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Subject: Boulton Paul Defiant
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https://en.wikipedia.org/wiki/Boulton_Paul_Defiant
The Boulton Paul Defiant was 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. It
was a contemporary of the Royal Navy's Blackburn Roc. The concept of a turret
fighter related directly to the successful First World War-era Bristol F.2
Fighter.
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".
During 1935, the concept of a turret-armed defensive fighter to counter the
bomber threat emerged during a time in which the RAF anticipated having to
defend Great Britain against massed formations of unescorted enemy bombers. In
theory, turret-armed fighters would approach an enemy bomber from below or from
the side and coordinate their fire. The separation of the tasks of flying the
aircraft and firing the guns would allow the pilot to concentrate on putting the
fighter into the best position for the gunner to engage the enemy. However,
manually-traversed turrets were viewed as having becoming more problematic and
increasingly inadequate to effectively respond to ever-faster hostile aircraft,
thus there was considerable interest in using a power-augmented turret.
The earlier Hawker Demon biplane had tested the concept with 59 of the fighters,
which had been manufactured by Boulton Paul under a sub-contract, having been
equipped with a hydraulically-powered rear turret, while a number of aircraft
already built were also converted as such. Boulton Paul and its managing
director John Dudley North had gained considerable experience with defensive
turrets from producing several earlier aircraft, including the Boulton Paul
Overstrand bomber, and had devised a four-gun power-operated turret, the concept
and development work of which would later be a core part of the Defiant design.
The primary mission of the Defiant was the destruction of incoming enemy
bombers. The principal armament of the aircraft is its powered dorsal turret,
equipped with four 0.303 in (7.7 mm) Browning machine guns. The fuselage was
fitted with aerodynamic fairings that helped mitigate the drag of the turret;
they were pneumatically powered and could be lowered into the fuselage so that
the turret could rotate freely. The Brownings were electrically fired and
insulated cut-off points in the turret ring prevented the guns firing when they
were pointing at the propeller disc or tailplane. The gunner could rotate the
turret directly forward and transfer firing control of the guns to the pilot,
with the guns firing along each side of the cockpit canopy; this was rarely done
gunsight, possibly because the Defiant was outfitted to perform zero deflection
shooting, as were several contemporaneous designs arising from Air Ministry
specifications.
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
In October 1939, No. 264 (Madras Presidency) Squadron was reformed at RAF Sutton
Bridge to operate the Defiant. Initial training, formal squadron acceptance, and
development of tactics began with other aircraft as it received its first
Defiants only in early December at Martlesham Heath. In February 1940, the
Defiant commenced night fighter training operations; the squadron tested its
flew against Robert Stanford Tuck in a Spitfire, showing that the Defiant could
defend itself by circling and keeping its speed up. It became clear during these
trials that the Defiant was suited only to performing bomber-destroyer duties.
Defiant night fighters typically attacked enemy bombers from below, in a similar
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.
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)
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)
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)
Power/mass: 0.124 hp/lb (204 W/kg)
Climb to 15,000 ft (4,600 m): 8.5 min
Armament
dorsal turret (600 rpg)
*
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