LMS Record of 114mph

Cox Locomotive panorama

Britania topped drawbar power at 45 mph /2000 dbhp.
At 100 mph it can be extrapolated to ca 1400 dbhp.This drop is normally explained as machine friction going up but at 100 mph it is air resistance.
Air resistance power needed is 8 times higher if You want to go two times as fast.

 

What happened on the 1934 run?

Interesting because O.S.Nock was a passenger in the Didcot accident and describes it happening in his book on accidents.

 

It does seem at odds with events, I'm wondering if I'm just remembering it wrong, or if it's one of the several myths around from that era.

 

Sounds most likely as A4 were the most efficient locomotive tested during 1948 trials .
From Cox figures the LNER/LMS boilers were quite even in efficiency but the cylinders were not

 

You can see the film of Coronation doing the 114 miles an hour here.

 

Proves that even in the 1930's High Speed rail was faster than travel by air (7.16)

 

Trying to get my head around the concept of sticking a trainload of joe public behind a loco in less than controlled circumstances and then seeing how fast we can go!

 

IIRC the passenger consist was invited guests only and has been replicated in modern times by the invited guests on a Pendelino during the attempted 4-hour Glasgow - Euston run. Some things are (mercifully ?) not available to "Joe Public".

 

That's correct, which is why the tare and loaded tonnage figures were so close.

 

With all the attention on bearings, one thing which puzzles me concerning the 1930's bout of willy waving .... sorry .... scientific evaluation of speed capabilities, was that the braking technology of the day was being asked to cope with conditions at nearly 50% above ordinary line speeds. Were brake blocks used for frontline speed locos (and presumably, associated premium stock) still of some particular grade of iron, or were composites being developed by this point? Did vacuum braking systems provide the sort of power needed to function effectively so far above their workaday range of performance parameters

On a slight tangent, but still brakes related ..... was reliance on a driver's reaction the only available means of responding to brake locking in the 1930's? Were any ingenious mechanical means of detection or control under investigation before the days of (silicon) chips with everything? I'd imagine the effects at 100mph and over of a heavy hand on the brakes with 100-odd tons of loco and another >250 tons behind the drawbar could get 'interesting' very quickly indeed.

 

The brake blocks were the usual cast iron, nothing more, and the normal vacuum system was all that was in operation on most of the LMS, at least south of the border.

Vacuum brakes are stronger than people realise; the main advantage of air systems is their speed of operation. Brake force can be increased by enlarging the cylinder ad infinitum, but then comes the danger of wheel lock. Anti-slide systems and traction control were very much in the future in 1937.

 

Mallard's run was of course a brake test, not a world speed record attempt Oh, that HNG, he did like his little laugh.

What's the point of being a CME if you can't have a little fun occasionally? Unlike the LMS attempt, precautions that would have been thought adequate at the time were taken.

But seriously, if he wanted a go at 130 and world events had allowed him to do so, I wonder if he would have realised the middle big end was the limiting factor and done something about it?

 

I believe that for the LNER streamliners at least, “double block” working was instituted, i.e. which required a greater distance clear before accepting a train than a normal block, to take account of increased stopping distances.

The timetable implications are interesting. A fast train averaging, say, 90mph will take 60 minutes to cover 90 miles. An “ordinary” express travelling at 60mph will take 90 minutes to cover the same distance; a freight or local passenger will take three hours. So the ordinary express has to have at least half an hour headway to avoid blocking it if they proceed along the same line; the slow train basically doesn’t have a hope. It’s why mixing trains of widely varying speeds is difficult on the same line, and why in some places, pre-war timetables had long gaps at certain parts of the day, to keep the line clear for a fast train rapidly gaining on the traffic in front — I can’t help thinking that the fast LMS and LNER trains must have been a considerable operational headache relative to the publicity they provided.

Tom

 

Did they sign a waver?! Even so, going by some of the hair raising anecdotes listed above, I smell publicity outranking safety. You have to admire the overly large kahunas that went with the spirit of the age!

 

Which was a major problem on the east coast, where normal expresses had to be by-passed to allow the streamliners to run so far over the normal speeds. The LMS, to its credit, did not pursue such ultra high speeds but were fitted in more easily with other traffic. This is reflected in the Coronation Scot's 6.5 hour schedule against the Coronation's 6 hours timings.

 

Bearings in general, inaccessible bearings in particular. This has jogged my memory back to the trailing axle bearings which were so problematic on Bowen-Cooke's 'Claughtons'.

It seems clear that by the 1930's, locomotive engineering was attempting to advance some way ahead of contemporary metallurgy (though considering early boiler explosions, tired tyres or shattered springs .... was that ever any different?). True in other fields too. Witness the early days of jet engines, where operational lives were measured in minutes rather than hours.

As famously innovative and self-contained as many railway works were, it's worth noting that, like injectors and brake valves, advanced bearings became one of those fertile fields for indpendent specialist manufacturers.

Considering the lack of knowledge concerning metal fatigue, the absence of sophisticated welding techniques, applied x-ray technology, ultrasonics, electron microscopes and the power of computors, such advances as were made become all the more remarkable.

Never mind Mozart on a Moog ..... picture Aspinall on an Apple .... while Drummond - either Drummond - stuck resolutely to a ZX-80!

 

Much as the Coronation Scot was put into a platform off the main line at Crewe, Flying Scotsman on its Nov 1934 run started from a suburban platform in KX. The short train was set well back and by the time it reached the points was going much faster than a normal train - hence the flange marks on the rails. It did manage to stay on the rails though.

 

This is one of the interesting features of cast iron brake blocks; the coefficient of friction is inversely proportional to speed and block temperature. So no, a full brake application at 100+mph is not going to cause problems in itself. In fact, one of the detail differences between the A4 and A3 is that the A4 has extra brake cylinders to increase available brake force and compensate for this effect. I believe you have to be a bit delicate with the brakes at low speed as a consequence.

The kit being tested in conjunction with Mallard's record run was Westinghouse 'Quick service' valves, which effectively treat the train pipe as a command signal during brake application and admit air to the cylinder direct from the atmosphere, thus allowing faster propagation of the brake application down the train. These became pretty much standard on passenger vacuum stock afterwards, I believe.

 

Yes, DA (Direct Acting) valves.

 

We know very little about locomotive resistance at high speeds - no one has ever measured it at speeds over 80 mph. We know even less about the resistance of a streamlined loco like an A4. However it seems likely that the power was >3000 ihp - sustained for five miles.

Regarding the 3350 claimed by the LMS - I have seen that described as on the high side - due to an overly large allowance for loco resistance - also I'm not sure how long it was sustained for. Do you have any more details?

Hence my *perhaps*.