Steam speed records including City of Truro and Mallard

I suspect what this thread most demonstrates is why other speed records have some kind of independant ratification body which establishes standards for conditions, timing etc. As I've said too many times before the vast majority of rail speed records would fail any reasonable ratification, be it because of gravity assistance, inadequate measurement techniques, huge variations in load, all the rest of it.

The tendency to ignore decimals or reasonably consider rounding doesn't help either. Not really sensible to talk about acceleration from 125 to 126, for instance, especially if you count 125.999 as 125...

 

It's never really mattered since, except possibly in @Hermod 's mind, there has never been any serious engineering or corporate competition over railway top-speed records. Therefore no need for ratification. Similarly no need for level track, measured miles, equal loading and all the rest. The only disqualifiers for a claimed record should be inadequate or uncheckable measurement techniques. A speed is a speed regardless of gravity assistance, variations in load, how many Weetabix the fireman had that day and all the rest. Otherwise this thread would be no fun at all.

 

Hear hear.

A kind of stock car racing that Mallard did not win.
My main interest was finding a well documented full power run to calibrate my model.
1990 ihp at mp 91 and 124 mph.
Thank You LNER for doing a crazy stunt.
It has not been cheap I think.
The German run over 200 kmph came about because a wagon ran a hot bearing and was taken out.
I can now calculate what speed LNER could have seen with one coach less.

 

A lot of sensible thinking here. I will check with my supervisor to see if I can publish the graphs I have produced. If not, I will make everyone aware when it is published in a few years time.

Either way even with decent error bars, 05 002 and Mallard's runs have insufficient overlap to say they are no faster than each other, from my observations from the evidence we have available - if anything, it just cements that you can be so close and yet so far!

Hmmm - I think we need more nuance on both locomotives' designs. They're arguably showcasing very different technology. Mallard is running with an almost full streamlined train behind and better braking technology, the 05 is actually a very basic design sized up for the specific purpose of high speed runs and testing at speed.

I do not believe the three built 05 locomotives were intended to form a serious new class, it was all about data gathering towards other developments (especially in light of the other streamlined locomotives and diesel units being developed around the same time).

I disagree. Fundamentally piston valve steam locomotives have significant barriers (both mechanically and in terms of aerodynamics) to overcome to reach these high speeds.

That anything approaching 100mph was relatively rare until we get into much powerful, high power to weight ratio steam locomotives into the late 1930s is actually an indication of the limits of the technology of the steam locomotive. These upper limits were lowered almost exclusively by the addition of streamlining and better understanding of aerodynamics from other industries' work.

(Had the 05 had a full streamlined rake of coaches behind it, I am pretty certain it would have exceeded its own record. That's a by the by though).

Maintaining over 120mph was exceptional in the UK and Germany and only achieved for a few miles each, both locomotives being at the absolute limits of their available power and reserves of steam in their boilers (the 05 was arguably less limited).

It is precisely because of the rise of diesel and electric traction that we see such high speed running for steam pre WW2 so rarely, IMO.

In 1939 the ETR 200 electric streamlined set in Italy was achieving high average speeds in excess of the top speeds of the steam locomotives around it.

In 1903, Siemens and AEG had already achieved 128 and 130mph with their experimental three phase electric trains.

It's why for anything pre 1934 and at 100mph I am sceptical, anything post 1934 and high power to weight ratio and streamlined, looks far more likely.

There's no doubt that post war there were more achieved 100mph runs than pre Ww2. Much of this is with Pacifics of varying types on short form or fixed rake trains that are aerodynamically superior to most of those being used pre WW2.

Part of the reason this has fascinated me so much is that it becomes pretty obvious from today's railway engineering that the role of aerodynamics is much better understood across the board - and from enthusiasts many assumptions are made which simply do not hold scrutiny when tested.

 

I would argue that there's a fundamental misunderstanding of how steam locomotives work and how the dynamometer cars work too. There also seems to be a misconception or assumption being made that the power from the locomotives is being applied uniformly and smoothly.

I have been out with the NMT this year on the very stretch of track we have discussed and the one thing I identified from the on board recordings versus my GPS data is that the speed recorded fluctuates constantly when working at the upper limits of power, even with a diesel-electric train with electric traction motors. It did not, therefore, surprise me to see fluctuations in the recorded speed for Mallard's dynamometer car roll when at the limits of her power and at the highest speeds.

 

This is no longer the case. (At least in the USA but I believe globally.)
"The user range error (URE) of the GPS signals in space is actually the same for the civilian and military GPS services. However, most of today's civilian devices use only one GPS frequency, while military receivers use two.
Using two GPS frequencies improves accuracy by correcting signal distortions caused by Earth's atmosphere. Dual-frequency GPS equipment is commercially available for civilian use, but its cost and size has limited it to professional applications.
With augmentation systems, civilian users can actually receive better GPS accuracy than the military.".

https://www.gps.gov/systems/gps/performance/accuracy/

 

Yes if analysed properly. I've discussed this earlier in the thread, but what GPS does is to give a position in 3 dimensions and a time. A typical GPS device will have a logging capability, so what it delivers you is a series of positions, and that's what you should work with. Although it will typically give you instantaneous speeds, its best not to take them too seriously as there will be the odd glitch. The positions might be at one second intervals. Being on a train allows you to do some sanity checking. Height is going to be a straight line of course, subject to suspension movement and any track unevenness, but you can bet anything wild is a bad position, the same is true for points that apparently show the carriage coming off the rails and back on again! You can then work out speed between positions.

 

Moderator adviced to write understandably and not waste time of others.
I will try.
A 400 ton train goes down an 1 in 480 incline that is 1609.3 m(+-0.4m) long in 29.05seconds(+-.025sec).
That is a velocity of 55.397m/sec if constant.
And a gravity assist of 453 kW.
Propulsion system has demonstrated max power under optimum conditions of 1465 kW.
These up to 1918 kW are balanced by air and rolling resistances times speed.

If passing time is same but velocity has touched 55.878msec(125mph) somewhere ,it must have been lower than 55.397msec somewhere else within the 1609.3m as well.
An acceleration from 54.91 to 55.878 lasting 14.5 second as example.
Resistance and gravity gift power will vary,but not much.
Kinetic energy will be 603 and 624.5 or a difference of 21.5MJ supplied over 14.5 sec needs 1480 kW extra.
Propulsive power demand around 1465 plus 1480 kW

 

There is a serious threat to this record from the steam powered class 60!!!! It will have about 2700hp and a record must be in the offing?

 

The 3100hp diesel electric version of the class 60 has a maximum speed of 60mph, and I seriously doubt the bogies are going to be so modified as to more than double their speed capabilities on what is still planned to be a primarily freight engine. Hence I doubt there is any risk of Mallard or the 05's achievements being matched (by anything in this continent at least) any time soon. Whether the American T1 replica has a go when it gets finished, we'll, that's a question for then.

John

 

A question.
Could the Dynocar register both ways?
If, then there must be a kind of tumbler gear arrangement in the system from ninth wheel to paper drum.
The four ramps on end of paper drum will not function in reverse and are ,I think,responsible for the blue speed curve with max 126 mph.

 

Not normally, they had a 'live' and 'dead' end so probably not directional, but I understand they could register buffer compressive forces at the live end.

 

Thank You
If turntables were long enough 1904 ,no problem.

 

Pushing a coach on to a turntable to be turned separately would not be a huge problem. It happened with the various observation / scenic cars too.

 

Like numbers and simulations
I am dreaming of a Ricardian like Society , named something like Physical Speed Limits for a duck in low orbit .
The raw data needed and allowed are gradients,air density,temperature,2 meter over ground wind velocity and direction
Mass, length and time on each quarter mile marking like given by mr Andrews.
We will then be able to make a function of location over seconds .
Let Excel make a five or six power polynomium with very good resolution,many decimals.
Polynomiums are easy to differentiate and we have velocity over same seconds.
Once more gives accelerations

And then arguing will be possible on a much higher level.

 

Bang went my Nobel Price.
To assign precise time on each quartemile mark we will have to draw a new line paralel with the mark but placed correctly relative to the closest in time second marks.
Problem number one remain:if the drum does not rotate excactly in step with train.
See eventually letter 1086 to1092.
We still have the options of putting seconds to the best of our ability to one mile apart quartermile marks and then even out.
And hope that paper creep due to clikety clock ramp action is smal.And ramp actions are uniform and independent of speed.
No need to make a society.Yet.

 

Read the room Hermod.

 

Going back a few pages, thank-you for pointing out the Henschel-Wegmann train, with which I was unfamiliar. I had also forgotten the East German 18.201, which in 1972 achieved a speed of 182 km/hr (113 mph).

It is noticeable that these German high-speed engines existed as one-offs or in very small numbers. That was quite different from the normal Reichsbahn locomotive policy, which aimed to build simple, reliable and standardized engines, easy to maintain and operate, in large numbers. The bulk of the German pacific fleet was comprised of the two-cylinder Class 01 (231 units) and Class 03 (298 units) built between 1926 and 1938.

The three-cylinder developments of these classes appeared just as WW2 was starting, with just 55 of Class 01.10 and 60 of Class 03.10 built in 1939-41. Originally, these engines were streamlined and approved to run up to 150 km/hr (94 mph). However, according to the book "The German Pacific Locomotive" by David Maidment, early Class 01.10 locomotives suffered damage when trialed at that speed, so the permitted maximum was reduced. They also suffered from difficulties of access for maintenance and local overheating, blamed on the streamlining. After the war, the streamlining was removed and teething problems resolved, but they never appear to have achieved the high speeds that were often reached by Gresley pacifics.

A feature of the Class 05s and other high-speed German engines was driving wheels of 2.3m (7ft 6in). In Britain, it was not possible to have engines with large boilers over such large drivers, due to our limited tunnel and bridge clearances restricting engines to a height of about 4m (13ft). Although it might have been possible on the GWR broad gauge. Has any forum member sketched out a large-wheeled broad gauge pacific?