New-build steam strategy coordination?

Gas turbines work most efficiently when you can run them at near constant power output for extended periods: ideal on aeroplanes, ships, power stations etc, but near useless for vehicles that do a lot of stopping and starting with a large variation in power output such as railway (and road) vehicles. That was even more the case with the very primitive gas turbines in the immediate post-war period.

Tom

 

Its the old power storage problem again, and we still haven't cracked it. In an ideal world one would would have a power generation system that was sized for the average demands over the trip, and power conversion system capable of delivering peak requirements, and a power storage system to be able to deliver the power to the conversion system when required, all without so much extra weight that you wouldn't simply be better off carrying a generation system sized for peak demand and accepting the inefficiencies. We're beginning to see the beginnings of something hopeful in some hybrid automobile technology... Ironic of course that the steam locomotive boiler is historically one of the more effective ways of providing short term power storage, but that the inefficiencies of the rest of the system meant that it was still outperformed by other setups.

The only thing that stops me really condemning the Leader project is that there is some evidence Bulleid's contemporaries thought aspects of the thing might have worked. Of course they may simply have been playing it cautious: if I think there's a 1 in 50 chance something might come off then I sure as hell aren't going to try it myself, but I may well be measured in public criticism just in case the unlikely does happen. Its ironic that I, at least, may be prepared to criticise a design on paper that is not especially radical and does fall within my comfort zone, but I try to be very wary of criticising something that is way out of the park, most likely ludicrous, but is so far off my experience that I might end up looking silly. [Avoidance of] Clarke's first law I suppose (When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.)

On the other hand, when we consider that those who permitted a degree of further work on the doomed Leader were also those whose judgement gave us the fairly ludicrous standard range with far too many similar sized locomotives, we may consider their judgement wasn't that much better than Bulleid's anyway, if in the equal but opposite direction...

 

Tom, hence "turbo-electric". You use the combustion power source (be it diesel or turbine) as an on/off generator, electric power for traction. That said, direct drive turbines aren't that bad, Rover managed an eighth place finish in the BRM gas turbine at Le Mans in 1963.

Any thoughts on my lengthier post above about a modern steam engine?

 

For my money Bulleid's coaches are even better than the Mk.1s in terms of comfort and design, and certainly the most successful of the post war company carriages.

 

Turbo-electric allows the turbine to run at constant speed, regardless of the road speed, but it doesn't allow constant power. If you need, say, 500 dbhp along a particular section of track and your turbine is most efficient when delivering, say, 1500, do you run it for one minute with the train accelerating and then shut it off for two minutes? Or do you add a whacking great lead-acid battery (about the only kind available in those days) for power storage?

 

It's called 5AT.

 

Indeed: if they wanted a replacement for the M7s, it should have been a similar size, or perhaps somewhat larger. It ended up twice the size, with a ridiculously low power-to-weight ratio.

If you take off the tin box, you've got something a bit like a Fairlie, with most of the same good and bad features. Power bogies make good sense if you want more power than can be comfortably delivered by a single set of coupled wheels, but are an unnecessary complication for a small- or medium-sized locomotive.

 

Not really no IMHO. They're just lead/acid technology, and that really doesn't cut the mustard. Too much weight and bulk for the amount of power storage. Its two orders of magnitude worse than diesel fuel for goodness sake. We need an energy storage medium of comparable density to liquid hydrocarbon fuels if these things are to be anything other than marginal. It seems to me the answer may well be an energy efficient way of synthesising hydrocarbons, but I haven't heard there's anything on the horizon. Maybe some of you youngsters will see it in your time.

 

It may be that the turbine could be clutched directly into the drivetrain where you need more power.

5AT's problem was it looked too modern but wasn't modern enough in engineering terms. Two big outside cylinders (restricting gauging), outside Walschaerts valve gear, lots of hammerblow...

Oh, and I stumbled across this earlier... a Double Fairlie-inspired Leader prototype?! ;-)

 

One of the appeals of the Leader was that it was double ended, obviating the inconvenience of having a whopping big boiler obstructing your view ahead.
Ignoring for a second the extra crews involved, would there be any merit to a steam loco with two boilers that converged at the smokebox end, like a Fairlie, but the other way around? You'd probably need two crews admittedly each time it went out, but with a large saddle tank straddling both boilers, it could have decent water capacity and a bunker would face forward whichever way it went, so better forward visibility and also no issues with drifting smoke

 

Collect didn't go to all this trouble when the Armstrong 0-4-2Ts needed replacing. Which approach made most business sense, it's hard to decide?

Didn't the M7s end up being replaced by 3MTs on the Devon branches, which thankfully brings us back to new builds at last!

 

The funny thing is that Collett is recorded as going to a lot of trouble. According to Cook he had the design office going round in circles sketching 2-4-2Ts, 2-6-2Ts, 4-4-4Ts, 4-6-4Ts and who knows what else, until Collett reluctantly accepted that to do the same basic job as the time expired Armstrong locos he was going to have to build locos of the same basic configuration, if much updated mechanically.

I think you have to say that whilst Collett was not remotely in the same league as Bulleid when it comes to being an innovative designer, he was a rather better practical CME.

 

The Leader was designed to replace the elderly tank engines working branch services around the Southern.

Basically, as a design it was a resounding success with just one or two little teething issues, that could be easily sorted out as follows:

1) For the designed duties of moving two or three coaches at relatively low speeds, 150 tons of metal was clearly extravagant. So a modest weight reduction programme down to, ooh, about 60 tons, would be undertaken.

2) Having reduced the weight, clearly the loco does not need to be supported on six axles - four should be ample to support the weight without an excessive axle load.

3) The redesigned, lighter loco would also be shorter, so in order to allow adequate space for the firebox and ashpan, two of the axles would need smaller "carrying" wheels, leaving two axles with larger "driving" wheels.

4) A single driving cab would simplify construction and, as the redesigned loco is shorter, visibility should be adequate whichever way the loco is travelling. By a system of rods and compressed air (supplied from a small pump mounted alongside the boiler), it might be possible to control the locomotive remotely from its carriages, saving time by not needing to "run round" at each end of the journey.

5) The relatively low speeds attained and frequent stopping and starting do not place great demands on the boiler, so a simplified, more conventional boiler could be provided, dispensing with the superheater and novel firebox construction. An airier cab should mean that environmental conditions for the fireman would be more tolerable, as well as improving communication between driver and fireman.

6) The simpler, shorter, rigid frame mean that a smaller number of larger cylinders, which could be double-acting, would suffice for propulsion. The lower pressure and greater amount of space would also mean a simpler, more reliable system of slide valves could be employed.

Apart from that, the basic concept was sound and large parts could be incorporated into the revised design. Obviously, as a production rather than a prototype, livery would follow the then corporate standards of lined black.

So, ladies and gentlemen, here it is: the production Leader Mark II with all the major problems ironed out:



Drummond M7 30053 at Norden station by Tom James, on Flickr

Hmmm ... somewhere the design process may have gone astray...

Tom

 

It's interesting on the Southern that Maunsell spent almost his entire career working within severe constraints (mostly financial, but sometimes infrastructure-related, such as the Hastings Line gauge). As such almost all his locos were to some extent a compromise, yet he built, rebuilt and adapted a series of outstandingly successful locos: indeed possibly the most compromised of the lot - the Schools - was the greatest. On the one occasion that he had more or less free rein, the result was arguably his least successful design, the Lord Nelson.

Whereas Bulleid, who (the exigencies of the war accepted) was given a much freer rein in design terms ...

Tom

 

I'm sure the Midland would have loved it as being the next best thing to double heading with two inadequate 0-6-0s ...

 

Thanks for starting this thread. As has been posted, people will start and others will contribute to whichever scheme takes their fancy. However, many of these people / organisations will in future be regarded merely as philanthropists to the railway preservation scene. This is because the only way for any loco to make money to cover it's costs, let alone produce a profit for the owners, is to operate on the main line.
There are only so many dates, routes and time paths available throughout the year. If perhaps 82045, the Patriot, Grange and Brighton Atlantic are hauling excursions, that's less work available for say, Tornado and D of G. Existing loco owners will be trying to secure long term contracts for their loco on main line duties. This in turn means we will be turning out new builds only for them to sit in sheds or potter about on preserved lines.

At the risk of being a heretic, we don't have to build WORKING example of extinct classes.
Look at the aircraft gate guards at many RAF stations; some are not real aircraft, they are life size fibreglass replicas.
They represent aircraft that are perhaps no longer with us and they don't deteriorate outside all day everyday.
For those with limited funding, it may be an affordable even if not wholey desirable way of producing an example of a lost class.

 

I would strongly recommend David Wardales book 'The Red Devil' for the low down on Steam Locomotive Engineering and the alternatives