Niels

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.

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.

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?

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.

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?

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?

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.

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.

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.

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

Ten 4 feet8 wheels is better. WD 2-10-0 with 50% reciprocatory balance and better frame

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

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

A bridge/tunnel were part of vision behind the GC London extension. Instead Europe became part of USAs empire.

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.

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.

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.

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.

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.