Interview with Mike Rennie: Building the Union Pacific FEF-3 Part 2

Written by: TrainSim-James

We continue our interview with Smokebox developer Mike Rennie, looking at the technical innovations of the FEF-3 and some driving and firing tips for drivers of this incredibly-detailed locomotive. Click here to read Part 1.

What was your starting point with the FEF-3? What made you want to recreate this loco in particular?

As soon as I finished the AT&N Consolidation, I wanted to get straight on and build another North American steam locomotive. After all, there really aren’t that many of us doing them, and for me they have a certain mystique. However, to keep things interesting (for me as a modeller), it had to be something even more challenging. I also knew that to maintain the bar high, I would have to continue to work from original builders’ engineering drawings. By that I mean not just a few front and side erecting diagrams but a near-complete set with detailed drawings for as many parts as possible.

Another important consideration, one that hadn’t been a factor when I chose the Consolidation, was that it had to be a well-known prototype because, let’s face it, that’s what gets the big sales numbers. The Consolidation started life as a hobby project, but now I have to be a little bit more commercially minded, as this is now my day job.

Lastly, the subject for my next model had to be one that would inspire me personally. It takes me a long time to build a model, so if it didn’t inspire me, it would be pretty difficult to avoid the temptation to give up and do something easier. Luckily, I happened to come across a video of Union Pacific 844. I also found out that an almost complete set of original Alco drawings (from the 1940s) is available for the FEF-3. It was only after I started to model the FEF-3 that I discovered just how much love and admiration there is, not just in the USA, but around the world, for the “Living Legend”. It’s easy to understand why, and I myself still get goose bumps when I watch those videos and hear the distinctive whistle of UP844. I hope that one day I’ll be able to visit the USA and see 844 in person!

I understand you have worked closely with steam locomotive engineers in the USA. How did they help with the project?

I’m not secretive about my projects but instead have given blow-by-blow accounts of the development, on the forum at Railworks America as well as on my own “Smokebox” Facebook page, right from the beginning. That has been essential to the development of the model because it’s allowed everyone to give me feedback and constructive criticism on what I’ve done at every stage. One person in particular has been a huge help in explaining how things work on real life steam locomotives – Justin Kardas is a full-time conductor, fireman and engineer at the Georgetown Loop Railroad in Colorado and is now President of the Colorado & Southern Railway Society. Many aspects of the advanced version’s simulation of oil firing, air brakes and the feedwater injection system, among other things, arose from the frequent conversations I had with Justin.

I have heard that some well-known people at Union Pacific, associated with UP844, are looking forward to running my model and I’m very excited to find out what they think of it.

You have clearly done a huge amount of work, both in terms of modelling and scripting, to bring the FEF-3 to life. What kinds of innovations and new features are included?

I estimate that twice as much work has gone into the FEF-3 as went into the Consolidation. The engine script alone took several months to write and debug – it’s almost 7000 lines in length.

Probably the three most important innovations are (1) the scripted animation of the driving wheels and motion, (2) the simulation of oil-firing with its associated controls and the rapid reaction of the boiler to changes in the firing, and (3) the extremely advanced air brake simulation that includes the most realistic, to-date, simulation of engine (independent) brake bail-off as well as brake pipe pressure propagation delays and a simulation of the Head-of-Train device that shows the pressure reading obtained from the End-of-Train device.

The scripted animation of the driving wheels and motion opened up lots of possibilities that I tried to exploit fully. The method of controlling those animations through the engine script means that only the forwards and backwards movement of the entire locomotive is left to the core code. The script knows the exact position of the pistons and that allows it to synchronise several other things with the piston movement, such as: the cylinder cock exhausts (alternating between the front and rear of the cylinder as the pistons move back and forth); the double-stack exhausts (that’s right, the stack exhausts are controlled entirely by the engine script, not by the core code at all); the movement of the ratchets, attached to the valve gear, that turn the mechanical lubricators; and the feedwater heater exhaust that also depends on the cylinder exhaust.

Most exciting of all is that the scripted physics simulate the loss of adhesion in wheel slip and skid conditions, including the inertia and momentum of the driving wheels – this is especially noticeable when the wheels lose and regain traction. I recommend watching that Facebook video, mentioned earlier, to see what you can now do with the locomotive, such as what happens when you get wheel slip, close the throttle, put the cut-off in reverse (be sure to watch how the reverser and valve gear moves from forward to reverse) and open the throttle again while the locomotive is still going forwards.

The TS2015 core code simulates coal-fired locomotives, where coal is shovelled into the firebox and mixed with air to burn, generating hot gases that get sucked through the flues running through the boiler, which evaporate the water to generate the steam that powers the locomotive. An oil-fired steam locomotive works in a similar way, but with important differences. Instead of having a coal fire that burns slowly, with slow changes to the rate of steam generation, it uses oil as its fuel. The oil is mixed with steam in something called an atomizer which sprays it into the firebox as a fine mist of oil droplets, where it mixes with air and is ignited by a burner. The amount of air is controlled by the dampers. The amount of oil being fed to the atomizer is controlled by the oil regulator (also called a firing handle).

The fuel-air mixture has to be in just the right proportions to produce the required heat and to avoid problems caused by unburnt oil dripping into the oil pan or the burner. Crucially, the rate of steam generation changes rapidly when the firing controls are adjusted, so the fireman has to pay close attention to how the demand for steam changes when the engineer adjusts the throttle and cut-off. The challenge was to simulate all of that, realistically, using controls that are meant for a coal-fired locomotive. I’m certain that when you run the FEF-3, you’ll notice how different it feels to a coal-fired steam locomotive.

Your previous locomotive was the Consolidation – how does that compare with the FEF-3 in terms of operation and running? I imagine they are very different beasts.

They are at almost opposite ends of the scale in terms of size, power and speed.

The Consolidation is comparatively small and not particularly powerful or fast, but she’s still a lot of fun because you have to be careful to keep the boiler pressure up when climbing a grade and if you fail to keep the fire mass at the ideal level, it can be a struggle. I think the “Connie” has a lot of quirky charm to make up for that. She’s ideal for those backwater shortline railroads, trundling along with a local freight or a short excursion train.

The FEF-3, on the other hand, is from the zenith of the “Superpower” era. She’s big, powerful and fast – ideal for hauling heavy passenger or express freight consists over any kind of mainline route. Thanks to the FEF-3’s oil-firing, if you get over-excited with the throttle and cut-off and find yourself quickly losing steam, it doesn’t take very long to build it back up again, provided you know what to do with the oil-regulator, atomizer and damper (or you can just let the scripted, expert auto-fireman do it for you).

One other notable difference is that the Consolidation has a very early 20th century appearance, especially in the small cab, with its old-style gauges. The FEF-3, by contrast, has a huge cab, that even has a suite of modern electronics, so it has a present-day feel to it despite being a 1940s steam locomotive. That makes the FEF-3 perfect for recreating excursions with UP844 (and, thanks to the functional multiple-unit controller in 844’s cab, the SD70Ace diesel, UP8444).

Nevertheless, if you want a more retro feel, you can actually make the electronics vanish from the cab.

What will you be working on next? Do you think you will recreate another North American steam locomotive or is it time for a change of pace?

I’ll definitely stay with the North American railroad scene. There are probably more developers making content for the UK, where I happen to live, than for the USA and Canada, so I’m more than happy to continue to focus my attention on North America. As for doing another steam locomotive, well, perhaps. Or I might do something different for a change. I haven’t decided yet. The FEF-3 has taken about 20 months to develop. That’s a long time! I’m not sure if I’m ready to dive into another 20-month project right at this moment.

Finally: any tips for driving the FEF-3? Any real ‘do’ or ‘don’ts’ for the users?

The most important ‘do’ of all is this: read the manual! Otherwise, you might end up scratching your head and wondering why the headlights won’t come on, or something like that.

Another absolutely essential ‘do’ is to turn off the game’s auto fireman.

If you’re new to Train Simulator and not very confident at running steam locomotives, my advice would be to start by running a “HUD” version in “Simple” mode and choose a Quick Drive scenario in a summer season (to reduce the chance of wheelslip). It can’t get any easier than that.

Don’t try to run the Advanced version in Simple mode or using the F4 HUD.

If you’re comfortable with “Simple” mode, progress to running a “HUD” version in “Expert” mode. The HUD versions of the locomotive have the scripted expert auto-fireman (“Ted”) enabled permanently, so you only have to concern yourself with playing as the engineer, working the throttle, reverser (cut-off) and brakes. Watch and learn as “Ted” adjusts the firing controls to keep the boiler pressure at close to 300psi without the safety pop valves lifting all the time.

When you feel ready for something more realistic and challenging, pick the Advanced version, but as soon as you’re in the cab, mouse click on the front of the fireman’s seat to enable “Ted”. You’ll have enough to do managing the advanced brakes without the extra worry of firing manually. Those brakes are especially tricky with long consists because they simulate the time it takes for the brake pipe pressure to rise or fall depending on the length of the brake pipe. Trying to maintain track speed without speeding or skidding while going downhill with a long consist is a lot of fun!

Don’t turn on the F4 HUD when using the Advanced version – the controls and gauges will appear to do strange things and won’t behave as you’d expect with other models.

When you feel ready for it, go for the ultimate challenge – pick the Advanced version with a long consist, leave “Ted” turned off, and set the track conditions to wet, snow or (for the absolutely ultimate challenge) “leaves on the track”. You’ll have to remember a lot of things:

• Use the sanders when starting from a standstill with the reverser fully forward.
• Open the cylinder cocks before moving off, so that any condensation will be expelled from the cylinders.
• Don’t forget to turn on the tank heater if the fuel isn’t warm enough (look at the temperature gauge on the front of the tender).
• Check the fire frequently in case it’s gone out because of an obstruction in the heater (more likely if the fuel is too cold or if the atomizer isn’t on strong enough)
• Blow down the water sight glasses (if they get clogged, you might think you’ve got more water in the boiler than there actually is) and blow off the boiler and water jacket sludge.
• As soon as the loco is moving, “hook up” the reverser (move it closer to the neutral position to reduce the cut-off), so that you’re less likely to get wheelslip and will use less steam.
• Anticipate when you’ll need more steam pressure and set the firing controls to generate more steam before you open the throttle or push forward the reverser. That’ll help to avoid sudden drops in boiler pressure.
• Likewise, before closing the throttle or shortening the cut-off, if the boiler pressure is already close to 300psi, set the firing controls for less steam, to avoid lifting the safety valves.
• Keep looking at the colour of the smoke from the stack – black means you’ve probably got the oil regulator open too far or the damper closed too much, if it’s blue, reduce the atomizer, if it’s white (and not because the air compressors are pumping and exhausting steam from the small nozzle between the stacks), increase the fuel flow, and if you see grey smoke, try to keep it that way.
• Get used to braking by setting the desired equalising reservoir pressure and then letting the brake pipe pressure catch up.
• If you get wheel slip, immediately close the throttle and reduce the cut-off. Applying a bit of engine brake will also help to slow down the driving wheels (the friction between tyre and brake shoe is greater than between tyre and rail).
• If you get wheel slide/skid, immediately bail-off the engine brake – you can do this without needing to release the train (automatic) brakes. In fact, you should make it a habit to bail off before the brake cylinder pressure reaches the maximum.
• Be careful not to accidentally apply the emergency brakes. If you move the handle to the right, it stops before entering the emergency brake zone and won’t move all the way to the right unless you release the mouse button for a second and then continue to move it all the way to the right. If you do apply the emergency brakes, the Mars light will come on and you won’t be able to release the brakes immediately even if you try to.
• Pay attention to the alerter and don’t take too long to acknowledge it (press ‘Q’), otherwise there’ll be an automatic full application of the automatic brakes.
• Don’t forget to turn on the feedwater pump and remember that it has to be higher than the boiler pressure to pump water into the boiler.
• If you’ve got the feedwater pump on full, but the engine is working very hard and the water level in the boiler is still going down (it can be a bit tricky to judge because of the sloshing), remember that you can top it up for a short time using the live injector (near the fireman’s seat).

Above all else, ‘do’ have fun and ‘don’t’ hesitate to ask questions on Facebook or in the forums if there’s anything about the FEF-3 that you need help with.


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