Nunney Castle

I have had a number of runs with 5029 over the years. My first run with a Castle on the ML was with 5029 on a Past Time excursion to Kingswear & she suffered with steaming problems on the outward run but ran well on the return. On another PT run to Worcester 5029 (running as 7005 & 7007) performed very well with a heavy train (12 or 13 on IIRC). She has also done well when she has been overloaded. On one of the doubleheaders over the South Devon banks with 5051 she had to haul the train on her own
after 5051 failed with a hot axlebox. Nunney did very well on the return until she needed a blowup before Bristol. I was also on the train to Shrewsbury where she was really overloaded. An astonishing performance from 5029 and her crews to get her as far as they did with the load they had on the drawbar. Sadly the brake pump caused problems before she was failed with valve problems.

 

I think people must remember that quite often (in fact, most of the time) it wasn't the loco that "failed" or "steamed poorly", it was in fact crew unfamiliarity. The loco was a very able beast when in the right hands. A trip that stands out to me is The Cornishman in 2011 - that day we nearly stopped on Rattery due to a signal check, but with the A team (Ray Churchill and Dean Morris) the loco accelerated up the bank! Having said that, on the way back (after a crew change) it was a somewhat different story, and let me tell you now that on Hemerdon the needle wasn't necessarily at the better end of the scale...

5043 on the other hand, whilst having a double chimney and increased superheat it also has regular crews from Tyseley that know the engine inside and out, plus the loadings are always sensible. To compare the 2 seems a little unfair.

Also, air pumps tend to give up below a certain boiler pressure too. I'll leave it at that...

 

I was also on the Cornishman. On most of the best runs I have had behind 5029 it has been with the A team.

Edit Just found video of the climb of Rattery in 2011 by Mark Walker -

 

Well, as they are the same class, I think it is quite fair to compare the performance between single and double chimney versions, if only to suggest that the latter seems more capable of pulling things out of the hat at locations not usually graced by the class. However, remembering my one and only run behind 5051 from Swansea to Paddington in 2007, (it was rather tired by that point), it has to be said that 5029 was the better of the two. Stopping to blow up at Patchway and thus causing a 30 minute delay was not exactly conducive to a barnstorming performance from 5051! Those were also the days of Alison 'let's get rid of steam on the FGW network' Forster. Thankfully, more enlightened counsels prevail in that organisation, to the extent that I'll be slightly sad if they don't retain the franchise when it finally comes up for grabs (even if it is a poisoned chalice for as long as electrification causes disruption).

 

Based on the various published logs and associated calculations of horsepower output, there is a quite remarkable difference between the single and double chimney versions. The highest output that I've seen quoted for the former has been in the region of 1,200 - 1,300 hp at the drawbar, whereas 5043 produced almost 2,000 hp on the climb to Ais Gill, with the highest power output being produced after 20 miles of sustained climbing. That's a huge increase in available power compared to the single chimney version. I'd be very interested to know what the highest recorded output by a single chimney version has been, but I'd be surprised if it comes anywhere near The Earl's maximum.

David

 

Are you sure? A 50% increase seems an awful lot for simply fitting double chimney.

 

Spam, you should know the GW lot are prone to exaggeration!

 

7036 Taunton Castle logged by O.S Nock in the 1950's going up Bruton heading towards Westbury 1600 hp 15cars 490 tons tare 535 tons full. Refered to as original form.
5043 the late Mike Notley recorded 2030 hp 470 tons tare/ 503 tons gross on the climb to Ais Gil. Around 69edhph for every square foot of grate.

 

Thanks for this. Even on these figures thats around a 25% increase. That double chimney sure made an improvement.

 

It's not quite as simple as that, you also take into account boiler pressure at the time, cylinder and valve bore size, piston and valve ring fit in bores I.e is one passing steam and not as powerful etc etc

5043 will probably be able to run at a longer cut off when at speed than 5029 as the double blast pipe will exhaust it's steam quicker and hence less back pressure to slow the loco down.

 

I don't see how stopping for a blow up is the fault of a locomotive? Going back to the point I was trying to make earlier... Crew unfamiliarity.

 

Not necessarily. A variety of factors could have been to blame.

 

The rumour on the return was that the firehole doors had jammed during the run through the Severn Tunnel, which meant that once freed, the crew were on the back foot when it came to firing between Pilning and Patchway. Net result- plummeting boiler pressure with a stiff gradient to climb. So you could say it was the engine's fault if that was indeed the case on the day...

 

Insufficient steaming capacity for the power output needed to move the load up the full length of the gradient - any loco can suffer from it, either inherently due to the design, or due to temporary fault on the day - so yes it can be the fault of the loco. Alternatively it could be due to operator error or overload ( a different kind of operator error)

 

I suspect there will also be differences in superheater to take into account?

 

Judging by photos I *think* she's just got a two row superheat boiler so that's an awful lot less superheat than the four row superheat boilers on the double chimney locomotives.

 

From memory 5043 & 7029 are both 4 row, 7027 is 3 row and all the others are 2 row so yes quite a difference.

Further reason why the decay of 7027 is a crying shame.

 

That's incorrect though isn't it? From 5098 they were built with three row superheat boilers.
According to RCTS steam temperature was reckoned at 525F, 580F and 660F. respectively.

Thought: is there current data on oil consumption, which I understand was a good deal higher with the increased superheat, and is the cost significant in modern running in the way it was to the GWR back in the 1930s (apparently it was significant enough to be separated out in the running dept reports to the board).

 

It's not secret GWR are less accepting of dubious quality coal than some others, a prime reason double chimneys came about as single chimney performance pre war was acceptable on quality welsh coal.

That said I'm pretty sure usually having one of Ray Churchill, Ray Poole or Andy Taylor on the regulator and Alistair/Bob Meanley or Dean Morris on the shovel regularly is a help to 5043.