Boulton Paul Defiant

https://en.wikipedia.org/wiki/Boulton_Paul_Defiant

The Boulton Paul Defiant is a British interceptor aircraft that served with the
Royal Air Force (RAF) during World War II. The Defiant was designed and built by
Boulton Paul Aircraft as a "turret fighter", without any forward-firing guns, a
concept also implemented by the Royal Navy's Blackburn Roc.

In combat, the Defiant was found to be reasonably effective at its intended task
of destroying bombers but was vulnerable to the Luftwaffe's more manoeuvrable,
single-seat Messerschmitt Bf 109 fighters. The lack of forward-firing armament
proved to be a great weakness in daylight combat and its potential was realised
only when it was converted to night fighting. It was supplanted in the night
fighter role by the Bristol Beaufighter and de Havilland Mosquito. The Defiant
found use in gunnery training, target towing, electronic countermeasures and
air-sea rescue. Among RAF pilots it had the nickname "Daffy".

In April 1935, the Air Ministry released Specification F.9/35, which required a
two-seater day and night "turret fighter" capable of 290 miles per hour (470
km/h) at 15,000 feet (4,600 m). The aircraft was to feature a clean design,
concentrating its armament within a power-operated turret, and the accepted
performance was to be only slightly beneath that of other emergent fighter
designs of the period, along with a sufficient fuel capacity to allow it to
perform standing patrols. In particular, the powered turret was to offer
considerable flexibility, possessing both a 360-degree upper hemisphere field of
fire and be able to engage enemy bombers from a range of quarters, including
below the aircraft itself.

Specification F.9/35 had followed the earlier Specification F.5/33, which had
sought a pusher design combined with a forward-set turret; F.5/33 had been
unceremoniously abandoned as the proposals had offered little in terms of
performance gains over existing fighters, and the corresponding Armstrong
Whitworth AW.34 design which had been ordered was not completed.

Boulton Paul, having been focused on turret-equipped aircraft for some time
already, decided to make a submission in response to Specification F.9/35; their
design was given the internal designation of P.82. The proposed fighter was
broadly similar in both size and appearance to the more conventional Hawker
Hurricane, differing in weight primarily due to the use of turret-based
armaments. The central feature of the P.82 was its four-gun turret, based on a
design by French aviation company Societe d'Applications des Machines Motrices
(SAMM), which 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 in the Blackburn Roc naval fighter. The 'Type A'
turret was an electro-hydraulically powered "drop-in" unit, outfitted with a
crank-operated mechanical backup. In addition, small bombs could be housed in
recesses within the outer wing. Some of the development work from the company's
earlier B.1/35 tender was carried over into the P.82.


Role
Two-seat fighter, night fighter, trainer, target tug

Manufacturer
Boulton Paul Aircraft

Designer
John Dudley North

First flight
11 August 1937

Introduction
December 1939

Status
Retired

Primary users
Royal Air Force
Royal Australian Air Force
Royal Canadian Air Force
Polish Air Force

Number built
1,064


By March 1940, 264 Squadron had two flights operational with Defiants and No.
141 Squadron received its first Defiant. When the Defiant was first introduced
to the public, the RAF put out a disinformation campaign, stating that the
Defiant had 21 guns: four in the turret, 14 in the wings and three cannon in the
nose. On 12 May 1940, the first operational sortie occurred as a flight of six
Defiants flew with six Spitfires of 66 Squadron over the English Channel to the
coastline in the vicinity of The Hague, Netherlands; during this flight, a
single Ju 88, which had been in the process of attacking a destroyer, was shot
down. The following day, in a patrol that was a repetition of the first,
Defiants claimed four Junkers Ju 87 Stuka dive bombers, but were subsequently
attacked by a flight of Bf 109Es. The escorting Spitfires were unable to prevent
five of the six Defiants being shot down by a frontal attack.

During the evacuation of the British Expeditionary Force from Dunkirk, the
squadron was based at RAF Manston, as one of the 16 squadrons that No. 11 Group
had for the evacuation. On 27 May 264 Squadron claimed three He 111 and two
damaged. On 28 May, shortly after take-off, 10 Defiants were attacked by about
30 Bf 109s – forming a circle, they claimed six German fighters for the loss of
three Defiants. The Defiant was initially successful against enemy aircraft and
its best day was 29 May, when No. 264 Squadron claimed 37 kills in two sorties:
19 Ju 87 Stukas, mostly picked off as they came out of their dives, nine
Messerschmitt Bf 110 twin-engined heavy fighters, eight Bf 109s and a Ju-88; one
Defiant gunner was lost after he bailed out, although the aircraft made it back
to its base to be repaired. On 31 May, seven Defiants were lost in one day.

The improved Defiant Mk II model was fitted with the AI Mk. IV Airborne
Interception radar and a Merlin XX engine, increasing the aircraft's
performance, particularly at night time. In September 1941, 264 Squadron became
the first to receive the Defiant Mk II, bringing them into operational use by
mid-September. The principal uses of the Mk II night fighter were 96, 151, and
262 Squadrons. As the radar-equipped Defiants began filtering through to
operational squadrons, the Luftwaffe's bombing campaign petered out as German
forces had become heavily engaged on the Eastern Front as they embarked upon the
invasion of the Soviet Union.

Defiant night fighters typically attacked enemy bombers from below, in a similar
manoeuvre to the later German Schräge Musik methods. Defiants attacked more
often from slightly ahead or to one side, rather than from directly under the
tail. The turret-fighter concept was not immediately discarded and the fitting
of Defiant-type turrets to Beaufighter and Mosquito night fighters was tried to
enable these aircraft to duplicate these methods but the deleterious effect on
performance proved drastic and the idea was abandoned.

In the air-sea rescue role, the Defiant was the intended replacement for the
Westland Lysander in shallow air-sea rescue units. In order for this task to be
performed, Defiants in this capacity were equipped with a pair of underwing pods
that each contained two M-type dinghies. In March 1942, No. 281 Squadron formed
at RAF Ouston, Northumberland, partially operating Defiant Mk Is; four more
squadrons received the type within the next two months. However, six months
following their introduction to the role, the Defiant had proved to be a poor
choice for the role, in part due to the aircraft already been worn out by their
previous service, which limited the sortie rate; other issues included its high
stalling speed and wide turning radius. By the end of 1942, the Defiant had been
phased out of the air-sea role.

Defiants were also used for "special" work including tactical evaluations with
the RAF Gunnery Research Unit and the Air Fighting Development Unit (AFDU) at
Farnborough. Two Defiants were issued for ejection seat development work; to R
Malcolm Ltd and Martin-Baker. On 11 December 1944, Defiant DR944 was delivered
to Martin-Baker's facility at Denham; sometime thereafter, a primitive ejector
seat was fitted into the observers position for trial purposes. On 11 May 1945,
Martin-Baker used DR944 to test their first ejection seat with dummy launches.
Various trials using DR944 took place until May 1948; another Defiant, AA292,
was also used for ejector seat trials.

The last operational use of Defiants was in India, where they were used as
target tugs.

Specifications (Mk I)

General characteristics
Crew: two: pilot, gunner
Length: 35 ft 4 in (10.77 m)
Wingspan: 39 ft 4 in (11.99 m)
Height: 11 ft 4 in (3.46 m)
Wing area: 250 ft² (23.2 m²)
Empty weight: 6,078 lb (2,763 kg)
Loaded weight: 8,318 lb (3,781 kg)
Max. takeoff weight: 8,600 lb (3,909 kg)
Powerplant: 1 × Rolls-Royce Merlin III liquid-cooled V12 engine, 1,030 hp (768
kW)

Performance
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)
Range: 465 mi (404 nmi, 749 km)
Endurance: 1.78 hr
Service ceiling: 31,000 ft (9,250 m)
Wing loading: 33.27 lb/ft² (163.0 kg/m²)
Power/mass: 0.124 hp/lb (204 W/kg)
Climb to 15,000 ft (4,600 m): 8.5 min

Armament

Guns: 4 × 0.303 in (7.7 mm) Browning machine guns in hydraulically powered
dorsal turret (600 rpg)




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