BR Double blastpipes

A stated aim of the BR Standard designs was to maintain rather than improve on the performances of existing pre-nationalisation classes and not necessarily to improve on their fuel consumption either. The Britannias were intended to compare with the Class 7 types: Royal Scots, V2s, Castles and not the big Pacifics. Fitting a double chimney - or more likely a Kylchap - might allow them to do this but then leave a hole in the Class 7 provision. And what would be the implications for additional wear and tear and, yes, increased maintenance costs?

The professional engineer considers the design package from many viewpoints of which performance output is but one. Unfortunately, the enthusiast sees that performance output as the be-all and end-all and the other criteria should be sacrificed to achieve the maximum. Possibly the biggest example of this was their disappointment that 9Fs were not allowed to work passenger trains at 90 mph irrespective of the damage they would inflict on themselves, track and other infrastructure while so doing.

 

Totally agree, I wasn't advocating for a dc Brit simply noting that if capability was improved that would take it into a notionally higher power category.
Or more in hand for occasional extremis.

 

Alas for the Britannia is already insufficiently robust to handle the power output it already produces, making that output more sustainable would only exacerbate those issues.

 

I'd be grateful for this to be expanded please

 

Several Problems with Brits to my mind were adaptations from other locos that were found wanting on a 2 Large Cylinder as opposed to 3 cylinder loco.
The Slide bars Lner/ Bullied pacific Laird type ... unsuficiently robust/supported for a 28inch stroke
Wheel axle interface - only upto the job when executed perfectly under careful supervision
Frame design - Influenced by Bulleid pacifics with frames moved into centre lines of horn guides, but lack of suppport along bottom of frames leading to cracking, remedial welding on Brits, design improved for 71000 and later batches ( which never materialised).
Hindsight is a marvellous thing but a 3 Cylinder/Caprotti Double chimney Britannia ( so its 71000 with a smaller Firebox) would have been a better performing /balanced loco. Similarly a Brit with a 250psi Clan Boiler, possibly a double chimney and slightly smaller cylinders a more resilient one ?

 

You need to look at the 9Fs and the frame design on that Class.