Andy in Germany
Guru
- Location
- Rottenburg am Neckar
Next train, so that's six minutes apart. It's like this most of the day.
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Next train, so that's six minutes apart. It's like this most of the day.
Andy in Germany
Guru
- Location
- Rottenburg am Neckar
...and again. Six-seven minute headways.
rogerzilla
Legendary Member
Been reading E S Cox's memoirs (he was largely responsible for the BR Standard steam locos, as well as the Horwich Crab). He was obviously a really good engineer and, despite having a soft spot for steam, explains why it's so woefully inefficient. The boiler is, surprisingly, about 80% efficient at turning burned coal into steam. The problem is in the cylinders. The theoretical Rankine efficiency is only about 15% with typical locomotive temperatures and pressures, and most locomotives achieve quite a lot less than that because of sub-optimal valve events (wire-drawing etc). Add it all up and you get a dismal 5-10% overall. You can't increase boiler pressure beyond 300psi because the weight of the thicker shell and tubes becomes too much for the track.
Worse, the locomotive wastes a lot of fuel just sitting around keeping warm or heating up from cold, and dusty coal or a careless crew can mean lots of fuel literally goes up the chimney, unburnt.
You can see why we have diesels. Cox reckons there were no more technical gains possible with steam beyond the mid-20th century, apart from a few labour-saving tweaks.
Worse, the locomotive wastes a lot of fuel just sitting around keeping warm or heating up from cold, and dusty coal or a careless crew can mean lots of fuel literally goes up the chimney, unburnt.
You can see why we have diesels. Cox reckons there were no more technical gains possible with steam beyond the mid-20th century, apart from a few labour-saving tweaks.
Jameshow
Veteran
Dud they ever build a steam powered turbine engine or a steam powered turbine / electric engine.....
rogerzilla
Legendary Member
Yes to both.
The LMS had the former (6202, unofficially "Turbomotive"), which was quite successful, and a little more efficient than a piston engine. My dad had a ride on the footplate when he was a boy. In the end they couldn't get parts to repair it after a turbine failure, so rebuilt it as an almost-normal Princess class. It was written off shortly afterwards in the Harrow and Wealdstone crash. It was a good design as they got around the usual problem of turbines being inefficient at part throttle by simply having six nozzles which were fully opened in sequence to vary the power.
The steam-powered electric engine was tried on the Continent, I believe.
The LNER and LMS tried very high-pressure boilers, which can't be done with a conventional firetube boiler because of weight and safety (LNER 10000 used a marine water-tube boiler, LMS Fury used a complex three-stage design with compound expansion on top). The LMS design still managed to kill someone when an ultra-high pressure tube burst. Neither were successful. 10000 was rebuilt as a conventional streamliner, looking a bit like an A4.
Andy in Germany
Guru
- Location
- Rottenburg am Neckar
Andre Chapelon managed to make a few improvements, although it was probably still too little, too late to stop electrification.
rogerzilla
Legendary Member
Even Chapelon and (later) Porta couldn't beat thermodynamics, although they could double efficiency from, say 5% to 10%, which was obviously well worth doing. To get high efficiency (by which I mean a meagre 30-35%) from the Rankine cycle, you need stupendously high input temperatures and pressures (supercritical steam) with exhaust to condenser vacuum. Power plants can do this as weight/size is not an issue.
Andy in Germany
Guru
- Location
- Rottenburg am Neckar
09:30 and the two-wagon wood diesel hauled train has gone past again. I wonder if it's a daily service?
Andy in Germany
Guru
- Location
- Rottenburg am Neckar
The daily Sylt-Lörrach sleeper and car train has passed. As well as German, Swiss, and Austrian stock, it had a sleeper carriage from Swedish Railways. I really hope that's due to some common carriage pool arrangement and there aren't some people on board expecting to wake up in Stockholm in half an hour...
robjh
Legendary Member
- Location
- Cambridgeshire - almost Essex
Andy, you're giving us all these tantalising descriptions but no photos. What's happening?
Andy in Germany
Guru
- Location
- Rottenburg am Neckar
Apart from the fact I'm supposed to be working, the window is south facing so even if I could react quickly enough, all you'd get until about 1pm is glare...
Spartak
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- Location
- Bristolian
Andy in Germany
Guru
- Location
- Rottenburg am Neckar
Oh, fer goodness' sake.
This isn't from work but a few kilometres outside of the town which is why it looks rather rural but it gives the idea, Also it shows that phone cameras and strong sunlight don't mix very well.
I haven't been linesiding for a while, I should probably go now while the trees are nicely autumnal.
There. I'll find/take a picture of the view out of the window next week; honestly, the things I do for you...
robjh
Legendary Member
- Location
- Cambridgeshire - almost Essex
Don't think we don't appreciate it! Some of us on the island are quite envious of the variety that you get to see on your local lines.
Spartak
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- Location
- Bristolian
Thank you.... 😉
