Realise a proposed British steam engine

Quite true of course, so presumably that penalty would have had to be accepted when anything larger than the largest British Pacifics was being contemplated; for instance an LMS 4-8-2 that has been mentioned somewhere on here.

 

Why does it always have to be big stuff? (says he who mentioned the LYR 2-10-0 design!)

Stanier suggested a lighter 4-6-0 for Scotland early in his time at the LMS, but bridge strengthening made this idea redundant

 

If you want to discuss smaller locomotives, bring it on!

 

Shorter tubes might reduce the resistance to flow a little but care is needed to select the appropriate tube diameter to length ratio to limit heat loss up the chimney. The combustion chamber does not help with the area of the boiler barrel and it is only possible to fit a certain number of tubes into a barrel of a given diameter. Too many tubes will restrict the water flow around them and/or restrict the height over the firebox crown.

Sent from my SM-A105FN using Tapatalk

 

I've always thought the Highland "River" / Caley "938" would've been a superb starting point. Aside from the short travel valves, a strikingly modern native Scottish design. Very good looking too, IMO.

 

You are not the first to raise that question. Too many locomotives suffer from poor design. The specific fuel and water consumption figures are too high and so they need a larger boiler than would be necessary otherwise. The boiler in question, as well as being hampered by poor design decisions, is frequently restricted by poor exhaust system design. If 2120 dbhp can be obtained from a metre gauge of locomotive weighing 68 tons in working order this points to the need to design and build better locomotives and not larger ones.

 

As a supporter and monthly doner to the Patriot project I was a bit disappointed that they didn't go for an improvement in boiler design. The small tubes were recognized by Powell (and Langridge?) as being slightly too large in diameter, meaning that when working at full power gases would take the easier route through them instead of through the superheater flues. However I guess that would have meant more design and certification costs.

Dave

 

If it was me, a Hawksworth Cathedral.

 

Did that ever get as far as a general arrangement or even a proposal ?

 

Yep

it is called a Princess

 

Sort of. There was a preliminary design study done in the drawing office, but Hawksworth didn't know about it, and had all work stopped when he found out.

 

Presumably he didn't want his reputation eternally saddled with the 'Hawksworth Cathedral'. Wonder how that worked out?

 

Its amusing to note that some 20 years or so earlier Hawksworth and Stanier had taken a similar drawing office study - for a compound Castle - to Collett and had it dismissed in double quick time.

 

Stanier did indeed outline a design for a small 4-6-0 with a 15½ ton axle-load, which would have been rather smaller than the later BR 75XXX Class 4MT. I believe it was particularly intended for the Stirling to Oban route. But as you say, the LMS instead upgraded the Oban route to accept the larger Class 5MT 4-6-0.

The Stanier small 4-6-0 would have been of similar size to the Caledonian "Oban Bogie" 4-6-0s of the 55-Class and 191-Class.

https://railway-photography.smugmug...Engines/Assorted-McIntosh-designs/i-jv8mhWr/A

https://railway-photography.smugmug...Assorted-Pickersgill-Tender-Locos/i-2CDT2pG/A

The 191-Class had been built without superheaters as late as 1921 and appear not to have been highly regarded. But maybe if any had survived,they might have been found useful on a heritage railway. For an actual small 4-6-0 in preservation, here is NSB Class 30a in the mountains of Norway:

http://www.railfaneurope.net/pix/no/steam/30/NSBsteam_001.jpg

 

20 sq ft - that’s a very small grate for a nominal class 4. (A BR 76xxx is 23 sq ft; a 75xxx is 26.7sq ft).

Tom

 

Probably based on the similar small grates and fireboxes of the Caledonian "Oban Bogie" 4-6-0s.

For a few years in the mid 1930s, the LMS drafted-in ex-Highland Castle and Clan Class 4-6-0s to help-out on the Oban Line while it was being upgraded. These had 8-ft long fireboxes and 26 sq ft grates, so a sort of half-way house between the small Caledonian Oban Bogies and the Stanier 5MT. They were available because some of the first batches of "Black 5s" had gone to the Highland Line, as well as the Smith River-Class 4-6-0s that had been banned from the Highland in 1915 but cleared by the LMS in 1928.

 

The Stanier design was bound to have been better than the Caley efforts, which were universally poor, apart from the Rivers which they bought off the Highland, and were ok

 

Indeed. Having just checked, that's a fair bit smaller than the 24sq ft of the very compact 5'-3" gauge 'Bandon Tanks' .... which by T.E. were closer to BR Class 2

 

Because just about everyone who proposes a new build wants to run it on the main line and small locos aren't suited to that under todays conditions.