Top Speed of King Class?

[almark]

In comparison on the Torbay Express with 12mk1s 6024 has to be held back at 75-80 on the down grade through Nailsea. Think i'll purchase it so I can understand the loco on RW for myself.

[ChrisBarnes]

I've noticed a general trend where most of the RSC steamers that I've bought, particularly the jubilee, V2, and possibly hall, drive as if they have most power at the lower speeds, and its a damn struggle to get any over 75mph (Green Arrow should easily reach 90mph with 12 Mk1s on the flattish ECML), however they will happily trot up hills and Beattock, even when they are, what I consider, overloaded. I'm guessing the King is probably no different.
Going North, I was testing the TPR Leander with 10 VP Mk1 reskins and a DT Brake as support coach up Beattock, which I'd say is pretty heavy for a 5XP on a 1 in 75, but it never dropped below about 28mph (yet to change the sim file). RSC 4472 was only got a very short run-up to the bottom, hence 30mph when it hit the incline, sustained 55mph with 12Mk1s and reached 60mph at the summit. You'd think I'd be impressed, but I wasn't.

Chris

[windberg]

I have problems with the Kings water injectors. The I, O, K and L keys do not work in the Cornish Riviera scenario sometimes. Do anyone have the same problems?

And general I think the RW steam engines use much to less water. I.e. the King is a water wonder.

[FoggyMorning]

And general I think the RW steam engines use much to less water. I.e. the King is a water wonder.

As we are in for a drought I think RS.com are just doing their bit for water conservation!

[Kariban]

I've noticed a general trend where most of the RSC steamers that I've bought, particularly the jubilee, V2, and possibly hall, drive as if they have most power at the lower speeds, and its a damn struggle to get any over 75mph (Green Arrow should easily reach 90mph with 12 Mk1s on the flattish ECML), however they will happily trot up hills and Beattock, even when they are, what I consider, overloaded. I'm guessing the King is probably no different.
Going North, I was testing the TPR Leander with 10 VP Mk1 reskins and a DT Brake as support coach up Beattock, which I'd say is pretty heavy for a 5XP on a 1 in 75, but it never dropped below about 28mph (yet to change the sim file). RSC 4472 was only got a very short run-up to the bottom, hence 30mph when it hit the incline, sustained 55mph with 12Mk1s and reached 60mph at the summit. You'd think I'd be impressed, but I wasn't.

Chris

I've been poking at steam engines recently - I think they suffer a bit from the same constant-speed thing the diesel hydraulics do to some extent. The Jubilee is a 6XP btw and I wrote a Beattock scenario for it, 12+dead 47 and you tend to go over the top at 20mph in almost full gear if you keep everything perfect, which if it could make it at all - I think it's the equivalent of a 37 so I guess it's possible although really it'd probably just slip to a stop - is probably not too unreasonable. Beattock isn't actually all that steep ( compare it to Rattery or something! ), it's just quite long.

There's two basic factors with steam engines, boiler output and adhesion - pretty much any steam engine can produce enough torque to break adhesion. Top speed ( on the flat ) arrives when the drag of the train crosses the amount of force the engine is producing at the biggest cutoff you can use for the steam output for the boiler. The relationship between cutoff and force is roughly linear for walschaerts gear - it isn't really because of back pressure issues so force drops off faster with bigger cutoffs but we can't do anything about that - so the place to start looking if you think it's overperforming in a certain speed range is the cutoff graph. I am trying to make it a straight line but keep running into aerodynamic walls - the train gets to a certain speed and then just stops accelerating instead of tailing off - so I'm not sure you can really get away with that yet. It's helpful to make the TEvsSpeed graph a straight flat line though and work from there.

So, the King - I have it, not driven much, and I do have to say it does not perform like I'd expect it to. No it isn't a Castle, but capping out at 60ish mph with the amount of steam it uses at that speed is like it having a fairly bad steam leak somewhere. I would probably start by copying the TE/Speed graph over from the Jubilee and then restraining it elsewhere if that makes it a bit fast. The freeware one is a bit far the other way really.

[bigvern]

Does the King exhibit the same "cap" on low boiler pressure as the German loco? This means no matter how hard you work the thing, it never runs out of puff and keeps going even though in reality there would be insufficient pressure to move the pistons or to keep the vacuum up.

[chrisreb]

I thought the excellent freeware one represents an improved double chimney King which I understood gave better performanceertainly from a trip last year behind KE I and 13 on suggests the double chimney King is much more powerful than the RSC one.

[Oldpufferspotter]

The Jubilees were 5XP indeed in my day! The LMS cassified the Black5 as 5P5F, the Jubilee 5XP, the Royal Scots 6P and the Duchesses 7P.
I believe it was BR who upped the Scots to 7P and the Pacifics to 8P. But to my workmates on the railway in the 1950s Jubilees were always 5XP. (I know a bit off topic, but there are a lot of misconceptions going around these days.)
regards Ted.

[stuart666]

I thought the excellent freeware one represents an improved double chimney King which I understood gave better performanceertainly from a trip last year behind KE I and 13 on suggests the double chimney King is much more powerful than the RSC one.

Exactly. People are comparing King George V or King Edward 1st on railtour in the 21st Century with the King as built in the 1920s. There were a considerable amount of work make on redraughting them in the 1950s, which made them rather more powerful than the version RSC have modelled. Indeed I looked at performance logs of the down Cornish Riviera in the late 30s, and whilst there were spikes into the 70s and 80s when going downhil, the majority of the run was at around 65mph. So I dont think RSC are far wrong. Where I think it could do with tweaking is boiler output (which is difficult to keep under control) and I think the Centenary carriages are a bit draggy. It would be interesting to compare performance with Gordons Colletts when they become available.

Even single Chimney King Edward II will be more powerful than this version, because there was some work on superheaters at Swindon in the late 40s if memory serves.

[Kariban]

The Jubilees were 5XP indeed in my day! The LMS cassified the Black5 as 5P5F, the Jubilee 5XP, the Royal Scots 6P and the Duchesses 7P.
I believe it was BR who upped the Scots to 7P and the Pacifics to 8P. But to my workmates on the railway in the 1950s Jubilees were always 5XP. (I know a bit off topic, but there are a lot of misconceptions going around these days.)
regards Ted.

Interesting - although you have to wonder what the difference between 5XP and 5P5F is ( and also why you even need a complicated 3cyl engine if it doesn't offer any gross advantage over a 2cyl one ).

Stuart, how many tons on that CR run? half a dozen slip coaches still attached or no? the issue I have with the RSC one is it's not doing the work it's steam production ( and fuel use ) would seem to imply. And well, did it keep time or was it running early? speed restrictions? redraughting would have made a noticeable difference, but the extra superheater advantage would be taken up by the poorer quality coal.

Hook it up to a bunch of Mk1s if you want a reference, I'd imagine most people use the default ones as a performance reference point.

[Rockdoc2174]

Interesting - although you have to wonder what the difference between 5XP and 5P5F is ( and also why you even need a complicated 3cyl engine if it doesn't offer any gross advantage over a 2cyl one ).

The Jubilee was smoother, more powerful and faster for a given speed of the driving gear because they had 6ft 9in drivers compared to the B5's 6ft 0in ones. The tractive efforts weren't all that different:

Jubilee - 26,610lb
Black 5 - 25,455lb.

The difference must have been significant, though, because the load limits for the S&C (in UKTS 1347) show that a Class 5 could take 310t from Carlisle to Ais Gill, a 5X 350t and a Class 6 405t. With coaches weighing, roughly, 35t gross that's about one coach more for a 5X over a 5 and two more over a 5X for a 6.

For comparison, the Kings had a TE of 40,300lb and 6ft 6in drivers, a Merchant Navy 33,493lb and 6ft 2in drivers, Princess Coronations 40,285lb and 6ft 9in drivers and the A4 35,455ln and 6ft 8in drivers, details being taken from a 1964 Observer's book. The 1955 Observer's gives the same figures for the Kings but adds "Have done the Paddington to Bristol run of 117.5 miles in 100 minutes quite easily and have been credited with reaching 100mph." The last bit suggests that such speeds were quite uncommon and the first suggests that a cruising speed of about 70-75 would be ample. Googling The Bristolian brings up a page (http://www.greatwestern.org.uk/m_in_gwr_services.htm) saying that the normal load for this train was 7 coaches of 220t tare, which is not a particularly heavy load for such a powerful engine.

Keith

[Kariban]

Right, 5X is a 5-and-a-half sort of thing. Having three cylinders is some advantage when you're moving volumes of fluids around too. The boilers look much the same though, which is the ultimate limit on power ( although the Jubilee was perhaps a bit more efficient at using the output ). But still, not a huge advantage over the B5 really.

The MN figure surprises me, with it's boiler pressure, unless that was a rebuilt one.

[Rockdoc2174]

As-built MN TE was 37,515lb.

Keith

[stuart666]

The Jubilees were 5XP indeed in my day! The LMS cassified the Black5 as 5P5F, the Jubilee 5XP, the Royal Scots 6P and the Duchesses 7P.
I believe it was BR who upped the Scots to 7P and the Pacifics to 8P. But to my workmates on the railway in the 1950s Jubilees were always 5XP. (I know a bit off topic, but there are a lot of misconceptions going around these days.)
regards Ted.

Interesting - although you have to wonder what the difference between 5XP and 5P5F is ( and also why you even need a complicated 3cyl engine if it doesn't offer any gross advantage over a 2cyl one ).

Stuart, how many tons on that CR run? half a dozen slip coaches still attached or no? the issue I have with the RSC one is it's not doing the work it's steam production ( and fuel use ) would seem to imply. And well, did it keep time or was it running early? speed restrictions? redraughting would have made a noticeable difference, but the extra superheater advantage would be taken up by the poorer quality coal.

Hook it up to a bunch of Mk1s if you want a reference, I'd imagine most people use the default ones as a performance reference point.

I forget, though I seem to recall it had already dropped at least one maybe two. The most interesting thing is that from the data existing is that the speeds were lowest of all after it dropped the slip coaches. Though Devon is not exactly suited for high speeds, or at least back then. Suffice to say high speeds were not being held for long, which gives the impression the boiler was being morgaged.

Tried the Mk1s. Top speed on the flat with about 10 Mk1s on was about 75mph which strikes me as not too bad. Problems are the Centenary stock is about 10 mph slower which is what is confusing people. It was a bit draggy, but I wouldnt expect it that bad. Adjusting the carriages and its quite possible to get a heavy consist of Centenaries up to 75mph, and pretty good it looks too.

As for the boiler im tempted to prat around with it and discover what exactly is wrong with it, but suffice to say I dont think its a very hard fix. Just adjusting boiler efficiency would probably do it. And of course your multiple safety valve mod woudl help.

Bear in mind, it was only the lead Kings that had 40000lbs tractive effort. The GWR did it to win the tractive effort war. Afterwards they made some adjustments and I think they only did 37000lbs tractive effort if memory serves.

Suffice to say I think for a GWR king of that period is not so far wrong as believe. They were not really any better than a Castle till the 1950s, and even then its not like Castle development was standing still.

[Kariban]

Devon is 60mph everywhere past Exeter even now, that might have something to do with it...