Historical sources for the WOG RAF SE.5a.
RAF SE.5a
The initial models of the S.E.5a differed from late production examples of the S.E.5 only in the type of engine installed – a geared 200*hp Hispano-Suiza 8b, often turning a large clockwise-rotation four-bladed propeller, replacing the 150*hp H.S. 8A model.
Beauchamp-Proctor's former wingman, "Child Yank" Boudwin (center) with 25th Aero Squadron groundcrew, and his last S.E. 5a, F8010.
https://en.wikipedia.org/wiki/Royal_Aircraft_Factory_S.E.5
The introduction of the 200*hp (149*kW) Wolseley Viper, a high-compression, direct-drive version of the Hispano-Suiza 8a made under licence by Wolseley Motors Limited, solved the S.E.5a's engine problems and was promptly adopted as the type's standard powerplant.
