Re: Thought exercise - steam VFT

["William Pearce" <ben_issacs@optusnet.com.au>]

  Sorry about the 'non-message' that went out under my name yesterday, a
stuff-up on my part!
  The intended message follows:
    In re Dave Bromage's High Speed Steam Train exercise, firstly one must
think about the herbs that would be required to run such a train. I had some
info on calculating horse powers required at various speeds, but cannot find
it, however, using figures for a Shinkansen set running at 270 km/h (about
180 mph), it seems that one requires about 30 hp/ton of train to attain that
speed. Assuming ten 50 ton SOP type cars, plus say 250 tons for the
locomotive, we get a total train weight of 750 tons, multiplying this figure
by 30 gives us a horse power of 22,500! I think that the most powerful steam
loco of that era gave about 7,000 hp. (Challenger or Big Boy?)
  That amount of power would require a lot of steam, therefore a lot of
water, too much to haul in a tender, so one should look at a condensing
tender, such were in use at that time in Russia and South Africa, so not an
impossible technique.
  As for fuel, coal is impossible, for the horse power required a grate area
of about 350 or so square feet area would be needed, so look at light oil,
or possibly petroleum gas. For light oil, and assuming that an oil burner is
about half as thermally efficent as a diesel engine, we might expect to get
about 0.7 lbs fuel per hp per hour through the burners, allowing four hours
endurance, so we need 0.7 x 4 x 22,5000 = 63,000 lbs or about 30 tonnes of
fuel oil to be carried in the tender.
  Now we have to get this horsepower onto the rails. Ordinary direct drive
reciprocating steam engines are out at such a speed, balancing and piston
speeds would be problems, perhaps a number of horizontally opposed piston
engines, each driving an axle through gearing could be used, the control of
such a group of engines may be difficult, and we would require a fair number
of these powered axles to get this power onto the rails, this is all
beginning to sound a bit like a steam-powered mu train.
  So, it does look like a steam turbine, driving an electric genny set,
sending power all along the train and driving all, or at least half of  the
train axles. This turbine, to work efficently, should really have a proper
condenser, working at a vacuum, but that could not be done in the space
available, so the simple air-cooled water saving condenser would have to
suffice.
  I suspect that by now my 250 ton allowance for the locomotive has been
well exceeded as I have given no thought to a boiler design, such types as
high pressure or water tube would probably be required, and these weren't
all that reliable, one can only say that the boiler would be a big un.
Loading gauge limits have not been considered, perhaps this line would have
to have a loading gauge, or even perhaps a rail gauge greater than the
normal.
  Now, having put this fantasy up, someone has to knock it down!
                                        Regards,   Bill Pearce

"David Bromage" <dbromage@fang.omni.com.au> wrote in message
E3fy5.52$nQ.6020@news0.optus.net.au">news:E3fy5.52$nQ.6020@news0.optus.net.au...
> Here's an interesting paper exercise. Suppose a multi squillionaire had
> decided to build a 200mph train between Melbourne and Sydney in the late
> 40s or early 50s with the technology available at the time.
>
> What sort of steam locomotive would have been required for such a service?
>
> I've done some rough calculations, and yes I think it could have been
> done, at least with today's hindsight about what did and didn't work.
> You do need be a bit unconventional in your thinking, but the design is
> not really all that radical.
>
> Go grab the Tuplin, Cox and Nock books, a calculator and lots of paper,
> then post your thoughts.
>
> Cheers
> David