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Tornado

Discussion in 'Steam Traction' started by Leander's Shovel, Oct 20, 2007.

  1. 35B

    35B Nat Pres stalwart

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    For this non engineer, what are the issues?


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  2. 242A1

    242A1 Well-Known Member

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    The American Association of Railways rules are regarded as the best set of rules that we have available for us to use. You must remember that the Phillipson and English book Steam Locomotive Design: Data and Formulae was first printed in 1936 and it looked at practice from the UK up to that date. In 1941 the N & W produced the Class J which regularly hauled trains at over 100 mph with driving wheels only 5' 10" in diameter and with their lightweight motion made from Timken High Dynamic alloy steel and good attention to the design of the balancing it was calculated that speeds up to 140 mph could be reached without rail damage. I admit to frequently referring to this design but it was and remains an outstanding example of the U.S. 4-8-4 type. Chapelon produced the rebuild that was classified as 242A1 in 1946, his experimental 160-A-1 appeared in 1940. In 1948/9 a metre gauge Pacific was rebuilt by a young man in his mid 20s. With a driving wheel diameter of 4' 2" this machine had a design speed of 120 kmh, This was a four cylinder compound design weighing 68 tons and with an adhesive weight of 54 tons.This machine produced a drawbar horsepower of 2120 and the tractive effort figure given by established formulae gives a figure far in excess of any UK non articulated locomotive (54,635 lbf).

    Phillipson is useful, but is of far less value when considering locomotives developed after 1936 and a great deal happened after that year. It appears that no one thought about creating a new and revised edition which included the many advances made after its date of publication. Things moved on with better design techniques, better materials and new ideas, you can find them and apply them, they have pretty well all been tested but you won't find them in the book that you are referring to.
     
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  3. 242A1

    242A1 Well-Known Member

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    There aren't any so long as you understand the rules and can design accordingly. If you only use what might be termed as outdated and superseded rules your design will reflect the limitations of those rules. Use a set of guidance rules from the 1930s and you will get a 1930s locomotive which is fine if that is what you want to build however modern regulations won't let you do that, you will have to make some compromises.
    Thinking when it comes to locomotive design does change. An example is driving wheel diameter, there was a time when wheels around 8' were felt to be necessary for express running, now we can go faster than the Stirling Singles with wheels 5' in diameter. Just a simple example but there are a numbers of factors involved in driving this change. The steam locomotive is not really all that simple.
     
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  4. Big Al

    Big Al Nat Pres stalwart Staff Member Moderator

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    As we are talking about Tornado on this thread, let's acknowledge that this locomotive is noted for its water efficiency that I understand is better than the class average used to be, so that must be down to improved design. In common with all main line steam, it also operates in not the most ideal of circumstances with plenty of stop/stop running yet it is capable of putting in about 120 miles between top-ups without too much difficulty. So it is correct to say that loco design can evolve over the years for the better. When the Bulleid Pacifics were redesigned by Ronald Jarvis, the steaming capabilities of the boiler were carried over into the rebuild as a more serviceable locomotive was created. But as far as speed is concerned, I have always understood that there are applied mathematics and mechanics at work here and any discussion about speed will always come back to what may be physically possible and also what is sensible given the nature of the unconventional life that these locomotives have to lead.

    My personal view is that whilst speed may be of interest, what is far more important for the timely operation of steam on the network is the range of a locomotive between the stops to refuel with water, and with coal.
     
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  5. Jamessquared

    Jamessquared Nat Pres stalwart

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    The obvious issues would be that for a given locomotive, hammer blow will scale with the square of the rpm (so 540 rpm would be more than twice as bad as 360); frictional resistance and heating would go up, which puts more demands on lubrication; then there is the issue of whether the steam can get in and out of the cylinders given shorter time that the valves are open.

    @242A1 makes much of the (unrealised?) possibilities later steam locomotive design. But we aren't talking about that: the discussion is about what are appropriate limits for the locos we have in operation on our network in 2020, not locos that don't exist.

    Tom
     
  6. Jamessquared

    Jamessquared Nat Pres stalwart

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    My own hunch is that trying to run closer to a constant power output is probably better than trying to run at closer to constant speed. (So, within reason, slow down on climbs and then run a bit on the descents). But I suspect the timing fraternity may not agree!

    Tom
     
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  7. Steve

    Steve Resident of Nat Pres Friend

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    In many ways you are probably right; it would certainly be true of the boiler (and fireman.) However, the steam locomotive consists of both a boiler and an engine and the latter is much more of a constant torque machine, as long as you can get the steam into and out of the cylinders. Thus, the power will increase as the speed increases. It is at its peak when the boiler and the engine are matched.
     
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  8. Jamessquared

    Jamessquared Nat Pres stalwart

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    I have a singular view in such matters! ;)

    Tom
     
  9. Steve

    Steve Resident of Nat Pres Friend

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    As Tom has said in his post, this discussion originated around the subject of maximum speeds for the steam locomotives we are currently operating and Tornado in particular. It is not a theoretical treatise on what might be achievable if all the wonders of modern technology were thrown into its design.
     
  10. Big Al

    Big Al Nat Pres stalwart Staff Member Moderator

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    Some of the timing fraternity probably will agree! The Top Gear run in 2009 was the start of a period when the A1ST tried to break all records with Tornado - Drumochter, Shap, Ais Gill etc - you get the drift. After taking water at Berwick we blasted up to Grantshouse at a little under 70 and then had to drag the brakes down to Dunbar to keep close to the 75 limit. It was the most inefficient way of getting to Edinburgh quickly and all brought about by an overriding speed limit that did little for efficient running and made for a curious log.
     
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  11. MellishR

    MellishR Resident of Nat Pres Friend

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    It is however relevant to how fast Tornado should be allowed to run in which circumstances, e.g. up- and downhill, regularly or occasionally.
     
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  12. guycarr360

    guycarr360 Part of the furniture

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    You would think letting her run up to 85mph downhill, would make retaining speed uphill or on the level so much easier, and make pathing easier.

    In that case its a no brainer, or, the level of extra maintenance does not make it worthwhile???
     
  13. Bikermike

    Bikermike Well-Known Member

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    Re-built Bulleids were doing the ton until 1967 with limited maintenance, so I think the formula might be best treated as guidance, not the end. Surely, it has to be about maximal allowable forces on the tracks, which is about weight of motion, balance etc.

    With Tornado running poppet gear, does it have less metal rotating about the place, and so have a lower hammer blow?
     
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  14. Kylchap

    Kylchap Member

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    Some time ago, but well after the Ebor Flyer, I asked a very senior person in A1SLT if Tornado still retained its clearance to run at up to 90mph. The answer was "Yes". If this remains the case, it may be possible for things to quietly happen along the lines that @guycarr360 suggests. It was stated at the recent virtual convention that the loco will be maintained with 90mph capability in mind.
     
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  15. Big Al

    Big Al Nat Pres stalwart Staff Member Moderator

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    That surprises me. Other locos have been restricted for far less. Take for example when Sir Lamiel threw its fire all over the ECML. That cramped its style in the eyes of Network Rail quite a lot. I would be amazed if Tornado could operate again at up to 90 without a test. I suggest that a good starting point might be to give it a path where it was required to run for a sustained period at 75 mph. Stevenage to Grantham in 65-70 minutes comes to mind.
     
  16. Johnb

    Johnb Nat Pres stalwart

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    Back in 67 it didn’t matter how many engines they broke though
     
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  17. guycarr360

    guycarr360 Part of the furniture

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    Track standards have vastly improved as well, since then???
     
  18. Bikermike

    Bikermike Well-Known Member

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    That is a double-edged sword I suspect - diesels and electrics will have no hammer blow (honourable exception for the 08), so modern standards may not cater for it (I suspect that steam engines make use of the flex in the track, with heavier section rail and closer sleeper spacings, you will get less flex. Then there's slab track...)

    P.S. my reference to Tornado having poppet gear is a mistake - I meant the P2
     
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  19. Bikermike

    Bikermike Well-Known Member

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    Presumably even then it was frowned upon to fail en route?
    But yes, OK, back to say 1965?
     
  20. Johnb

    Johnb Nat Pres stalwart

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    I don’t recall many failing en route. They did get a few Brush Type 4s towards the end and from what I remember, their reliability was a bit questionable
     

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