Napier Culverin

In the late 1920’s the Air Ministry entered in discussions with Hugo Junkers of Dessau, Germany to produce their new 6-cylinder opposed piston compression-ignition engine which was later designated Junkers Jumo 204.  The engine was fuel efficient and, being a diesel, didn’t have the inherent risk of fire that petrol engines had.  The Air Ministry identified an immediate use for the engine in airships and long range patrol craft.  Unfortunatey the R101 airship for which it was originally intended crashed on its maiden voyage.

Initially Vickers were approached however the Ministry turned its attention to Napiers who were asked to produce the design under licence from Junkers.  This was partly in compensation for the early development work carried out on their own 24-cylinder H layout CI aero engine originally designated E101 and later resurrected as the conventional E107 Napier Sabre.  The Jump 204 engine was re-drawn to imperial measurements and seven Napier Culverin engines were produced in 1936.  One was fitted in Hawker Horsley J8620 and three in Blackburn Iris seaplane S-1593 and underwent flight development test.  Unfortunately the build up to WWII meant that this engine was swept away to prepare for wartime requirements.

Whilst the Culverin ceased production after only seven engines had been produced all was not lost for the Company.  In 1946 Napiers started to design a revolutionary marine engine based on three Culverins in a triangular layout; this was the famous “Deltic” engine.

As well as the Culverin which was based on the Junkers Jumo 204, Napiers also had the licence to produce the smaller and much more successful Junkers Jumo 205.  This was designated the name Napier Cutlass however it was never developed or produced.

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