David
Wardale on the 5AT design and its relationship to the BR Standard 5MT:
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"It
is a state of the art design based on the size and format of the Class
5 only. It is not merely a development of it." |
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There
is very little point in me writing a huge amount here on the 5AT.
The excellent project website - www.5AT.co.uk
- contains a huge amount of useful and highly readable information.
If it doesn't have what you want please ask! The project team can be e-mailed at info@5AT.co.uk. |
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To
whet your appetite for more below are some of the 'headline' specifications
for the Class 5AT. As can be seen the performance, from a locomotive
of this size, will be truly A1*: |
IMPERIAL
|
METRIC
|
|
Tractive
Effort |
32830
lb |
146kN |
Boiler
Pressure |
305
psi |
2100
kPa |
Coupled
wheel diameter |
6'
2" |
1880
mm |
Maximum
Continuous Operating Speed |
112.5mph |
180
km/h |
Maximum
Rated Steam Supply from the Boiler |
37500 lb/h |
17000
kg/h |
Maximum
Continuous Drawbar Power |
2535
hp (at 71mph) |
1890
kW (at 113kph) |
Maximum
Indicated Cylinder Power |
3460
hp (at 106mph) |
2580
kW (at 170kph) |
Power
to Weight ratio at Maximum Cylinder Power |
43.3
hp/ton** |
32,3
kW/ton** |
Overall
Thermal Efficiency |
13.9% |
|
** Assumes an engine weight of 80t.
Note: The project calculations are undertaken in S.I. units and converted to Imperial to provide an easy guide to performance that can be compared with locomotives of the past.
For an excellent programme to allow conversion between imperial and metric measures visit this site.
The project group maintains an informal interest group. You do not need to be an engineer or a railway professional to be a member. The only requirement is a desire to see the 5AT run. To become a member of this group contact the project team at info@5AT.co.uk. Robin Barnes has produced a series of excellent artists impressions of the 5AT as it may appear one day. |
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5AT in Silver Arrow livery with matching BR MkIII stock. Note the Scullin type driving wheels. © Robin Barnes 2001
The 5AT uses the BR Standard 5MT as a basic starting point. The locomotive, excluding the tender, will approximately adhere to the external dimensions of the 5MT but will be of a totally new design. Below is an interesting comparison of 5MT (top) and 5AT (bottom) on the same scale. The comparison highlights just how big the tender of the 5AT will be. To the British enthusiast the size of the tender will be something of a culture shock !
An option does exist for an even larger tender..... As it is above the 5AT fuel and water ranges are calculated to be 920 km (570 miles) and 610 km (380 miles) respectively under representative average service conditions; and 550 km (340 miles) and 360 km (220 miles) respectively at a continuous 113kph (71mph) when generating 1890 kW (2535hp) at the drawbar. © Wardale Engineering & Associates
Again with Scullin wheels the 5AT sits in a yard with other items of modern traction. © Robin Barnes 2003
The 5AT as Silver Arrow runs at speed against the setting sun. © Robin Barnes 2003
Above is the early outline of the 5AT as proposed by David Wardale. This version has a smaller tender, a different location of the feedwater heater and other detail differences to the second version shown below.
Following the completion of the Fundamental Design Calculations in late 2004 David Wardale re-drew the outline drawing of the 5AT taking into account the alterations now found to be necessary.
Initially it had been intended to use the Scullin wheel but at the moment it has not be been possible to find sufficient data on these wheels to be sure of their performance in service and how to manufacture them. As a result the BFB type has had to be substituted as seen in the latest outline. This type were extensively used on Bulleid designs in the UK and are not the same type as a Boxpok as many in the UK seem to think.
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The BFB type driving wheel. This one belongs to 35028 Clan Lane. Also note the brake rodding drive to blocks on two driven axles. Such a system is also proposed for the 5AT. |
The Scullin type, whilst not widely used in the past, were used in the USA for example. Perhaps their most high profile use was on certain locos of the New York Central fleet. The legendary streamlined J3a class 4-6-4s received them as illustrated below:
NYC J3a 4-6-4 5450 - a locomotive fitted with Scullin type driving wheels.
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Following the completion of the FDCs and to compliment the re-drawing of the 5AT outline Robin Barnes produced the next of his excellent 5AT paintings. © Robin Barnes 2005 |
Now please visit the project website at www.5AT.co.uk. Thanks!!
* With apologies to David Wardale!