Niels

14 hours ago, rockershovel said:

 

The only conclusion I can draw is that the wide firebox was not a sufficient advantage under U.K. conditions. 

 

 

Wide fireboxes are easier to repair for  broken or leaking stays.

That was the reason behind the german postWW2 designs.

A three squaremeter,wide firebox over five feet drivers and three cylinders could have given Royal Scotts a good run.

1 hour ago, rodent279 said:

For Mallard on 03.07.1938?

Assuming 7 coaches @ ~ 19m, that's 133m, plus loco, 21m, that's 154m.

Thank you

Drag plate area was then 154 * 0.215=33 square meter

Air power 0.5 *1.23*(56.5**3)*33=3660kW.

Rolling took 345 kW and thus total was 4015 kW and 1150 came from gravity.

Mallard must have given 2865kW or 3892 horsepower and that is impossible.

The drag plate per meter train was estimated from a known danish case and danish loading gauge and trains  are wider and higher than UK trains.

If we asume that a tape around a uk train is 15% shorte than a continental it calculates to 2300 kW locopower or 3133horsepower  or more or less what was the absolute max measured on a LMS Pacific.

If we asume UK trains have a drag plate area of ca 0.215*.85=0.18 square meter per meter train length we can use it to calculate power demand versus speed from locomotives be they ,steam,diesel or electric.

11 hours ago, Niels said:

Imaginary train power.

 

Let us see if Mallard fits

 

Length  of whole train in meters?

 

Mass of whole train in kgs?  407000kg

Speed in m per seconds?       56.5 m per second

Gradient?                        1 in 200

 

The gravity power assist was        mass*g*56.5/200=1150 kW

Rolling resistance used                  mass*g*0.0015*56.5=345 kW

What was total length of train?

Imaginary train power.

A danish IC3 train is 59m long,had a mass of 100000kg and ran 28m down over 5 km length at 204 km/h.Installed diesel power was 1180kW.

204kmh is Mallard speed and is 56,66m/sec

28 m over 5000 is a down gradient of 1 to 178

Gravity power is

mass * gravity constant *speed horizontal/gradient

100000*10*56.66/178=318314W or 320 kW or 430 horsepower.

Rolling power is

Mass *gravity constant*0.0015*56,66=85kW

Air resistance power at 56,66m/sec therefore was 1180+320-85=1415kW.

Dynamic air pressure at 56,66 *flatplate drag  area * 55,56=1415kW

0.5*air density*(56.66*56.66*56.66)* drag  area=1415 kW

0.5*1.23*181899*area=1415000

area=1415000/111867=12.6 square m

drag area for a 59 meter long train is 12.6m**2 or 0.215m**2 per meter train length.

Let us see if Mallard fits

Length  of whole train in meters?

Mass of whole train in kgs?

Speed in m per seconds?

Gradient?

On 14/08/2019 at 14:27, rodent279 said:

Thanks, that was my next step!

So you can easily see that Shap with 11 on is going to need 2,500hp +, and also why electrics, with 4000+ hp available at the rail at 50-odd mph, could sail over with speeds in the 80's.

We can make a train power/speed  calculator that is based on first years physics if we use sensible units.

I have never been using apps or excel sheets but did lots of Fortran.

Please help.

Power(W)  is used to overcome rolling resistance, gradients and air resistance.

We need mass of complete train  in kg,

length of complete train in m

Gradient.

Air density is asumed 1.23 kg/cubic metre for over90% of trains worldwide.

g is not 9.81 but 10.Here

Velocity m/sec

Rolling resitance is ( 0.0015 times g times mass.) (Newton) and multiplied with speed we get rolling power.

Small Gradient (from level where gradient is infinite to 1/200)  power (W) is mass times g times horizontal  velocity divided by  gradient

Air resistance  is dynamic pressure( 0.5 times  air density times velocity power two) times equivalent drag plate area.

Air resitance power is air resistance multiplied by velocity.

Equivalent drag plate area for trains (trains are much longer than wide or high) is proportional to length of train and we must estimate it from known runs but can use it for other kinds of trains.

8 hours ago, The Johnster said:

 Nobody here to my knowledge complained about reflections, presumably of sunlight, and there were, towards the end of steam, a good number of locos with wedge shaped cabs or at least angled windows, including the LMS pacifics, Bullieds, and most of the BR standards, including one of the tanks...

I seem to remember that it was night time opperations that was endangered,but i do not remember where I read it.

Ligth from open firedor maybe?

3 hours ago, Flying Pig said:

To get back to the subject, in my not-so-original view The Great Bear is quite likely and Thompson Pacifics an outside possibility, particularly if changes in manufacturing continue to make smaller runs more viable (and guess what colour they would all be - yuk).

I  like all the Thompsons but some more than other.

The wedge shaped cab was tried around WW1 in Denmark,Sweden and Germany and dropped again as drivers complained over reflections.

Was that ever an UK-issue?

Hopefully not as I think A2/1 and A2/2 looks best.

Are there some informed oppinion on their value to mankind?

5 hours ago, scottystitch said:

 

 

I appreciate this may be viewed as heresy on this thread, but I am now firmly in Princess Coronation camp these days. In my opinion the most handsome and purposeful British Pacific ever built. To me, a perfectly balanced locomotive, aesthetically speaking.  And am I correct in thinking they were the most powerful (excluding the P2) ? 

 

How would Stanier's finest have fared on the ECML, do you think?  Where do you stand on them in general?

Scott

On a power/ ton basis Britannia was most powerful.

The LNER A2s were higher tractive effort and used less coal.

A four cylinder LMS pacific was tested on LNER against A4s and royal Scott and came not best.

Best looking to my eyes were A2/2.Long and racers.

2 hours ago, 34theletterbetweenB&D said:

A conversation elsewhere has reminded me of a project that I never proceeded with. What if Stanier had realised that all this faffing around with 4-6-0s was no way to go on for a fast loco of greater than power class 5. So the 'Jubilee' emerges as a 3 cylinder light pacific, scaled much as OVSB's later design and acceptable for the Midland branch of the LMS, among other secondary main lines. It's 'building itself' very attractively as I sketch it out in my mind. No patent on this, so other design concepts welcome...

One could also put five or six feet drivers under  the three cylinder 4-6-0s.

Four or six tons saved that can go to a bigger boiler and max speed is not limited by revs anymore but horsepower.

3 hours ago, rodent279 said:

Speaking of Franco-Crosti boilers, which I know aren't Imaginery, does anyone know if they had any application outside of rail traction?

Franco Crosti tried to cool smoke lower than dew-point of sulphuric acid.Unless You use noble metal for that end of boiler,it was a bad idea.

2 minutes ago, RLBH said:

Certainly the adhesive weight and tractive effort on a WD 2-10-0 is, again, about the same. And with a similarly-sized wide firebox, though I'd be curious about ash pan capacity.

 

 

Ashpan capacity on 9Fs with five feet drivers were bigger than on Stannier Pacifics.

3 hours ago, RLBH said:

 

 

Thinking of 2-6-2s and 2-8-2s – the Gresley V2 and Powell's Britannia-boilered 2-8-2 have pretty similar adhesive weights and tractive efforts. And both proposed for similar fast freight work. Presumably the Coleman 2-6-2 would have been similar again. The main difference is the size of the driving wheels and how heavily they're loaded. So, what's to choose between six 6'2" drivers and eight 5'6" ones on an express freight locomotive?

Ten 4 feet8  wheels is better.

WD 2-10-0 with 50% reciprocatory balance and better frame

On 09/07/2019 at 10:18, Clive Mortimore said:

Is that why the LMS built 195 3 cylinder compounds after WW1?

it was the best they had and a mr Diamond said it was rather lousy in efficiency.

It was not so important this efficiency thing.

Lets play the game of rebuilding P2 into a two cylinder simple Pacific for wartime austerity.

B1 has 51 tons adhesive and 27000 lbsf tractive effort.

The P2Be will have 66 tons and therefore can use  a cylinder volume  1,3 times greater and still  be  as surefooted as the B1.

Cylinder  can either be placed as Thompson did ala de Glenh and driving second driver or be put between the bogie wheels like Claughtons,B16,Myriads of 4-4-0s etc.

On the  de Glehn scheme it will just be possible to have cylinder diameters like the P2 to go where P2 was supposed to rule.

That is 21 inch diameter and therefore needs 30 inch stroke.

Going the best Raven way will allow ca 22.5 inch  cylinder diameter as it can be placed closer to center.26 inch stroke.

My favourite is the Raven scheme with 21 inch and three driving wheels borrowed from Halls that is 30 inch stroke.

A two cylinder compound can be made by pairing one of these cylinders with a 2.5 times as big a lowpressure one that is 34 inch dia times 26 inch stroke so we can keep the crankshaft.

Between the frames has room for this monster cylinder like had  did for mr Webb.

Mr Corbs has already photographed one side of this animal.

de Corbs compound high pressure view

8 hours ago, Corbs said:

On the outside, maybe, but LP inside cylinders were not unknown. I know I keep banging on about Chapelon but I've been reading a bit about him recently because he's pretty cool. The 231 Nord's specs:

HP

15.52 in x 25.59 in (420 x 650 mm) (outside)

LP

25.19 in x 25.59 in (640 x 650 mm) (inside)

 

LP cylinder is 152.38% the size of the HP cylinder (? - my maths is sketchy at best)

 

For comparison a 9F with two outside cylinders:

20 in × 28 in (508 mm × 711 mm)

 

LNER P2 (3 cylinders)

21 in × 26 in (530 mm × 660 mm)

 

LMS Princess Coronation (4 cylinders)

16.5 in × 28 in (419 mm × 711 mm)

 

Was it a question of maintenance burden, or ease of construction, maybe?

Mr Cox explains it in World Steam 20 century.

If Low pressure cylinders of a four cylinder compound has to be inside for loading gauge consideration,crankshaft design is difficult.

This  left only three or two cylinder compounds as realistic candidates in UK after WW1.

Three cylinder compounds died of neglect.

A front drive three cylinder  compound Royal Scott  size was proposed by Fowler.

There was more glamour in making streamlined pacifics .

Streamlining a 55 mph train like Elizabethanian sounds expensive.

The two cylinder compound was never considered but is interesting.

A two cylinder compound has same cylinder volume in high presure cylinder as one in the corresponding simple and the low pressure cylinder can be 2.25 times bigger in volume.

Lets try it on an alternative A2/2 rebuild of  LNER P2 .

The A2/2 was wildly overcylindered and slipping prone and if rebuilt with two cylinders they could be sized from lets say a B1.

Dog wants airing.

Se You later

1 minute ago, scots region said:

 

Thats why I felt that the 1880s-90s would be the best time for a project of this scale, before economic and security concerns made it impractical. Although a bridge straight across the channel would probably change things enough to prevent or alter WW1 all together. 

A bridge/tunnel were part of  vision behind the GC London extension.

Instead  Europe became part of   USAs empire.

4 minutes ago, scots region said:

So an idea for a kind of 'dream layout' that I've come up with recently is a Calais to Dover Bridge being constructed in the later part of the nineteenth century. Would this lead to a stronger continental influence over British designs or would there be no overall change? 

To pay for the construction of the bridge it would be nessecary to allow running continental loading gauge waggons in UK.

It could maybe have been done before WW1 where railways  paid dividends.

Not after where lorries took over.

26 minutes ago, melmerby said:

Plenty of UK locos with more than 17" cylinders outside

The LMS compound's LP cylinders, which were outside, were 21" x 26"

If the connecting rods attack second or third driver it is not possible to  have cylinders closer than 6 feet 8 and a half inch apart as conrods must be outside coupling rods.

UK loading gauge many places  did allow 8 feet 8 and a half inch at platform level and this left 24 inches for outside of cylinders.

Flanges took 4 inches so cylinders over 20 inch was not very common.

If conrods worked first driver inside of coupling rods it was possible to have 6 feet 3 cylinder distance and thus something like22-23 inch cylinders on straigth track.

Further to the UK 4-8-0

If The outside 17 inch high-pressure cylinders were put forward between boggie wheels it should have been possible to be UK loading gauge legal.

The efficiency of a very good fourcylinder compound versus a very good two-cylinder simple was measured in Germany 1941.

A Norwegian Compound 2-8-4 with 1550mm wheels were pitted against a two cylinder simple 01 Pacific with 2000mm wheels and won.

It is somehow described here in german.

Norwegian 2-8-4 versus German Pacific.

I will try and plot the Norwegian against the 01.

Steam consumption

Three cylindered simples used 6% more and four cylindered around 10% more than twins for same job.

On 06/07/2019 at 00:19, Corbs said:

Mucking around with some drawings wondering how one might make a UK version of a Chapelon loco, taking the 240A/240P as inspiration.

Top one is a Chapelon 240A rebuild of the pacifics.

2nd from top is Tuplin examining how a simple expansion 4 cylinder 4-8-0 could be made in the UK loading gauge

3rd is Tuplin's drawing overlaid on a King (centre driver of King is on the 2nd driving wheel of the 4-8-0)

4th is a King for reference

 

Chapelon was able to make use of narrow fireboxes on the 240 designs (I assume these were not mechanically stoked?), I chose the King as a comparison because of this and also the driving wheel diameter.

The King's driving wheels are 6 ft 6 in (1981mm), the 240A's are 6ft 2.8in (1900mm), so not a great difference.*

Tuplin's 4-8-0 is shorter than the King, which makes sense as the main line ones these days have cut down boiler fittings etc. to fit on the modern railway/non GWR lines, but Tuplin has used all the available space as evidenced by the stubby dome and chimney.

 

It's odd how Tuplin seems to have drawn the loco with 4 x 20" diameter cylinders abreast of each other rather than 2 pairs of larger cylinders offset from one another like the King, Princess etc.

 

*although listed as 6ft 0in on the drawing, not sure why.

 

I wonder, if one were so inclined, that a 'Princess' boiler could be used, with the wide firebox cut off and substituted for a narrow one, the smokebox extended. Using a P2 chassis for four 6ft 2in driving wheels, closely spaced, rear of chassis removed and front adapted to take a bogie.

Chapelon had the LP cylinders inside and the HP ones outside on the 240A/240P, and the HP cylinders were only marginally bigger than a 'King's, so a slight size reduction could be made.

 

On 22/06/2019 at 11:25, jonhall said:

 I could take the S-bahn into the city, leave my case at the hotel and get out to Königstein im Taunus to spend all afternoon photographing the Pentecost specials.

 

jon

https://imgur.com/FSADUC1

My picture is from 2017

Can we see some more of Yours?
CO2 is one thing that will calm down.

Either we go nuclear or reduce number of humans drastically,but the 1.5 ton of concrete we pour per human per year is forever.

Or at least until next Ice Age.

14 hours ago, Neil said:

My eye was caught by this article in Sunday's Observer comparing the levels of CO2 generated by plane, train and car to typical holiday destinations on the continent. I suspect that over the coming years we'll see more international travel by rail; it would fit well with the current aim of cutting greenhouse gas emissions to almost zero by 2050. On our recent visit to Hamburg by rail Mrs R and I chatted to a Swedish Journalist and his partner returning home after a three week grand tour. They deliberately chose rail over flying because of the lower ecological impact. Perhaps a good time to sell your shares in BA and invest in Eurostar instead.

Sunday observer is wrong,

England-Corfu and back for four is roughly 16000seat-km and a modern aircraft (319neo) eats about 16 gram jetfuel for each.

320 kg Jetfuel cannot make 2.6 tons CO2

New Pacific

The best UK 4-6-2 will be a Pacified B16/3.

Will look and perform better than the Thompson A2s.

Raven B16s have cylinder Throw-over  clearance problems  due to utilizing cylinders and valve gear from a three-cylinder mineral engine.

On such an 0-8-0 animal 6 feet 8 is the absolute minimum outside cylinder centerline distance.

On a front driven 4-6-0 or 4-6-2 it can be 6 feet two or three as on Midland Compound or Adams 4-4-0s.

And most American 4-4-0s.

Using B1 cylinders and valve gear outside is possible because pacifics do not need to have frame plates as close to wheel insides as 4-6-0s.

That is the Bulleid  pacific scheme that is  tranfered  to BR Britanias and gives frame cracks.

Two big piston thrusts farther out from frames with no inside cylinder to stiffen the cylinder zone is not smart.

Wheelbase not longer than other UK pacifics and much better  accessability to inside mechanic.

32 minutes ago, Traintresta said:

 

 

This was something I pondered a few pages back, would a 5'8" drivered Pacific be of any use and would it be able to run at the speeds usually typical of pacifics on express trains?

 

 

 

Bulleids were 6 feet two and surely fast enough.

Many express pacifics hauled trains were less than a mile per minute on the level.

ISBN: 978-3-88255-770-1

Pacifics main force was  big grates that kept clean longer than on 4-6-0s

The Raven A2 had a loco wheelbase of  37 feet and two.

Three cylinder pacifics do not really need big wheels.

He could have put B16 machinery with five feet 8 drivers on and would have had a more pleasing apperance.