Thursday, September 5, 2013
1829 Stephenson Rocket
I decided to go with white wheels, natural wood tender floor planks and a brown barrel. Though the rocket was basically all yellow I wanted a bit of contrast.
The Rocket was the most advanced steam engine of its day. It was built for the Rainhill Trials held by the Liverpool & Manchester Railway in 1829 to choose the best and most competent design. It set the standard for a hundred and fifty years of steam locomotive power. Though the Rocket was not the first steam locomotive, Rocket's claim to fame is that it was the first steam locomotive to bring together several innovations to produce the most advanced locomotive of its day, and the template for most steam locomotives since. In fact, the standard steam locomotive design is often called the "Stephensonian" locomotive.
Rocket used a multi-tubular boiler, which made for much more efficient and effective heat transfer between the exhaust gases and the water. Previous locomotive boilers consisted of a single pipe surrounded by water. Rocket had 25 copper tubes running the length of the boiler to carry the hot exhaust gases from the firebox. This was a significant development, as it greatly increased the amount of steam produced, and subsequent designs used increased numbers of boiler tubes. Rocket also used a blastpipe, feeding the exhaust steam from the cylinders into the base of the chimney so as to induce a partial vacuum and pull air through the fire. Credit for the invention of the blastpipe is disputed between Sir Goldsworthy Gurney and Timothy Hackworth. The blastpipe worked well on the multi-tube boiler of Rocket but on earlier designs with a single pipe through the boiler it created so much suction that it tended to rip the top off the fire and throw burning cinders out of the chimney, vastly increasing the fuel consumption.
A closer view
Rocket had two cylinders set at 35 degrees from the horizontal, with the pistons driving a pair of 4 ft 8 in (1.42 m) diameter wheels. Most previous designs had the cylinders positioned vertically, which gave the engines an uneven swaying motion as they progressed along the track. Subsequently Rocket was modified so that the cylinders were set horizontally, a layout used on nearly all designs that followed. The second pair of wheels was 2 ft 6 in (0.76 m) in diameter, and uncoupled from the driving wheels, giving an 0-2-2 wheel arrangement. The firebox was separate from the boiler and was double thickness, being surrounded with water. Copper pipes led the heated water into the boiler.
A cutaway view of the cylinder and steam valve of the replica Rocket
There have been differences in opinion on who should be given the credit for designing Rocket. George Stephenson had designed several locomotives before but none as advanced as Rocket. At the time that Rocket was being designed and built at the Forth Banks Works, he was living in Liverpool overseeing the building of the Liverpool and Manchester Railway. His son Robert had recently returned from a stint working in South America and resumed as managing director of Robert Stephenson and Company. He was in daily charge of designing and constructing the new locomotive. Although he was in frequent contact with his father in Liverpool and probably received advice from him, it is difficult not to give the majority of the credit for the design to Robert. A third person who deserves a significant amount of credit is Henry Booth, the treasurer of the Liverpool and Manchester Railway. He is believed to have suggested to Robert Stephenson that a multi-tube boiler should be used.
The opening ceremony of the L&MR, on 15 September 1830, was a considerable event, drawing luminaries from the government and industry, including the Prime Minister, the Duke of Wellington. The day started with a procession of eight trains setting out from Liverpool. The parade was led by Northumbrian driven by George Stephenson, and included Phoenix driven by his son Robert, North Star driven by his brother Robert Sr. and Rocket driven by assistant engineer Joseph Locke. The day was marred by the death of William Huskisson, the Member of Parliament for Liverpool, who was struck and killed by Rocket at Parkside.
In 1834, the engine was selected for modifications to test a newly-developed rotary steam engine designed by Lord Dundonald. At a cost of nearly £80, Rocket's cylinders and driving rods were removed and two of the engines were installed directly on its driving axle with a feedwater pump in between. On October 22, of that year, an operational trial was held with disappointing results; one witness observing, that "the engine could not be made to draw a train of empty carriages". Due to inherent design flaws and engineering difficulties associated with their design, Dundonald's engines were simply too feeble for the task.