Recent posts

#1
N Gauge Discussion / Re: A Coarse Guide to the Stea...
Last post by Bealman - Yesterday at 11:38:12 PM
As a physics teacher, the SI unit is Celsius, so that's what I'm used to. But I also agree with Mick to remove the replies (including this one), as we don't want them clogging up this superbly educational thread.  :thumbsup:
#2
General Discussion / Re: what are you listening to ...
Last post by Bealman - Yesterday at 10:45:10 PM
Cheers. Second one doesn't work though
#3
General Discussion / Re: what are you listening to ...
Last post by Newportnobby - Yesterday at 09:57:23 PM
Sorry, but back to Sandy Denny for Tim and George


#4
General Discussion / Re: what are you listening to ...
Last post by Moonglum - Yesterday at 08:30:13 PM
Hi Martin, @port perran , whilst you are working on your critical path analysis to get trains running on Sprey Point to Teignmouth next weekend, here is a little bit of fun from Solstice to listen to...

https://youtu.be/CyPnjsi7i-Q?feature=shared

I love this band and have tickets to see them in September at "The Stables", Milton Keynes. Here is a bonus song from them...

https://youtu.be/c9oUAahdKoI?feature=shared

Cheers,

Tim
 
#5
N Gauge Discussion / Re: A Coarse Guide to the Stea...
Last post by martyn - Yesterday at 05:26:59 PM
@grumbeast

tractive effort was calculated based on a formula which included number of cylinders, cylinder diameter, cylinder stroke, 85% of boiler pressure, driving wheel diameter, and, usually, a 'constant' which was different for saturated or superheated steam.

See Google

The formula was slightly different between North American and European calculations.

This means that TE was not dependent upon grate size.

Martyn

#6
N Gauge Discussion / Re: A Coarse Guide to the Stea...
Last post by martyn - Yesterday at 05:15:31 PM
I think you may have forgotten one LNER wide firebox loco, John; the Thompson A1/1 rebuild of 'Great Northern'.

Martyn
#7
N Gauge Discussion / Re: A Coarse Guide to the Stea...
Last post by Firstone18 - Yesterday at 03:15:24 PM
I'm old enough to have been taught both, so I don't mind F or C.
Fascinating series and like other I'm learning a lot,; again, as others I'm probably going to forget it quickly! I've book marked the thread and hope it stays available for years to come.
ATB
#8
N Gauge Discussion / Re: A Coarse Guide to the Stea...
Last post by martyn - Yesterday at 02:28:07 PM
Interestingly, the RCTS green Bible is critical of the 50 sq ft fireboxes fitted to the Thompson and Peppercorn boilers, and adds that 'Doncaster's whole [later] policy with boilers was wrong'. Without getting too technical (some of which I don't understand anyway), was that the firebox was producing too much heat for the small evaporating tubes to handle, and the superheaters were having to heat the steam to the required temperatures.

it was also stated after road tests that the large grates were wasteful of coal, as locos fitted with smaller grates could handle the trains with adequate steaming rates. Interestingly, the A4s with a 42.25 sq ft grate were much more economical in general; it was said that at times, the large grates were being fired 'just to cover all the firebars'. But then the A4s came out best of all the locos trialed in the 1948 exchanges.......

I've also read comments alluded to already; the original A1 boiler was effectively a scaled down Pennsy K4 one to fit the UK loading gauge. Further boiler development at Doncaster gradually departed from the ratios first used for the A1 boilers, seemingly not always to advantage.

And of course there is a subject about which I know little; the 'boiler horsepower' and the 'cylinder horsepower'. 
It was no good having a huge boiler and firebox if the cylinders could not effectively use the steam generated.

The RCTS History of the BR Standard Pacifics has a table of test results for the BR Standard tender locos, and principal express locos of the four regions, plus the Black 5. It gives boiler efficiency of ~70% for all classes tested, but cylinder efficiency of ~14%. I think it is the latter which shows just how inefficient the steam loco was, though things like compounding and re-superheating could add a few percent to the overall ratio.

Thanks again for another fascinating postingham, John.

Martyn
#9
N Gauge Discussion / Re: A Coarse Guide to the Stea...
Last post by grumbeast - Yesterday at 02:22:35 PM
Another fine post John.

I am so glad you mentioned the LMS Princess Coronations.  While ostensibly a GW man given my place of birth I can't help but be in awe of the Duchesses and was able to recently procure one (in BR Maroon).  It is a testament to their effect on the local populace that I feel an affinity for the GWR even though I was born over 20 years after its demise!

Back to technical things, I think the grate area of UPs big boys is a bit like apples and oranges, one does have to remember that they did use automatic stokers, it would be simply impossible to fire such a monster by hand!

I was curious about the firebox size of other articulated locos of other companies and was surprised to discover that both the N&W y6bs and the DM&IR yellowstones have grates quite a bit smaller.  The y6b I get as it doesn't have the same tractive effort / HP as the Big Boy but the yellowstones are pretty much on par (slightly higher tractive effort at a whopping 140000lbs) but will a grate area of *only* 125sqft. I wonder why that is?

As for F or C, its fine, I have to endure those south of the border here insisting on using Fahrenheit all the time :)

Graham
#10
N Gauge Discussion / Re: A Coarse Guide to the Stea...
Last post by Ali Smith - Yesterday at 01:02:17 PM
Farengrade or Centiheit, I don't mind. I am finding this series both interesting and informative and hope you will continue with it. There is a great deal of information out there about such matters as when no.1234 received the new type of safety valve, but not so much about how no.1234 worked or indeed how it went about its business.

Perhaps you could include the temperature conversion formula, which if I remember correctly isn't too complicated.
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