The Handley Page HALIFAX

The Boulton Paul Turrets

Due to the outstanding success of the turret fitted on the Boulton Paul Defiant, it was decided to adapt these turrets for use on Avro, Shorts & Handley Page aircraft. Two turrets were initially produces, the nose-turret and the tail-turret. After testing, it was only Handley Page who opted for the BP designed turrets and these were produced for fitting on the HP 57 (Halifax).
July 7th 1940 saw the two prototype Halifaxes, L7244 and L7245 tested with mock-up turrets in position at Farnborough. L9485 was air tested with the first Type C and E prototypes turrets fitted. During air tests, there was severe vibration in the front-airframe of the Halifax. This turned out to be caused by turbulance made by the nose turret, which, when turned to either Port or Starboard made controlling the aircaft difficult. What made things worse was that during flight, air drag prevented the turret from being centralized. Various modifaications were carried out and although this improved things, there was still some 'yawing' movement, which could not be entirely eliminated when the turret was turned. The C Type MK.I was fitted after these initial 'teething' troubles were rectified.

Halifax L9485 became an armament 'guinea pig'. Seen here with BP Type C dorsal turret, hatch for beam guns and Boulton-Paul Type 'R' ventral turret. Well Armed !!!

The C Type (nose) Turret.(Pictures)

The C Type (nose) turret was initially armed with two 0.303in Browning guns and was mounted over the bomb aimers position, yet it still allowed both gunner & bomb aimer to operate together without problems.
It was powered by an electro-hydraulic system, the power-unit was fitted to the front lower part of the chassis. To either side of the gunner were the ammunition boxes containing 1,000 rounds for each gun. An unusual feature of the fitting of the guns is that they were mounted on their sides with the cocking studs uppermost, the ammunition belts being drawn along rollers and through apertures in the gun trunnions from the boxes below.
Although it gave some protection in daylight raids, the C.Mk.I turret was not used a great deal. It was mainly used as a deterrent against head-on attacks, hence it's nickname of 'scare gun'.

The C Type Mk.II mid-upper turret.(Picture)
The A Type mid-upper turret.[Picture]

As production of the nose turret progressed, it was suggested that if a rear section was added, it could accomodate a gunner and that it could be used as a mid-upper turret.
The first operational Halifaxes were protected from beam attacks by twin Vickers guns firing from hatches in the fuselage sides. These aircraft were used in daylight attacks on German ships in the harbour at Brest, and reports suggested that adding a mid-upper turret would improve the defensive armament. The ideal choice would have been the four-gun A Type, but for some reason it was decided to use the C Mk.II. Although giving an improved defence in the beam and overhead zones, it reduced the top speed of the aircraft by 6mph.
When the Halifaxes turned to night operations, attacks from these sectors were very rare, so the nose and the mid-upper turrets were dispensed with. Halifax crew soon made it known that they were not happy with single-turret Halifaxes operating over Germany, and when the Series 1A Halifaxes appeared they came armed with a new A Type, four-gun, mid-upper turret, the A Mk.VIII.

Details of the Type C Mks.I and II

	Position in aircraft	front/mid-upper (dorsal)
	Power system		Electro-hydraulic
	Armament		Two 0.303in. Browning Mk.II
	Ammunition		1,000 rounds per gun
	Gun firing gear		24v electrical solenoid sear-release
	Field of fire		Mk.I rotation 100° either beam
				Mk.II rotation 360° either beam
				Elevation Mk.I and II 60°
				Depression Mk.I 45deg., Mk.II 10°	
	Speed of operation	Normally 24°/sec.  High speed 48°/sec.
	Gunsight		Free gun deflector sight Mk.IIIA
	Weight (empty)		396lb (180kg)
	Weight (armed)		575lb (261kg)
	Elecrical power		24v motor from 1,000 watt engine-driven generator

The Type A Mk.VIII

To improve aircraft performance from the Srs IA, the C Type was replaced with a modified A Type four-gun turret, the Mk.VIII. At first, the Mk.VIII was mounted on a raised surround with a contour track for a mechanical interrupter gear, but on the Halifax Mk.II Srs IA, it was lowered 5in. and fitted with a simple skirt fairing. There was also trouble with the interrupter gear and the original Boulton Paul drum-type system was refitted. Another modification was the deletion of the sliding double doors at the back of the turret. These were originally fitted to provide a means of escape on the Boulton Paul Defiant fighter and were retained on the early Mk.VIII models. However, after many reports of them opening whilst airbourne, the doors were deleted.

Details of the Type A

	Position in aircraft	mid-upper
	Power system		Electro-hydraulic system	
	Armament		Four Browning Mk.II guns
	Ammunition		600 rounds per gun in boxes within turret
	Gun firing gear		Magnavox 24v soleniod sear-release units
	Field of fire		Traverse 360°
				Elevation 0-84°
				Depression nil
	Speed of operation
	Gunsight		Mk.IIA reflector sight
	Weight (empty)		373lb (170kg)		
	Weight (armed)		621lb (282kg)		
	Speed of operation	Normal: 24deg/sec (motor @ 3000rpm)
	Armour protection	9mm face visor. Early models: 9mm armoured apron
				surrounding turret body.
	Gunfire Protection	Interrupter: cylinder type with following brushes

The Type E tail defence turret.(Pictures)

The Boulton Paul Type E turret was one of the most successful turrets produced and provided the rear defense for the Halifax and also the American Liberator.
To the front of the gunner was the control table, through which the operating stick protruded. Above the table was a panel facing the gunner with the main motor switch, sight switch and oxygen supply socket. Two armrests were provided which were lowered into position when the gunner was seated, giving him some support and enabling him to control the operating handle accurately. Directly in front was the Mk.III reflector sight fixed to an arm which in turn was connected to the gun arms. Below the gun was a 9mm armoured visor fixed on a frame which moved in elevation with the sight to provide frontal protection, although some gunners had it removed to provide a better field of view. All-round visibility was adequate. but the rear downward view was somewhat restricted by the guns and controls. This was partly overcome by a feature which had been first used on other turrets, which was when the guns were depressed, two small hydraulic rams raised the seat, keeping the gunners line-of-sight parallel with the gun barrels and giving him a good view downwards.
The four Browning Mk.II 0.303in. guns were mounted on their sides in pairs on either side of the gunner, with the cocking handles uppermost and within reach for stoppage clearance. Each gun was provided with 2,500 rounds of ammunition, and the ammo boxes were fixed on the port side of the fuselage, well forward and remote from the turret.
The Type E was a popular turret with the gunners, and over 8000 were produced. It was fitted to all Halifax aircraft until the introduction of the Type D turret armed with the larger calibre 0.5in Browning guns.

Details of the Type E, Mks.I, II and III

	Position 	Tail
	Power system	Electro-hydraulic
	Armament	Four Browning Mk.II 0.303in. guns
	Ammunition	2,500 rounds per gun
	Field of fire	Rotation 65° to either side
			Elevation 60°
			Depression 50°
	Gunsight	Reflector gunsight Mk.III		
	Weight (empty)	403lb. (183kg)	
	Weight (armed)	679lb. (309kg)		
	Mk.I		First production batch
	Mk.II		Modified controls and elevation to 56.5deg
	Mk.III		Fitted to Liberator and later Halifaxes

The Type D tail turret.(Pictures)

After 4 years it was decided to produce turrets armed with heavy-calibre guns. Earlier designs had been submitted for such turrets, but circumstances had prevented their production.
This new turret was armed with 0.5in Browning guns, mounted low and to each side of the seated gunner. The turret had a fabricated structure, most of which was above mounting ring level, the guns being mounted upright in cradles. The ammunition supply was located in the center fuselage well forward of the turret, thus placing the heavy boxes near the center of gravity. The original sight, the Mk IC gyro was replaced by the improved Mk IIC gyro.
The power system was the usual electro-hydraulic unit, the one difference being the elevation mechanism. This was changed from a hydraulic ram to a hydraulic motor, which was found to be more accurate in control at slow speeds. There was provision for manually turning the turret in the event of a power failure. The 'Free/Engaged' lever was set to the 'Free' postion which automatically disengaged the firing circuit and disengaged the drive. If the gunner was incapacitated, the turret could be turned by pressing a switch in the fuselage outside the turret, which enabled it to be turned until the doors could be opened. The ammunition belts were stored in boxes in the rear fuselage
The Type D was the first turret to be fitted with the AGLT Blind Tracking Radar System, codenamed Village Inn. A system of IFF identification was devised by fitting an infra-red detector. Any friendly aircraft approaching from the rear fitted with an infra-red lamp in the nose would be detected. The first squadron to be fitted with the new turret was the Handley Page Halifax VII, which used the Type D in operations in the last months of the war.

Details of the Type D

 Aircraft	     HP Halifax B VII, Avro Lincoln, Shackleton MR I
 Position	     Tail
 Motive Power	     Electro-hydraulic				
 Power source        Accumulators charged by aircraft generators.
 Operating voltage   24 volts
 Armament	     Two Browning 0.5in. No.2 Mk.II 
 Ammunition	     1,515 rounds per gun
 Firing system	     Dunlop Magnavox Soleniods Type 14 D,I:G:S
 Gun chargers        Hand lever, BP design
 Armour shielding    9mm plate, front aspect
 Field of fire	     Rotation 90deg either side of aft.
		     Elevation 45deg above hrizontal
		     Depression 45deg below horizontal
 Gunsight	     GGS Mk IIC or Mk IIIA sight.
		     Light models AGLT Radar Blind Tracking
 Weight (armed)      548lb (249kg)
 Weight (empty)      440lb (200kg)
 Weight of guns      72.5lbs (33kg) each
 Speed		     Rotation/Elevation 35deg/sec

The Type R ventral turret.(Picture)

Just like the other turret manufacturers, Handley Page considered the need for an under defence turret on the Halifax. A design for one was submitted by Boulton Paul, using two Browning guns. The gunner sat in a seat and controlled the guns by means of a small joystick, the only view he could get of any approaching fighters was through a wide-angle periscope sight and this gave him only a few seconds to aim and fire.
Although a very efficient turret, it having full 360deg. traverse and sufficient depression and speed of operation, as with almost every other ventral turret with periscope sights, gunners just could not track fast moving targets.
Only 27 turrets were producted, and after unfavourable reports about them were received from the first Squadrons to be equipped with the them, they were taken out by Squadron armourers. After their removal, some Squadrons fitted hand-held guns firing through hatches cut in the fuselage floor. The most effective of these simple under defence positions was the Preston Green mounting, which was used by several Squadrons

Details of the Type R

	Power system	     Electro-hydraulic system		
	Armament	     Two Browning 0.303in. Mk.II		
	Ammunition	     500 rounds per gun	
	Dia of turret ring   35in.		
	Field of fire	     Rotation 360°
			     Elevation 25°
			     Depression 90°		
	Gunsight       	     Wide angle periscope sight
	Weight (empty)	     330lb (150kg)		
	Weight (armed)	     504lb (229kg)	

Preston Green under defence mounting Mk.II

On 29th February 1944, a Halifax III, (LW650), took off from Boscombe Down. It appeared to be just another Halifax, with the bulging blister of H2S radar beneath the fuselage, but close inspection would have revealed a 0.5in. Browning protruding through the rear of the blister. The aircraft was being used for trials of the Preston Green under-defence turret.
Preston Green began with an American mounting used by USAAF bombers. It gave free movement of the gun whilst providing a firm anchorage. Work had begun 18 months earlier, when it was suspected that enemy night fighters were attacking from below. At this time, the H2S sets were looked on as an essential aid, but production of bombers was outstripping the supply of radars, and it was decided to install Preston Green mountings in all Halifax IIIs.
The adapter was fixed across the base of a bowl-shaped enclosure immediately behind the bomb bay. The gunner had an aft-facing bucket seat within the blister, with a tilting back rest. The gun could be swung clear of its aperture when searching, but could rapidly locked in the firing position if needed.
Had more Bomber Command aircraft been fitted with the Preston Green turret, this previously non-existent protection from attack from below would have cut down the toll taken by Luftwaffe night fighters using upwards firing cannon. Unfortunately, when H2S production increased, the turrets were taken out, much to the annoyance of bomber crews.

Details of the Preston Green Mk.II

	Aircraft	Halifax B Mk.III
	Position	Mid-under	
	Motive power	Hand controlled
	Gun mounting	Bell adapter (US)		
	Armament	0.5in. Browning Mk.II		
	Ammunition	200 rounds in box and 50 rounds in duct
	Field of fire	Rotation 30° to each beam.
			Elevation between 45°-90°		
	Gunsight	Free gun reflector sight Mk.III
	Dia. of bowl	49in.
	Fire control	Manual or electrical		

The Browning gun

One of the most important decisions made by the Air Staff in the mid-1930s was the adoption of the 0.303in. Colt-Browning machine gun as the main weapon for all British military aircraft. Some earlier turrets were armed with Lewis guns, and the Vickers GO gun was also used on some front turrets, but the Browning armed most operational aircraft in the early war period.
The gun was a recoil operated belt-fed weapon with a cyclic rate of 1,100-1,200 rounds per minute. It proved to be an ideal turret gun, most stoppages being caused by badly made-up ammunition belts. The BSA and Vickers companies were given extensive production contracts, but even with round-the-clock working, at the outbreak of hostilities production could not satisfy demand.
The 1930 Pattern Colt-Browning was chosen for RAF use after trials in 1934 in which six guns were evaluated.During service trials it was found that the action of the gun was not suitable for British cordite-based ammunition, and Major Adams of the RAF gun sectioncarried out a successful modification, after which the gun was accepted for service use.
When hostilites commenced in 1939 it was found that excessive fouling occurred in the muzzle extension. This resulted in a hold-up in production until a BSA-designed replacement unit was fittedin which the muzzle attachment was chromed, and fins were added for extra cooling. The modified gun, known as the Browning 0.303in. Mk.II, was the gun fitted to most of the turrets used by the Royal Air Force.

Details of the 0.303in. Browning gun

	Calibre		   0.303in.
	Weight		   21lb 14oz (9.9kg)
	Muzzle velocity	   2,660ft/sec
	Cyclic rate	   1,150 rpm
	Maximum Range	   3,000ft.
	Weight of bullet   0.4oz (Mk.VIII)
	Length of gun	   3ft 8.5in.
	Action		   Recoil
	Ammunition	   Disintergration belt

The Browning 'Point five'

At the request of General John Pershing in 1917, John Browning designed a heavy calibre version of his successful rifle-calibre machine-gun. Known as the Model 1921, the gun was progressively developed into the standard aircraft gun of the US Army and Navy in the Second World War. It was also fitted to the new turrets introduced by Bomber Command in the later stages of the war.
The Browning 0.5in. gun proved to be the most successful aircraft gun ever produced. After 60 years in production it is still in high demand, mostly in helicopter turrets. The HB (heavy barrel) ground service version, made by the Belgian FN concern, is used by every Western army.
The turret version used in the Second World War was usually fired by electrical soleniod release units mounted on the rear of the gun body. It was charged by a large recocking handle or a pulley system remote from the gun. The rimless ammunition is unusual in that there is no copper driving band normally found on such weapons: in consequence, the armour-piercing rounds caused heavy barrel wear. The recoil action has been very successful, and any stoppages are usually caused by badly made-up ammunition belts.

Details of the Browning 0.5in.

	Calibre		   0.5in.
	Weight		   64lb. (27kg)
	Muzzle velocity	   2,900 ft/sec
	Cyclic rate	   750-850 rpm
	Maximum range	   21,600 ft
	Weight of bullet   1.4 oz
	Length of gun	   65.125 in.
	Action		   Recoil
	Ammunition feed	   Disintegrating link belt

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