Isambard Kingdom Brunel is one of Geoff's engineering heroes. The son of Mark Brunel, already a well respected engineer himself, he cut his teeth in construction building his father's design for the first tunnel under the Thames. By the age of 24, and needing to establish his own reputation as an Engineer, he boldly entered 4 designs in a competition for a long span suspension bridge over the river Avon in Bristol.
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The Clifton Suspension Bridge |
His designs were commended, but ultimately rejected by the appointed adjudicator, Thomas Telford, as the spans were "unrealistic" and "unstable". ( Telford - reputedly the greatest engineer of his generation had recently experienced the failure of one of his bridge designs and was cautious of ambitious spans). Brunel however, undeterred, re-designed the bridge, narrowing the span to meet Telfords requirements and challenged the competition administrators to reconsider. They did and his design was chosen. Building commenced on what was at the time the largest ever span and the highest suspension bridge in the world, but due to delays (wars, lack of funding, etc), Brunel would never see it completed. The bridge (known as the Clifton Suspension Bridge) between the suburbs of Clifton and Ashton now stands as a monument to him and remains impressive both in its size and height above the river. Nowadays with our modern materials we have bridges with much larger spans, but Brunel's bridge was far ahead of his time.
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The steel work is impressive, and innovative considering high tension steel was not yet available. |
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There are pedestrian walkways over the bridge and a great info centre. |
Continuing with Brunel, the next day we headed down to the SS Great Britain - a large steam/sailing ship.
Brunel designed her for the Great Western Steamship Company to run between England and the United States and to tie in with the extensive road and rail network that the Great Western Rail Company was developing. (Brunel incidentally also designed much of the rail network too. The SS Great Britian was designed to be one of the biggest paddle steamers in her day and Brunel used many breakthrough technologies on her such as a hull made of overlapping steel plates instead of wood. In 1840, more than a year after construction on the SS Great Britain had commenced a small wooden steamer called the Archimedes called in at Bristol harbour. Brunel was so impressed with the innovative propeller system to drive her, that he persuaded the Great Western Steamship Company to abandon the paddle wheels that he'd designed for the ship and allow him to re-design the ship's machinery to work with a propeller instead. Pretty gutsy considering construction on the ship had started 18 months earlier and the new engines were already partly built!! Not only would the change delay the completion of the ship, but it would have to be completely redesigned. Brunel was absolutely convinced of the benefits of a propeller and stated the reasons clearly to his Client including a lower centre of gravity, better control when the ship was heeling, more power etc. Brunel used contacts in the royal navy to test out different propeller designs and showcased his new propeller by setting a paddle tug and a propeller driven tug with equivalent sized engines against each other each pulling on one end of a rope. The propeller driven tug very quickly pulled the steam paddler backwards through the water. However, Brunel's propeller was extraordinarily efficient (similar to propellers nowadays, and the iron blades used at the time could not withstand the stresses imposed on them and damaged easily. As a result the ship's owners replaced the original propeller with a more robust and less efficient one. On her first transatlantic voyage from England to the United States (with Brunel's propeller), she cut the paddle steamer crossing time from 31 days to just 12. This propeller had a diameter of 4,7m and weighed 3,9 tonnes. It drove the ship at up to 12 knots - pretty impressive.
Another impressive design that Brunel came up with, and we were very impressed by was for the rudder. Conventional rudders pivoted on the front of the rudder blade. Brunel designed the rudder to have the stock (the pivot point) so that the area in front and behind the pivoting point were equal. This meant that the water pressure on the rudder was balanced and so the crew could turn the rudder with much more ease. Modern rudders work in exactly the same way as Brunel's rudder.
We could go on about the innovated designs Brunel used on the SS Great Britain, but they're probably only interesting to the Engineers and Sailors among us.
Work started on the SS Great Britain in 1839 and she was launched in 1843. In her working lifetime of 90 years (she is now over almost 170), the SS Great Britain sailed round the globe, passing both the Cape of Good Hope and Cape Horn, no less than 32 times! She sailed both as a steamship and as a sailing ship and has worked as a passenger liner, Australian Immigrant vessel (transporting people and goods between England and Australia), as a troop carrier and as a coal store. She has now been restored in the dock that she was built in and we can thoroughly recommend a visit to the ship and museum. Leave yourselves most of a day though.
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Lucy on the deck - she has both sailing masts and a funnel. |
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In the engine room. They have set the engines to move as if they were working so you can see how they run . |
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The dry dock has a glass roof which they keep covered in a layer of water so that it looks like the SS Great Britain is floating. This not only serves an aesthetic purpose, but creates a sealed environment below the waterline which they dry with big de-humidifiers and heaters. There is quite a lot of corrosion in the hull caused by salt bonding to the steel and the only way to minimise further damage is to keep it as dry as possible. The topsides have not been exposed to as much salt as the underside, so they can overcome the corrosion there by painting the ship above the waterline. |
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Lucy always loves an overhanging stern on a sailing vessel. |
Brunel died at the age of 53 from over working and was responsible for many engineering breakthroughs and new technologies that changed the world.