The Armistice Kentish Belle 11/11/23

Thank you for your comments, I didn’t get to be an active member until it’s latest mainline ticket when it started to come south to find work, Buckinghamshire is a bit far from the Worth Valley.
I had assumed that it was the same chimney that did the rounds but the society did a lot of research into it and found that the one now carried by 5596 was manufactured for it. That leaves two questions, if the double chimney did improve performance and there seems to be no doubt, why wasn’t the whole class given the cheap modification years before. The other puzzler is why did they carry out such a modification so late in the day when steam was already on its way out?
As a footnote to performance one driver told me that at low power output there is no difference to a standard Jubilee but when working hard it’s more like a 6.5P rather than a 6P engine. Having been privileged to be on the footplate up Sapperton with ten on the back and no diesel on a wet rail I can see what he means

 

For some accurate information about Bahamas double chimney why not take a look at the BLS website with more information on the double chimney if you scroll down the page, we also have an online shop with BLS souvenirs etc

45596 LMS Jubilee Class 'Bahamas' - The Bahamas Locomotive Society (bahamas45596.co.uk)

"It was not until May 1961 that Bahamas became the first and only member of the class to receive the equipment, which was fitted during an overhaul at Crewe works. This experiment proved to be the last attempt by British Railways to specifically improve the steaming capabilities of its fleet of steam locomotives.
The tests at Rugby had proved that the boiler could produce 30 per cent more steam than previous using good quality coal, and using that of lesser quality would still have been able to meet the requirements of the operating department."

We're a volunteer led Charity and funds raised help keep our locomotives active.

 

"Roar of sorts"......lovely expression, no offence intended. Question...does it vary between Bullied Pacific types, both unrebuilt and rebuilt? ....just curious....

 

Peter, is the Silver Link book still available? If it is I would recommend that anyone interested in the engine parts with the £8 price, a bargain considering a magazine is now the wrong side of a fiver

 

No one who was behind 34102 Lapford the 1967 evening that The New Cross Lip, aka Nine Elms driver Gaffney, thrashed that original condition Bulleid up to 100 mph around Fleet, would ever associate the class with anything other than an almost ear bursting roar when worked totally flat out!

Some time after the end of the world on 9 July 1967, and in a new existence on a different planet, I was very close to the Gatwick runway when what must have been a fully loaded Boeing cargo 707 taking off did its very best to emulate Lapford so far as noise was concerned. But it missed out on the very large number of glowing fire embers that Lapford spewed out over the Hampshire country side that evening back in 1967.

And my first experienc of a rebuilt Bulleid being worked close to its limit was behind a Merchant Navy climbing the grade from Brockenhurst to Lymington Junction, and then up from Christchurch to Pokesdown, on the 08.30 ex Waterloo with Gordon Hooper driving. None of this soft exhaust stuff I read about, a harsh very, very loud exhuast beat but different to that from 34102. Gordon wasn't a loco thrasher, but he certainly new how to get the very best out of a Mechant Navy on a 1/100 grade when, as happened almost all the time on a down 2 hour express from Waterloo, he was late away from Southampton because of the delay into that stop caused by the cross country DEMU scheduled just in front at St Denys.

 

It is, takes you up to and through the lates overhaul, as you say a bargain,

Locomotives & Recollections - The Bahamas Locomotive Society (bahamas45596.co.uk)

 

Having done a lot of sound recording of my own and listened to Peter Handford's lovely recordings, I can say that, certainly at lower speeds, there is a distinct difference between the sound of an original versus a rebuilt. Never had the experience of one being worked as hard as the examples witnessed by the Gricing Owl.

 

I was told by an old SR steam driver that Bulleid Pacific's "chatter" when working hard.
He brought this up when we used to watch the VSOE (now Belmond Pullman) climbing up through Chilworth behind either 34067 or 35028. He said 35028 always sounded spot on and "she was chattering well" but 34067 sometimes sounded a bit off.
When 4472 took over the duty he wasn't very complimentary. The A3 sounded ok when she first took over the duty but later on he said she sounded like "someone dropped a bag of spanners down a metal staircase".
Sadly the driver is not around anymore but I would love to know what he thought about the Jubilee Class.

Sent from my XQ-BT52 using Tapatalk

 

Thanks for the info re the double chimney and book ordered.

 

Thanks for the info and "the penny has finally dropped"; Bahamas is fitted with a double chimney as developed at Rugby - not of the original design. [I relied on two sources, one makes no distinction and whilst reading the other I had "missed" the key part of the sentence about the double chimney as tested. ". . . each half following the same design consideration as the modified single chimney . . ."

To answer your questions, ES Cox covers the subject in his book, Chronicles of Steam. (At the time Cox was Chairman of the Locomotive Testing Committee of British Railways).

"Late in the day", in 1955 the Operating Department of BR made a formal request to the Locomotive Testing Group to examine Jubilees because of operational difficulties caused by worsening of their known steaming difficulties caused by the lack of good coal.

45722 was tested in late 1956 and a report issued in 1957. Both the modified single and double chimneyed boilers could sustain a maximum steaming rate of 25,000lbs/hr (20,760 with original chimney) and consequent increase in power, 1620ihp (1350). This, of course required more coal, 4435lbs/hr (3324). In service a firing rate of 3000lbs/hr was considered to be the max. continuous rate for a single fireman. At this rate (3000lbs/hr) steam production and power were identical across all 3 variants.

Cox records,

"in respect of fitting the double blastpipe and chimney as tested at Rugby, it could be said that at ordinary express speeds the potential power output could have been increased by one third.

Conversely for normal power outputs the steaming could have attained that rock-like steadiness which would be a joy to all locomotive men, surmounting the various adverse features which were increasingly clogging steam engine performance as time went on."

So, as requested, a means to improve the poor steaming had been found and the higher power output was a (very useful) side-effect, but attained at the cost of higher coal consumption. Why was it not adopted? Cox concludes,

"It is unfortunate indeed that these results were not available earlier, and that by the time the report was issued in 1957, the great changeover to Diesel power had already begun so no more money was spared for steam engine modifications."

Cox also observed that, "The boiler irrespective of its draughting was a badly balanced one." (The better solution, had money been no object, was conversion as per Comet & Phoenix).

It is worth noting that, as tested in terms of max steaming rate and power output the modified single and double chimneys are identical. The double chimney may hold a small advantage when burning poorer coal.

 

Here's a photo of a model of Bahamas blast pipe made fairly recently by one of our highly skilled long term volunteers, it's on display in the BLS museum at Ingrow.

 

A thing of beauty! It’s been a few years since I visited Ingrow, I think a return is in order.

 

Have you ever heard one being worked really hard? 35012 on the up Belle doing 75 up Roundwood or 35005 accelerating to 78 at Brookwood from a dead stand at Esher with 12 on. Full and 40% cut off. An amazing deep roar

 

Its also about how they are fired. Some of the runs behind 45699 on the Carnforth to Carlisle section with heavy loads are well into class 7 territory. .l also had a fantastic run with a Jub on the 10 am Dundee with Willie Jardine driving

 

Yet the A3s were fitted with double chimneys from about this time. A regional difference of opinion or testament to Townend's lobbying?

 

IIRC The modifications to the Gresley Pacifics paid for themselves in quite a short time. With data available from the handful already fitted with double chimneys, maybe an economic case for the fitment to the rest of the class was much easier to make

 

Yes indeed. That run on the 17.30 ex Waterloo must be my most incredible restart from a dead stand from signals that I have ever experienced. As you so rightly say, an amazing deep roar. My notes put the signal stop at MP 15.5, which is close to Hersham, from where we were up to 75 mph in the Byfleet 'dip', before that incredible acceleration on the climb to MP 31. That followed passing Surbiton in 14 min 16 secs from Waterloo, at 78 mph! And let's not forget 34090 on the 17.30 in November that year, after the electrification works had started with much slower timings. 10 cars, not 12, but a Light Pacific. 14.20 to pass Surbiton at 76 mph, 82 at Hersham and 78 over the small summit at Oatlands box - I can still remember the wonderful roar echoing off the walls alongside the track in part of that area, as I sat in a six person compartment with 5 other timing gricers! Woking passed in 23.32, I think my fastest ever from Waterloo. Driver Saunders on both runs, Dave Wilson firing 35005 and fireman Rowe on 34090.

Very unlikely to get those sorts of incredible extreme roaring performances these days - when the costs of running and maintaining steam locomotives on the main line have to be paid for from hire fees and by the owners - not by BR Southern Region back at the loco shed or main loco works whenever any work was needed!

Incidentally Bulleids can have a very quiet exhaust even when climbing Roundwood. Shown by a certain Bournemouth driver who, on the two hour express schedule, came up from Southampton (schedule 85 minutes) in over 94 minutes unchecked. 34017 recently ex works. But we knew it was a steam loco because of the regular lifting of the safety valves! 'Wrong Class of engine' was the driver's response when asked at Waterloo what was wrong with the loco - presumably reacting to not having a Merchant Navy to drive quietly.

 

I can only talk of the preservation era, being just a small child when Don and Brian were recording the amazing exploits of the Bulleids in the years before July 1967. Sometimes their quietness has been quite remarkable. I recall going to see 35028 taking the Pullmans round a slightly longer circuit than usual probably in about 2008 (can't find the actual date) due to engineering works on the usual "Surrey Hills" route. I went to a spot near Buriton Tunnel on the Portsmouth Direct line where the gradient is 1 in 80 uphill, yet in spite of the effort involved in lugging that heavy train up a pretty steep gradient, I actually saw the steam before I heard anything! I couldn't believe how any engine could be making so little noise in such circumstances.

Conversely, however, when I took the picture below, you could hear Clan Line for several minutes before it came into view. It was taken in May 1995 at a spot somewhere between Walmer and Martin Mill, which I think is on a marginally steeper climb than the ascent to Buriton (1 in 74??) Having bought into the perceived wisdom of the quietness of Bulleids. I was quite taken aback by the sheer volume of the noise coming from 35028 as soon as it hit the bottom of the bank at Deal, probably 3 miles from my vantage point

 

Following a string of impressive performances, I agree Bahamas with her modified (double) chimney does appear to be special. There can be little doubt that the chimney has fixed the “steaming difficulties” that troubled the Jubilees, especially with poorer grade coal. Not only did it fix the problem it also increased the max. steaming rate of the boiler from 20.760lbs/hr to 25,000lbs/hr and, consequently, increased the max ihp from 1350 to 1620ihp compared with the original single chimney. [The quoted values are from tests made at Rugby Testing station. Those outputs could be sustained for a minimum of 1 hour. ihp, indicated horsepower is the power produced in the cylinders and was calculated from the pressures measured in the locomotive cylinders.]

It is important to note that although Bahamas may have a better performing boiler than other class members, she still has the same cylinders, valves and wheels as other Jubilees. In short, she is no more (or less) efficient at turning steam into mechanical power than the rest.

So, where does the upper limit of Jubilee performance lie? What have other class members achieved in terms of sustained maximum ihp and how do these values compare to the Rugby test value?

The zenith of Jubilee performance is invariably cited as that of 5660 Rooke during a series of test runs in October 1937. On the 13th Rooke ran from Settle Jn SB to Blea Moor SB in 16m 20s hauling a 305-ton train which included a dynamometer car. 13.9 miles, average gradient 1/111r, average speed 51mph. From measurements taken in the dynamometer car the edhp was calculated to be 1375 and the ihp 1675. These were the values average values over the full climb – higher instantaneous values were recorded/calculated. It is these average values that are a more accurate measure of the output that the loco can sustain. It is generally acknowledged that Rooke was pressed to her absolute limit.

Sadly, in the recent preservation era the S&C is not what it once was; an overall 60mph limit with further speed restrictions at Ribblehead. These restrictions together with the use of heavier trains means that a comparison of Rooke’s performance with modern day climbs of “the Long Drag” would be meaningless. A more valid comparison would be Grayrigg; 13 miles, average gradient 1/140r and, for a very good climb by a Jubilee, with an average speed of around 50mph. [The pull exerted needed to overcome the gradient is almost identical. Rooke + 305-tons climbing 1/111r requires a pull of 3.96-tons, a Jubilee with 11 coaches climbing 1/140r requires 4.03-tons.]

In 2019 I had the good fortune to travel on two exceptional climbs made by Leander. On 18 May 45690 with 11 coaches climbed the 13 miles to Grayrigg summit in 15m 44s, average speed 49.6mph. This gives a calculated average edhp of 1300 and a corresponding ihp of 1600. This was bettered on 13 July with the same load; a time of 14m 38s gave an average speed of 53.3mph. The average edhp was 1425 with a corresponding ihp of 1725.

Given the methods of arriving at the figures for edhp and ihp, those for Rooke are likely to be more accurate as they involved time, distance, speed and pull measurements made in the dynamometer car and then calculations, whilst those for Leander’s runs involved the measurement of time, distance and speed but not pull.

It is perhaps reasonable to say that all three runs were similar rather than claim that any one run was the outright winner. Leander is fitted with the modified single chimney as designed at Rugby. On test at Rugby there was no discernable difference between the performance of the modified SC (as fitted to Leander) and the modified DC (as fitted to Bahamas).

There is agreement between the ihps obtained at Rugby with those “out on the road”. Road tests were often found to produce higher figures, often attributed to outputs being over a shorter period, vibration breaking up the fire bed and aiding air flow through the fire with possibly some mortgaging of the boiler.

Dr David Pawson has analysed logs of 62 runs by Jubilees to find the best ihps (sustained for 15mins) and has arrived at a mean figure of 1430. The runs by Rooke and Leander comfortably exceed this figure.

The bar has been set high. Bahamas should be capable of achieving similar results, but it may be a question of opportunity and the quality of the coal. Whether Bahamas can better those results remains to be seen. I suspect not; even with her super DC the Jubilee boiler has now reached the limit imposed by a relatively small firebox. Also spare a thought for the fireman, at Rugby running near “flat-out” required a firing rate of 4435lbs/hr (this equates to half a ton every 15 minutes).

In the meantime, Bahamas should continue to provide consistent high-quality running – as well as looking like a million dollars! (and the soundtrack is not too shabby). It is a pity that she needed to head south to ply her trade, but encouraging to see how quickly “the locals” have become fans. Long may she continue – a credit to her minders and the footplate crews.