astronomy

GWR Star Class

GWR Star Class is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand GWR Star Class rather than just read about it. In short: The Great Western Railway (GWR) Star Class of 2-2-2 broad gauge steam locomotives were used for passenger train work. Designed by Robert Stephenson, the class was introduced into service between November 1838 and November 1841, and withdrawn between April 1864 and September 1871.

Key takeaways

GWR Star Class belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect GWR Star Class to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of GWR Star Class from memory before moving on to harder problems.

Reference excerpt

The Great Western Railway (GWR) Star Class of 2-2-2 broad gauge steam locomotives were used for passenger train work. Designed by Robert Stephenson, the class was introduced into service between November 1838 and November 1841, and withdrawn between April 1864 and September 1871. A total of twelve Star Class locomotives were manufactured. Notably, they were given the romantic or colloquial (rather than scientific) names of astronomical bodies. By the time the last had been delivered, GWR engineer Daniel Gooch had designed and taken delivery of several of his larger Firefly Class.

North Star and Morning Star These two were built in 1836 by Robert Stephenson & Co. for the New Orleans Railway, which had a gauge of 5 ft 6 in (1,676 mm). That railway experienced financial difficulties, and was unable to accept them; Stephensons sold the locomotives to the GWR, altering the gauge to 7 ft 1⁄4 in (2,140 mm) before delivery, and in the case of North Star, also fitting 7 ft 0 in (2,134 mm) driving wheels in place of the original 6 ft 6 in (1,981 mm) wheels.

North Star (1837–1871) North Star arrived at Maidenhead Bridge station by barge on 28 November 1837; on 31 May 1838 it worked the inaugural train for the company's directors. In 1854 it was rebuilt with 16 in × 18 in (406 mm × 457 mm) cylinders and the wheelbase lengthened by 1 foot (305 mm). It was withdrawn in 1871 but kept at Swindon Works along with Lord of the Isles until 1906, when both were dismantled. However, many parts were later recovered to build a replica. 'The north star' is one of two common alternative names for Polaris (its other being 'the pole star'). It is the only visible polar star in either hemisphere, and has long been used for navigation due to its constant fixed and unmoving appearance due north in the night sky. The commercial park north of Swindon Station is called North Star after the engine and includes streets named North Star Avenue and Polaris Way. Morning Star (1839–1869) This, the second Star Class, was not delivered until 14 months after the North Star. It had smaller 6 ft 6 in (1,981 mm) wheels, as had been intended when it was constructed for the New Orleans Railway; the wheelbase was 12 ft 6 in (3,810 mm). Named after 'the morning star', the common periodic name for the planet Venus (at times the brightest object in the night sky) when seen in the eastern sky just before sunrise, its motion then appearing to "lead" the sun for many mornings.

Later locomotives

North Star and Morning Star having proved successful (in contrast to those from other makers delivered between 1837 and 1840), Gooch ordered ten more from Stephensons to basically the same design as the first two; they were built in 1839–41, although there were variations in design.

Bright Star (1841–1864) A 'bright star' is one clearly visible in the night sky, and generally denotes one of a few that appear to shine more than most. Dog Star (1839–1869) After withdrawal, Dog Star was used as a stationary boiler at Paddington. Named after 'the dog star', the common name for Sirius, brightest star in the night sky and found in the constellation Canis Major (Lat: 'greater dog', from whence Sirius' common name). Evening Star (1839–1871) Named after 'the evening star', the common periodic name for the planet Venus (at times the brightest object in the night sky) when seen in the western sky just before sunset, its motion then appearing to "follow" the sun for many evenings. Lode Star (1841–1870) A 'lodestar' denotes any easily found star that is used to aid navigation (for example Polaris). Now an archaic term, in Middle English it meant 'course star' or 'lead star'. Polar Star (1840–1870) This locomotive was built with 15+1⁄2 in × 18 in (394 mm × 457 mm) cylinders. It was rebuilt as a 4-2-2T. Its name is assisted with navigation: a polar star is one that appears fixed and unmoving over the Earth's North or South Pole and is thus used for a guide. The only one visible is Polaris (a.k.a. the Pole Star or North Star). Red Star (1840–1865) This locomotive was rebuilt as a 4-2-2T tank locomotive. Its name has no particular association with any specific star, although prominent red stars visible from the northern hemisphere include Aldebaran, Arcturus, Antares and Betelgeuse. Rising Star (1840–1871) This locomotive had a 14 ft 6 in (4,420 mm) wheelbase; at some time it was rebuilt as a 4-2-2T tank locomotive. On 7 September 1841 it ran over an earthslip near Chippenham, but the rest of the train (including Tiger, coupled behind) was derailed. The locomotive's name reflected the company's status: a 'rising star' is the term for any star appearing to climb the sky (rather than moving low across the horizon), and is often used metaphorically to mean someone "new" whose reputation is increasing rapidly. Royal Star (1841–1871) This locomotive was built with 15+1⁄2 in × 19 in (394 mm × 483 mm) cylinders and a 12 ft 7 in (3,835 mm) wheelbase. The four Persian 'royal stars' are Aldebaran, Regulus, Antares and Fomalhaut, said to guard the four quarters of the annual night sky. Shooting Star (1841–1871) This locomotive was rebuilt as a 4-2-2T tank locomotive. A 'shooting star' is the descriptive term for a meteor. Western Star (1841–1866) This locomotive was built with 15+1⁄2 in × 19 in (394 mm × 483 mm) cylinders and a 12 ft 7 in (3,835 mm) wheelbase. After withdrawal it was used as a stationary boiler at Oxford. Its name reflected the GWR's westerly direction: 'the western star' has no particular association with any specific star (although Antares was the quarter guardian of the western gate in Persian 'royal star' mythology).

Replica

A non-working replica of North Star was constructed for the 1923 Cavalcade, and is now housed at Swindon Steam Railway Museum. It made use of some of the parts of the original North Star, scrapped as recently as 1906, but is not capable of being steamed. Although it was featured in the railway's centenary film in 1935, it was pushed by another locomotive.

References

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with GWR Star Class

Start with the simplest possible case. Write down what GWR Star Class claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to GWR Star Class before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about GWR Star Class ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of GWR Star Class

In research: GWR Star Class appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses GWR Star Class in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: GWR Star Class is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2-2-2 locomotives, 4-2-2 locomotives, Broad gauge (7 feet) railway locomotives, so understanding it makes those chapters shorter.
In everyday life: Look for GWR Star Class outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study GWR Star Class in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what GWR Star Class means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain GWR Star Class out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is GWR Star Class in simple terms?

Why does GWR Star Class matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study GWR Star Class?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on GWR Star Class.