Making a Merlin Engine Part 1

One of the most distinct sounds from World War Two was the Rolls Royce Merlin engine. The 27 litre 1,500 hp V-12 powered some of the most famous aircraft of the war, like the Supermarine Spitfire, the Hawker Hurricane and the Avro Lancaster. It was also used in British tank designs without a supercharger and other aircraft specific components as the Meteor. This collection of images shows some of the factory processes and workmanship required to build one of these engines.

Non-ferrous metal ingots; the raw materials for the Merlin engines which will be produced here, come into the factory on a roller track or conveyor belt and are transferred into separate ‘stalls’ by these female workers. The original description of the photo states: “the metal will not go into the foundry until a test of each consignment has been made by the foundry laboratory”.

A female worker carries out Izod impact testing on a metal bar, in the material and mechanical testing department of the factory. This test involves striking the material with a heavy pendulum to find the point at which the bar fractures. According to the original caption, tensile, hardness and impact tests are all worked in conjunction with heat treatment and fracture testing, in order to ensure that all material is correct to specification and satisfactory for use.

Scientists at work in the laboratory at this aircraft engine factory. Chemical analysis is used to confirm materials testing and investigations are also carried out into electro-plating, pickling, etching and the development of oils and coolants. Also, the development of rubber substitutes is being examined, in conjunction with rubber companies.

Merlin Engine components are heat treated at this aircraft engine factory. This process is called ‘oil-blacking’. The engine components are taken from the furnace at 500 degrees C and dipped into oil. The oil burns into the surface of the metal and helps to prevent corrosion.

Two workers at this aircraft engine factory test the temperature of molten metal before it is poured into a mould. The metal must be 720 degrees C before it can be moulded. Mr A Hamid inserts the thermocouple of the pyrometer into the molten metal and waits for the thumbs-up signal from his colleague, as she lets him know that the correct temperature has been reached. According to the original caption, Mr Hamid, who is from India, was discharged from the army on medical grounds.

In the foundry of this aircraft engine factory, 100 kgs of molten aluminium is emptied into a cylinder head mould by workers in an operation known as the ‘two-handed pour’.

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A wide view of the factory floor showing multi-spindle automatic machines manufacturing nuts, adaptors and unions from bar material. Each machine is operated by a worker.

Mary Gordon operates a No 7 Ward combination lathe, producing sealing rings for the pistons. This is precision work, as an error of just 0.0254 mm could lead to the entire engine seizing up. Mary was a textile finisher before the war and her brother, a Commando, had been taken prisoner by the Italians.

A view of the notice board at this aircraft engine factory. Notices for dances and other social events and activities can be seen, as can a notice warning workers about oil dermatitis which can cause blisters on the skin.

To continue reading Part 2, click here.