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Great Western Railway Fire Fly class
Great Britain | 1840 | 62 produced
Replica in April 2011 at Didcot
Replica in April 2011 at Didcot
Tony Hisgett

Daniel Gooch used the Star class, more precisely the “North Star” locomotive developed by Robert Stephenson, as a basis for developing a new broad-gauge express locomotive. He stayed with the 2-2-2 wheel arrangement and a driving wheel diameter of seven feet, but installed a larger boiler.

In the years 1840 to 1842, seven manufacturers made a total of 62 locomotives. The names of the locomotives did not follow a uniform scheme. In addition to names that began with “Fire”, there were also those that came from Greek mythology or from animals. From 1865 they were counted to the Priam class.

The “Fire Fly” is said to have traveled the almost 31 miles from Twyford to London Paddington in 1840 at an average of 50 mph, which was a record at the time. Later, the locomotives were fitted with new cylinders that were 16 by 20 inches instead of 15 by 18 inches. The decommissioning took place between 1864 and 1879. A working replica of “Fire Fly” was completed in 2005.

Variantas builtrebuilt
ManufacturerJones, Turner and Evans, Sharp, Roberts & Co., Fenton, Murray and Jackson, G. and J. Rennie, R. B. Longridge and Company, Stothert, Slaughter & Co., Nasmyth, Gaskell and Company
Axle config2-2-2 (Jenny Lind) 
Gauge7 ft 0 1/4 in (GWR broad gauge)
Dimensions and Weights
Wheelbase13 ft 2 in
Fixed wheelbase13 ft 2 in
Total wheelbase20 ft 4 in
Service weight54,208 lbs
Adhesive weight26,096 lbs
Axle load26,096 lbs
Water capacity2,162 us gal
Fuel capacity3,808 lbs (coal)
Power sourcesteam
Estimated power150 hp (112 kW)
Optimal speed47 mph37 mph
Top speed58 mph61 mph
Starting effort2,049 lbf2,590 lbf
Power Plant
Driver diameter84 in
Boiler pressure50 psi
Expansion typesimple
Cylinderstwo, 15 x 18 intwo, 16 x 20 in
Grate area13.4 sq ft
Firebox area97 sq ft
Tube heating area732 sq ft
Evaporative heating area829 sq ft
Total heating area829 sq ft
Calculated Values
steam locomotive
Daniel Gooch
last changed: 07/2023

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