P2 Locomotive Company and related matters

My father got one....then died two weeks later. He also said he was dying all his life....if I've inherited his genes I'll rephrase .."death row...a bit more to go". Excuse my humour..but it runs in the family....

 

Yes, another one here. I'm approaching sixty but forever wondering if my various health issues and lifestyle will have a say in the matter.

I suppose the time to worry is when the build of 2007 is overtaken by that of 2001.

 

You’d like to think that was about as likely as the Tory’s winning the GE …..

Mind you it’s not inconceivable that my other runner in the new build stakes, Clan Hengist, could beat PoW to the starter signal, They certainly have the technical and project management skills, and access to excellent commercial engineering facilities. The limiting factor of course is fund raising.

 

Here 's a question, so when this new boiler is finished, with a water space suited to its make up and a reduced grate area of, lets say 5% which i think is a conservative estimate - it suddenly becomes a bit tongue in cheek to suggest its Britains most powerful locomotive when other locos ( Duchess, merchant Navy, Duke of Gloucester) have a larger boiler, and grate, which is the ultimate supplier of power. ..

 

It is but when power is a function of pull and speed, not to mention the complexities of converting the prime energy of the coal into the energy at the wheel, it isn't as simple as grate area. The ability to drag air through the grate is unlikely to be significantly diminished by a slightly smaller grate area as the prime factors in that have not altered neither has the steam circuit and engine.
Where does the claim to be Britain's most powerful come from in any case?

 

Latterly from the A1 Trust as one of the selling points for their project.
Before that, did the LNER make that claim? If so, that could have been using the GWR's criterion of nominal tractive effort, while excluding non-express locos such as their own U1.

 

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Thanks Steve I Understand that there is more to it than a massive firebox or boiler (Im not American). i
All the locomotives mentioned have good steam circuits, augmented draughting, good or in some cases ( fingers crossed) very good steam distribution all have slightly different strengths and weaknesses. All Can produce exceptional power outputs for short periods in excess of what the boiler can actually sustain or the wheel to rail traction can actually handle in anything less than ideal conditions, But in as much as steam locomotives had in the UK reached a similar stage of development in terms of steam utilisation and the ability to raise x lbs of steam per foot of grate area then the ultimate reality of sustained steam production for them is grate area, and the stamina to meet exceptional steam demand for longer is boiler volume - which is why Duchess of Abercorns record will never be beaten, and making claims based on starting TE are disingenuous. To pre empt someone saying that Mallard only had a 42sq foot grate then i suspect that the rebuilt Hush hush would have beaten that record ( with an extra fireman)

 

The misunderstanding - and I hope the Trust realise this and don't actually believe that claim - is that Nominal Tractive Effort is a measure of power output. As Steve says, speed is a factor in any power development: the basic definition of Power is Force (Tractive Effort, not Nominal but as measured at the time) x Velocity, a value which fails to appear in the Nominal T.E. equation. Even more simply put, T.E., which is a force, is measured (in Britain) in pounds or tons, while power is measured in Horsepower (indicated, drawbar or brake). Two different quantities.

 

Oh come on people. Most powerful in steam locomotives is an extraordinarily nebulous concept. Arguing over it is rather like two 13 year olds arguing who has the biggest w****y... Anything based on a few top trumps numbers is pretty much useless as it ignores competence or otherwise in design, and anything based on road performance is completely unrepeatable and largely depends on the willingness of the crew to thrash the locomotive beyond what is safe in terms of mechanical integrity and longevity, not to mention the fireman's body.

 

You are correct of coure, but nevertheless there is a broad correlation between TE and power (IHP = TE x M / 375 where TE is the indicated TE using the actual MEP, and M is the speed in mph - from the Locomotive Engineers Pocket Book). Nominal TE also has the advantage of being able to be calculated from fixed parameters, even if the validity of an 85% or whatever constant is arguable and the MEP will tail off at different rates.

If we look at the indicator diagrams for a number of the wide firebox locos the subject of BR P&E Tests, which admittedly is a bit arbitrary as it is of course dependent on which ones they chose to publish, the highest ihps shown are:
71000 ihp 2,310 @ 75mph 17% cutoff, 30,000lb/hr steam rate, nominal TE 39,080 / actual TE 11,550 (working back from the formula quoted above for this speed/MEP)
35022 ihp 2,230 @ 50mph 30% cutoff, 38,950lb/hr, nominal TE 37,515 / actual 16,725
60845 ihp 1,870 @ 74.5mph 25% cutoff, 28,400lb/hr, nominal TE33,730 / actual 9,412
70005 ihp 2,006 @ 40mph 45% cutoff, 29,850lb/hr, nominal TE32,150 / actual 18,806

As noted, it is a bit arbitrary as it is based on the published material but I don't think it is accidental that the two locos with greatest nominal TEs also showed the greatest ihp. But this to my mind should be viewed as a generalisation and one would I suspect immediately run into difficulties in trying to draw up table of rankings between locos based on relatively small differences.

 

Indeed. Chapelon's 242A1 managed 4000dbhp at 90kph with a grate area of 54 sq ft.

 

To a point - though it is demonstrably true that the P2 Project claims to be "Building Britain's Most Powerful Steam Locomotive" and, almost 100 years ago, the GWR publicity department was happy to promote a similar claim for the "King" class locos - based presumably on TE.

So while making such a claim may be willy-waving, it is willy-waving that has a long and honourable history!

Pound-for-pound, nothing much beats a "Schools" though an Adams T3 comes close.

Tom

 

Provided you're looking at similar types of engine, there is some correlation but once you spread the net a bit, it all falls apart. Many goods engines had Nominal T.Es. within these ranges but could never achieve anything like those power outputs because they simply could not make the speed. A very extreme example is Gresley's U1 2-8-0+0-8-2: 72,940 lbf of T.E. but it would be a brave man who went much over 30 mph. However, on the Trust's basis it is far and away the most powerful steam engine ever to run in Britain, but I can't see it heading the Elizebethan in the event of an A4 failure. An 08 shunter is in the same area at 30,000 lbf but limited to around 20 mph and probably less than that, and 350 b.h.p. doesn't compare well to 3,300 from a Deltic with only 20,000 lb more T.E., and only 500 more at a continuous rating.

Nominal T.E. is rough guide of the load an engine might start from rest, assuming 100% adhesion. Start taking it beyond that and you're going to hit problems.

 

Minor typo corrected above

 

Other than very short term, on a loco with 50 square feet of grate I would expect the fireman's shovelling limit to be reached well before the limit of what is safe for the loco.

 

Wouldn't they have a stoker? Except in the UK!

 

Oil fire it then....

 

Yes based on the little information that they publish these days on engineering and fundraising progress - or rather lack of!