The Barracuda had originally been intended to be powered by the Rolls-Royce Exe X block, sleeve valve engine. However, production of this powerplant was problematic and eventually abandoned, which in turn delayed the prototype's trials. Instead, it was decided to adopt the lower-powered 12-cylinder Vee type Rolls-Royce Merlin 30 engine (1,260 hp/940 kW) to drive a three-bladed de Havilland propeller; the prototypes eventually flew in this configuration. Experiences gained from the prototype's flight testing, as well as operations with the first production aircraft, designated "Barracuda Mk I", revealed the aircraft to be underpowered; this has been attributed to have largely resulted from the weight of extra equipment that had been added since the initial design phase. Only 23 Barracuda Mk Is were constructed, including five by Westland Aircraft, these aircraft were only used for trials and conversion training.