They live amongst us ………

[mossmonaco]

Surely, in this context, the word 'pedant' should be capitalised?

[Escadrille Ecosse]

1 hour ago, mossmonaco said:

Surely, in this context, the word 'pedant' should be capitalised?

Don't call me Shirley...

Are you really sure about the capitalisation? Do we start a new thread to discuss in greater depth?

[Nick Jones]

Pedants and the grammar mafia also live amongst us…..

[PaulAA]

6 hours ago, mossmonaco said:

Surely, in this context, the word 'pedant' should be capitalised?

I read an amusing paper a little while ago, about the correlation between capitalisation in social media and intelligence. It's an inverse ratio.

[PaulAA]

On 6/13/2023 at 5:33 PM, JohnD said:

Without them, we wouldn't have Einstein or Tim Berners-Lee, or the unfortunates who wear Bacofoil hats or believe in Flying Saucers.
 

John, I would be cautious about the beatification of TB-L. Without him, we might have avoided the single most destructive aspect of the internet - anonymity.

[JohnD]

Well, Paul, without Einstein we might not have had the nuclear bomb as soon as we did.

Alternative History (capitalisatin again!) is indulged in by respectable historians.   I have a whole book  of such speculations to read while on holiday! It includes "Atomic Alternatives in Europe" (caps in a title surely allowed, Shirley?) by Stephen Ambrose, Boyd Professor of History at the Uni.of New Orleans.  We shall see - or read.    The book is based on a series in the Quarterly J.of Mil.Hist, a most academic journal!

John 

[Escadrille Ecosse]

4 hours ago, PaulAA said:

I read an amusing paper a little while ago, about the correlation between capitalisation in social media and intelligence. It's an inverse ratio.

Used to see it in the in the daily rags back in the day, Sun, Star, Mirror, Scottish Dialy Express, etc. too. 'Big letters' and underlining to highlight the important words.

6 hours ago, Nick Jones said:

Pedants and the grammar mafia also live amongst us…..

Don't worry Nick I was joking.

Although regards grammar it depends on who is doing the writing (what level of professed superiority) and the nature of the audience (internaI or external) and signage. I must admit to thinking that a certain level of grammar is important, my view as an engineer where the position of the decimal point usually matters, when I was working and especially with 'professional' and management was that if you can't be bothered writing properly what else can't you be bothered with - and when might that kill me?

If challenged too much by an reverse-pedant I would start corresponding with them in emails without any gammar.

sotheirwouldbenospasesbeweenwordsandlotsofspellnstakes

 

[Nick Jones]

2 hours ago, Escadrille Ecosse said:

Don't worry Nick I was joking

 yes..... I also..... but the response was worth provoking as it turned out 

 

2 hours ago, Escadrille Ecosse said:

as an engineer where the position of the decimal point usually matters

only usually...... 

2 hours ago, Escadrille Ecosse said:

what else can't you be bothered with - and when might that kill me?

Quite.....  You definitely wouldn't want them doing the stress calcs on your composite submarine hull.....

[Escadrille Ecosse]

16 hours ago, Nick Jones said:

Quite.....  You definitely wouldn't want them doing the stress calcs on your composite submarine hull.....

No indeed

[JohnD]

Is this a rerun of the Comet tragedy?   Poor understanding of metal fatigue, now of fatigue in carbon composites?

One hopes, when Airbus and Boeing (and others?) are using carbon composites widely that the first will not be repeated.

John

[mpbarrett]

"Quite.....  You definitely wouldn't want them doing the stress calcs on your composite submarine hull....."

I don't think anyone would bother doing the calculations after they had looked at the shape, the materials to be used and the application...
 

mike

[mpbarrett]

Maybe we should start a new topic on submarines and risk taking.

[Nick Jones]

I did wonder in another place as to whether signing up to travel (rather expensively) on such a dodgy device for mere tourism purposes should qualify one for a Darwin Award….

Opinion was divided, though I’m inclined to think yes……

[RogerH]

2 hours ago, JohnD said:

Is this a rerun of the Comet tragedy?   Poor understanding of metal fatigue, now of fatigue in carbon composites?

One hopes, when Airbus and Boeing (and others?) are using carbon composites widely that the first will not be repeated.

John

Hi John,

 the designers of the De Havilland Comet  knew what they were doing regarding stresses of all the materials they had played with beforehand 

Sadly they did not know about pressurisation  and  square windows.  It is obvious - but it wasn't.

New materials are tested for every conceivable issue and some that haven't been conceived.

However mother nature still has the ace up her sleeve and gets the last laugh.

 

Roger

[Escadrille Ecosse]

2 hours ago, RogerH said:

Hi John,

 the designers of the De Havilland Comet  knew what they were doing regarding stresses of all the materials they had played with beforehand 

Sadly they did not know about pressurisation  and  square windows.  It is obvious - but it wasn't.

New materials are tested for every conceivable issue and some that haven't been conceived.

However mother nature still has the ace up her sleeve and gets the last laugh.

 

Roger

Just this

deHavilland, the creators of the Mosquito and the Vampire were anything but incompetent.

@JohnDComposites have been used in aircraft such as various Airbus very successfully for very many years. If you have flown in the last 20 years you'll almost certainly put your life in the hands of composite airframe components. 

As Mike says though, the Airbus is the right application, right shape and just as importantly the right design, manufacturing and testing processes.

Unlike that submarine....

 

[Nick Jones]

1 hour ago, Escadrille Ecosse said:

Unlike that submarine....

There are, inevitably, videos beginning to appear on YouTube discussing the engineering quality (or otherwise) that show footage of its build process and various safety features.

I’ve temporarily (I hope) misplaced the link I was going post. Maybe save it for a new thread. However, the thoughts I took away from it was that perhaps the bigger surprise was the number of successful dives made without (serious) incident, and that I wouldn’t have got in it if there were any chance of it going in the water….

[JohnD]

I'll look forward to that discussion!

Meanwhile, I had no intention of slandering the Comet designers.   Pushing the boundaries of technology is how we advance. 

John

[John I]

42 minutes ago, JohnD said:

Pushing the boundaries of technology is how we advance. 

It has in the past and no doubt will in the future claim lives. The space race and shuttle disasters are examples where money and technology investment could still sadly not avoid loss of life though unforeseen circumstances.

[Gt64fun]

I managed to catch one of the youtube videos talking about the build. Very interesting.

To date all deep submersibles have had the pressure compartment built as titanium spheres, typically 50mm thick.

The Titan was constructed with a central cylindrical section built from a 125mm thick carbon fibre spiral wound laminate, with hemispherical titanium end caps.

Knowledge in respect of the fatigue cycle of the carbon fibre in this extreme environment would be limited and fatigue (as in the case of the early Comets) may turn out to have been its undoing.

I for one prefer to be on the water rather than under it!

Ian

[RedRooster]

Of course the American obsession of putting a man at the sharp end could all be designed out. 

Carbon Fibre pods have been used subsea for the last couple of decades. It's the 4000msw rating and the size /shape of the sub that was the problem. 

[RogerH]

All carbon and Kevlar composites are at their strongest in tension.  They buckle in compression.

Also I wouldn't put Titanium is sea water unless it is very well protected.  Chlorine is  the killer.

Regarding new technology - in the early 2000's I was asked to help a well known racing group in Woking.

They were making a carbon fibre body shells for a German car manufacture.  After building  five or six bodies somebody suggested it may be a good idea to inspect what they had done  (they really hadn't a clue)  A friend of mine did a very specialised inspection (Shearography).  This brought up a dozen or so dodgy  areas.

I then radiographed these areas and found many alarming images - not aerospace quality but the car will be flying very low.  They asked how they could resolve the issues.

A number of shells were to be impact destroyed.  So check the dodgy areas after impact to see how they failed.

They never came back with results.

 

 

Roger

[JohnD]

Is carbon fibre tech that new?   It's 30 years since the first CF car the XJR-15.  Different use but stressed are stresses.   I searched for papers on fatigue in CF structures, and there are many, but way beyond my understanding.

John

[mpbarrett]

This is interesting but could one of the administrator move these comments to a new thread? Not sure I can do it.

cheers

mike

[Escadrille Ecosse]

1 hour ago, JohnD said:

Is carbon fibre tech that new?

It's new to anyone who hasn't used it before...

And obviously the carbon fibre itself, the resins and the manufacturing techniques have developed and continue to develop since the beginning. Just like all technologies.

[Escadrille Ecosse]

4 hours ago, RogerH said:

All carbon and Kevlar composites are at their strongest in tension.

Compressive forces, especially on slender structures, like the shell of a hollow vessel are much harder to deal with where buckling is as important factor as material properties. And buckling mechanisms are also a lot less deterministic.

This will not even be absolute vacuum. Despite one comment suggesting a 1 bar (14.5psi) difference, I would suggest it is a lot less. I have seen a similar vessel fail at a few psi due to a plastic bag over the vent.