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September 2024 Newsletter

The Workbench

Last month, we were almost at the 'finishing touches' stage with our revamped HST pack and rather predictably, these took the whole month! Let us go through week by week what we got up to, to try and bring this pack into a finished item.

Week 1 - Mk3s

Two liveries still remained for us to sort out on the Mk3s; Network Rail & Midland Pullman. Network Rail has been around for 20 years now on the New Measurement Train (NMT), so there were oodles of logo/decal variations to tackle, as well as the numerous model variants required for each coach of the train with their unusual window arrangements, and even grilles on a couple of them for an on-board generator. Midland Pullman also required some out of the ordinary variants with plated up windows on the kitchen cars and TGF.

Next up was some passenger views. We had already sorted the older passenger views with the original 'IC70' seats but something was required for the more modern variants with 'Primarius' seats. See below for a screenshot of the luxurious GWR variant.

Week 2 - Sounds

Air conditioning sounds were added to the Mk3 interiors. These vary from what you hear on the Mk3A-B Coach Pack as the air conditioning on an HST works off the voltage provided by the power car providing Electric Train Supply (ETS). This varies from 274v when idling to 415v in power notch 5. As a result, the air conditioning revs up and down in tandem with the engine of the ETS supplying power car. Something sure to bring back memories of long journeys on these fine trains.

Brake squeal was then added to the power cars and for all you flange fans out there, some new sounds recorded from 43159 at the Midland Railway Centre.

Finally, cab sounds were implemented for all of the switches/buttons/handles etc. Part of this featured the driver to guard buzzer of course where three variants are provided. The first, the original buzzer, which carried on in use with East Midlands Trains power cars until the very end. Secondly, a variant brought in by First Great Western in the early 2000s and finally, a variant received upon MTU conversion on all non-First Great Western power cars.

Week 3 - Gradient Correction

By now we were properly getting into 'finishing touches' territory. One of the things we wanted to double check was the physics so armed with data from a cab ride between Nottingham & London, we drove from Kettering to Bedford (some of you may have noticed the track is laid for this on our MML enhancement pack) and applied power in sync with our cab ride data to see how well the physics stacked up. Allowing for performance differences between different pairings of power cars, everything matched up well on the flat section between Kettering & Wellingborough. From here to the foot of the climb to Sharnbrook summit, things were a little quicker than they should be but once on the 1 in 120 climb to Sharnbrook, the speed was balancing fairly well at around 95mph, just like reality. Once over the top of the summit, power is shut off for the 110mph speed limit before it is reapplied at Sharnbrook viaduct for the descent to Bedford. It was at this point that performance between reality and Train Simulator started to diverge quite significantly. In reality, you should be able to happily reach 130mph at Bedford but in the simulator, we were only getting to 120mph. The reason for this? A long-standing limitation of the simulator.

It has always been understood that for any gradients shallower than around 1 in 200, Train Simulator Classic does not apply any physics to the train so even if on a 1 in 200 gradient, the train behaves as if it is on level track. This has long been a bugbear and is why our HST was unable to perform as expected in the test above where there is a ruling gradient of between 1 in 175 & 1 in 330 downhill to Bedford from Oakley (3 miles north of Bedford). Whilst this is something we would usually shrug off, it felt time to finally investigate this to see if there was a way around it. The prospect of ragging through Bedford at 130mph was too good to shy away from!

After much testing, we discovered that actually Train Simulator Classic only starts to apply gradient physics to a train from a gradient of 1 in 185 or steeper and doesn't reach realistic-ish levels until the gradient is around 1 in 125 or steeper; hence the realistic performance heading up the 1 in 120 in our test but not on the shallower gradients on the approach to Bedford.

With this information in hand, we managed to get rid of this limitation by making the train invisibly power or brake itself to simulate the effect that gravity has where Train Simulator Classic by default doesn't do so. This is all invisible to you as the player so you won't suddenly find the power or brake handles moving without your say so, but it does mean you have to drive to the gradients of the route a lot more than before, just like a real driver, especially on mainline routes where gradients rarely reach the severity where Train Simulator Classic has them behave realistically.

We intend to roll this out to most of our existing packs at some point but it will be seen first on this revamped HST.

Week 4 - Bits & Bobs

It was now time to work through all those niggly bits that have been on the to-do list for weeks but ignored in favour of more pressing matters. Please find a quick summary below of some of the bobs we attended to:

Cold start. You can now start an HST from cold with your main reservoir pressure at 0, parking brake on and engine turned off.

Exhaust. The existing MTU enhancement pack had arguably too subtle exhaust and no clag factor so this has been rectified to something more realistic. The Valenta exhaust has also been honed to try and eek some extra smoky glory out of it. For example, how long the engine has been sitting idle is now taken into account so the longer you stand around with carbon deposits building up in the exhaust, the smokier it is when you unleash the power! The engine then 'clears its throat' and the exhaust eases. If you are at speed and regularly applying power, the exhaust stays cleaner. This works on top of the existing 'clag factor' logic so there will always be power cars that are generally cleaner or smokier than others; this now just varies with idling time too.

Mk3 roof vents. Something missing from our Mk3A-B Coach Pack was roof vents on the restaurant/buffet vehicles. Thanks to a kind offer from James Ivell, a keen tinkerer in the Train Simulator community, all catering vehicles now have roof vents in their various configurations for each vehicle type. An update will be released in due course for the Mk3A-B Coach Pack to include these too.

AI headlights. This is usually quite simple in that you have AI trains show their 'day' headlight during the day and 'night' headlight after dark. This logic also applies to the newer light clusters as fitted to the HST in latter years but in the days of the original light clusters, our research shows that 99% of the time, only the left-hand headlight (equivalent to modern 'night' headlight) was used regardless of time of day. Upon privatisation, both headlights were commonly used instead so these changes throughout eras have been simulated, as well as of course the odd chance of a driver breaking from protocol...!

Brush WSP (Wheel Slip Protection). Upon conversion to use MTU engines, non-First Great Western power cars also received an electronics upgrade with a more sophisticated kind of WSP. A simulation of this is provided where instead of the fast removal and application of power of the original system, power is reapplied more slowly in an attempt to better control the slip.

In reality, for various reasons such as engine issues or risk of high water temperature (engine overheating), power cars can have power notches 'taped out' to prevent a certain power notch from being selected. This is where a fitter literally tapes over the contact which provides a certain power setting. This is possible in our pack by changing the power car's number in the scenario to provide that extra bit of variety to the driving experience from scenario to scenario.