Flying Scotsman

Alan Pegler returned the locomotive to a condition typical of that of a 1930s A3, single chimney, LNER livery and that was all that was required to tick the main boxes. Who wanted to return the engine to A1 condition as Flying Scotsman was in the 1930s? I don't believe this was even mentioned.

There is little problem in returning the locomotive to March '63 external condition. If you think that subjecting the existing frame structure to the impact of the double Kylchap exhaust system is in the long term interest of the machine in spite of historical evidence very much to the contrary that is very much up to you. On the subject of surviving original material, it is highly debatable if any original material was present in 1963.

The engine has a long and complicated history. It would not be without cost to return it to an authentic condition for any period of its working life prior to preservation. Anyone with a streamlined non corridor tender in their back garden, or a GN original 8 wheel? Thought not.

Yes, it is a bit of a mongrel to the purists. But it is known to millions as 4472, that identity that became so established in the 1960s, 70s and 80s. This engine was the first to be completed at Doncaster works after grouping. Does it have any real business appearing in the corpse shroud colours of B.R? Mind you some folk are so B.R. obsessed that they would paint everything in B.R. livery, even if the locomotive were withdrawn from service before nationalisation came about.

 

He made it the best looking loco in the world, and the most famous and most beloved.
I speak as someone who isn't particularly an LNER fan, but knows a stunner when he sees one...
In 'Pegler' condition: World greatest steam loco.
In BR dingy green with ridiculous Teutonic earmuffs: Any old tired end-of-life second rank Eastern region pacific.
Which Hornby version do you think sells better....

(Crimson Lake still rules, though).

 

In your dreams!

Though, you're forgiven for your first comment.

 

My apologies Tom - took you a little bit too literally there! You are right of course.

 

Let's get a bit of perspective here. We are desperately short of working steam locos at the moment. Ian Riley is about to make available a large pacific which he will no doubt attempt to maintain to the same high standards as his two black fives. The loco in question is the only survivor of its class and hasn't steamed for several years. The price to be paid for this is that Mr Riley woud like the engine to run for the initial period of its main line spell in a livery and condition which isn't everyone's cup of tea but which could be changed a few years down the line.

Like you, I wouldn't say the LNER is my favourite of the "big four"companies, but I am very pleased that Scotsman will be re-joining the ranks of main line certified locos. The question of whether it will be 4472 or 60103, is secondary - and I am sure that RTC and Steam Dreams (who wil be running most, if not all the tours during this initial period of main lne operation) would agree with this sentiment.

 

NatPres doesn't like my email address so I was blocked for some time. Regarding the earlier arguments, we are dealing with preserved locomotives that, given their restorations costs, need all the care we can give them. So I myself am not discussing the performance improvements of the thirtees or fiftees but proper treatment in 2015! Since the exhaust improvements I like result
in less effort for identical performance, the load on the locomotive is lessened. After all a larger blast orifice does not stress the driving equipment as much as a smaller one. Regarding the 500 hp improvement of an A3 Kylchap, I am curious for a reference. All I can find is Nock: double chimney A3 equals single chimney A4. Since we are discussing 1500 to 3000(?) hp
performances 500 appears far too much, 50 to 150 would look about right to me.
Kind regards
Jos Koopmans

 

The problem here is that there are several variables. The consequences of changing one depend on how, if at all, the others are changed.

A larger blast orifice means lower back pressure. At a given speed, if the regulator and cutoff settings are changed to produce the same net forces on the pistons, the output power remains the same, while using less steam. That seems good. But it is also possible to use the same amount of steam as before, producing the same forces that side of the pistons. With lower back pressure the net forces on the pistons are then higher, delivering more power but increasing the stresses on other parts. If the improved draughting also allows the boiler to produce more steam, the output power can be more still, at the cost of even higher stresses.

 

I regret that you are, Sir, an ignoramus and a Philistine.

 

A question...
Wouldn't the maximum stresses on a steam locomotive occur as it starts from rest, or is moving very slowly, and therefore be a consequence of cylinder size and boiler pressure rather than efficient draughting? My understanding is that better draughting will help reduce the inevitable decay in tractive effort as speed rises, as well as improving the the boiler's ability to raise steam. The power output would be improved, but the forces would still be lower than from rest.

As an example, didn't the crank axle failures on the P2s occur at very low speeds?

As ever, as a non-engineer I will be happy to be corrected.

Dave

 

Of course you are correct. However, when I write "less effort for identical performance" I mean a larger blast area giving the same vacuum as used before. No extra steam, higher velocities or heavier loads.
Kind regards
Jos Koopmans

 

When we think about this, how many engine classes can be given/were given full regulator from a standing start? The Sandringhams and the King Arthurs are two that I have books referring to, there are references on line to the B7 class being similar.

The correct way to drive a locomotive is with full regulator with power output being tailored by adjusting the cut off. Some readers will be aware of LDP writing about a particularly enlightened driver who removed the regular handle after opening it and controlled the locomotive on the cut off (and brakes, one assumes). Other readers, or maybe some of the same will be aware of DW making sure that drivers could not drive on partially opened regulator.

Back to 4472. LNER engines had valve gear optimised for short cut off working once the company had got to grip with long lap, long travel and valve ring wear. Anyone fancy trying to start a Gresley Pacific away with full regulator? No?
So the force on the piston at starting is not derived from full boiler pressure. But it is pretty close to it when the engine is at work. The somewhat maligned Gresley Pacific chassis is perfectly happy, not the best choice of words, with short cut off working though the original Bulleids are far less so.

An improved exhaust system allows the cylinders to deliver more tractive power because of the reduced back pressure. It also increases the maximum evaporation that the engine is capable of. So, though the cylinders require less steam in order to deliver the same amount of power as prior to the modification, when it comes to the maximum evaporation that the boiler is capable of this is increased. For the same rate of steam consumption as before the new exhaust system the engine produces more power. The new higher evaporation rate can be made use of, providing valves and valve gear permit, to allow the locomotive to deliver more output. Before modification, when climbing grades at speed the locomotive could not be extended beyond say 45%, after modification you can, as they say! put the handle in the oil cans. You get more power, but the chassis has to absorb it. The cylinders, providing lead is sufficient, are withstanding full boiler pressure and the chassis is having to absorb a pulsating output, though three cylinder simples are not the worst in this regard.

The A3s in single chimney form reached their maximum output at about 45mph. The double chimney improved steam flow and evaporation substantially. Static tests with the A3 boiler gave an maximum evaporation of 27,360 lb per hour, though the testing mechanism was not ideal. Indicator trials showed a maximum output of 1700 while working 540 tons at 40mph at 35% cut off. Single chimney A4s were capable of between 2500 and 2600 ihp, double chimney versions could cross 3100. An extra 500ihp for a double chimney A3 does not appear unreasonable.

 

I find it rather amazing that despite that this wonderful loco will steam again there are so many having a hissy fit about its apperance. Hows about the NRM paint 6000 red, 4468 malachite green, 34051 garter blue and 6229 middle chrome green? I understand we all have our favorite colours but a little sense of perspective wouldnt go amiss.

 

I'm just thrilled that FS is returning to steam at this point. The double chimney is not a problem for me. The smoke deflectors are what ruins it.

 

ed w

Mike, they did try running without deflectors and err well unfortunatly they do come as a pair! Even Mr Towend questioned the NRM's wisdom at the time. Why take them off? There was a reason they went on in the first place!

 

I tend to not like deflectors on most locomotives though. There are a few expections though.

 

Yes but the clue is in the name, Smoke Deflectors. They're not there to nake the loco look pretty.

 

Great Scot, the lad's onto something! Run it in BR green numbered 60103 with an ear muff on one side, and apple green without ear muff numbered 4472 on the other ...

Tom

 

Surely this depends whether the TE with full boiler pressure in the cylinders is within what the wheels can deliver without slipping or more than they can deliver. If there is a risk of slipping, then you need to restrict the TE. When the train is barely moving, even a small regulator opening is enough the fill the cylinders. Hence the technique of opening for a moment and then closing again. At low speed not much steam is used anyway, so the advantage of short cut-off for cylinder efficiency isn't an issue, and full cut-off with small regulator opening gives more even TE, so more average TE for the same peak TE.

Some of these recent postings might deserve a separate thread, but some are still specific to Flying Scotsman, and it would be difficult to split them and still keep a coherent discussion.

 

with 60103 and shed plate on the smokebox and 4472 and shed code on the buffer beam?

And can the tender look like different versions on opposite sides?