Why did the GWR not use smoke deflectors?

Tom

This sort of argument rather reminds me of the old Lanchester car company which only fitted their chauffeur driven models with two wheeled brakes on the grounds that professional drivers did not drive on the brakes. Buyers said "Huh! They were right and Lanchesters complied. People can always think of "good" reasons for doing nothing if it causes you just a little bit of trouble to carry something out.

PH

 

Post Churchward, now and then.

PH

 

four wheel brakes were not the norm in my youth. I remember my old Headmistresses old A40 which bore the legend "CAUTION: four wheel brakes" in the 60s

 

She must have salvaged them from a Morris Cowley. They were general from the mid nineteen twenties although not always very effective (e.g. Austin 7)
(This thread is getting very wayward even by N.P. standards! Plead guilty for my part in this. Call a halt?)

Paul H.

 

Scots were introduced without them but they were fitted during their parallel boiler existence. The first two Patriots, that is the reasonably genuine Claughton rebuilds, didn't have them but they appeared on the series production locomotives. Both Scots and Patriots had them in their rebuilt form and, as both involved a change from a parallel to a taper boiler I wondered if it was a case of carrying on as before. Contrary to LMS2968, the two Jubilees rebuilt with 2A boilers never had them and I am not aware of any reputation for smoke drifting down. The Princess Royal class didn't have them and. of course, their boiler and smokebox were similar to the big GWR locomotives. The streamlined Coronations managed without and the original non-streamlined series didn't have them originally. I'm not sure that their fitment came with double chimneys; I understood that it was as a result of experience in their original form but I stand to be corrected.

 

Returning to our sheep, as the French would say, LMS2968 has explained this well.
From what I've read elsewhere, the worst conditions for smoke obscuring forward view is cold moist air (more visible water vapour as opposed to invisible steam in the exhaust) and a sidewind (creates an even worst low pressure area due to flow separation I two directions)

 

Sure about that?

https://www.flickr.com/photos/bigkris/5757937346/in/set-72157626676993961

 

The 2A boiler locos (oh if only the LMS had had a sensible class system instead of just the power classes...) started off without them - well into BR days in some cases.

 

Oh yes they did.
http://en.wikipedia.org/wiki/LMS_Re...estern_2_railway_station_2107179_37fd7339.jpg
http://www.jubilees.co.uk/photos/45736d.html

 

You are wrong about the 2a boilered jibs, I only saw Comet on shed at Annesley but it sure had deflectors, the same ones as the Pates & Scots.

 

I was writing from memory and am wrong! The rebuilding was done in 1942 and there is a photograph of 45735 at Bletchley in 1948 without smoke deflectors in Nock's The Stanier 4-6-0s of the LMS. However, I have now discovered a note that they were fitted in 1950; I assume that this was thought logical as their front ends were virtually the same as the Scots rebuilt from 1943 onwards. I always assumed that no more Jubilees were converted because the parallel boiler locomotives were in need of rebuilding and it made more sense to devote investment to upgrading (some of the) Patriots rather than the Jubilees which were, by then, performing satisfactorily on the duties to which they were assigned.

 

As admitted above! It just strikes me that Annesley must have been a real letdown for any Jubilee, let alone a rebuilt one!

 

Langridge (from memory) was of the opinion that Ivatt wanted to rebuild all the Patriots at least, and probably more Jubilees, but Riddles vetoed it after nationalisation. I can certainly understand prioritising the Patriots, but I'm sure that more rebuilds would not have gone amiss.

 

The reasoning for the rebuilds was as follows: post-war express services, it was calculated, would require 91 Class 6P (LMS power rating) locos. The 71 (including the rebuilt No. 6170) were already so rated, while the Baby Scots were 5XP only. The two Rebuilt Jubilees were now rated as 6P, which left a gap of 18 locos. Several Scots had been rebuilt with the 2A boiler, but this process slowed down or stopped while the 18 chosen Baby Scots were rebuilt, after which work recommenced on the Royal Scots. That is why these locos lasted so longer in parallel boiler form, and no more Baby Scots were rebuilt.

91 does sound a rather odd number, and it might be wondered why itwasn't rounded down, or up. But loco building and rebuilding was a great expense and, during WWII and after, money was tight, and like many, the LMS seemed to be working with the bare minimum it could get away with.

Sorry for this slight excursion away from GWR smoke deflectors!

PS: Apologies to the Saggin' Dragon. I was making the point that, after double chimneys, two of the three criteria still applied, but the sarcasm was a bit OTT!

 

Two factors I don't think have been mentioned with regard to GWR visibility requirements are ATC and the visibility of signals with the driver still on the right.

 

The argument about door locks would be best made with statistics. What was the incidence of door related accidents on the different door lock types?
Without the numbers there's no real value in arguing.

 

I suspect the introduction of slam doors had more to do with the speed of passenger turnaround at stations than safety. Someone already pointed its earliest use on the Brighton line with its dense suburban network.

 

The 'flatter' the front, the softer the blast, and the shorter the chimney the more need there is for something to stop the wind eddy that is caused by the flat front pulling smoke down in front of the cab windows. Softer blasts are more efficient so there is a trade-off. GW engines had a notoriously sharp blast, though they were so efficient otherwise it was never really considered as a problem - after all, if the blast proportions worked on a Dean Goods than that must have been OK, yes?

I wonder what improvements a Kylchap (properly calculated) could have made to a Castle? But it might then have needed smoke deflectors - a pair off an A3 maybe?

The A4 shape is very good at lifting the exhaust, and yes, tiny changes to the shape in the chimney area can make a big difference. This is why Thompson put rimless chimneys on his A2's. When they were fitted with rims for aesthetic reasons it did sometimes cause exhaust to be pulled down along the boiler despite the big deflectors- there are pictures illustrating this, and similar pictures of the big deflectors on 9f's failing to clear the exhaust, possibly because not travelling fast enough for them to be effective.

The A3 deflectors seem to have been the best solution short of an A4 shaped front end. But I expect the Royal Scot 'shaped' deflectors were better than the Thompson/Peppercorn/Standard virtually flat ones. I don't know if any tests were ever carried out.

 

I have read that Scot deflectors were poor at lifting the exhaust, and I can believe it: basically they are too short to channel the air effectively down the sides of the boiler. The air would reach the rear of the deflector before its direction had stabilised. This might explain the BR Standard-type delectors fitted to 6106, but not why there weren't fitted to any other class member.