case contraction rates would be different. I can see how that might lead to some bonded components becoming un-bonded, and smush.
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The vid showing the tech applying the adhesive like Bondo...:eek:
 
xjmark said:
screw.jpg

They're stainless to resist rusting.
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Wrong, apparently they used these:

61nzLm-0uHL._AC_SX522_.jpg
 
CDA 455 II said:
Last time I followed pro cycling (Tour de France '17) CF frames/forks/and all part made had an indirect expiration date on them.

When I worked for McDonnell Douglas designers and engineers told me CF in aircraft definitely had expiration dates via hours meter.
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You are confusing a completed part with raw carbon material.

in all likelihood some type of tow unidirectional strand if the hull was wrapped.

Any completed part in any material will have a lifespan typically determined in cycles. This subs lifespan =
Number of completed trips + number of incomplete trips - 1.

The only airframe that I am aware of that never had a lifespan limit in hours or cycles was the original DC3 Gooneybird.

Aerospace applications track materials from raw components to completed part to end of lifespan. If the raw material is getting close to time ex, they sell it to the secondary market. Happens on .gov and .mil projects all the time when they get behind schedule.

AS LONG, as the correct storage procedures have been followed there is zero problem using these materials. Some of these materials have been used on private aerospace projects with zero issue. A lot of it makes its way to Motorsports use.

Even pre preg material IF it has been correctly stored (there are tell tales that show if min and max temps were exceeded at any point since manufacture) can be used, with caution and post production testing.

Epoxies and hardeners way past time ex. Definite no.

I have used carbon twill in the past that was more than a decade old, correctly stored and admittedly not used for a prototype destined for 12k feet. :lmao:
 
Donk said:
It looks pretty standard from what I've seen of winding pressure vessels in the past.

Another thing to consider is that for aircraft in particular weight is an issue so the processes used for their composite structures are going to be the best available to achieve the perfect resin to cloth ratio and minimise fabrication defects to prevent the need for over engineering to achieve their required safety factor. An item that's not weight limited like a boat or in this case a sub could be over engineered to make up from inferior processes but I'd argue that in the case of these ultra DSVs that construction and engineering standards should be well proven and of the highest quality available.
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Winding a pressure vessel with the pressure inside is a lot different than winding a ressure vessel with the pressure outside.
 
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