Clerget 9B

130hp Clerget 9B rotary aeroengine

It was in the middle of 1915 that WO Bentley, then a Lieutenant in the Royal Naval Volunteer Reserve (RNVR), was sent to the Thames side factory of Gwynnes in Chiswick.  This was originally a Thornycroft works but had been taken over by Gwynnes before the War and used for the manufacture of pumping engines and centrifugal pumps.


Church Warf Chiswick in 1896 when still a Thornycroft works.

HMS Angler is seen alongside being fitted out.



Gwynnes had obtained a licence to build the French designed 110hp Clerget 9 engine which was being used by the Royal Naval Air Service (RNAS), but the quality of the output was not good. 



WO's brief was to improve the quality of the manufacture and to fit his engineering innovation of Aluminium pistons.  He achieved both elements of his remit and the resulting engine, with an increase in stroke and rev limit, was rated as the 130hp Clerget 9B. 

Thus the Clerget 9B was the result of WO's initial efforts during World War 1, the first aeroengine to benefit from his engineering expertise and the start of his journey to the Bentley Rotary 2 (BR2).

 The W.O.Bentley Memorial Foundation, W O Bentley Memorial Building, Ironstone Lane, WROXTON, Banbury, Oxfordshire, OX15 6ED, England.  

Tel: +44(0)1295 738886, Fax: +44(0)1295 738811,     

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