Blackburn B - 54 The Blackburn B - 54 and B - 88 were prototype carrier - borne Anti - submarine warfare aircraft of the immediate post Second World War - era developed for the Royal Navy ' s Fleet Air Arm ( FAA ) . They shared a conventional monoplane design with a mid - mounted inverted - gull wing and tricycle undercarriage . The pilot and observer sat in tandem under a long canopy atop the fuselage . The B - 54 had a piston engine and the B - 88 a gas turbine driving a large contra - rotating propeller . The radar scanner was mounted in a retractable radome in the rear fuselage , behind a long internal weapons bay . The program was cancelled in favour of the Fairey Gannet aircraft . History . The B - 54 , or Y . A . 5 , was designed to meet Specification " G . R . 17 / 45 " for an advanced carrier - borne anti - submarine aircraft by Blackburn Aircraft . Rivals Fairey designed their Fairey 17 to the same specification , which would eventually evolve into the winning design , the Fairey Gannet . The original Y . A . 5 was designed to take the new Napier Coupled Naiad turboprop engine , consisting of two single Naiads driving a contra - rotating propeller through a common gearbox . This engine was ultimately cancelled , so the Y . A . 5 flew as the Y . A . 7 with a Rolls Royce Griffon 56 piston engine driving a contra - rotating propeller . This aircraft made its maiden flight on 20 September 1949 ahead of the compteting Fairey design . In 1950 , the Admiralty added the requirement for a radar and radar operator to the specification . The Y . A . 7 was further refined into the Y . A . 8 , first flying on 3 May 1950 , with aerodynamic refinements to improve handling and the third crew position . The Y . A . 8 design was used as the basis for the B - 88 Y . B . 1 which first flew on 19 July 1950 . The B - 88 had an Armstrong Siddeley Double Mamba engine similar in design to the original Naiad that was to be fitted to the Y . A . 5 . Development of this design was protracted and the FAA lost interest in favour of the promising Fairey Gannet , which had already flown with the Double Mamba and carried out landing trials , and which was to enter operational service fulfilling the original specification . Design . The B - 54 / B - 88 shared a common airframe . It was a large , single - propeller conventional monoplane with a mid - mounted , inverted - gull wing and a mid - mounted horizontal tail - plane with considerable dihedral . Unlike the Fairey Gannet , it had a simple wing folding mechanism that split once at the angle of the gull - wing . The deep fuselage accommodated the engine ( s ) , a large weapons bay and the crew of two were seated high up in tandem under a single canopy ( the third crewman in the Gannet was specified after the cancellation of the Blackburn design ) . The undercarriage was a conventional tricycle type and a radar scanner was carried in the rear fuselage in a retractable dome , much like in the Fairey Gannet . Engine . After the cancellation of the Napier Naiad programme , the prototype was fitted with the readily available Rolls - Royce Griffon 56 engine , delivering 2 , 000 hp ( 1 , 491 kW ) to a 13 ft ( 4 m ) , six - blade ( two three - bladed propellors ) contra rotating propeller mechanism . In the B - 88 , an engine plant based on the Armstrong Siddeley Mamba gas turbine ; the Double Mamba - also known as the " Twin Mamba " - driving an eight - blade counter - rotating propeller through a common gearbox . The ASMD . 1 engine used on the B - 88 was rated at 2 , 950 hp ( 2 , 200 kW ) .