Top Speed of King Class?

[stuart666]

Yeah, shoot the fireman. He is an inferior specimen from one of the 'other' grouped companies. To simulate the heroic work of an average GWR fireman, you have to do it yourself.

Thought you would like that one mate. In actual fact I do the LMS a disservice. You needed to be Geoff Capes in order to keep the firebox of a Princess Coronation stacked up when running up shap or the S and C. I digress....


Which actually neatly brings me to another point, its not just steam flow that is the key to speed of the locomotive in real life, its the weight of the vehicle. I note that in one recent book on the Princess Coronation class it was revealed at least one of the number went above 100mph without the driver noticing. It was in the dark hauling a very heavy wartime sleeper train, and it partly ran away on him without him being aware. He discovered he was doing a ton without any apparent ill effects. If there was above average usage of steam doing it, you cant help but think he would have noticed the poor fireman bringing on a heart attack.

I dont think Railworks calculates things entirely like that. It uses a formula based primarily on drag and friction, which still applies going downhill sometimes. I dont criticize that I might add, I just make the point with that criteria, achieving accurate performance is always going to be a bit of a task.

Bear in mind in terms of tractive effort, it was only the first few (Perhaps even one?) Kings that had the 40,000lb tractive effort. I gather after they made their point to the Southern Railway they had changes made (I vaguely recall they had the cylinders slightly downsized) which brought it down to a still not inconsiderable 37-38000lb tractive effort. So other than tractive effort, they really were not really any more powerful than a Castle of that period, though perhaps the distinction ought to be made between power and sustained power. Castle was quite good for short periods, but then you had to pay the boiler back. I gather the King was perhaps better in that regard, but it was never comparable to the other grouped locomotives until postwar. At least in my opinion anyway.

Collett nearly built the king with the same wheel diameter as a 4300 mogul after seeing the castle he was riding in overtaken by one. Now that would have been interesting, rather like a Grange on steroids I would have thought.

[rivimey]

I thought this article, from Rail UK was instructive. While the peak 40,000 was only kept for a while, many of the first batch of Kings had it, and the loss was only back to 39,700lb. I expect this was to reduce the hammerblow on the track somewhat (having proved they could do it!).

The boiler was the biggest yet built at Swindon and was never used on any other class. With 250lb pressure and four 16in by 28in cylinders the tractive effort worked out at 39,700lb. At this point management stepped in, and for publicity purposes, requested over 40,000lb to substantiate another most powerful locomotive claim. The cylinder diameter was therefore increased to 16.25in, giving 40,300lb tractive effort. However, when they were re-cylindered during the course of their service, the extra quarter inch was dropped. Other features were an increase of one inch in piston valve diameter to 9in and 6ft 6in coupled wheels, this being the first departure in a GW express engine from Churchward's 6ft 8.5in.

In the production of a locomotive of more than 40,000 pounds tractive effort on a 4-6-0 in chassis, the Swindon drawing office had achieved a masterpiece of design and the performance of these locomotives very soon showed that the tractive force was no theoretical figure only to be realised in the most favourable circumstances.

At this stage it is enough to state that the advance in tractive effort over the Castle was achieved in four ways:

Boiler pressure increased from 225 to 250 p.s.i.
Driving wheel diameter reduced from 6ft 8.5in to 6ft 6in.
Cylinder diameter increased from 16 to 16.25in.
Piston stroke increased from 26 to 28 inches.
The boiler was a very carefully designed enlargement of the classic Churchward Swindon No. 1 Standard, having in the new designed a grate area of 34.3 square feet.

The large cylinders brought a clearance problem between the inside pair and the leading bogie. This was overcome by shaping the bogie frames so that the rear axle boxes were inside the frames but the front ones were outside. This became a very notable characteristic of the King class and was necessary to give adequate clearances on curves.

It was in 1947 that Hawksworth fitted No. 6022 with a four-row superheated boiler and mechanical lubricator with some improvement in performance. No. 6015 appeared in September 1955 with a double blast pipe and chimney. The performance of this loco was superb, resulting in the whole class receiving the modification, plus new cylinders, new frames, valve gear and motion parts. It was in this condition that the Kings gave their finest performances.

I haven't yet found any revised performance characteristics for Kings in the 1955+ state.

Ruth

[Kariban]

Which actually neatly brings me to another point, its not just steam flow that is the key to speed of the locomotive in real life, its the weight of the vehicle. I note that in one recent book on the Princess Coronation class it was revealed at least one of the number went above 100mph without the driver noticing. It was in the dark hauling a very heavy wartime sleeper train, and it partly ran away on him without him being aware. He discovered he was doing a ton without any apparent ill effects. If there was above average usage of steam doing it, you cant help but think he would have noticed the poor fireman bringing on a heart attack.

I dont think Railworks calculates things entirely like that. It uses a formula based primarily on drag and friction, which still applies going downhill sometimes. I dont criticize that I might add, I just make the point with that criteria, achieving accurate performance is always going to be a bit of a task.

Weight of the train, weight of the engine itself won't make any *specific* difference. RW uses weight for resistance on hills just fine, they seem to use basic real life physics equations for all this which is perfectly fine. Perhaps they could have modelled stiction ( and of course the adhesion is screwy ) and the effects of wind are missing, but the laws of mechanics have been refined over centuries, why not use 'em

I suspect there's far too much effect from whatever RW uses for back-pressure, after trying to get some more speed out of the RLP without making it excessively powerful. That's one of those funny things that was added later I suspect.

Bear in mind in terms of tractive effort, it was only the first few (Perhaps even one?) Kings that had the 40,000lb tractive effort. I gather after they made their point to the Southern Railway they had changes made (I vaguely recall they had the cylinders slightly downsized) which brought it down to a still not inconsiderable 37-38000lb tractive effort. So other than tractive effort, they really were not really any more powerful than a Castle of that period, though perhaps the distinction ought to be made between power and sustained power. Castle was quite good for short periods, but then you had to pay the boiler back. I gather the King was perhaps better in that regard, but it was never comparable to the other grouped locomotives until postwar. At least in my opinion anyway.

That I find a bit odd - GWR crews were meant to keep boiler pressure up because the superheaters were not so good, letting it drop enough where you have to actually pay it back I'd have imagined would have been a bit frowned on...

Anyway power is a function of tractive effort and speed - if you can sustain the same tractive effort at a higher speed ( or a higher TE at the same speed ) then you've got a more powerful engine. In a steam engine, that's basically how much steam you can get the boiler to produce.

[stuart666]

Which actually neatly brings me to another point, its not just steam flow that is the key to speed of the locomotive in real life, its the weight of the vehicle. I note that in one recent book on the Princess Coronation class it was revealed at least one of the number went above 100mph without the driver noticing. It was in the dark hauling a very heavy wartime sleeper train, and it partly ran away on him without him being aware. He discovered he was doing a ton without any apparent ill effects. If there was above average usage of steam doing it, you cant help but think he would have noticed the poor fireman bringing on a heart attack.

I dont think Railworks calculates things entirely like that. It uses a formula based primarily on drag and friction, which still applies going downhill sometimes. I dont criticize that I might add, I just make the point with that criteria, achieving accurate performance is always going to be a bit of a task.

Weight of the train, weight of the engine itself won't make any *specific* difference. RW uses weight for resistance on hills just fine, they seem to use basic real life physics equations for all this which is perfectly fine. Perhaps they could have modelled stiction ( and of course the adhesion is screwy ) and the effects of wind are missing, but the laws of mechanics have been refined over centuries, why not use 'em

I suspect there's far too much effect from whatever RW uses for back-pressure, after trying to get some more speed out of the RLP without making it excessively powerful. That's one of those funny things that was added later I suspect.

Bear in mind in terms of tractive effort, it was only the first few (Perhaps even one?) Kings that had the 40,000lb tractive effort. I gather after they made their point to the Southern Railway they had changes made (I vaguely recall they had the cylinders slightly downsized) which brought it down to a still not inconsiderable 37-38000lb tractive effort. So other than tractive effort, they really were not really any more powerful than a Castle of that period, though perhaps the distinction ought to be made between power and sustained power. Castle was quite good for short periods, but then you had to pay the boiler back. I gather the King was perhaps better in that regard, but it was never comparable to the other grouped locomotives until postwar. At least in my opinion anyway.

That I find a bit odd - GWR crews were meant to keep boiler pressure up because the superheaters were not so good, letting it drop enough where you have to actually pay it back I'd have imagined would have been a bit frowned on...

Anyway power is a function of tractive effort and speed - if you can sustain the same tractive effort at a higher speed ( or a higher TE at the same speed ) then you've got a more powerful engine. In a steam engine, that's basically how much steam you can get the boiler to produce.

Well any locomotive is going to consume more steam than its producing in some parts of its run. Either pulling away or trying to make up time after a stop. In those circumstances the Castle was very good indeed. Its been suggested the real indication of a locomotives power is the size of its firebox, and in the respect the Castle was comparable with much larger boilers.

However it did have a shorter boiler than originally considered (I gather that had been an intention to reuse the 4700 boiler which turned out to be too heavy) and from what OS Nock has suggested, this translated in less sustained steam output than what the King was able to produce. How accurate that assertion Is, is debateable. For example, a Castle was switched onto the Bristolian post because it was discovered they were entirely able to sustain the speeds of the King hauled service. I also know that there is one claim that a Saint prewar actually beat the best time for the Castle hauled Cheltenham flyer, which most people would tell you ought to be impossible.

Equally I will say that there havent been many Castles that have made it over the Settle and Carlisle. Perhaps signficantly the only one that has, Earl of Mount Edgecumbe, is a double chimney variant maintained at an absolutely superb condition by Tyseley. Locomotive condition can count for an awful lot.

What does all this tell us? Not much. Just that in theory a King was able to sustain performance longer than a Castle. That a Saint was still putting in superb performances in the 1940s and early 50s perhaps shows how little GWR locomotive design had moved on since the 1900s, or indeed, how little it actually needed to.

Id like to see further elaboration on the integers of steam locomotive performance in Railworks, but in fairness, most of them wouldnt be useable without a full size steam locomotive performance editor to go with it. Is it worth their investing in such elaborations? Probably not.

[Makeone]

Did i understand it correctly, King's (and probably others as well) had 4 uniform cylinders? Ie. no compounding at all? Altho after reading wikipedia's entry of the compounding, there wasn't many british engines mentioned, one notoriusly known was obviously Webb Compound 0-8-0, also remembered from orginal Railroad Tycoon. Kinda odd after all, it was United Kingdom where compounds were found...

[Rockdoc2174]

Compounds were rare on British railways. I believe it was partly down to the loading gauge, which made fitting appropriately-sized cylinders tricky, but also because they work best on long runs and those are not common on our metals.

Keith

[Kariban]

Yeah, compounds went out of favour pretty early in the C20. Churchward tried some french compounds & didn't find any advantage over the Star class, so that was the end of that on the GWR. Stanier was a GWR man, so that was that for the LMS

Probably the best known British one would be the Midland compound, that was pretty much a standard class for a while.

[Springer6]

I don't understand why the RSC King's auto fireman is being maligned. I've always used auto fireman as I prefer to look at what's around me. I've just taken the RSC King from Reading to Paddington at a consistent 78.9 mph hauling 12 Mark1's. Regulator 100% Reverser 36% Running 23% and boiler pressure a stable max of 249.8. An admirable performance for a GWR King which lags considerably behind the kind of performances achieved on the East and West Coasts.

Have you enabled the dampers with the 'M' key? They are 'off' by default on my installation and a considerable performance boost will be achieved by enabling them. Actually I find the RSC KIng great fun to drive as it's performance seems virtually spot on to me, considering the above performance is what I usually achieve with the King on level terrain and 12 Mark 1's

Mark

Mark,

I now agree with you. Having tried the manual fireman and failed miserably ( certainly my fault through lack of experience) , I decided to give your settings a try.

I went back to the auto fireman as he certainly couldn't do a worse job than me ( and I like to enjoy the scenery without all that hard work)

I was intrigued by your brake "running" setting of 23%. My normal practice, which has served me well up to now was to run at the minimum "running " setting ( usually around 7-9% ) for most locos.

The King certainly needs a much higher brake setting than this. Once I went to minimum 23% ( and it will run with up to 30% before "Hold" ) the steam generation rate shot up and it's relatively easy to maintain max boiler pressure.

On the default scenario "Cornish Riveria Ltd" I was able to get the King up to around 67 mph on the flat under the wires near Langley ( 100% Reg. and 30% cut off ). I even arrived nearly 2 minutes early at Paddington, so there was a sustained high ( mid 60s ) speed throughout. This was with the 10 Cetenary carriages, which certainly drag quite a lot more than Mk1s.

Maybe this performance is now fairly typical for the pre-war King ? I don't consider it blistering considering it was on Brunel's "bowling green" and it would probably be a poor performer slogging up Beattock on the WCML, but then again that's not what it was designed for.
I have yet to try it on "South Devon Banks" up Dainton Bank, I fearit might struggle ?

Anyway, thanks for the tip, I will certainly be using the maximum running brake setting on this loco in future.

[FoggyMorning]

I don't understand why the RSC King's auto fireman is being maligned. I've always used auto fireman as I prefer to look at what's around me. I've just taken the RSC King from Reading to Paddington at a consistent 78.9 mph hauling 12 Mark1's. Regulator 100% Reverser 36% Running 23% and boiler pressure a stable max of 249.8. An admirable performance for a GWR King which lags considerably behind the kind of performances achieved on the East and West Coasts.

Have you enabled the dampers with the 'M' key? They are 'off' by default on my installation and a considerable performance boost will be achieved by enabling them. Actually I find the RSC KIng great fun to drive as it's performance seems virtually spot on to me, considering the above performance is what I usually achieve with the King on level terrain and 12 Mark 1's

Mark

Mark,

I now agree with you. Having tried the manual fireman and failed miserably ( certainly my fault through lack of experience) , I decided to give your settings a try.

I went back to the auto fireman as he certainly couldn't do a worse job than me ( and I like to enjoy the scenery without all that hard work)

I was intrigued by your brake "running" setting of 23%. My normal practice, which has served me well up to now was to run at the minimum "running " setting ( usually around 7-9% ) for most locos.

The King certainly needs a much higher brake setting than this. Once I went to minimum 23% ( and it will run with up to 30% before "Hold" ) the steam generation rate shot up and it's relatively easy to maintain max boiler pressure.

On the default scenario "Cornish Riveria Ltd" I was able to get the King up to around 67 mph on the flat under the wires near Langley ( 100% Reg. and 30% cut off ). I even arrived nearly 2 minutes early at Paddington, so there was a sustained high ( mid 60s ) speed throughout. This was with the 10 Cetenary carriages, which certainly drag quite a lot more than Mk1s.

Maybe this performance is now fairly typical for the pre-war King ? I don't consider it blistering considering it was on Brunel's "bowling green" and it would probably be a poor performer slogging up Beattock on the WCML, but then again that's not what it was designed for.
I have yet to try it on "South Devon Banks" up Dainton Bank, I fearit might struggle ?

Anyway, thanks for the tip, I will certainly be using the maximum running brake setting on this loco in future.

That's interesting about using a relatively high value for the running brake position. I too generally use the lowest possible setting for this - I'll have to experiment some with a higher value

[stuart666]

Bear in mind, GWR brakes are off at 25, so if you have anything less than this it may explain why its hard to get any speed out of it.

Yeah 67 is about top with those carriages. If you swap them out with Mk1s you will do rather better. Should be ok on South Devon banks, just keep the steam pressure up and as said, make sure the dampers are full open.

[black8]

This is interesting info about the Kings 'running' settings and GWR brakes being off at 25. Need to try that. I am a bit puzzled though by the 100% regulator setting. You mean full regulator all the way or only up hill?

And btw, what are dampers doing again? Default in the sim is closed?

[Kariban]

Regulator *should* be full ( or half but I don't think that's modelled properly ) open, adjust the reverser to get your cruising speed and then adjust the fire to stop overproducing steam. Dampers control the airflow into the fire which controls how quick it burns and how hot it is, which effects how much you need to fire and how much steam you make.

[stuart666]

This is interesting info about the Kings 'running' settings and GWR brakes being off at 25. Need to try that. I am a bit puzzled though by the 100% regulator setting. You mean full regulator all the way or only up hill?

And btw, what are dampers doing again? Default in the sim is closed?

Basically open they allow air to get into the firebox and aide combustion. They are set in off which I quite like. They probably would be like that in a station if you wanted to try and keep steam production down. But they need to be set to full on when trying to make up steam. May be worth setting to halfway if you are trying to balance steam output at speed. Bear in mind, it does take a few minutes to start having a noticeable effect.

GWR regulators did have intermediate positions, ive certainly seen some records indicating positions such as 75 or 35 percent. But usually to get the best output, they put the regulator to 100 percent and set the speed of the locomotive on the reverser. Though clearly they didnt work to well with pole reversers, like in the 56xx.

[ttjph]

For those who are interested in such things, there's lots of technical stuff at the 5AT Project website, including these:

http://5at.co.uk/index.php/modern-steam ... ffort.html
http://5at.co.uk/index.php/definitions/ ... power.html

[Kariban]

GWR regulators did have intermediate positions, ive certainly seen some records indicating positions such as 75 or 35 percent.

That King dyno run you had was all 100% or 50% or 0% ( aside from starting off, when you're trying not to throw the fire up the chimney ), which matches the regulator valves & makes sure you've never got a partly open regulator - it's effectively two regulators in one, so no partial valve openings. While I'd imagine that was a crew performing their special best, I can't really imagine many situations where you wouldn't either be at one of the two full open positions or coasting. It's surprising how much time you can spend coasting.