The Night Mail

[jjb1970]

7 hours ago, Chris Snowdon said:

Hi jjb1970

Is this the place to discuss fluid dynamics?  Yes, I think that it is, for a few reasons.

The strength of rail was to get mail from the first port of call to its destination, and speed and efficiency both mattered - "City of Truro" and her crew were doing just that, and it was also the point of TPOs.

Later, the "Blue Riband" wasn't just about showing off to rich 1st Class pax, or shifting huge numbers of people in search of a better life, but keeping the mail-boats going as started by Brunel a century earlier.  Streamlining on the railways had a different driver - definitely to impress 1st Class and business travellers - but also the efficiency angle - either more speed for same effort, or same speed for less effort.  Neither the Brits nor the Germans got that right, and most aerodynamic styling in the US was just "styling" as well.

Whether the subject is an aircraft, ship or train, the various ratios between cross-sectional frontal area and length are mainly equally important and the relationships between the six degrees of freedom are also affected.  I still know of no aircraft or railway design which uses a "bulbous bow", which basically uses a 3d version of the bernoulli effect to reduce drag.  Instead, aircraft get wider rather than longer (or, at least, they should increase in proportion) whereas HSTs seem to go for the "duck-bill" for down-force at the ends.

Thompson should have cared about this (he was a mathematician) but he had no reason to.  Gresley and Stanier were just showing off to Wagner and Witte (who were just showing off in return) and I personally believe that Bulleid just got lucky.  Collett's "ping-pong ball" on KH7 was useless, but he never realised that (1) the A4-style cab-front was a Good Thing and (2) the fairing behind the chimney helped with smoke-deflection: Double-win.

Finally, Raymond Loewe designed some incredibly handsome machines, but Kenneth Graham's worked better, whether you consider his food-mixers or his locomotive body-shells.

regards

cs

 

Hull design still uses a lot of work done in the 19th century by people like Froude and Stokes (why is it a Reynolds number instead of a Stokes number?) but tools like CFD and just the sheer computing power we now take for granted has allowed huge improvements in hull form. 

The bulbous bow is primarily about controlling the bow wave, which has a significant influence on resistance. The length to beam ratio is one of those things that looks simple until it isn't. Many assume that a long, thin, very fine hull form will be tip top but performance is also about how a ship behaves in a sea state and for commercial ships hull volume for cargo. The first generation post Panamax container ships increased beam and reduced length with no increase in capacity over the last of the big Panamax ships but the overall efficiency of a shorter, fatter hull was better.

There's a big assumption in many shipping circles that the EEDI values of container ships (EEDI is like those ratings you get on fridges and washing machines, it gives a value for design technical efficiency at defined conditions) improved enormously and way more quickly and by much bigger margins than anticipated by reducing speed. I can understand why people might make that assumption, but the only speed value that matters for the EEDI calculation is the reference speed (operational speed is irrelevant to the EEDI) and reference speed didn't actually change much, hull design and propulsion packages did actually improve very significantly and increasing size helped a lot.

[iL Dottore]

1 hour ago, Happy Hippo said:

Then hung out to dry by their supposed (by this time) allies, the USSR.

 

Who stopped their offensive against  occupied Warsaw, and sat back to watch.

Well that was because the wrong kind of Anti-Nazi Poles led the uprising, being directed from the Polish Government in Exile in London, not the puppets in Moscow (the Soviet backed Polish Committee of National Liberation).

 

For Stalin, not intervening in the Warsaw Uprising was very much a win-win scenario: he was able to rid himself of a lot of pro-Western Polish insurgents and inflict casualties on the Germans at the same time.

 

Casualties from the 63 days of fighting were appalling: 15,200 killed and missing from the Polish resistance, up to 17,000 killed and missing on the German side and between 150,000 to 200,000 Polish civilians also lost their lives.

 

Stalin was very pleased.

[polybear]

36 minutes ago, Compound2632 said:

 

indeed, in Oxford colleges too, with the refinement that the most junior fellow sits at the extreme left of the circle around the senior common room fireplace and has the job of carrying the bottle back across to the most senior fellow at the other side of the semicircle. There was one college where the most junior fellow happened to be an engineer - the port slide was invented. 

Junior? JUNIOR?? 😱

And not once but twice in the same post……

[Compound2632]

18 minutes ago, polybear said:

Junior? JUNIOR?? 😱

And not once but twice in the same post……

 

Baffled. The most junior fellow is the fellow most recently appointed. Not to be confused with Junior Research Fellows and the like, who are not full fellows.

[polybear]

1 hour ago, Compound2632 said:

 

Baffled. The most junior fellow is the fellow most recently appointed. Not to be confused with Junior Research Fellows and the like, who are not full fellows.

Discussion on ER’ers about this:

 

https://www.bbc.co.uk/search?d=NEWS_PS&q=Junior+Doctors&seqId=e92565b0-7678-11ef-a1f5-79aa65ff6af7

[Compound2632]

4 minutes ago, polybear said:

Discussion on ER’ers about this:

 

https://www.bbc.co.uk/search?d=NEWS_PS&q=Junior+Doctors&seqId=e92565b0-7678-11ef-a1f5-79aa65ff6af7

 

Nothing to do with academic positions, especially pecking order in Oxford Senior Common Rooms. 

[polybear]

8 minutes ago, Compound2632 said:

 

Nothing to do with academic positions, especially pecking order in Oxford Senior Common Rooms. 

Agreed - but I’ll bet others will soon start thinking, if not already….

[monkeysarefun]

24 minutes ago, polybear said:

Agreed - but I’ll bet others will soon start thinking, if not already….

 

Nah.   None of that pommy nonsense down here.

 

 

 

 

(Hmmmm, amazing how non-PC that is now.......!)

 

 

 

 

 

Edited 9 hours ago by monkeysarefun

[J. S. Bach]

10 hours ago, AndyID said:

 You can discuss pretty much anything here. Just don't mention sheds.

Or GREEN panniers! Like this one 😇:

 

 

Edited 8 hours ago by J. S. Bach
To edit the post

[J. S. Bach]

11 hours ago, jjb1970 said:

Over here we use Kelvin, another brilliant man all but unknown outside of scientific and engineering fields.

I know about Kelvin but I think that 525º R  is more impressive than 255º K for our current 66º F! 😸

[Compound2632]

15 minutes ago, J. S. Bach said:

I know about Kelvin

 

He has a whole area of Glasgow named after him. 

[PhilJ W]

5 hours ago, Happy Hippo said:

Of course, in an Army Officers or Warrant Officers and Sgts Mess, the decanter goes around faster than passing the parcel pager on a Belfast Beirut bus.

Thats more like it.

Edited 7 hours ago by PhilJ W

[PhilJ W]

13 hours ago, Chris Snowdon said:

Have had a brainstorm.  A possible model RMS, if one has the enormous aounts of time, money and space necessary, would be a down-scaled conversion of the old Marcle Models SD 14.  Leaving out most of the 'tween-deck detail, reduction of scale of above-decks equipment, masking over the superstructure and adding a RO-RO ramp at the stern, and then it might just work...

I've been to a few meetings at a place which has an HO-scale vehicle-ferry in their collection of models, including a couple of goods trains on the rail-deck (tankers and Interferry vans).  If memory serves, then it really can't be that much more than about twelve feet long...

regards

cs

There is a model container ship that is 1/76 scale available. It's produced by Deans Marine and represents a coastal vessel. The model is 1.1 metres long (3' 8") so should fit a standard baseboard.

[SM42]

14 minutes ago, PhilJ W said:

There is a model container ship that is 1/76 scale available. It's produced by Deans Marine and represents a coastal vessel. The model is 1.1 metres long (3' 8") so should fit a standard baseboard.

 

You could get 2 on the dining room table. 

 

 What livery choices are there? 

 

Andy

[PhilJ W]

1 minute ago, SM42 said:

 

You could get 2 on the dining room table. 

 

 What livery choices are there? 

 

Andy

It's a kit, whatever livery you want.

[DenysW]

3 hours ago, J. S. Bach said:

Or GREEN panniers! Like this one 😇:

That can't be a proper paneer - it hasn't got any ridiculously polishable copper on the chimney.

[bbishop]

7 hours ago, Compound2632 said:

 

F13. E14. G14. P14. T14. As I said the other day, Robert Urie must have been a very frustrated man.

 

But the great Dugald Drummond gave us the 'Abbotsford' class of 1877, the progenitor of so many superb 4-4-0s, so may be forgiven the sins of his old age.

Interesting list.  Excluding the "extended 4-4-0s" (incl. GER, LNWR Experiment and arguably Cardean and her sisters) lets consider the British 4-6-0 narrow gauge classes.  On the LSWR the F13s and the single E14 were truly awful.  The G14 and P14 classes could at least pull, even if they couldn't run, and were flogged to death on the South Wales to Portsmouth coal trains during WW1.  These four classes were designed by George Sisterson, who was replaced by James Hunter in 1906 and who designed the T14 class.  Maybe Dugald Drummond only made two contributions to the design of his 4-6-0s, make sure a superheated hadn't been included without his knowledge and to sign the drawing.

 

Let us consider the other narrow gauge 4-6-0s.  LNWR Claughtons, L&YR, CR (Pickersgill), G&SWR, Highland, NER, GCR.  I can only think of three classes that were relatively unflawed - the two Manson superheated locos, the Highland Rivers and the NER S3 (and that was after a lot of wasted metal on the three preceding NER classes).  The T14s were undoubtedly flawed, but so were most other British 4-6-0s, and they did slog up and down the LSWR main line for nigh on 40 years.

[bbishop]

Hazel and I went to the Van Gogh exhibition in the National Gallery today.  It is on until January and, if you are coming to London, is really, really worth a visit.  But you will need to book in advance.  And we have an added benefit - not just one, but two trains.

[iL Dottore]

20 minutes ago, bbishop said:

Hazel and I went to the Van Gogh exhibition in the National Gallery today.  It is on until January and, if you are coming to London, is really, really worth a visit.  But you will need to book in advance.  And we have an added benefit - not just one, but two trains.

Good to know, Bill. I'll book my tickets in the next day or so

[Happy Hippo]

1 hour ago, DenysW said:

That can't be a proper paneer - it hasn't got any ridiculously polishable copper on the chimney.

Of the modern pannier tanks, only the 94/84/34xx had that luxury, the rest were cast iron chimneys as befitted proper working engines.

 

I think the main perpetrators of the myth is the 'model engineer' who builds a loco to plans such as 'Pansy' and fails to realise that this is the equivalent of a live steam Gaiety pannier model. ie Vaguely looking like a GWR engine.  The extra detailing is down to the builder, which they can't really be bothered with as long as it works.

 

However it's GWR so it must have a copper capped chimney, so they put one on, without any reference to the real thing!

Edited 3 hours ago by Happy Hippo

[Willie Whizz]

Well … bu%%er!  There goes yet another belief I’ve held all my life!!

[SM42]

4 hours ago, PhilJ W said:

It's a kit, whatever livery you want.

 

You mean decals aren't included.  

 

Andy

[AndyID]

3 hours ago, bbishop said:

Interesting list.  Excluding the "extended 4-4-0s" (incl. GER, LNWR Experiment and arguably Cardean and her sisters) lets consider the British 4-6-0 narrow gauge classes.  On the LSWR the F13s and the single E14 were truly awful.  The G14 and P14 classes could at least pull, even if they couldn't run, and were flogged to death on the South Wales to Portsmouth coal trains during WW1.  These four classes were designed by George Sisterson, who was replaced by James Hunter in 1906 and who designed the T14 class.  Maybe Dugald Drummond only made two contributions to the design of his 4-6-0s, make sure a superheated hadn't been included without his knowledge and to sign the drawing.

 

Let us consider the other narrow gauge 4-6-0s.  LNWR Claughtons, L&YR, CR (Pickersgill), G&SWR, Highland, NER, GCR.  I can only think of three classes that were relatively unflawed - the two Manson superheated locos, the Highland Rivers and the NER S3 (and that was after a lot of wasted metal on the three preceding NER classes).  The T14s were undoubtedly flawed, but so were most other British 4-6-0s, and they did slog up and down the LSWR main line for nigh on 40 years.

 

It was all the fault of the permanent way departments. Contrary to popular belief adding extra drivers does burglar-all to improve traction. All it does is spreads the weight over a greater area.

[DenysW]

46 minutes ago, AndyID said:

Contrary to popular belief adding extra drivers does burglar-all to improve traction. All it does is spreads the weight over a greater area.

Not fully convinced.

 

If the Civil Engineer only believes in tons/axle (which seems to have been most of them), then extra drivers within the same rigid wheelbase, say 0-6-0 to 0-8-0 allows for 33% more weight, thus 33% more traction before slippage. If the Civil Engineer also believes in ton/ft (the Midland, and the ex-Midland LMS and possibly BR) then extra drivers achieve nothing, not even a greater area for the weight. 

 

If you absolutely must increase the numbers on tractive effort without going articulated (e.g. the Standard 9Fs) then you have to increase the rigid wheelbase and then play silly whatsits with the flanges because otherwise the locomotive gets stuck or derails on the sorts of curves seen in sidings and/or on points. Even dead slow.

[AndyID]

39 minutes ago, DenysW said:

Not fully convinced.

 

If the Civil Engineer only believes in tons/axle (which seems to have been most of them), then extra drivers within the same rigid wheelbase, say 0-6-0 to 0-8-0 allows for 33% more weight, thus 33% more traction before slippage. If the Civil Engineer also believes in ton/ft (the Midland, and the ex-Midland LMS and possibly BR) then extra drivers achieve nothing, not even a greater area for the weight. 

 

If you absolutely must increase the numbers on tractive effort without going articulated (e.g. the Standard 9Fs) then you have to increase the rigid wheelbase and then play silly whatsits with the flanges because otherwise the locomotive gets stuck or derails on the sorts of curves seen in sidings and/or on points. Even dead slow.

 

Nope. It's "easy enough" to increase the tractive effort by increasing the boiler size, pressure, cylinder area etc. but there is no way to do that without increasing the weight. If you could could put all that weight on a pair of single drivers you'd get just as much tractive effort as an 0-10-0. 😄

 

EDIT: If you find this perplexing it's because friction has nothing to do with contact area. It's simply a function of the force between the two surfaces and the coefficient of friction between those surfaces. In this case it would likely be steel on steel.

 

 

 

Edited 18 minutes ago by AndyID