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Boulton Paul P.92

Twin-Engine Turret Fighter / Heavy Fighter Prototype Aircraft

The Boulton Paul P.92 was planned in the late 1930s as a Turret Fighter carrying 4 x 20mm automatic cannon into battle - it was not adopted.
Authored By: Staff Writer | Edited: 6/14/2018
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Year: 1937
Status: Cancelled
Manufacturer(s): Boulton Paul / Heston Aircraft - UK
Production: 1
Capabilities: Fighter; Interception; X-Plane;
Crew: 3
Length: 54.30 ft (16.55 m)
Width: 62.50 ft (19.05 m)
Weight (MTOW): 22,046 lb (10,000 kg)
Power: PROPOSED: 2 x Rolls-Royce Vulture II OR Napier Sabre I liquid-cooled inline piston engines driving three-bladed propellers.
Speed: 385 mph (620 kph; 335 kts)
Ceiling: 38,058 feet (11,600 m; 7.21 miles)
Rate-of-Climb: 3,220 ft/min (981 m/min)
Operators: United Kingdom (cancelled)
In the build-up to war against Germany during the 1930s, the British began to invest in defensive-minded fighter platforms capable of intercepting and destroying the expected waves of inbound enemy bombers crossing the Channel. In May of 1937, Specification F.11/37 was drawn up for this purpose and saw several of the British defense "power players" submit proposals. Boulton Paul, already having secured orders with the Royal Air Force (RAF) for its "turret-armed" Defiant fighter (detailed elsewhere on this site), was selected for its "P.92" project submission.

There were some prerequisites of the design pushed by RAF authorities, namely a minimum top speed of 370 miles per hour and a service ceiling up to 35,000 feet. Armament was to be a concentrated battery of 4 x 20mm cannons, giving appropriate firepower against bombers of the day. The original commitment covered two flyable prototypes which would vary in their engine fit: one featuring the Rolls-Royce "Vulture II" and other to fly with the Napier "Sabre I". To achieve the desired performance and armament-carrying capability, a twin-engine arrangement was selected. The crew would number two, a pilot and a dedicated gunner to his rear - operating the power-operated turret featuring the automatic cannons set.

A mock-up was made ready for May of 1938 and this review forced some revisions to the proposed heavy fighter for Boulton. Wind tunnel testing commenced that November to prove various aspects of its aerodynamics sound. The overall design was somewhat conventional with the cockpit seated aft of a short nose section. Each engine was carried at the leading edges of straight winged mainplanes and the fuselage tapered to the rear in typical fashion. The tail incorporated a single rounded vertical fin and low-mounted horizontal planes. A tail-dragger undercarriage would be used for ground-running. Long and slender, the P.92 had the makings of a very advanced-looking aircraft.

Perhaps the most notable of all the P.92's features was the oversized, circular turret position worked into the aircraft's center (at the point where the two mainplanes were joined at the fuselage spine). The turret emplacement was contoured nicely to help promote good aerodynamics by helping to reduce drag. However, this was not the case in practice for testing showed considerable drag generated by the turret when it was either turned or the guns elevated beyond certain degrees.

Owing to the difficulties in solving several major issues with this turret installation aboard a high-speed aircraft (as well as ongoing issues with the proposed Vulture engines), the P.92 was cancelled in May of 1940 and the prototype's construction barely started.

Engineers estimated their P.92 to have a maximum speed of 384 miles per hour with a service ceiling nearing 38,000 feet. Rate-of-climb was 3,220 feet-per-minute. Dimensions included an overall length of 54.3 feet with a wingspan of 62.5 feet. Power from the Rolls-Royce Vulture II engines was 1,760 horsepower each (these driving three-bladed propeller units).

However, despite the cancellation of the P.92, the Air Ministry allowed the second prototype to gestate a little longer and, for this part of the program, the P.92.2 scale model (half-sized at 27.5 x 33 x 7.6 feet) test aircraft was built by Heston Aircraft (Boulton Paul was busy manufacturing for the war effort). Of note was its fixed, spatted main landing gear legs and 2 x de Havilland "Gipsy Major II" engines of 130 horsepower (each) installed (driving two-bladed propellers). To mimic the in-flight dynamics of the proposed turret emplacement, a dummy turret was installed over the center wing section. Construction was largely of wood (plywood) to keep things relatively economical and easy to repair. A first-flight was recorded in early 1941 but deeper trials were not had until mid-1943 at Boscombe Down. Test pilots did not hold the design in high regard for some of its inherent characteristics but judged handling to be quite good. Maximum speed in these trials reached around 155 miles per hour.

Besides some additional flying done with the prototype by the company, the P.92.2 went nowhere in terms of advancing to a viable combat form. Specification F.11/37 was stalled by this time and ultimately not revisited as the war turned attention to other projects and actions. The sole demonstrator was then purposely burned sometime during the 1950s, ending its test life in full.


4 x 20mm automatic cannons in dorsal turret.

Graphical image of an aircrat automatic cannon

Variants / Models

• P.92 - base Series Designation
• P.92/2 - Scale Model Test Aircraft
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