P2 Locomotive Company and related matters

Could that not simply be the (unfortunate) situation that aircraft designers did NOT realise / appreciate that railway technology and aircraft technology had more in common that first thought ?

 

But could you imagine someone at say Avro or DeHaviland taking a phone call or paying a visit from someone involved with 'old fashioned steam' they'd be be laughed down the phone or out the building. Especially when you think that in the early '50s steam was portrayed as belonging to the past and Jet engines were the nice big shiny next thing.

 

Metallurgy is metallurgy, and applies whether the application is a steam locomotive, a jet airliner or a tin can. Take your point though

 

Probably going to get myself into trouble again, but genuine question: are there parallels where something like a steam loco wheel, with the associated inertia and lateral forces, is fitted to a diesel engine crankshaft using an interference fit? Surely far better and safer to use proven technology?

Dave

 

Doubt it. A friend of mine restores aircraft and whilst the scale of the engineering is quite different, he notes the similarities also and would be as happy with a big spanner on a loco as he is with a small one on an aircraft. An engineering challenge is an engineering challenge no matter what age of the technology.

 

I understood that built up crank axles were adopted because of failures with forged crank axles and because forged axles have to have curved fillets reducing the beating area. The Kruger's forged axles with 14” cranks suffered repeated failures while the Kings had no problem.

Also didn't the Britannias have a problem with wheels shifting on the axles, was this because they were an interference fit without keyways.

 

Never noticed that bit.

 

Oh they knew about metal fatigue, they just didn't know *enough* about metal fatigue in the case of the behaviour of the specific alloys in use.

We should also note that the windows did have radiused corners, they weren't actually square, and didn't have sharp corners.

 

I heard a tale about this some years ago that I've been unable to corroborate from any other sources, but the source was a damn good university lecturer who was probably old enough to have been around at the time.

De Havilland knew all about metal fatigue, and even tested a Comet fuselage to the requisite number of pressure cycles. Did just fine. The issue was with the one they used, because (in typically British parsimonious style) they used the same one they'd already done the over-pressure test on. Now, intuitively you'd think that would be a conservative test, but in this case it wasn't, because the overpressure test had caused local yielding at those troublesome sharp window corners, with the result that when the pressure was released there were residual compressive stresses at the corners.

Residual compressive stresses are a wonderful way of increasing fatigue life for something like that, because although the stress cycle magnitude stays the same, the tensile peak is lowered, and it's the tensile stresses that elongate cracks. It's why racing crankshafts and similar are shot-peened, to put compressive stress into the surface and delay crack initiation, which causes fatigue failure.

Even if that tale is incorrect, the simple fact is that mild steel is a wonderfully forgiving metal, that below certain stress levels can go on for a near infinite life without fatigue failure (generally known as the endurance limit, but bloody difficult to be certain of). Despite that, cracked mainframes were still endemic on certain classes, so it's hard to say that the railways had good knowledge of how to avoid fatigue failures with a straight face. Aluminium alloys require much more care, ultimately it's a case of when not if they will fail due to fatigue, especially when you're designing something to be as light as possible.

De Havilland were victims of being pioneers. You can be damn sure that once Comets started falling out the sky the likes of Boeing and Lockheed were taking notes very carefully and breathing a sigh of relief that somebody else got there first.

 

Believe that the axle is definitely keyed. on a brit.
The problem is due to the roller bearings being an 'afterthought' with the hornspaces dictating the size of the bearings rather than the other way round, as a consequence the size of axle available to fit the wheel on is a little on the small size for such a powerful loco.
It is thought that the failures on britts may also be attributeable to the forces absorbed on recovery from minor slips at speed.... because when traction is reestablished it isnt to all wheels simultaneously (independant, rather than compensated springing) and therefore the full force of the 'catch' is transmited initially to one or two wheels... the seat is fatigued and sometimes fails , and then another one or two, which may also fail or be fatigued, and finally to all 6 by which time the shock is disipated. There is very little give in a roller bearing axle box and very little play with close fitted manganese liners on axle boxes / horn faces which doesnt help....

 

The following message was posted on the www.Lensmen.org.uk forum by one of its members who had obviously just received his copy of the latest 'Steam Railway' magazine:

Issue No 439
Unlike last month, this month's issue seems to have materialised in the local WHS bang on time!

Leaving it for others to comment upon yet another collection of generally poor and uninspiring images that have made it into the 'Gallery' pages ... along with Wilcock's gazumping of anyone else who might have contributed pictures of SS&S4 (as a result of that person's usual insistence that only his own pictures accompany his scribblings), it also didn't fail to escape my notice that the April 1st date is highly imminent!

Bearing in mind some of the more spectacular (and successful) pi**-takes in past years - such as that with the BR-black 'City of Truro' - it was perhaps inevitable that, sooner or later, efforts would be made to attempt something even more outlandish ...

And here it is ... on Page 30!

The real clue should have been on the front cover, or even in the Contents Page ... but where Page 30 did not even merit a mention.

In the feature itself - significantly concocted by a totally anonymous author - and headed up with "First For News" - "Exclusive" - "P2 to Pioneer Nuclear Steam" , accompanied by a sketch of a "LENR" P2 with a 25kv pantograph mounted on its tender-top, there follows a most unconvincing whole page of sheer twaddle ... containing quotations allegedly made by P2SLC chairman Mark Allatt, director of electricals Rob Morland and director of operations Graeme Bunker.

Yes, maybe, these three actually had been party to this latest hoax, egged on, no doubt, by a SR editorial team anxious to revive the flagging popularity of their periodical. But, in this instance it will undoubtedly fail to raise even a smile on the faces of the greater majority who must surely have seen through the ruse ... and, certainly, not even Mr Angry of Crawley is likely to be composing his usual knee-jerk letters of protest!

 

Dear oh dear oh dear. Was he bound and gagged and had every page first shown to him and then pushed down his throat?

 

I should know this! I knew he was a Stokie so it makes sense. Always annoys me those southern softies claim the Spit as their own yet the designer was a Stokie and the factory that built the most was Castle Bromwich.

 

Obviously RJM realised there was no future amongst the dark satanic mills of the Potteries so moved to the broad, sunlit South.

 

I'd have much rather the magazine had provided a good article on the P2 - they're currently up to the delivery of the roller bearings for the wheels and number of other parts.

At least it's only once a year!

 

For information, there is an article on the P2 in Heritage Railway. Pretty much confirms the intention, as expected, to use Franklin B valve gear (a development of the Lentz gear as fitted to 2001). Seems sensible both from an engineering and authenticity perspective.

Also, returning to metallurgy, there is an explanation of the foundation ring corners being forged from now on, to give control of the crystal grain alignment and hence improved fatigue resistance. The new design to be used on Tornado's boiler as well.

Dave

 

Not much in the way of mills, dark, satanic, or otherwise in Stoke, Spamcan, unless you count the rolling mills of Shelton Bar. Just loads of potbanks, some brick and tile works and 30 - odd collieries. At least there were when I was growing up there in the Sixties. I also went to Hanley High School, although I haven't designed any aircraft.

 

I used to get dragged by me ma to Clarke's on Hanley high street for new shoes when I was a kid...... but we MAJORLY digress!

As you were chaps - interesting times for the P2 - lets hope the manage to iron out the faults, which would have happened no doubt, had the class persisted........

 

Interesting stuff, though I thought SR was the preferred mag for such releases? I trust we founders and covenantors will be informed of these developments asap.