Aviation of World War II

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P.82 Defiant

Interceptor Fighter

Boulton Paul

P.82 Defiant

BOULTON PAUL P.82 DEFIANT - The Boulton Paul Defiant was designed by a team headed by J D North to meet requirements of Specification F.9/35 for a two-seat interceptor fighter with armament concentrated in powered dorsal turret with 360° traverse. First of two prototypes flown August 11, 1937 (without turret fitted until February 1938), powered by Merlin I engine. Second prototype, with turret and Merlin II, flown May 18, 1939. Prototype trials later with single 20-mm cannon in place of machine guns, and as single-seat 'stop-gap' fighter minus turret but with four wing guns.

Boulton Paul Defiant Mk I: Initial contract for 87 Boulton Paul Defiant Mk Is placed March 1937. First example flown July 30, 1939, with Merlin III rated at 1,030 hp at 16,250 ft (4,953 m). Boulton Paul A.Mk.IID turret with four 0.303-in (7.7-mm) Browning guns. First day fighter unit (of two) to receive Boulton Paul Defiant Is, No 264 Sqn, received first aircraft December 8, 1939; first operational deployment May 1940. Philosophy of turret-equipped single-engined fighter proved ill-founded for day fighting role, and Boulton Paul Defiant (Mks I & II) assigned to night fighting. First night operations (No 141 Sqn) September 1940 and 11 NF squadrons eventually Boulton Paul Defiant-equipped AI Mk IV radar added on Mk I night fighters from autumn 1941, with designation Boulton Paul Defiant IA. Some 76 modified Boulton Paul Defiants (Mks I & II) used by five air-sea rescue squadrons, carrying two M-type dinghies in underwing containers, 1942/43. Total Mk I contracts for 930 aircraft.

Boulton Paul Defiant Mk II: Final contract for Mk I amended to call for 210 Boulton Paul Defiant Mk IIs with 1,280 hp Merlin XX engine, slightly enlarged rudder and additional fuel. Prototype (Mk I conversion) first flown July 20, 1940. Normal loaded weight increased to 8,424 Ib (3,821 kg) and max speed to 315 mph (507 km/h) at 16,000 ft (4,877 m). Seven Mk Is also converted to Mk IIs on assembly line, with deliveries commencing February 1941. Mk IIs initially replaced Mk Is in night fighter squadrons, mostly equipped with AI Mk VI radar. Some for air-sea rescue duty alongside Mk Is, and 35 used by No 515 Sqn 1942/43 specially equipped with Moonshine and Mandrel radar jamming equipment. All Boulton Paul Defiants with-drawn from other operational roles by end of 1942.

Boulton Paul Defiant T.T.Mk I and T.T.Mk III: One hundred and forty examples of a target-towing version ordered July 1941 as T.T.Mk I. Turret removed and replaced by fixed canopy over winch operator's cockpit. Based on Boulton Paul Defiant II, first T.T.Mk I delivered January 31, 1942. Last 40 Mk II fighters on order built as T.T.Mk Is and, subsequently, 150 Merlin III-engined Boulton Paul Defiant Mk Is convened similarly as T.T.Mk IIIs. Some 60 Boulton Paul Defiant target tugs transferred to Admiralty for FAA use; others used by RAF in European and (suitably 'tropicalised') Middle East and Far East theatres.

Max speed, 250 mph (402 km/h) at sea level 304 mph (489 km/h) at 17,000ft (5,182 m). Initial climb, 1,900 ftlmin (9.65 m/sec). Service ceiling, 28,100 ft (8,565 m). Range 465 mis (748 km). Loaded weight, 8,318 Ib (3,773 kg). Span, 39 ft 4 in (11.99 m). Length, 35ft 4 in (10. 77 m).

 P-82 Defiant No K8310

Boulton Paul Defiant Mk I
Crew two: pilot, gunner
Wing span 39 ft 4 in (11.99 m)
Wing area 250 ft² (23.2 m²)
Length 35 ft 4 in (10.77 m)
Height 11 ft 4 in (3.46 m)
1 × PE 1 × Rolls-Royce Merlin III liquid-cooled V12 engine
Power 1,030 hp (768 kW)
Weight, kg:
Empty weight 6,078 lb (2,763 kg)
Loaded weight 8,318 lb (3,781 kg)
Maximum speed 304 mph (264 knots, 489 km/h) at 17,000 ft (5,180 m)
Cruise speed 175 mph (152 knots, 282 km/h) at 15,000 ft (4,570 m)
Climb to 15,000 ft (4,600 m) 8.5 min
Service ceiling 31,000 ft (9,250 m)
Service range 465 mi (404 nmi, 749 km)
Armament 4 × 0.303 in (7.7 mm) Browning machine guns in hydraulically powered dorsal turret (600 rpg)
Photo Description
Drawing Defiant Mk1 Merlin XX

Drawing Defiant Mk I Merlin III

Drawing Defiant Mk1 Merlin III

Drawing Defiant TT Mk I Merlin XX

The Defiant first prototype, K8310

The first prototype, K8310, but with further changes that make it more akin to production aircraft.

The Defiant second prototype, K8620

The Defiant second prototype, K8620, outside the flight sheds, with the prototype Blackburn Roc behind it. It has further changes to K8310, including ejector exhausts, a window between the pilot and gunner, and the retractable wireless aerial fitted.

The Defiant first prototype, K8310 with a single 20mm Hispano cannon

The Defiant prototype, K8310, at Boscombe Down, crudely camouflaged, and fitted with a standard turret adapted to take a single 20mm Hispano cannon; it was designated the Type F turret.

The Defiant cockpit

A Defiant cockpit, showing that the pilot had a gun button: he could fire the guns if they were fixed to fire forward.

The Defiant N1535 of No. 264 Squadron

Sqn Ldr Phillip Hunter leading A Flight of No. 264 Squadron in Defiant N1535.

A crew truck taking No. 264 Squadron

A crew truck taking No. 264 Squadron aircrew to their aircraft.

The prototype Mark II Defiant, N1550, with Merlin XX engine in August 1940

The prototype Mark II Defiant, N1550, with the more powerful Merlin XX engine, at Pendeford in August 1940.

Outside the factory on 31 January 1942: a forward view of DR863

Outside the factory on 31 January 1942: a forward view of DR863.

Defiant T.T.I, DR972

A production Defiant T.T.I, DR972, outside the factory showing the yellow/black stripes on the undersides.


  • "Encyclopedia of military engineering" /Aerospace Publising/
  • "British warplanes of World War II" /under cor. Daniel March/
  • "The Turret Fighters. Defiant and Roc" /Alek Brew/