A1 Trust announces P2 feasibility study

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Ferrybridge Flyer
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Re: A1 Trust announces P2 feasability study

Post by Ferrybridge Flyer »

I think the amount of "new build" projects are a marvellous thing,which should ensure Steam on the national network for a decades to come.Being born in 1969,i missed the excitement you more senior guys felt when you saw a new steam engine.Tornado was the first for me,and the more i feel that the better!!!Bring it on!!
Bring back Ferrybridge station!
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Atlantic 3279
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Re: A1 Trust announces P2 feasability study

Post by Atlantic 3279 »

Although this is merely another amateur view, the A1 team's emphasis on the commonality of boilers suggest to me a useful option in respect of the potentially all-important matter of sideplay on the leading coupled wheelset. If the later A1 boiler spec is to be used, operating at 250psi in lieu of COTN's original 220psi, then it appears to me to be possible to mainatain the original tractive effort / power figures with cylinders of 19.7" diameter instead of the original 21". Presumably this would make it possible, within the confines of our "quaint" loading gauge, to move the cylinder centre lines 1" 1/4 further apart, creating an extra 5/8" space behind each outside crosshead that was not available in the original design. A good opportunity to introduce the sort of wheel sideplay that might be deemed necessary?
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Re: A1 Trust announces P2 feasability study

Post by S.A.C. Martin »

Atlantic 3279 wrote:Although this is merely another amateur view, the A1 team's emphasis on the commonality of boilers suggest to me a useful option in respect of the potentially all-important matter of sideplay on the leading coupled wheelset. If the later A1 boiler spec is to be used, operating at 250psi in lieu of COTN's original 220psi, then it appears to me to be possible to mainatain the original tractive effort / power figures with cylinders of 19.7" diameter instead of the original 21". Presumably this would make it possible, within the confines of our "quaint" loading gauge, to move the cylinder centre lines 1" 1/4 further apart, creating an extra 5/8" space behind each outside crosshead that was not available in the original design. A good opportunity to introduce the sort of wheel sideplay that might be deemed necessary?
I'm fairly certain (though I could be heinously wrong!) that this was definitely an option they were looking at last time I asked them on it (GCR 2008). There were a whole host of other fixes they had in mind, I'm sure it's only a matter of time before the full details are available.
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Re: A1 Trust announces P2 feasability study

Post by Bill Bedford »

Atlantic 3279 wrote:Although this is merely another amateur view, the A1 team's emphasis on the commonality of boilers suggest to me a useful option in respect of the potentially all-important matter of sideplay on the leading coupled wheelset. If the later A1 boiler spec is to be used, operating at 250psi in lieu of COTN's original 220psi, then it appears to me to be possible to mainatain the original tractive effort / power figures with cylinders of 19.7" diameter instead of the original 21". Presumably this would make it possible, within the confines of our "quaint" loading gauge, to move the cylinder centre lines 1" 1/4 further apart, creating an extra 5/8" space behind each outside crosshead that was not available in the original design. A good opportunity to introduce the sort of wheel sideplay that might be deemed necessary?
If it isn't going to go to Aberdeen I don't see the point. The problem with the P2s was that they were the wrong answer to the route they were intended for.
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Atlantic 3279
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Re: A1 Trust announces P2 feasability study

Post by Atlantic 3279 »

Bill Bedford wrote:If it isn't going to go to Aberdeen I don't see the point.
Unless of course the national rail authority, whoever they might be by then, and the preserved lines that might give 2007 the opportunity to earn a living, would very much rather not have the loco trying to straighten out any of their twisting routes or break down with hot axleboxes in the attempt. It's only a thought. I gather we don't actually know how much of an Achilles heel the long rigid wheelbase of the P2s really was on the Aberdeen route, and how much of the "trouble" was due to maintenance teams on the NB section not being experienced in dealing with BIG Doncaster locos. Could the "trouble" have been just talk designed to mask a maintence quality problem? Surely the risk is that we won't know for sure until they build another one, and if no work is done to anticipate possible trouble, then the effect on the completed loco could be fatal?
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Bill Bedford
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Re: A1 Trust announces P2 feasability study

Post by Bill Bedford »

Atlantic 3279 wrote:
Bill Bedford wrote:If it isn't going to go to Aberdeen I don't see the point.
Unless of course the national rail authority, whoever they might be by then, and the preserved lines that might give 2007 the opportunity to earn a living, would very much rather not have the loco trying to straighten out any of their twisting routes or break down with hot axleboxes in the attempt. It's only a thought. I gather we don't actually know how much of an Achilles heel the long rigid wheelbase of the P2s really was on the Aberdeen route, and how much of the "trouble" was due to maintenance teams on the NB section not being experienced in dealing with BIG Doncaster locos. Could the "trouble" have been just talk designed to mask a maintence quality problem? Surely the risk is that we won't know for sure until they build another one, and if no work is done to anticipate possible trouble, then the effect on the completed loco could be fatal?
Lots of things have changed since 1935. Track is generally heavier, and straighter than it was then, at least on the main lines, (preserved lines which may have timber sleepering are generally limited to 25mph.) and we have computers which are able to simulations and finite element analysis. We also have experience of Austerity and 9F 2-10-0s which both have a longer fixed wheelbase than a P2. I suspect that a P2 would be able to go where ever a 9F was allowed, taking into account the different axle loadings, the only mod I would suggest is needed would be for the P2 to have thinner flanged wheels on the inner two axles.
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Atlantic 3279
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Re: A1 Trust announces P2 feasability study

Post by Atlantic 3279 »

All relevant points I agree Bill. I'd made the point about the 2-10-0s myself in discussion elsewhere. No doubt the skilled members of the A1 team will have more than enough ideas, knowledge and resources to sort the solution out anyway, regardless of how much hot air we ventilate on this forum. Still, it is interesting to speculate and discuss.
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mr B
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Re: A1 Trust announces P2 feasability study

Post by mr B »

Point to remember is if it dont work they could always rebuild it into a A2/2.

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Re: A1 Trust announces P2 feasability study

Post by 52D »

Very droll Mr B in all honesty im glad that an initial study has been launched into the possibility of a P2 new build. BTW how similar were the P1s to the P2s?
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Re: A1 Trust announces P2 feasability study

Post by S.A.C. Martin »

52D wrote:Very droll Mr B in all honesty im glad that an initial study has been launched into the possibility of a P2 new build. BTW how similar were the P1s to the P2s?
Not at all as far as I know! They used the original A1 standard boilers, had a smaller overall wheelbase and as far as Cecil J Allen suggests, were simply the goods version of the A1 pacifics. Certainly we've seen in model form one of the members here (take a bow Atlantic :) ) recreate one using a Flying Scotsman bodyshell as a basis.

The only thing vaguely similar is probably the cartazzi arrangement - the cab was not a windcutter as it was on the P2/A4/A1s/A2s I think.
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Re: A1 Trust announces P2 feasability study

Post by Atlantic 3279 »

Without going off at a complete tangent, there's a point of interest to mention in regard to that P1/P2 similarity question: The very first March 1932 scheme for the P2, shown in an outline drawing in the RCTS book, was in fact EXCEEDINGLY similar to the P1, using a standard Pacific boiler, cab, rear frame arrangement, cylinder layout , and Gresley-Walschaerts conjugated valve gear, but with an elongated smokebox to cope with the extra length required to accommodate the 4 sets of 6' 2" coupled wheels, which would have been provided with small splashers as on the Pacifics. At that stage a round dome was still shown but the double chimney had already been decided upon. Then came all the playing about with changes of ideas such as larger grate, various forms of the "Art-Deco" style boiler casing (which vanished entirely again in scheme 8 December '33 only to reappear on the final draft), sloping or swept back cab fronts, inclined outside cylinders, different profiles of running plate (some very angular), Lentz rotary cam poppet valve gear, steam banjo and ACFI feed water heater. The final loco(s) thus bore little outward resemblance to the Pacifics and freight Mikados but parts of the frames, much of the basic boiler, the cabsides and the standard Gresley pony truck were still there as common features.
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Re: A1 Trust announces P2 feasability study

Post by S.A.C. Martin »

That's very interesting Graeme - so would it be fair to say the P2s were some sort of design progression direct from the P1 but for a different purpose than heavy freight, on that basis?
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Re: A1 Trust announces P2 feasability study

Post by Atlantic 3279 »

I don't know if the progression from P1 to P2 would rate as "direct" and there will be many who are far better qualified than me to comment, but I believe it is a rarity in engineering for designs to be wholly or largely novel, evoloution based on tried and tested previous versions usually being the safer, cheaper and more predictable course. I think it may be true to say that only in the design of the first Pacifics did Gresley take the risk and the opportunity of starting with a virtually clean sheet of paper, without too much regard for what patterns and ready-made parts and tooling were to hand. The first of the moguls had the novelty of the pony truck and outside cylinders/Walschaerts, but the boilers were very much of the establised Doncaster pattern. The first 2-8-0s shared those new features but had a boiler derived from the large Ivatt atlantics. The enlargements of the moguls and the introduction of three cylinder propulsion with conjugated valve gear to the moguls and consolidations were later, cautious evolutionary steps.
ALL of the RA9 locos after the first Pacifics were "tweaks" on that first design, with elements of 2-6-0 or 2-8-0 thrown in in some cases. P1 = Pacific boiler and rear frames on 3 cylinder 2-8-0 running gear with slightly larger wheels. A4 = "tuned" A3. V2 = shortened A3 with smaller wheels and a pony truck. P2 = A3/P1 boiler with enlarged firebox, eight coupled chassis, pony truck, and a host of technical and cosmetic add-ons, several of which did not live up to expectations.
I've seen it suggested that the process started in the thirties of enlarging the grate and combustion chamber of the "balanced" boiler previously designed for the first Pacifics, whilst maintaining the tube layout but making the barrel shorter and shorter, was actually taken too far in the development of locos such as A2 and A1 , resulting in locos that had to be fired excessively just to keep the grate covered even when there was no demand for steam (also resulting in wastefully hot gases arriving in the smokebox rather than giving up maximum energy to the water) - albeit that the larger grates were handy when a lot of energy was wanted from poor coal. So evolution isn't always an unqualified success.
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Re: A1 Trust announces P2 feasability study

Post by stembok »

Atlantic3279: There is some evidence that the whole approach to boiler design at Doncaster had its weaknesses, particularly, as you say, with the later Pacific classes when grate area was enlarged and barrel length altered, without other dimensions being adjusted accordingly, resulting in reductions in the free gas area though the tubes. A 50sq ft grate was employed and a double Kylchap exhaust fitted to mask any resulting deficiencies .This was fine with the Peppercorn A1s -very free steaming locos - but there could be problems for example with the single chimney Peppercorn A2s at times. The 50 ft grate was employed in expectation of poorer coals and faster schedules with heavier trains, but the post-war trend tended towards lighter, more frequent services and on the locos with larger grate areas coal was being used merely to cover the grate, as you say. It would be interesting to know what part -if any- cost constraints played in the question of boiler design and construction at Doncaster. Having said that figures show that the boilers themselves were robust and very cost effective on the question of construction,repair and maintenence costs. And of course other railways had their trials ,tribulations and imperfections as regards boiler design and layout.
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Re: A1 Trust announces P2 feasability study

Post by coachmann »

....And of course other railways had their trials ,tribulations and imperfections as regards boiler design and layout.
Although Crew probably had the best boilers, history has shewn the LMS never stopped experimenting with the 'Black Fives'. And yet, the domeless 1934 verticle throatplate boilers were alongside the last-built 1949 Ivatt boilers at the end of steam in 1968.

It does look as if CME's 'kept messing around' to justify their roll! :wink:
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