B4899 with the second Viper installation arrived at Martlesham for tests on November 25, 1917.

D3511 of 40 Squadron in 1918, displaying an unusual camouflage scheme. In the cockpit is Maj R. S. Dallas, DSO, DSC, commander of the squadron from March 15, 1918, until his death in action on June 1.

Production Wolseley Motors-built Viper-powered S.E.5a D6933 was flown by Lt J. C. Rorison in 85 Squadron in July 1918.

The photograph of S.E.5a D7020 at Farnborough on November 21, 1919, shows the final standard twin-block Viper radiator with two rows of short horizontal shutters. This aircraft became G-EBQM and survived until December 1932.

Used by 56 and 60 Squadrons until it force-landed in Holland on January 6, 1918, B4885 is seen in service with the Netherlands Luchtvaart Afdeling as SE214.

S.E.5as under production in the Wolseley works.

This grey-painted aircraft was the personal mount of Capt K. M. St C. G. Leask when he was a fighting instructor.

Flown by Lt H. J. Burden of 56 Squadron, C1096 has an adaptation of a 200 h.p. Hispano-Suiza radiator, but the righthand airscrew and low thrust line denote a Viper engine.

Late Viper-powered S.E.5a C1148 displays its shortened exhaust pipes on June 11, 1920.

The first Wolseley Viper installation was made in B4862, seen at Martlesham Heath. Note standard 200 h.p. Hispano-Suiza radiators.

B4862 with the modified Viper installation employing an underslung radiator.

Possibly an experimental radiator installation that led to the standardisation of twin-block radiators for the Viper engine, this S.E.5a’s cooling system only differs slightly from final standard.

An S.E.5a of 40 Squadron with its full load of four 25lb Cooper bombs. The officer is distinguished fighter pilot Capt G. E. H. McElroy, MC, DFC.

Left, the standard armament installation on a geared Hispano S.E.5a. Right, this may well be one of the four aircraft with the gun at 7 1/2° upward angle.