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P.82 Defiant
A pair of No. 264 Squadron RAF Defiants.
Type	Two-seat turret fighter, night fighter, trainer
Manufacturer	Boulton Paul Aircraft
Designed by	John Dudley North
Maiden flight	11 August 1937
Introduced	December 1939
Status	Retired
Primary users	Royal Air Force Royal Australian Air Force Royal Canadian Air Force Polish Air Force
Number built	1,064

The Boulton Paul Defiant was a British fighter aircraft and bomber interceptor used early in the Second World War. The Defiant was designed and built by Boulton Paul Aircraft as a unique turret fighter that served with the Royal Air Force (RAF) . The concept of a turret fighter was similar to the successful World War I Bristol Fighter and the Fleet Air Arm's contemporary Blackburn Roc but, in practice, the Defiant was highly vulnerable to the more agile Luftwaffe Bf 109 escort fighters; crucially, the Defiant did not have any forward firing guns. It was later used in the night fighter role, where it proved successful against Luftwaffe bombers, before it was phased out of combat service in favour of the Bristol Beaufighter and de Havilland Mosquito. Among RAF pilots it had the irreverent nickname "Daffy."

Contents 1 Design and development 1.1 P.82 1.2 P.85 1.3 P.94 2 Operational history 3 Variants 4 Operators 5 Survivors 6 Specifications (Mk I) 7 References 8 External links 9 Related content

The Defiant emerged at a time when the RAF anticipated having to defend Great Britain against unescorted enemy bombers. Advances in aircraft design during the 1920s and 1930s resulted in a generation of multi-engined bombers that were faster than the single-engined biplane fighters then in service. The RAF believed that its own turret-armed bombers, such as the Vickers Wellington, would be able to penetrate enemy airspace and defend itself without fighter escort and that the German Luftwaffe - its most obvious future adversary - would do the same. A turret-armed fighter would be able to engage enemy bombers from angles that would defeat the bomber gunners. Thus, the Defiant was armed with a powered dorsal turret, equipped with four 0.303 in (7.7 mm) Browning machine guns. In theory, the Defiant would approach an enemy bomber from below or beside and destroy it with a concentrated burst of fire.

Designed to meet the Air Ministry Specification F.9/35, which specified a "turret fighter" with a powered turret as the sole armament. Boulton Paul, who had considerable experience with turrets from their earlier Overstrand bomber, submitted their P.82 project. This design was selected as the most promising of seven initial proposals and one of only two prototypes constructed. The other competing design was the Hotspur from Hawker Aviation.

The central feature of the P.82 was the four-gun turret based on a design by French aviation company SAMM and had been licensed by Boulton Paul for use in the earlier Boulton Paul Sidestrand bomber but eventually installed in the "follow-up" design, the Boulton Paul Overstrand and Blackburn Roc naval fighter^[1]. The turret was a hydraulically powered "drop-in" unit with a crank-operated mechanical backup. The fuselage was fitted with aerodynamic fairings that helped alleviate the drag of the turret; they were pneumatically powered and could be lowered into the fuselage so that the turret could rotate freely. The turret was armed with four .303 Browning machine guns, which were electrically fired. Insulated cut-off points in the turret ring prevented the guns from being activated when they were pointing at the propeller disc or tailplane.

The gunner entered and exited via a hatch in the rear of the turret, although there was a smaller exit in the lower fuselage that was more often used to load ammunition. As a consequence of this arrangement the gunner could not exit the Defiant quickly if the turret was rotated to point to the rear. There was not enough space in the turret for the gunner to wear a parachute, which was instead stowed in the Defiant's fuselage. In case of emergency, the gunner could transfer firing control of the guns to the pilot. In practice this was rarely done as the turret's minimum forward elevation was 19° and the pilot did not have a gunsight.

The first P.82 prototype (K83110) was rolled out in 1937 without its turret, looking superficially like the Hawker Hurricane although it weighed in at over 1,500 lbs more. A clean, simple and compact monoplane structure had been achieved with main landing gear retracting into a broad mainplane section. The pilot's cockpit and rear turret were faired into a streamlined upper fuselage section. Fuel was carried in the wing centre section along with a large ventral radiator that completed the resemblance to the Hawker fighter. With a Rolls-Royce Merlin I (1,030 hp) installed, the newly named "Defiant" prototype first flew on 11 August 1937, nearly a year ahead of the Hotspur. A second prototype, K8620, equipped with a turret, was modified with telescopic radio masts, revision to the canopy and a changes to the undercarriage fairing plates.

Completing its acceptance tests with the turret installed, the Defiant reached a top speed of 302 mph and subsequently was declared the victor of the turret fighter competition. Apart from detail changes, the production aircraft, Defiant Mk. I looked very similar to the two Defiant prototypes. However, its service entry was delayed to such an extent that only three aircraft had reached the RAF by the start of the war. The Mk. I was powered by the Rolls Royce Merlin III (1,280 hp) with a total of 713 aircraft built.

The P.85 was a version of the Defiant for Fleet Air Arm use but the Blackburn Roc was selected and the only FAA use was to be the target tug version of the Defiant.

The very first Defiant prototype had not been initially fitted with a turret and had shown a turn of speed. Consequently, in 1940, Boulton Paul developed a conventional, single-seat, turret-less version of the Defiant called the P.94, armed with 12 .303 Browning machine guns (six per wing). By that time, the RAF had sufficient quantities of Hurricanes and Spitfires and did not require a new single-seat fighter. With a top speed of about 360 mph, the P.94 was almost as fast as a contemporary Spitfire, although less manoeuvrable.

In December 1939, No. 264 Squadron at RAF Manston was the first to be equipped with the Defiant Mk. I. The first operational sortie came on 12 May 1940 during the evacuation of the BEF from Dunkirk. The Defiant was initially successful against enemy aircraft. Its high water mark was on 29 May 1940, on which date No. 264 Sqn claimed 65 kills, mostly Ju 87 Stukas and Messerschmitt Bf 110 twin-engined heavy fighters.

Initially, Luftwaffe fighters suffered losses when "bouncing" flights of Defiants from the rear, apparently mistaking them for Hurricane fighters^[2]. The German pilots were unaware of the Defiant's rear-firing armament and encountered concentrated defensive fire. However with a change in Luftwaffe tactics, opposing fighters were able to out-manoeuvre the Defiant and attack it from below or dead ahead, where the turret offered no defence. Defiant losses quickly mounted, particularly among the gunners, who were often unable to leave stricken aircraft. The additional weight of the turret and the second crewman plus the aerodynamic drag, gave the Defiant much poorer performance than conventional fighter aircraft^[3]. On 13 May, a flight of six Defiants was attacked by Bf 109Es; five of the Defiants were shot down from a frontal attack.

According to the book The Turret Fighters by aviation historian Alec Brew, 264 Sqn. developed effective countermeasures against single-seat aircraft such as the Bf109. By flying in an ever-descending "Lufberry" circle, Defiant crews sacrificed the advantage of height but eliminated the possibility of attack from underneath, while giving 360° of defensive fire^[4]. This tactic was used successfully by 264 Sqn. but when the Defiants of 141 Sqn. were committed to combat a few months later during the Battle of Britain, 141 Sqn. chose to ignore their advice, with devastating consequences. On 19 July 1940, six out of nine Defiants of 141 Sqn. were shot down and the remaining three only survived due to the intervention of Hurricanes of 111 Sqn.^[5]. Although 264 Sqn. claimed an astonishing 48 kills in eight days over Dunkirk (recent research suggests no more than 12 to 15 enemy aircraft were actually destroyed; the turret's wide angle of fire meant that several Defiants could engage the same target at one time), the cost was high at 14 Defiants lost.

With these prevailing losses, the Defiant was quickly withdrawn from daylight operations to night fighting duties and, as a night fighter, the Defiant achieved some success. Defiant night fighters typically attacked enemy bombers from below, in a similar manoeuvre to the later successful German Schräge Musik methods. Defiants attacked more often from slightly ahead or to one side, rather than from directly under the tail. During the winter Blitz on London of 1940-41, the Defiant equipped four squadrons, shooting down more enemy aircraft than any other type.^[6] The fitting of Defiant style turrets to Beaufighter and Mosquito night fighters was trialled to enable these aircraft to duplicate these methods, but the effect on performance proved drastic, and the idea was abandoned. The Defiant Mk. II model was fitted with the AI Mk IV airborne interception radar and a Merlin XX engine. A total of 207 Mk. II Defiants were built.

After trials in 1940 with the School of Army Co-operation to assess its capabilities in that role, the Defiant was re-evaluated as a high-speed gunnery trainer with the Air Ministry agreeing to keep the production lines open. The Defiant was removed from combat duties in 1942 and, thereafter, used for training, target towing, ECM and air sea rescue. In this latter role, the Defiant was equipped with a pair of under-wing pods that contained dinghies. A further 140 Defiant Mk III aircraft were built; this model lacked the dorsal turret and was used as a target tug. Many of the surviving Mk. I and Mk. II Defiants also had their turrets removed.

In this final target towing variant, the Defiant had ended up with a number of overseas assignments with both the RAF and Fleet Air Arm in the Middle East, Africa and India.^[1] Further deployments occurred to Canada where the Defiant fulfilled a role as both a target tug and trainer with the British Commonwealth Air Training Plan.

Defiants also were utilized for "special" work including tactical evaluations with the RAF Gunnery Research Unit and Air Fighter Development Unit (AFDU) at Farnborough. On 11 May 1945, Martin-Baker used a Defiant, DR944, to test their first ejection seat with dummy launches^[1].

Defiant I

Two-seat turret fighter for the RAF, powered by a 1,030-hp (768-kW) Rolls-Royce Merlin III piston engine; 723 built.

Defiant NF.I

Defiant Mk I converted into night fighters

Defiant NF.IA

NF Mk 1 with Airborne Interception radar.

Defiant II

Two-seat night fighter for the RAF, powered by a 1,280-hp (954-kW) Roll-Royce Merlin XX piston engine, and fitted with the AI Mk IV airborne interception radar; 210 built.

Defiant TT.I

Defiant Mk IIs were converted into target tugs; 140 built from new.

Defiant TT.III

Defiant Mk Is were converted into target tugs; 150 conversions.

Defiant ASR.I

air-sea rescue variant carrying dinghy

Main article: List of Boulton Paul Defiant operators

•  Australia
•  Canada
• British India
•  Poland
•  United Kingdom
•  United States

The single surviving Defiant, N1617, is on display as a night fighter at the Royal Air Force museum in Hendon, London^[1]. It belonged to No. 307 Polish Night Fighter Squadron.

General characteristics

• Crew: 2: pilot, gunner
• Length: 35 ft 4 in (10.77 m)
• Wingspan: 39 ft 4 in (11.99 m)
• Height: 12 ft 2 in (3.71 m)
• Wing area: 250 ft² (23 m²)
• Empty weight: 6,078 lb (2,755 kg)
• Loaded weight: 8,318 lb (3,773 kg)
• Powerplant: 1× Rolls-Royce Merlin III liquid-cooled V12 engine, 1,030 hp (780 kW)

Performance

• Maximum speed: 304 mph (264 knots, 489 km/h)
• Range: 465 mi (404 nm, 748 km)
• Service ceiling: 30,350 ft (9,250 m)
• Rate of climb: 1,900 ft/min (9.65 m/s)
• Power/mass: 0.124 hp/lb (204 W/kg)

Armament

• Guns: 4 × 0.303 in (7.7 mm) Browning machine guns in hydraulically-powered dorsal turret (600 rounds per gun, 2,400 rounds total)

Notes

Bibliography

• Fleet Air Arm Archive
• Aeroflight.co.uk
• The Boulton Paul Association

Comparable aircraft

• Blackburn Roc
• Hawker Hotspur

Designation sequence

• P.9 - P.29 - P.75 - P.82 - P.92/2 -P.93 -P.108 - P.111

Related lists

• List of aircraft of the RAF

See also

• YFM Airacuda
• Boulton Paul P.92 - cannon armed turret fighter design

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