P2 Locomotive Company and related matters

Interesting. But as has been said it wasn't these windows where the cracks originated which downed them. It was the small ADF ones on top of the cockpit.

 

Indeed, this adf aerial window was the cause of at least one accident, see: http://aviation-safety.net/database/record.php?id=19540110-1
but the "square" windows along the fuselage were also weak points as the fragment on display (which was from the aircraft pressure tested in the tank) shows.

 

Yes, according to my information the crack started at the ADF 'window in the roof and ran backwards. The cabin then burst open sideways along the line of the regular cabin windows. Farnborough was able to prove this by matching scratches and paint particles from the cabin sections left behind on the wing upper surfaces.

 

For my sins I studied materials science formy degree...we did a lot of work on fracture mechanics, square windows, with sharp corners give rise to stress concentrations which vastly accelerate fatigue crack growth, hence the catastrophic failure of the fuselage.

 

Frankly I don't think the P2 should ever be allowed to fly

 

Oh, it will just not in the air, but on rails, though its wings maybe a bit clipped at 75mph!

 

I once saw a demonstration where a component had been copied in perspex and a load was applied to it. When polarised light was shone through, the stress lines became visible, and as the load was varied the concentrations around square corners were clear to see.

To be honest my knowledge aviation could be written on a postage stamp, but wouldn't it be fairly academic whether the final catastrophic failure initiated at the ADF window or one of the passenger windows? I believe the latter were changed to oval, so their original design must have been seen as equally flawed.

Sorry to drag the discussion off topic, but as I said earlier in the thread I thought that finding that photograph in the archives was fascinating.

Agreed.

Dave

 

Dragging the discussion back to railways, though not to the P2 (so maybe we should have a new thread?) the late-lamented BR research department at Derby used that method to work out how to strengthen the Royal Albert Bridge with the minimum of change to its appearance.

 

You can see the same effect at home with cheap dark sunglasses and a plastic ruler. You need to put the lenses either side of the ruler (either dismantling the glasses or using two pairs) and then shine a light through the lot. Looking from the other side of the light will show up the residual stresses and putting a force on the ruler will show the stresses, best results were with those 'shatterproof' rulers. How disappointing to learn as a kid that shatterproof and unbreakable were not the same thing.....

 

Some excellent shots on Facebook of the first new P2 smokebox door for over 80 years. The face of the engine is really starting to come together.

 

I am wondering whether they considered "explosive forming". The method used is so 19th century!
Kind regards
Jos Koopmans

 

I suspect that the stresses caused by explosive forming would be difficult to control and, whilst a smokebox door is probably not subject to much stress during use of the loco, you would not want it to fail.

 

I'm a little confused. There's P2 Steam building 2007 Prince of Wales who are part of A1 Steam, and Cock O' The North fronted by Brian Blessed (with thumbs up) building 2001. Surely there aren't 2 separate organisations building a P2 at the minute?

 

A masterly summing up of the situation, Nick. I can't believe it either.

 

There are indeed two groups, one based at Darlington building an original design of the P2 (A1SLT), the other apparently in Doncaster building a rebuilt form P2 with A4 streamlining (the P2 Locomotive Company).

 

The whole thing is crazy, if you want to see a new P2 who would get your hard earned cash, a group who've got a track record of successfully building and operating a new locomotive or a lot of hopefuls with no experience. As a Founder Member of the the 2007 lot I can say where my money has gone.
Not sure what the Doncaster group are going to do about boiler design, 2007 will have what is basically the same boiler as Tornado.

 

Read all about it on their websites - this is the site for the original design with rotary gear by the A1 team .... http://www.p2steam.com/

and this is the A4 fronted walschaerts gear one ... http://www.cockothenorth.co.uk/

Incidentally this page is for the P2 Locomotive Co Ltd - the one allied to the A1 Trust.

Yer pays yer money etc ...... ;

 

OK, so it isn't me then reading that wrong. Shocked and stunned.

Were there not only 6 built in the first place? I think with more commitment and effort all round we can easily double that number ;-)

 

The chances of one new P2 being completed are excellent, two being built are fairly good but I cannot believe for a moment that there will be another one constructed unless they are phenomenally successful.

 

The one positive thing about there being 2 groups one is building another to outwardly at least with modern improvements in light of experience/history. The other a replica of the original engine as modified in line with the bulk of the class with an A4 style nose and conventional Gresley valve gear. Rather than an identical pair, as Earl Marichal looked pretty well the same as Cock o' the North with blinkers and conventional in lieu of poppet valve gear.