Sabre V (Series VII) aero engine, 1946

OBJECTS OF ENGINEERING-Sabre model

The Sabre model can be seen at IMechE, made by the company it is a detailed example of an engine model.

Napier Sabre V (series VII) aero engine, 1946, scale model
Napier Sabre V (series VII) aero engine, 1946, scale model. From Napier’s Archive at IMechE.

D Napier & Son had been working on large aero engines since the end of World War I. The Lion, in modified form, had powered several of the Supermarine Schneider Trophy competitors and several land speed record cars. However, by the late 1920s, work had started on replacements.

Gloster VI seaplane with Napier Lion VIID engine, winner of the 1929 Schneider Trophy.
Gloster VI seaplane with Napier Lion VIID engine, winner of the 1929 Schneider Trophy. From Napier’s Archive at IMechE.

Two H-block designs, the H-16 Rapier and the H-24 Dagger were then produced. The H-block consisted of two horizontally opposed engines, lying one atop or beside another. In 1927, Harry Ricardo published a study on the concept of the sleeve valve engine. He argued that traditional poppet valve engines would be unlikely to produce much more than 1,500 hp; to pass this limit a sleeve valve would have to be used, to increase volumetric efficiency. Ricardo started work with Bristol Engines on sleeve-valve designs and Major Frank Halford started work with Napier.

Halford and Napier used the opposed H layout of the Dagger but the new design positioned the cylinder blocks horizontally so to use sleeve valves. All of the accessories were grouped above and below the cylinder blocks, rather than being at the front and rear of the engine as in most contemporary designs.

Sabre crankshaft. Pt No 19800/1.
Sabre crankshaft. Pt No 19800/1. From Napier’s Archive at IMechE.

The first Sabre engines were ready for testing in January 1938, limited to 1,350 hp. By March, they were passing tests at 2,050 hp and by June 1940, when the Sabre passed the Air Ministry’s 100-hour test, the first production versions were delivering 2,200 hp. By the end of the year, they were producing 2,400 hp – the 1940 Rolls-Royce Merlin II was generating just over 1,000 hp.

The first operational aircraft to be powered by Sabre were the Hawker Typhoon and Hawker Tempest. Other aircraft using the Sabre were, early prototype and production variants of the Blackburn Firebrand, the Martin-Baker MB 3 and a Hawker Fury. However, the introduction of jet engines after World War II led to the quick demise of the Sabre – there was less need for high power military piston aero engines. Napier turned to turboprop engines instead.

Napier’s Archive is at IMechE, email us for information.

Archives, Institution of Mechanical Engineers

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