GWR 81xx Class Large Prarie

An Introduction

This first release of the 81xx for OpenBVE represents the culmination of over 18 months worth of hard work.
Oddly enough, this all started when I looked at my steam locomotive models for passing trains- I decided that they needed a ‘little’ work, and started building this 81xx.
From there, things rather snowballed, and I’ve ended up with a result which I think is probably among the most detailed locomotive models currently available for OpenBVE!

GWR 81xx Class Large Prarie

No locomotive would be complete without a train to pull, and the 81xx is no exception- This version contains a 10 wagon unfitted freight, together with a fully working 2D cab and a more basic 3D cab.


Beta Version V1.2.0:
This beta of the 81xx is supplied in openBVE package format. ( ) , and requires a recent nightly build of openBVE.

Changes (02nd June 2016):

  • OS_ATS replaced with BVEC_ATS- Now compatible with Mac and Linux.
  • BR Black livery added.
  • Passenger and freight variants added.
  • Full 3D cab added.
  • Animations considerably improved.

Stable Version V1.0.0
The 81xx is supplied as an OpenBVE standard 7-Zip file. Please extract this into your root OpenBVE\Train folder.

Driving Instructions

To pull off, you first need to wind the cutoff up to maximum, using the PgUp key.
When you’ve done this, release the brakes, and apply power. The small ejector can be toggled using the 6 key, although this is a non-functional dummy.
As you build up speed, wind the cutoff back down gradually, using the PgDn key.
Remember to keep an eye on the boiler water level- The injectors can be turned on to top this up, using the End key.
Unlike most other UK trains, the 81xx is not fitted with AWS- This was a deliberate decision on my part, as in their working lives, these would never have been fitted with AWS, and means that you need to keep a healthy eye on your signals!

Further Notes:
Being a steam engine, the 81xx is a slightly more finicky beast to drive than your modern diesel or electric.
Using excessive amounts of cutoff or regulator will quickly deplete your steam pressure, and you’ll stall.
In general, by somewhere around 35mph you should have dropped to close to the minimum cutoff level. Wherever possible, also try dropping the throttle and letting your momentum carry you to conserve steam pressure.
Normal working pressure for this loco is 200- 220psi, and dropping to below 150psi or so will give you problems!

Limitations & Apologies

The 81xx uses the OS_ATS plugin to provide traction modelling. As such, this actually works quite well, but has some limitations:
* The sounds are synced as best as I can to the wheelspeed. Unfortunately, the transitions between them and the effect that OS_ATS’s cutoff modelling has means they’re not always the best.
* Similarly, the OpenBVE soundsystem was never really setup for steam whistles. Brief toots are fine, but holding it will produce odd effects!
* I’ve placed the gauges from the left-hand (Firemans) side of the cab in a bar at the bottom of the panel for the moment.
* AWS is not fitted to this loco.
* Using the 2D cab, you need to remember to stop ~8- 10m short of stop markers. Again, this is somewhat of an OpenBVE limitation, which expects the front of the first car to be level with the stop marker, wheras the drivers position in a steam loco is nearly 10m back! I considered changing the markers on the Plynouth route, but this would case almost as much confusion with any other train.
* This train has two ‘errors’. These are benign, and there’s nothing I can do about them without causing other problems. (Specifically, if I correct these ‘errors’ you can then see a rather lonely front pony truck sitting on the track)


Many, many people have contributed over the years to both the Plymouth route, and the other projects that have come out of it.
I’m not going to list everyone specifically here, but:
* The Great Western Archive- Scale drawings, photos and all sorts of helpful stuff.
* Oskari Saarekas- Built the original OS_ATS plugin, without which this loco wouldn’t have come about.
* Michelle- Built a framework that I suspect I’ve rather exceeded in many ways, but again without OpenBVE there would never have been an external view.
* Alan Wheeler and the rest of the BVE Terminus people- Gave me many of the original ideas for moving bogies and some of the formulas that make this loco work.
* Hijau Kuda- Encouragement, and invaluable help with some of the extensions configuration, as well as tidying up a lot of the code.