Nigel Gresley’s mighty Mikados – and more!
In the light of some exciting forthcoming releases from Hornby, Pete Kelly recounts the story of the six original Gresley P2 2-8-2s – and touches on the great engineer's bold but costly experiment with the high-pressure marine-boilered ‘Hush-Hush' 4-6-4 o
THE last time we touched on Nigel Gresley's mighty P2 Mikados – the first of which, No. 2001 Cock o’ the North, appeared two years before the great locomotive engineer was knighted in 1936 – it was in the context of their rebuilding into A2/2 Pacifics by his successor, Edward Thompson, in 1943 and 1944.
This time, with the new-build P2 Steam Locomotive Company's P2 2-8-2 No. 2007 Prince of Wales rapidly nearing completion, and the eager anticipation of three newly-tooled OO-scale models of the class from Hornby covering original and streamlined body styles, we're concentrating on the Mikados themselves.
Cross-Channel jaunt
With their eight 6ft 2in driving wheels and high tractive effort of 43,462lb, the three-cylinder P2s were designed to eliminate the double-heading of trains that often grossed 600 tons over the arduous, twisting main line between Edinburgh and Aberdeen; the cutting and laying of the frames for the pioneering No. 2001 Cock o’ the North to the locomotive's final emergence from Doncaster Works in February 1934 took just over three months.
After running-in trials, No. 2001 was launched to the press at King's Cross on June 1, 1934, when it looked magnificent with its semi-streamlined front end and cab. Announcing its presence with a Crosby chime whistle that had been presented to Gresley by Captain Howey of the Romney, Hythe & Dymchurch Railway in Kent, it caused a sensation, and was also shown to an adoring public at Ilford, Aberdeen and Edinburgh.
Coupled to the legendary North Eastern dynamometer car, on June 19, 1934 Cock o’ the North took a 649ton train of 19 carriages from King's Cross to Barkston and back, recording a maximum drawbar horsepower of 2100 and a maximum speed of 76mph, and on the final day of that month it was finally transferred to
Edinburgh's Haymarket shed to do the work it was designed for.
Gresley cultivated a close working relationship with brilliant French locomotive engineer André Chapelon, who inspired much of No. 2001's design, including its eight-nozzle Kylchap exhaust system and double chimney. The locomotive was also fitted with Lentz rotary-cam poppet valve gear, allowing an infinitely variable cut-off, but after signs of premature cam wear following 10,000 miles in service, the valve gear was replaced by a stepped-cam design that gave only predetermined cut-off positions.
As the LNER had no stationary test plant of its own, and the only one in the UK could not accommodate such a large engine, Gresley arranged with Chapelon for the P2 to visit the then recently-opened locomotive testing plant facility at Vitry, near Paris.
On December 4, 1934, accompanied by a footplate crew and test observers from Doncaster, the locomotive boarded a train ferry for the crossing. Although the results were virtually as the LNER had expected, the locomotive never quite matched the performance of its French counterparts, either at the test plant or while running on French metals.
The original front-end styling of No. 2001 wasn't quite replicated on the second locomotive, No. 2002 Earl Marischal, completed in 1935, which was fitted with more conventional outside Walschaerts valve gear working the middle cylinder by derived motion.
Thanks to larger-diameter tubes, it also boasted a more extensive superheater heating surface than its predecessor, and in that guise smoke drift became more of a problem at low cut-offs until windtunnel experiments determined the answer to be a second pair of smoke deflectors, although the problem was not completely solved until the locomotive later received an A4-style streamlined front. The following P2s,
Nos. 2003 Lord President, 2004 Mons Meg, 2005 Thane of Fife and 2006
Wolf of Badenoch, were all built with A4-type front ends which lifted the exhaust perfectly well, but there remained plenty of minor differences between them.
To prevent fire-lifting at high cutoff settings, for example, No. 2004 was first built with a butterfly-valve blastpipe bypass that was later changed to a different system, although the inevitable carbon deposits caused sticking with both designs. No. 2005 emerged without the double Kylchap exhaust, and the boiler of No. 2006 had a longer combustion chamber, a greater firebox heating area and a Robinson superheater.
In this way, different improvements could be compared between each member of the class, and had it not been for the outbreak of war in 1939 and the death of Sir Nigel Gresley at the age of 64 after a short illness in April 1941, such experiments would almost certainly have continued until the locomotives' true potential had been reached.
With all of the P2 Mikados now long gone, however, achieving that potential 77 years after the last one was rebuilt into an A2/2 Pacific by Edward Thompson remains the steadfast aim of the P2 Steam Locomotive Company with No. 2007
Prince of Wales – and after the remarkable performances of newbuild Peppercorn A1 Pacific No. 60163
Tornado over the past 13 years, who can doubt that they will do just that?
To ensure there are no smoke-drift problems with No. 2007, which is sticking to the original front-end boiler casing design, a CFD study into the ‘Coanda effect' is being undertaken. The P2SLC describes this effect as the tendency for fluids to follow a flat or curved surface, which means that in the case of the P2, a cross-wind travelling over the casing will ‘stick' to the casing and draw the exhaust steam down over the surface, obscuring the driver's vision of the track ahead. The study will carefully simulate such dynamics in a bid to influence the steam and air flow in a
way that does not change the design outline of the boiler casing.
Following the main line success of Tornado, which emerged from the same Darlington premises in which No. 2007 is now being built, it is gratifying to note that the P2 will be sharing a 70% parts commonality with the A1, including the boiler, tender and the fitting of roller bearings.
Design improvements
Cock o’the North became the last of the original class of six to receive the A4-style appearance when it emerged from Doncaster Works after a seven-and-a-half month stay in 1938. It also lost its Lentz valve gear and impressive-looking ACFI feed water heater in favour of Gresley's traditional derived-motion Walschaerts valve gear and a normal injector. After resuming its duties in Scotland in midApril, the only attention it required during the rest of that year was the fitting of a new middle connecting rod along with minor boiler repairs.
The most serious fault suffered by the class was broken crank axles and crankpins, an affliction only Cock o’the North managed to escape. The first incident occurred when a sister locomotive with a mere 133,000 miles on the clock broke its crank axle while leaving Stonehaven in 1939, fortunately at low speed – but on the new-build Prince of Wales, the P2SLC has utilised the strongest A4T material rather than the standard A1T in the manufacture of its own.
Prince of Wales is also sticking to Gresley's pioneering spirit by not only following the original front-end styling but also fitting a redesigned, more reliable and efficient version of the Lentz gear. To underline the enthusiasm for the building of this much-improved bullet-proof version of Gresley's awe-inspiring design for main line use, the P2SLC engineering team has spent countless hours developing the cylinder block design to correct the flaws in those of the original class members.
Within just two months of the launch of the company's Cylinder Manufacturing Club, whose members each pledge £1000 towards the manufacture of this vital component, no less than £27,000 had been raised.
The block is being fabricated by the Howco Group PLC in Irvine, Scotland, from steel castings supplied by William Cook Cast Products Ltd in Sheffield. It will feature modifications including reducing the clearance volume by better valve design, rerouting steam and exhaust passages to prevent the outgoing exhaust being heated by incoming steam, improving the internal streamlining of passages, and reducing the overall width for better route availability. The structural integrity of the welded fabrication will be checked by Finite Element Analysis.
As well as offering all three design versions of the P2s, Hornby is also releasing some new models of another of Gresley's masterpieces, the Class W1 water-tube boiler highpressure four-cylinder compound No. 10000, in both its original and rebuilt forms. Known as the ‘Hush-Hush' because of the secrecy under which it was built in 1929, the long-gone 4-6-4 falls into much the same category as the P2s on account of its ingenuity and boldly imaginative design and appearance. Some argue that it is a 4-6-2-2, since the trailing wheelsets are not in a bogie, but Gresley considered it to be a 4-6-4 and it was officially referred to as such.
No. 10000's marine-type boiler worked at a phenomenal pressure of 450psi, and although it did successfully work a number of high-profile trains, it was dogged by so many problems that, of its 1888 days in service in its original form, it spent no fewer than 1105 undergoing attention in Darlington Works.
By October 13, 1936, the LNER had had enough, and No. 10000 travelled to Doncaster Works to be rebuilt as a normal three-cylinder locomotive with a conventional 250psi boiler fitted to the original frames, which were shortened by 18in. Other retained parts included the trailing wheels, and the locomotive's appearance was changed dramatically to resemble an elongated A4 Pacific.
The W1's number became 60700 after the formation of British Railways in 1948. One notable incident during the latter part of its career occurred when, soon after leaving Peterborough station on September 1, 1955, the front bogie frame fractured. The locomotive was derailed and went over onto its side while travelling at 20mph at Westwood Junction. What might have happened if the same thing had occurred at high speed doesn't bear thinking about!
The W1 was withdrawn in 1959 and scrapped, but the tender with which it ran until 1948 is preserved with A4 No. 60009 Union of South Africa, which has just been withdrawn from service.
The models
Hornby is producing newly-tooled OO-scale models of the LNER P2 2-8-2s in three variations, all finished in the classic LNER green livery. Accurate tooling variations of the highly-detailed models, all featuring separately-fitted parts, will represent new and original-build P2s as well as the different body styles.
The models will come with a digitalready eight-pin socket and NEM couplings, and will be powered by a five-pole skew motor.
The model of the P2 Steam Locomotive Company's new-build No. 2007 Prince of Wales (R3983) will be tooled to reflect its planned final appearance, while that of No. 2002
Earl Marischal (R3984) will allow for its original body style, which because of smoke-lift problems was slightly different from that of No. 2001 Cock o’ the North. The third new model will be that of the first P2 to sport an A4-style streamlined front from new, No. 2003
Lord President (R3985).
Although originally planned for release before the end of this year, it seems after speaking to one model shop proprietor that the P2 models are not likely to be in the shops until 2022, although they have been available to pre-order for many months.
The same applies to an eagerlyawaited range of models of the ‘HushHush'. The models of No. 10000 in original condition will be R3979 (LNER dark grey with double blastpipe); R3840 (LNER grey); R3841 (LNER grey with the intended, but never fitted,
British Enterprise nameplate) and R3842 (in LNER green).
In its modified form, the locomotive will be modelled as R3978 (LNER works grey); R3843 (LNER garter blue); R3844 (BR green with early crest as No. 60700) and R3980 (BR green with late crest as No. 60700).
Each model will feature a die-cast chassis, highly-detailed body and tender and five-pole skew-wound motor, and will have digital capability and NEM couplings.