Siddeley-Deasy received their first aviation order in June 1915 for 300 aero-engines at the rate of 10 per week at an agreed total price of £300,000; this was considerably more than they had been used to earning over such a period.

 

Initially, the order was for a 90hp V8 air cooled engine based on a Renault design, however, after 25 had been built this was changed to a 150hp V12 based on an R.A.F. 4a design. This engine needed a considerable amount of redesigning and was no doubt the beginning of their experience in producing reliable, powerful aero engines.

By mid 1916 the orders for engines was increased to 30 per week plus spares. Late in 1916, the company was asked to consider building a new six cylinder water cooled engine designed by Beardmore-Halford-Pullinger (B.H.P.) to this end, a completed engine was received at Coventry for testing. The engine proved to be unreliable and considerable re-engineering was required, thus it was not until later in 1917 that production of this engine started. During this time the factory continued to produce even more of the R.A.F 4a engines. The redesigned B.H.P. engines were at first known as the Siddeley1s but were quickly renamed the Puma, this was the first aero engine to carry the Siddeley name.

Aircraft production had started in 1916 with an order for 100 RE8 aircraft; the first two were completed in knock-down form for construction and flight testing at Farnborough. All subsequent aircraft were made and assembled in Coventry and flown from the nearby Radford aerodrome. A total of over 1,000 RE8’s were completed by the time of the Armistice.

A considerable help to Siddeley-Deasey’s aeronautical capability was the arrival of skilled designers following the closure of the Royal Aircraft Factory at Farnborough in 1917.

The end of the war caused most government contracts to be cancelled, however, the Puma engine production continued on a reduced scale and work began on a new B.H.P. 43.5 litre 500bhp V12 cylinder engine which became known as the Tiger.