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P2 Locomotive Company and related matters

Discussion in 'Steam Traction' started by class8mikado, Sep 13, 2013.

  1. osprey

    osprey Part of the furniture

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    Interesting all this tech stuff......but if it looks like a P2.....it''ll do for me......and if there's two......I'll have a laundry problem........
     
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  2. paulhitch

    paulhitch Part of the furniture

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    Here we go again. Two projects for essentially the same machine, therefore the likelihood of having one completed locomotive as opposed to two half done ones is dramatically reduced.

    PH
     
  3. 61624

    61624 Part of the furniture

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    I beg to differ on that -- I think the A1SLT one will prosper and the other will limp along, if that. Is it a coincidence that the Doncaster group have suddenly announced that they are ready to have their frames cut, just as the others have announced that they are to go ahead? It seems to me like a crude attempt to piggyback on the publicity by a group that is far less professional, organised and driven. I think the majority of donors will back the group with the track record. Just my opinion as an outside observer though, I'm not associated with either.
     
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  4. Jamessquared

    Jamessquared Resident of Nat Pres

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    To be fair, one of the two groups concerned does have a track record in successfully achieving projects of this magnitude. No reason why a group who has successfully built one new build shouldn't go on to build another. After all, there are several groups who have successfully restored multiple Barry locomotives. So maybe the market (in terms of whether none, one or two of the groups is successful in raising the money) will decide.

    Tom (not connected with either group, for the record)
     
  5. paulhitch

    paulhitch Part of the furniture

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    I actually agree with your forecast but some money is still going to get diverted which could be used by the more likely group. It's a bit like Omar Khayam's "four and twenty jarring sects" who need a good shake.

    PH
     
  6. Steve

    Steve Resident of Nat Pres Friend

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    Unless the cylinder is fitted with tail rods, the volume of steam on each side of the piston is different, leading to one 'heavy' and one 'light' beat per cylinder per revolution. Added to that, valve events are set on piston displacement and not the position of the wheel and angularity means that the front and back 'events' are not 180° apart so you do not get equally spaced exhaust releases. The interaction between the different cylinders exhausting into the same blastpipe also has an effect, as does cylinder clearance volume at each end of stroke. I'd suggest that all these have an effect on the 'beat' of a loco far greater than the increased length of exhaust pipe, but, as you say, I'm no expert on these matters and I don't have an Uncle Rudi to teach me.
     
  7. Pesmo

    Pesmo Active Member

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    Regarding smoke, there must be plenty of aerodynamic experts in the UK who could advise on discrete bolt on modifications to improve the upward flow of the exhaust. Its an area where the UK is still very much top drawer. It might even make a nice student project for someone. Motorsport as moved aerodynamics along massively since when the P2's were first designed and small changes can apparently make a big difference.
     
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  8. class8mikado

    class8mikado Well-Known Member

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    I wish i was good enough with graphics to put a big full depth ground effects dam on the front !
     
  9. Sheff

    Sheff Part of the furniture

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    As regards the exhaust arrangements, personally I'd go for a double Lempor, as it's easier to tune and has less iron-mongery in the smoke box. Like many of the other necessary or desirable modifications that will be incorporated (different front truck, roller bearings, rocker grate etc) it would be invisible to the naked eye.
     
  10. stuartreeder

    stuartreeder Member

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    would like to wish both groups the best of luck
     
  11. The Black Hat

    The Black Hat Active Member

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    You want to try the Q6 then.... even beat, really grips. Fantastic engine.
     
  12. Eightpot

    Eightpot Part of the furniture

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    Those that have seen and heard a German Class 44 3-cylinder 2-10-0 in action will recall the uneven exhaust beat due mostly to the inside cylinder being cocked up at a differing angle compared to the outside ones. However, few would deny that they were a very effective piece of machinery.
     
  13. The Black Hat

    The Black Hat Active Member

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    Its interesting that the two P2 groups are wanting to build the same class but in different forms. The A1 trust going for the original, the P2 Doncaster group going for the rebuild to match the recognised A4 profile.

    I know the A1 Trust scheme will charge ahead. The machine they have built around Tornado for merchandise, publicity and finance is now turning to a new scheme. I personally think most of this is due to the fact that they have to aim for another engine to justify such a large operation being maintained, like having a board and trust for postions like planning, design and whatever else. Now that Tornado is built, you dont need a lot of those postions to still go on. Tornado is fast becoming another steam engine on the network and will soon be yet another new build engine, thus the Trust should morph into a smaller more traditional locomotive group and should start concerning itself with the forthcoming overhaul, but only recently have many of us became aware that the engine still hasnt paid for its tender. Thank god covernentors are still paying for the engine thats built. It would be interesting to find where the money is going as Tornado should have made a lot and also be recieving more through covernentors compared with groups offering £15 memberships for a year.

    Despite all this, the main draw will be the name and the reputation of the A1ST as being good and experienced in the new build sector. Indeed they are very well placed to start the process and look into building a new P2. Whether so many parts can be used twice is something I might question. It sounds more like building a P2 out of the parts from an A1 than building a genuine P2. I have no doubt they could do it, but they have also tinkered with the A1s design which has led to complications. I think they will succeed and silence doubters, of which I am not one. I think they will build a P2 engine, more like a P3 really, and that it will become another symbol of the modern preserved era. It might be a last throw of the dice for this grand big new build scheme as I think the desire for them is waining and the modern network has steam on it as a luxuary when it can be accomodated.

    I will follow developments with interest...
     
  14. Spamcan81

    Spamcan81 Nat Pres stalwart

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    The Doncaster group are not going for a rebuild. 2003 - 2006 were built with the A4 nose, 2001 and 2002 were modified to match.
     
  15. pete2hogs

    pete2hogs Member

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    The Q6 no doubt is a fantastic engine - their very longevity as a class testifies to that.

    I'm not saying an even beat is a bad thing, I'm pointing out that of itself it has little or nothing to do with whether an engine is successful. Any engine without tail-rods will have slight differences in the power generated on a forward and backward piston stroke - makes no noticeable difference. The steam engine is very forgiving, and since the basic inefficiencies are the part where you turn water into steam, improvements in the operation of the actual engine parts can make only small differences.

    A Kylchap works primarily because it makes the engine steam better by getting more heat transfer out of the outer boiler tubes and hence reduces coal consumption for a given amount of steam generated - or alternatively produces more steam for the same amount of coals. It's not because it drastically improves cylinder efficiency, although it may be better at clearing the exhaust at very high rotational speeds. And it works equally well on a conjugated Gresley as it does on a 'even beat' Thompson or Peppercorn.

    All steam locomotives are effectively underboilered, in the sense that if you work them continuously at anything near the full power of which the cylinders are capable, they will exceed the boiler's ability to supply steam. Therefore a driver will regard an an engine as 'more powerful' if he can run at a higher power setting for longer without mortgaging the boiler - this of course has nothing to do with the engine's tractive effort or suchlike.
     
  16. class8mikado

    class8mikado Well-Known Member

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    A Kylchap works by being a more efficient ejector: for a given volume of exhaust steam at a given exhaust pressure it produces a greater smokebox vacuum, therefore stronger draw on the fire. It is therefore possible to get the required draw on the fire ( without making any change per se to heat transfer or steam production) with a much more 'open' blastpipe cross section, this in turn means there is less exhaust steam under pressure in the circuit between the cylinders and the blast pipe ( back pressure). With less back pressure to overcome the Cylinder efficiency is increased which if the circuit steamed ok before is a much more useful beneficial attribute..
    So whilst its entirely possible to fit a kylchap ( badly) that only assists draughting or as stated above that doesn't effect the boiler performance but does increase cylinder efficiency ideally it should be doing both ...
    As for being overboilered most of the new design BR standards are, but they were deliberately designed to operate at low ' efficient' steam outputs relative to the size of boiler.
    Theres a strong case to argue that if you draughted a Britannia closer to its potential grate limit then there would be more steam produced than its Cylinders could use transmit. Duke of Gloucester does potentially produce 'more steam than is good for it'. Heaven knows what you could get out of a Duchess with a tweaked front end.... but in all the cases the Pacific wheel configuration doesn't deliver enough adhesion (whereas a 2-8-2...) and the condition of the fire (and fireman) wouldn't allow such outputs to be sustainable
     
  17. pete2hogs

    pete2hogs Member

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    In reality, it is unwise to be dogmatic about anything to do with why a steam locomotive steams or not - real scientific analysis only started after the steam loco was already technically obsolete, and the work of the likes of Chapelon, Porta et al has never been followed up to its final conclusion.

    In reality, most drivers would prefer an engine that always had enough steam for its cylinder's demands - of which perhaps the classic example is an Ivatt Atlantic as tweaked by Gresley. Even firemen, I'm told, who have to shovel the stuff, would generally prefer a loco with a higher fuel consumption if they could guarantee its steaming. If you have to do the job day in and day out you want the loco to be master of its work and above all reliable.

    Your point about adhesion is entirely valid. But you can't combine a large firebox with large trailing wheels, so there has to be a compromise. The P2 might have been that compromise if the wartime loads had persisted (and of course Gresley had stayed in office another 5 years... )
     
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  18. class8mikado

    class8mikado Well-Known Member

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    Yes its easy to talk about the finer points of loco design, when all the crew wants is coal = steam = go. and a minor fault in construction takes out that supposed 'edge ' completely. One of the Black 5's in preservation cant remember which, nearly didnt make it as it was a bad'un a 'Poor steamer' ... you could have stuck any draughting you liked on it and it wouldnt have fixed the problem - a hole in the blower pipe...
     
  19. LMS2968

    LMS2968 Well-Known Member

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    5212
     
  20. Pesmo

    Pesmo Active Member

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    Are the CAD drawings of the frame at the bottom of the the 'Design' section of the P2SLC website new ? They say Sept 2012, but I don't remember seeing them before. Its interesting how few parts are the same as the original so even the frame is having a major rework.
     

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