[MOC] D800 Class "Warship"

[Hod Carrier]

A little treat for everyone for Easter. 

I've been working away quietly on my first full-size loco, and just this week I completed it. It's a D800 Class "Warship" diesel-hydraulic loco used by the Western Region of British Railways during the 1960s. My model is of D812 Royal Naval Reserve 1859-1959, one of only two members of the class not to carry the name of a Royal Navy warship (see Prototype Notes below).

Although the normal convention for British models is 7-wide, I was forced to build this as an 8-wide model which makes it rather large. On the plus side, this model scales at around 1:42 or 13.5 inches per stud, which brings it very close to UK O Scale.

The benefit of this scale is that instead of having to create my own graphics I was able to use the excellent range of O Scale waterslide graphics for all markings, crests and numbering. I was even able to lavish this model with etched nameplates and works plates.

As far as possible I have tried to keep everything to scale, and this extends to the bogies. They are a tad long to comfortably traverse standard LEGO curves, but they will go round even though the wheels are partially covered. Purists may be disappointed to see that some LEGO was hurt in this area of the model, but I wasn't going to give up on the sloped sideskirt ends.

The uncompromising head-on view shows the use of coloured vinyl to recreate the yellow warning panel and the windscreens. Admittedly the screens should be larger and extend to the roofline, but this is one of those compromises you make when you build with LEGO. Silver window frames have been achieved using a metallic silver Sharpie.

This is just a taster of the details of this loco as there is more to reveal in the coming months.

Prototype Notes:

Spoiler

Quite unlike any other British locomotive, the D800 Class came into existence as a direct consequence of the drive to modernise Britain's railways. While other types were being produced as a like-for-like replacements for outgoing steam locos, the D800s were designed as an engineering solution to meet the needs of the new modern railway as envisaged in the 1950s. Therefore, it's history is both unique and uniquely interesting.

Following nationalisation of the railways in 1948, British Railways found itself running a hotch-potch fleet of largely non-standard locomotives and rolling stock. The answer initially was to take the best features of each type and incorporate them into a fleet of "standard" steam locos. However, by 1955 the need to modernise was becoming dire and so, in that year, a report known as the Modernisation Plan was published. This called for a full reorganisation of freight and passenger services together with the eradication of steam traction to be replaced first with diesel and then electric traction in order to improve both performance and efficiency at a time when the railways were facing growing competition from road transport.

One of the other key recommendations of the Modernisation Plan was to provide all freight trains with continuous brakes, as previously the majority of freight services relied solely on the loco's brakes and the brake van (caboose) at the tail of the train. This restricted the speed at which freight trains could travel for safety reasons, but providing continuous brakes would allow them to run at higher speeds and, therefore, increase the capacity of any given route. The Chief Mechanical Engineer of the Western Region (WR) realised that providing continuous brakes would remove the requirement for locos to be so heavy in order to provide effective braking capacity for unbraked freight services. By using lightweight stressed-skin construction rather than more conventional construction methods, it ought to be possible to produce a loco in the 2000hp power range that weighed only 80 tons. This reduced weight would serve also to increase the power-to-weight ratio which would translate into sufficient performance that a loco of this type would be able to haul an additional coach compared to a heavier loco of the same output.

There was a strong feeling within the WR that diesel-hydraulic would be a better proposition than diesel-electric and it had been lobbying hard to have locos of this type included in British Railways' plans. Although the West German state railways had introduced diesel-hydraulics with great success it was not seen as politically or economically expedient to order from foreign suppliers. However, the North British Locomotive Company (NBL) in Glasgow had become license holders for both MAN diesel engines and Voith hydraulic transmissions and it was agreed that a small batch of diesel-hydraulics would be ordered from them to compare to the new English Electric 2000hp diesel-electric loco, later Class 40.

NBL duly produced six locos which became the D600 Class, each of which was named after a Royal Navy warship and so became the first of the "Warships". However, these locos were compromised from the start and, although they were allocated to the WR, fell a very long way short of their expectations. As NBL had no experience of stressed-skin construction, the D600s had been built conventionally with a heavy frame carrying the body, power plants, transmission and so on, and tipped the scales at 117 tons. This ruled out the proposed B-B power configuration as the locos would have exceeded the mandated 20 ton axle loading limit, and so they had an A1A-A1A configuration because NBL could not come up with a pivotless bogie design nor a hydraulic transmission capable of realising a C-C arrangement.

In the meantime, WR managers had approached West German manufacturer Krauss Maffei, who were at that time the largest and most experienced producers of diesel-hydraulic locos. It was agreed that a scaled-down version their V200 design would be suitable for British use and had agreed in principle to a licencing agreement that would permit them to be built in the UK. Presented with this, British Railways agreed for production to go ahead, initially with a small batch but eventually a full production run totalling 71 locos. Construction would be split between NBL with licence-built MAN/Voith powertrains, and the WR's own loco works at Swindon using Bristol-Siddeley built Maybach engines and Mekydro transmissions. Using stressed-skin construction these locos weighed just less than 80 tons each at a time when all other locos in the same power class weighed upwards of 115 tons, which allowed them to use B-B arrangement. These locos became the D800 Class and, by continuing the practice begun with the D600 Class of carrying the names of Royal Navy warships, became known as "Warships".

These locos were initially put to work on passenger services from London Paddington and could operate at speeds of up to 100mph in service, although this proved a problem as the high running speeds caused rough-riding due to the design of the bogies. They performed well but were displaced by the larger and more powerful D1000 "Western" Class diesel-hydraulics on top-link services. However, they remained a mainstay of WR services operating from London Waterloo and could be found operating many different types of passenger and freight services throughout the WR.

By the late-1960s the D800 Class, along with all the other diesel-hydraulic classes, were considered non-standard and earmarked for withdrawal. However, the writing was on the wall for the "Warships" as these locos were unsuited to the new rolling stock that was coming into use across the network. Whereas before trains used vacuum brakes and were heated by steam, the new coaches were air-braked and electrically heated and the "Warships" had no facility to provide air for the brakes nor electrical power for heating. For a loco design that was the result of far-sighted vision and engineering the D800s were sadly anchored in the past and could not survive for long. Any long-term future for these locos was not helped by the loss of NBL to insolvency in 1962 and the withdrawal of Bristol-Siddeley from the diesel engine market shortly afterwards. By the end of 1972 all had been withdrawn and the vast majority, including D812, scrapped.

 

Edited April 21, 2019 by Hod Carrier

[Pdaitabird]

That's a lovely engine (even though it's a diesel)! The decals look great in that scale and the customized parts are well done!

[waparesult]

Love it, reminds me of my time with my dad looking at trains in Laira Depot Plymouth... well done Sir a great job, cannot wait to see the final version

[Roadmonkeytj]

Lovely looking indeed.   I think the mutilated Lego makes marvelous skirting  ... Did you cut to keep it stud free then? 

[LEGO Train 12 Volts]

Your works are always gorgeous.

I like how looks rounded your locomotive and the green colour is a great touch.

The overall shape is perfect and the stickers do the right work.

Very nice train buffers (is the first time I see this fantastic solution using the new plate 1 x 2 and the two tiles)

[Hod Carrier]

12 hours ago, Pdaitabird said:

That's a lovely engine (even though it's a diesel)! The decals look great in that scale and the customized parts are well done!

I guess diesels aren't your thing, but thank you for the lovely comment. I'm pleased that it turns heads of steam fans too. 

4 hours ago, waparesult said:

Love it, reminds me of my time with my dad looking at trains in Laira Depot Plymouth... well done Sir a great job, cannot wait to see the final version

Your Dad was a western man? That's fantastic!! That sets the bar very high indeed. I'm very happy to receive your endorsement as someone who has probably seen these locos up close. 

Appearance wise the Warship is finished. There are one or two technical considerations that I'm still working on, details of which I'll post as they are dealt with.

3 hours ago, Roadmonkeytj said:

Lovely looking indeed.   I think the mutilated Lego makes marvelous skirting  ... Did you cut to keep it stud free then? 

Not specifically, no. I was intending to use 2x2 wedge plates which BL lists as being available in dark green. However, when it came to trying to buy some I discovered that one is rare and the other not available in any store due it only appearing in a one-off limited edition Brickheadz set distributed only at a New York Comicon. I wasn't going to give up on the shape, so sadly the 2x2 tiles had to be mutilated. The studless appearance is just a happy side-effect.

3 hours ago, LEGO Train 12 Volts said:

Your works are always gorgeous.

I like how looks rounded your locomotive and the green colour is a great touch.

The overall shape is perfect and the stickers do the right work.

Very nice train buffers (is the first time I see this fantastic solution using the new plate 1 x 2 and the two tiles)

Thank you. That's high praise. 

I guess I just got lucky with the scale which allowed me to use O Scale transfers for the majority of the markings. All I was left to do was the warning panel and the windscreens. I'm glad you like the buffers. I wanted to try and make them oval like the original locos and was lucky that the parts now exist to recreate this. The only downside is that they end up quite thick (2 plates) which does spoil the look from the side a bit, but I'm happier to have that than rectangular buffers.

[Hod Carrier]

I think I've been mysterious with this for long enough now. I think it's time to show you all what's going on inside.

First of all, let me just confirm that this model is motorised and does indeed run, and that it will traverse R40 curves (although it is slowed by them). Below is a little video showing this (click to play).

It's actually quite a smooth runner and doesn't mind pulling a tail load. But wait!! What's going on? It's almost as though this train has a mind of it's own!! 

Well it does, after a fashion. Yes, of course. This loco takes it's power and control from a Mindstorms EV3 intelligent brick.

I got the idea after finishing the signalbox lever frame. I enjoyed building it but I wasn't quite sure what it was for once I'd finished it. Ideally it would be a good way to control the movement of trains in exactly the same way as signalboxes do on the real railway. It would be even better if the trains could be automated so that they could interact with the signalling in a realistic way. But how to achieve this?

This was when I found @Hanso's work using Mindstorms to control train movements and integrate them into a larger display (click for thread). For this he used coloured tiles to determine the train's location in order for them to be integrated successfully, so surely the same principle could be used to convey instructions to the train using the appropriate programming. However, unlike Hanso, I wanted my trains to be realistic-looking, and for that I needed be able to fully enclose the EV3 brick within the bodywork.

This was one of two key criteria that I needed to fulfil before even considering going ahead. The second was the need for whichever loco type I chose to be British, as this would relieve me from the need to learn another country's signalling principles. It took very little thought to realise which way around the EV3 brick would have to go inside the model and that I would need a decent space between the bogies to accommodate it together with the colour sensor. This requirement alone is what brought me to the D800 class diesel, as this type's configuration made it the best candidate for an installation. However, I was not going to be able to employ exactly the same powertrain as Hanso had (EV3 controlled servo operating a PF battery box dial to power conventional PF train motors) as this simply wouldn't fit. This loco would have to work using the medium servo motor or it wouldn't work at all.

A huge amount of tiffling about with LDD finally brought me to a design that I felt could work and still look like a real locomotive. Having got that far there was nothing for it but to build the model and see how it would perform.

This is a short video of Robotrain v1.0 on test, and already there was a problem. The gearing for this model is 1:1 but, as Hanso discovered, the medium servo motor is not ideal for this application. The prototype had been programmed to accelerate to 100% power, slow to 50% power when it received a yellow signal and then slow to a stop after receiving a red. Testing the prototype suggested that it was always slow to respond to the yellow and did not reduce speed that much, which indicated a problem with the motors. Static testing with the motor disconnected from the drive shows a lovely linear increase in power up to around 70% after which the power output tails off markedly. Reconnecting the motors to the drive showed similar results. Clearly the model would need to be geared-up fairly dramatically to make it run at anything like a realistic speed.

On the plus side, the use of servo motors makes the loco very controllable and very precise. Even with the VGAs in tow it could start away with no wheelspin whatsoever and it would always stop in exactly the same place every single time. By altering the variables within the programme the performance of the loco can be fine-tuned to make it do exactly what I want it to do.

The quest to gear the loco up initially caused me a bit of a headache due to the internal configuration of the gears and shafts. However, it was at this moment that I made a realisation that would help solve this problem. It was only when looking at renders of the finished loco that I realised I'd made a miscalculation regarding scale. The height and width of the model had been dictated to me by the need to accommodate the EV3 brick, but it suddenly dawned on me that the loco was out of proportion because I had got the length wrong. Suddenly I had an extra six studs to play with that would permit me to move the bogie pivots and vertical shafts nearer to the ends of the motors which would permit me to use a bigger drive gear.

This is the final drivetrain configuration. The gearing has been increased from 1:1 to 1:3 which has increased the speed nicely without apparently affecting the loco's pulling power or the ability of the sensor to "see" the colour signals in the track. This has also allowed me to change the programming parameters so that I can avoid the drop-off in power output from the motors.

Cosmetically this model is now complete but I'm sure that there will be software tweaks still to come. I have tried to make the loco "think" and "react" to signalling in the way that a real train driver would in order that it will operate realistically. This is just Phase 1 of a fairly ambitious plan to create a layout featuring semi-autonomous trains operating under the supervision of a signalbox, so it is almost certain that there will need to be alterations to ensure that everything runs smoothly and reliably. Consequently there will, as I hinted above, be more to come on this. Now that I have proved that the loco works and that it can "see" track signals the next stage will be to design and construct the signals themselves and provide facilities for them to be remotely controlled.

[baard]

Nice model!

I especially liked the programmed functions.

You would gain a lot better tackling of the curves with on stud movement of 1 axle in each bogie without compromising too much on your sleek design.

Thanks for sharing!

[Hod Carrier]

@baard Thank you. I'm always happy to share with you all. 

About the bogies; yes I could make them a little shorter to help with curves, but that would not be quite to scale. I'm happy enough with the performance that I don't think I need to ban R40s completely, even though they do slow the loco down a bit. I shall just have to try some slightly larger curves until I find some that the loco is happy with.

[harnbak]

Beautiful

[Feuer Zug]

Nice classic diesel locomotive. The use of the Mindstorms really changes it up.

[Hod Carrier]

Thank you, gentlemen. 

[Paperinik77pk]

Hi @Hod Carrier, this is a true masterpiece, the use of Mindstorms (and the whole frame design to fit it inside the locomotive) is really fascinating! :) :) :)