A1
60163 'Tornado'
"No history
is written about the cowards"*
* A quote from correspondence between L.D.Porta and the A1 Trust dated February 26 1992.
In 1991 what has become known as the A1 Trust officially launched their plan to fill a gap in the list of preserved UK Pacific type locomotives. The A1 type to be recreated was specified as being as close to as now allowable to the LNER, Arthur Peppercorn designed, A1 which itself was an improvement on the previous A1 type designed by Peppercorn's predecessor and Gresley's successor, the much maligned, Edward Thompson. Whilst incorporating several notable differences, such as three sets of valvegear instead of two with conjugation to the inside cylinder as on Gresley Pacifics, the history of these machines can clearly be traced back to Gresley's first Pacific No. 1470 - itself classified as an A1 when built. This 1923 machine later became a member of the famous A3 class after a series of modifications.
None of the Peppercorn, or Thompson, A1's were preserved. The closest 'relative' being A2 Pacific 60532 Blue Peter.
Instead of building a replica of a scrapped machine the Trust decided to build 'the next' A1, that is the new locomotive would bear the next number in the series. Thus when the locomotive runs it will be numbered 60163. It will bear the name 'Tornado' which is in honour of the pilots of the Tornado aircraft that took part in the first Gulf War.
In September 2004 (when this was written) the A1 Trust had made considerable progress with the locomotive's construction with the boiler design and construction now in hand.
So in essence 60163 will be rolled out as something little different from 60162 with the only concessions being to modern requirements. 60163 will look and perform much like any previous A1. But, it need not have been this way.
On
hearing of the proposal Ing. L.D.Porta wrote a lengthy proposal (over 200 pages
in length) entitled "A
Proposal for the Tornado Project" detailing
how the trust could create an A1 look alike but with the performance to be expected
from a true Second Generation Steam Locomotive. In other words it would look
much the same but performance (in the widest terms) would be a world away from
that of 60162 and her fellow class members.
Porta proposed a locomotive capable of running at up to 120mph with peak indicated horsepower (ihp) predicted to be around 5000 at 105mph. This ihp figure would represent an increase in power over the original A1's in the order of 60%.
In one of his letters to the A1 Trust Porta stated:
"No doubt, the proposed scheme is a bold one, but it is THE opportunity for British steam to break the 2200 (sustained) DHP barrier, an attempt in which 'Duke of Gloucester' suffered a humiliating failure."
To achieve this level of performance significant deviation from the original design was required but it was still possible to retain the original form.
Note: Figures reproduced below, referred to in the summary, have been scanned from a photocopy of the original paper so are not of the highest quality but are included as they are of significant interest.
"Summary
The A1 Tornado project may be considered as a step (not to be the last one!) in the steam revival process. It may be look upon as the latest step (not to be the last one!) in the evolution of the GRESLEY Pacifics starting in 1922, seventy years ago! This proposal, in which 4000DBHP and 180km h-1 are spoken about, is a tribute to the soundness of the basic design. The unsurpassed elegance shown in Fig. 0, like that of MICHELANGELO’s David, cannot be improved nor altered, and fully justifies the strong feelings of the sponsors of the project. But under forms and liveries scrupulously respected, it is possible to introduce not substantial design alterations leading to the above figures, thus justifying an effort whose greatness does not detract, but enhances, GRESLEY’s name. In a changing world, when most of it is starting to enter the consumer society with its necessary transport explosion (read railway), steam is offered as a solution; the No.60163 Tornado Project is called to be the initial kick converting the silent revolution which occurred during the last 40 years into a public, powerful upheaval. But that will not come to fruition unless the above figures are REGULARLY attained day after day.
Redesign is necessary because of cost, skills and general convenience. Besides, some severe imperfections of the original scheme (e.g. accessibility to the middle cylinder) must be corrected, one of them being the unstable running at speed which at its time prevented high speed running. Fabricated new cylinders, incorporating the latest technology concerning internal streamlining, afford the opportunity for a better arrangement of the inside motion along the original GRESLEY philosophy, yet providing a separate valve gear as seen in Fig.3.
The aims are:
a)
To get the highest horsepower at high speeds;
b) To improve adhesion generally over tracks contaminated with diesel oil;
c) To achieve an honourable performance with not first-class coal;
d) High, reliably sustained power over long periods;
e) Continental tours;
f) To demonstrate that steam did not reach its climax and shows promise for
the future etc..
Special efforts are to be made bearing in mind that no chain is stronger that its weakest link. One of them is a thorough enquiry about minor (or large) defects amongst old people having worked with the A1 class.
An improved thermodynamic cycle (now standard for the writer’s Second Generation Steam proposals) requires a higher proportion of the heat transferred in the superheater. This leads to a redesigning of the barrel, still keeping to the original outline. Since the header is to be a (fabricated) new one, there is full freedom concerning the size and number of flues and tubes. Fig.3 shows how the economiser is incorporated; same for an exhaust steam air heater. Both lead to ~10% increased steam output for the same combustion rate, hence ~13% drawbar horsepower.
Traditional flanging operations, now very costly to reproduce, should be discarded for cost reasons; a firebox redesign with plane or cylindrical surfaces, now easy to fabricate because of welding, is proposed (particularly for the throat), yet keeping strictly to the original outline.
With polyamide antifoams (which are a MUST to avoid priming and get PURE steam), the “banjo” dome construction is of no advantage. In any case, the redesigned boiler is to pass the severe inspection (drawings and fabrication) of the boiler authority (or severe design criteria). Glass wool (or equivalent) insulation is to be provided; it leads to ~3% extra drawbar horsepower.
Tube-tubeplate
joints should be as per Fig.6 to guarantee no leakage under high heat impingement.
It is taken for granted that the GPCS will be adopted. In the present state of development it comprises some 20 items; the choice depends on the particular scheme. The aim is guarantee superb, instantaneous free steaming under all circumstances, placing absolutely no reliance on heat storage in the boiler.
The original feed arrangement is inadequate both concerning the feed (10m3 h-1 against 25) and thermodynamic desirability. The liveliness of the feed arrangement MUST be guaranteed (time lag 3 or 4 seconds). One of the essentials related to this question is automatic, air-tight dampers.
The elegance of the GRESLEY inside cylinder arrangement gave way to an unfortunate, retrograde step for the A1 with “worst-could-not-be” accessibility. Returning to the former is a MUST; this can be done without altering the external appearance of the machine (Fig.3).
The cylinders as per Ref. (42) embodying the latest technology incorporating items like the writer’s tribology, light-weight long lap valves, thorough glass wool insulation, large steam, large steam passage areas, suppression of snifting valves, etc. (see Fig.34).
COX recommendations on frames (45) are to be seriously considered if no difficulties are to be faced at the high powers (4500IHP) and high speeds (180km h-1 and above) that the engine will be capable of. Strengthening of the bottom part, and American type hornstays are a must to “corkscrew” distortions. If possible, the plates should be made to coincide with the axlebox plane.
The feedpump is to be located between the frame plates where the original steam brake cylinder was located. This is imperative for keeping unchanged the external appearance.
The information is that the A1 was unstable at speed, a most serious matter after the Bitha disaster. Changing the bogie for that of the A4 (a trial and error procedure) does not necessarily entail a solution. The new concept is that stability is not be ensured by flange forces (CARTER (12), 1926). WICKENS, of Derby, is the man to take the bull my the horns on this problems. At the very least a number of recommendations resulting from past experience are to be incorporated. The bogie should be loaded more and the back end lightened.
As
a matter of course, the TIMKEN, version of the original A1 will be taken as
a basis; more than the reduced friction, the better alignment will translate
into better performance. American type hornstays (Fig.14) should be used.
The unsurpassed elegance of the spoked wheel should be kept even if the cost is high. Otherwise a fabricated alternative is possible.
AAR standard formulae are proposed to check the various components for high speed (504rpm). Crankshaft design should be checked as per Ref (47), but under no circumstance is the abandonment of past LNER practice for balanced crankshafts to be permitted.
A number of improvements on locomotive tribology occurred in the last 30 years, but the most important ones refer to that of the cylinders; very high temperatures are possible with existing oils.
No summary can be provided for a review of the adhesion problem, so the reader is referred to Ref (52)(Appendix A9).
British Railways feedwater treatment is a must, incorporating POLYAMIDE antifoams.
Cab ergonomy is to be studied to the MINUTEST DETAIL, and the crew instructed to show the potential inbuilt in Tornado thanks to the engineering principles used in its design; this is for more than driving Sunday trains for steam lovers! Unlike what happened in the past, the Tornado will work within a hostile environment providing no help. Operation must be carefully planned, and the tuning up process be carried out with the help of instruments. CREW TRAINING based on engineering principles must substitute old methods; this is far different from driving an excursion train for cheerful fans!
The thermodynamic cycle shown in Fig.18 seeks the highest thermal efficiency not on grounds of economy, but because of the equation stating that:
Power = heat input x thermal efficiency
Valvegear dimensions are subjected to very small but significant alterations, yet keeping to the original appearance. An elegant solution for the middle cylinder is GOOGH gear.
Given
that the cylinders are new fabricated construction is to be much preferred.
This permits a redesign concerning the much needed internal streamlining –
the original dates back to 1945! Fig.34 shows a preliminary arrangement which
respects the OUTER DIMENSIONS. The resulting predicted indicator diagrams are
satisfactory for 180km h-1, but additional advantages can be expected
from a second iteration in the calculations shown in appendix A1. These result
in performance maps which keep to the familiar forms. The minimum predicted
specific steam consumption is 1.8kg CVi-1 h-1(10.7lb
HP-1 h-1), which compares well to experimental values
with due allowances for lower back pressure, higher steam temperature, better
insulation etc.. But the important point is not “economy” but power
at high speeds. It has been found that the latter is limited by internal streamlining
and cylinder volume, the latter leading to high incomplete expansion losses
associated with the long cut-off necessary to digest all the steam the boiler
is able to produce with the GPCS. Within the traditional loading gauge, cylinder
volume can be doubled, and if a 300psi pressure is adopted (as per American
practice) the virtual equivalent is even more. But this is TOO MUCH. The proposal
is to refine the internal streamlining, keep to the original 19”x26”
dimensions and increase the steam pressure. Some 5000IHP are possible, leaving
a substantial power at the drawbar.
The internal resistance leads to a severe distortion of the indicated “map”. Air resistance is of course largely influential. Some 3000 DBHP are left at 50 ms-1 (180km h-1).
References referred to in the Summary to Porta, L.D.: “A Proposal for the Tornado Project”. 1992.
(12) – Carter: “On the action of a Locomotive Driving Wheel”. Proc. Royal Soc., Series A, 112 (1926), p.151.
(42) – Porta, L.D.: “Cylinder Design in Advanced Steam Locomotive Design Facing the Oil-Energy Crisis”. In preparation, 1992.
(45) – Cox, E.S.: “Locomotive Frames” Paper No.473, The Journal of the Institute of Locomotive Engineers, Np.301 Vol. XXXVIII, Jan-Feb 1948.
(47) – Porta, L.D.: “Crankshaft Design for High Power Locomotives”. Revised edition, 1991 (nearly finished).
(52) – Porta, L.D.: “Adhesion in Advanced Steam Locomotive Engineering Facing the Oil-Energy Crisis”. 1976 *#
(*)
unpublished, manuscript copy available upon request.
(#) contains matter subjected to patent rights.
"THE PORTA PROPOSAL AND THE A1 LOCOMOTIVE TRUST:
What a locomotive! But, I hear you cry, surely this would not be a Peppercorn 'A1' Pacific?
There are a large number of rather radical proposals in Porta's ideas which would make the 'A1' markedly different from its predecessors - but they were nevertheless given the detailed consideration they deserved. After all, we had said quite clearly that we were building the next 'A1' and not a replica.
However, setting aside the theoretical benefits of the various proposed modifications made by Porta, there was also the question of technical risk to consider. Many of these innovative ideas have not been tried anywhere in the UK before - and nowhere in the world have they all been applied on a single locomotive!
As a consequence, Porta himself prudently suggests that no fewer than 20,000 miles of test running might be required to 'iron out the bugs' and optimise performance. Considering how difficult the 71000 Trust found organising a 200 miles test run with Duke of Gloucester, such a programme would hardly be realistic, so we had to approach such a swathe of innovation with some caution.
As previously stated, we are not building a replica. We have laid down certain criteria for some changes to the design of the locomotive, these being driven by the following factors:
All things considered, we therefore aim to adopt some - but not all - Ing. Porta's proposals, including a welded steel boiler and firebox, maybe increased superheat, streamlining of steam passages, redesigned valves, improved valve gear events and roller bearings. However, leading dimensions and the general layout of the locomotive will remain unchanged.
Other than from the changes that have been forced upon us by (2) and (3) above, we consider that our modifications would have been incorporated anyway had the 'A1s' survived to a normal 30 to 40-years life. This has been confirmed by people who were involved in the design and operation of the 'A1s' such as J. F. Harrison, Assistant to A. H. Peppercorn and Peter Townend, former King's Cross Shedmaster.
As a design point, we aim to take the Appleby-Ais Gill 'Blue Riband' conclusively! Given that the original 'A1' was similar in power to Duchess of Hamilton, Duke of Gloucester and Blue Peter with a theoretical disadvantage compared with the latter two engines over this route with 6ft 8in driving wheels, compared with 6ft 2in, we are looking for 10-15% improvement in performance to clinch it.
With an eye to the longer term and the possible disappearance of good quality steam coal, we intend to design the boiler to accept a quick change-over to - and from - oil firing; especially useful for dry summers. However, it should be stressed that the locomotive will be built for conventional manual coal firing."
Boiler:
Cylinders:
Steam Circuit:
Motion:
Wheels, Frames & Suspension:
Cab Fittings & Controls:
If the boiler is taken as an example there is no reason why high degree superheat could not have been adopted aiming to peak at 420°C thus not requiring the adoption of cooled valve liners to ensure adequate lubrication. None the less this would have been a very useful thermodynamic improvement. The Gas Producer Combustion System has been used widely enough (including in the UK) for a system to be installed which would require little more than tuning to achieve excellent results. Allied to this the inclusion of a Lempor front end in place of the Kylchap would have been a must. Performance is known to be considerably better. The locomotive would sound a little different but not anywhere near as different as some might expect!
There are, of course, many other hidden modifications that could easily be applied but, sadly, it appears that A1 60163 Tornado will in essence be a first generation steam locomotive. However I do not wish to belittle the efforts of the A1 Trust who have had to overcome many sizeable obstacles to prove it is still possible to build a mainline sized steam locomotive in the UK. It has long been the stated aim of the trust to go on to build something else once Tornado is rolled out. It is to be hoped that whatever does follow will be able to show the world just what a modern steam locomotive can really do.
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