ATTACKERS’ CAPABILITIES

To sink a battleship

Aircraft of Bomber Command

From the outset Bomber Command decided to attack Tirpitz using four-engined heavy bombers. Smaller twin-engined bombers lacked the range. In 1942 that meant the Short Stirling, the Handley Page Halifax or the brand-new Avro Lancaster. Of these the Stirling and the Halifax were broadly similar in terms of performance. However, the Stirling had a ceiling of just 16,500ft, while the other two heavy bombers could fly at least 5,000ft higher. This made the Stirling more susceptible to enemy flak. Both the Stirling and the Halifax carried a similar-sized payload (14,000lb and 13,000lb respectively. However, to reach Trondheim from the airfield at Lossiemouth in the north-east of Scotland, the Stirling would have to reduce its payload to 12,000lb. On the same mission the Halifax could carry its full payload. So, after the initial small bombing raid on 30/31 January 1942, when a combination of Stirlings and Halifaxes were used, the Stirling squadrons were returned to other bombing duties, and the task of dealing with the Tirpitz fell to the crews of the Halifaxes, augmented in April by Lancasters.

The Short Stirling was one of the three British four-engined bombers produced according to the Air Ministry’s specifications. The Stirling was used in the first RAF bombing raid on the Tirpitz in January 1942, while she was moored in the Faettenfjord. The Stirling’s major disadvantage when compared to the Halifax and the Lancaster was its low ceiling.

The Lancaster was one of the outstanding heavy bombers of the war. Although its general performance was similar to that of the Halifax, the Lancaster enjoyed a big advantage in terms of range. Also, while both bombers had a broadly similar payload (13,000lb for the Halifax, and 14,000lb for the Lancaster), the configuration of the Lancaster’s bomb bays proved far more versatile. That meant that while the Halifax could be converted to carry large bombs such as the 4,000lb ‘cookie’, or ‘blockbuster’ bomb, which was used during the spring raids on the Tirpitz in 1942, it was incapable of carrying larger bombs. As a result, only the Lancaster could carry the 12,000lb ‘Tallboy’, which was used against the Tirpitz with devastating effect in late 1944. Even then, to attain the range needed to reach their target, these bombers had to be lightened by removing their upper turret. That, of course, made them extremely vulnerable to German fighters.

Short Stirling heavy bomber
Entered service:	May 1940
Length:	87ft 3in (26.6m)
Wingspan:	99ft 1in (30.2m)
Weight when laden:	59,400lb (26,944kg)
Powerplant:	4× Bristol Hercules engines
Max. speed:	282mph (454kph) at 12,500ft (3,800m)
Range:	2,330 miles (3,750km) with bomb payload
Ceiling:	16,500ft (5,030m)
Armament:	2× machine guns (MG) in nose turret, 2× MG in upper turret, 4× MG in tail turret
Bomb payload:	14,000lb (6,350kg)
Crew:	7

Handley Page Halifax heavy bomber
Entered service:	November 1940
Length:	71ft 7in (21.82m)
Wingspan:	104ft 2in (31.75m)
Weight when laden:	54,400lb (24,675kg)
Powerplant:	4× Bristol Hercules engines
Max. speed:	282mph (454kph) at 13,500ft (4,115m)
Range:	1,860 miles (3,000km) with bomb payload
Ceiling:	24,000ft (7,315m)
Armament:	1× MG in nose cupola, 4× MG in upper turret, 4× MG in rear turret
Bomb payload:	13,000lb (5,897kg)
Crew:	7

Avro Lancaster heavy bomber
Entered service:	February 1942
Length:	69ft 4in (21.11m)
Wingspan:	102ft (31.09m)
Weight when laden:	55,000lb (24,948kg)
Powerplant:	4× Rolls Royce Merlin engines
Max. speed:	282mph (454kph) at 13,000ft (4,000m)
Range:	2,530 miles (4,073km) with bomb payload
Ceiling:	21,400ft (6,500m)
Armament:	2× MG in nose turret, 2× MG in upper turret, 4× MG in rear turret
Bomb payload:	14,000lb (6,400kg), although this could be modified to 22,000lb (10,000kg) for single heavy ordnance such as Tallboy or Grand Slam, at the expense of range and performance
Crew:	7

Aircraft of the Fleet Air Arm

Tirpitz’s sister ship Bismarck was crippled by a single 18in torpedo hit on her vulnerable rudder. The aircraft which released it was a Fairey Swordfish, a lumbering biplane which looked obsolete, but which actually proved a highly effective aircraft. The Swordfish was designated a Torpedo/Bomber/Reconnaissance aircraft (TBR) by the Fleet Air Arm, and so had to perform three roles. This merely added to its versatility, and explained why it remained in active service throughout the war. However, the Swordfish never saw action against the Tirpitz. That task fell to the Fairey Albacore, another biplane that was billed as the replacement for the elderly Swordfish, but which was actually taken out of service before its predecessor. The Albacore (nicknamed the ‘Applecore’ by the Navy) proved less manoeuvrable than the Swordfish, even though it was both faster and more comfortable, having an enclosed cockpit. However, in May 1942 it was the only aircraft embarked in the carrier Victorious which could damage the Tirpitz.

A Fairey Albacore taking off from the deck of an Illustrious-class fleet carrier – probably Victorious – while behind her a Seafire is preparing to begin her take-off run. This Albacore is unarmed, so is probably flying on a reconnaissance patrol.

During the Fleet Air Arm’s attacks on the Tirpitz in the Kaafjord in the summer of 1944, the fleet’s main strike aircraft was the Fairey Barracuda. It was designed as a replacement for the Swordfish and the Albacore, although with the exception of its speed and manoeuvrability, it was not significantly better than either of its predecessors. The Barracuda was slightly easier to fly, and its improved visibility made it better suited to carrier landings. The largest ordnance it could carry, apart from an 18in aerial torpedo, was a 1,600lb armour-piercing (AP) bomb, and it was this, together with the 500lb semi-armour-piercing (SAP) bomb and the 600lb anti-submarine bomb, that it used against the Tirpitz. For all this, though, it was still too slow to attack the German battleship effectively before word of its approach reached the ship and her protective smoke screen was deployed. Ultimately, it was this lack of speed which condemned the Fleet Air Arm to failure in their efforts to put Tirpitz out of action.

Fairey Albacore TBR
Entered service:	March 1940
Length:	39ft 10in (12.14m)
Wingspan:	50ft (15.24m) – wings could be folded for storage
Weight when laden:	10,460lb (4,755kg)
Powerplant:	1× Bristol Taurus II engine
Max. speed:	161mph (225kph) at 1,625ft (500m)
Range:	817 miles (1,497km) with torpedo or bomb payload
Ceiling:	20,700ft (6,310m)
Armament:	1× forward-facing MG on starboard wing, 1–2× MG in rear cockpit
Bomb/torpedo payload:	2,000lb (907kg) of bombs, or 1× 18in torpedo
Crew:	3

Fairey Barracuda TBR
Entered service:	January 1943
Length:	39ft 9in (12.12m)
Wingspan:	49ft 2in (14.99m) – wings could be folded for storage
Weight when laden:	13,200lb (6,000kg)
Powerplant:	1× Rolls Royce Merlin engine
Max. speed:	228mph (367kph) at 1,750ft (533m)
Range:	686 miles (1,104km) with torpedo or bomb payload
Ceiling:	16,600ft (5,080m)
Armament:	2× MG in rear cockpit
Bomb/torpedo payload:	1,800lb (820kg) of bombs, or 1× 18in torpedo
Crew:	3

In addition to these bombers, the Fleet Air Arm used a number of fighters in their air strikes against the battleship. Of these, the American-built Grumman Hellcats and Vought Corsairs were capable of carrying small 500lb bombs, and therefore inflicting some minor damage to the battleship, if they were able to target her. Other naval fighters of British design – the Supermarine Seafire and the two-seater Fairey Firefly – were purely used as fighters, although in theory both could also carry a small bomb payload. Incidentally the Firefly also functioned as an anti-submarine aircraft, and as a reconnaissance plane. The advantage of these naval fighters over the Barracuda was their speed. The Hellcat had a top speed of 391mph, while the Corsair could manage an even more impressive 446mph. During Operation Goodwood this proved invaluable, as they were able to reach the Tirpitz before she could deploy her protective smoke screen.

The American-built Grumman F6F Hellcat entered service with the Fleet Air Arm in late 1942, where for a time it was known as the Grumman Gannet, to conform with British nomenclature. During Operation Tungsten, Hellcats operating from the escort carrier Empress successfully strafed and bombed the Tirpitz in the Kaafjord.

Photographic reconnaissance

Before any operation could be planned, the attackers needed to know as much as they could about the battleship, her anchorage, and the defences around her. This information was supplied in part by Norwegian agents, but mostly it came from photographs, supplied by the Photographic Reconnaissance Unit (PRU). These flights, usually carried out by specially adapted Spitfires and later by Mosquitos, would continue for as long as the Tirpitz remained at large. When the battleship moved to the Kaafjord in northern Norway, the British planners had to rely on information gathered by Soviet reconnaissance planes, which lacked the specialist photographic equipment used by the PRU. However, by the summer of 1944 the PRU was able to operate from bases in northern Russia, and after an initial evaluation the photographs were flown to Britain by flying boats, where they were fully analyzed.

The Vought F4U Corsair was another American-built fighter, which entered service with the Fleet Air Arm in November 1943. After some minor modifications it proved a robust and highly effective aircraft. During the spring and summer of 1944 Corsairs operating from the carriers Formidable and Victorious provided fighter cover for the Fleet Air Arm strikes on the Tirpitz.

Between 1942 and 1944 these would provide operational planners with the basic information they needed. Not only did this reveal exactly where the Tirpitz was moored, and which direction she faced; it also showed her degree of operational readiness. In addition, regular PRU sorties gathered information on shore defences, torpedo nets, patrolling guard boats, the location of escort warships and supply ships, and weather conditions. Without this information the air operations against the Tirpitz would have had almost no chance of success.

The 2,000lb armour-piercing (AP) bomb was specifically designed to be used, as its manual claimed, ‘for attacks against heavily armoured targets, such as capital ships’. It was strongly built so that it didn’t break up on impact, and its sleek lines and hardened nose cone encouraged it to penetrate a ship’s armoured deck before exploding.

Ordnance

While Tirpitz was being built, the bombers attacking Wilhelmshaven and Kiel used 250lb and 500lb general purpose bombs, designated as medium-capacity (MC) ordnance by the RAF. These were dropped at night, from a high altitude, and so the chances of hitting the battleship were slim. Even if they did strike her they would do little damage due to her well-protected armoured deck. The best that could be hoped for was the reduction of her fighting potential through damage to sensors, fire-control equipment and flak guns. During 1944 these smaller bombs were used by the Fleet Air Arm during their attacks on Tirpitz. By then, semi-armour-piercing (SAP) and armour-piercing (AP) bombs were being used, but while these could pierce unarmoured decks, they were still incapable of inflicting a mortal wound.

A more powerful bomb was needed to inflict any real damage. In the port raids of 1940–41, a number of experimental 2,000lb high-capacity (HC) bombs were dropped. These were the first specialized British heavy bombs of the war. Their cast-steel cylinders were packed with Amatol explosive, and when released a drogue would deploy to stabilize the bomb as it fell. Although this type of ordnance proved ineffective in these port raids, by late 1941 a smaller but theoretically armour-piercing version was available. This was carried during the abortive January 1942 raid on Tirpitz in the Faettenfjord.

A larger 4,000lb HC version was developed, which had a similar cylindrical appearance, but due to its weight a drogue was omitted. The poor aerodynamic qualities of this bomb meant that its path was unpredictable once released, but by 1943 this problem was overcome by the addition of a nose cone and a circular drum fin. This allowed them to be optimistically designated AP bombs. These 4,000lb HC bombs were termed ‘blockbuster’ bombs by the press, as they were primarily designed to demolish urban areas. The airmen, though, nicknamed them ‘cookies’. Each contained over 3,000lb of Amatol, and if an AP version hit the Tirpitz it was hoped that it would pierce her armoured deck and explode deep inside the ship. In practice, however, these large, thin-skinned bombs proved little more effective than conventional bombs.

The Fleet Air Arm used an American-designed 1,600lb AP bomb. Specifically designed to penetrate the deck armour of an enemy warship, it had a hardened, pointed nose and a box fin. Although theoretically capable of piercing Tirpitz’s armoured deck if released at a high enough point during the dive, it proved another disappointment. The effectiveness of those bombs that hit Tirpitz was limited, as they had been filled with only half the requisite amount of explosive thanks to defects during production. They were also plagued by a faulty detonator.

250lb MC (medium capacity) bomb
User:	Royal Air Force, Fleet Air Arm. Introduced October 1941
Weight:	225lb (102kg). Explosive charge 63lb (28.58kg) Amatol
Fusing:	Instantaneous (contact)
Structure:	Cylindrical, with nose cone, thin casing and banded stabilizer at tail
Effect:	Conventional bomb, incapable of penetrating armoured plate
Note:	This superseded the 250lb GP (general purpose) bomb first introduced in 1926

500lb MC bomb
User:	Royal Air Force, Fleet Air Arm. Introduced October 1941
Weight:	499lb (226kg). Explosive charge varies depending on explosive, but usually 232lb (105kg) Torpex
Fusing:	Instantaneous (contact)
Structure:	Streamlined, with thin casing and banded stabilizer at tail
Effect:	Conventional bomb, incapable of penetrating armoured plate
Note:	This superseded the 250lb GP (general purpose) bomb first introduced in 1926

500lb SAP (semi-armour-piercing) or AP (armour-piercing) bomb
User:	Royal Air Force, Fleet Air Arm. Introduced February 1942 (SAP), March 1942 (AP)
Weight:	490lb (222kg) for SAP, 450lb (204kg) for AP. Explosive charge 90lb (41kg) TNT for SAP, 83lb (38kg) Shellite for AP
Fusing:	Delay (6 seconds) for SAP, delay (12 seconds) for AP
Structure:	Streamlined, with thickened casing (up to 1.3in/3.3cm), hardened nose cone and drum stabilizer at tail
Effect:	SAP capable of penetrating 2in (5cm) of deck armour from 2,500ft (762m). AP capable of penetrating 3.5in (8.9cm) of deck armour at 3,100ft (945m)

2,000lb HC (high capacity) Mark II bomb
User:	Royal Air Force. Introduced December 1941
Weight:	1,723lb (782kg). Explosive charge varies depending on explosive, but usually 1,230lb (558kg) Amatol
Fusing:	Delay (12 seconds)
Structure:	Cylindrical, tapering to rear, with thin casing and rear cylinder stabilizer, although some were adapted to use conventional MC banded stabilizer at tail
Effect:	Conventional bomb, capable of wreaking considerable damage to unarmoured structures
Note:	This was essentially a precursor of the larger Blast Bombs, designed to destroy non-armoured targets. Although available from late 1941, these bombs were still being developed, and only entered service officially in June 1943

2,000lb AP Mark I bomb
User:	Royal Air Force. Introduced October 1941
Weight:	1,934lb (877kg). Explosive charge 166lb (75.3kg) Shellite
Fusing:	Delay (11 seconds)
Structure:	Streamlined, thick-walled, with hardened nose cone and banded stabilizer at tail
Effect:	Developed specifically to use against ‘heavily armoured targets’ such as warships

4,000lb HC blast bomb Mark II ‘cookie’
User:	Royal Air Force. Introduced March 1941
Weight:	3,930lb (1,783kg). Explosive charge 2,882lb (1,307kg) Amatol
Fusing:	Delayed contact (12 seconds)
Structure:	Cylindrical, with thin casing and rear cylinder stabilizer in tail
Effect:	Blast bomb
Note:	These bombs were fitted with a light-gauge metal plate nose attachment to improve aerodynamic performance

On board HMS Furious, London-born naval armourer Bob Cotcher chalks a message on the side of a 1,600lb AP bomb slung beneath a Barracuda of 830 Squadron, shortly before the commencement of Operation Tungsten. The addition of graffiti to ordnance was not unknown in the Fleet Air Arm, although it was generally frowned upon in Bomber Command.

1,600lb AP Mark I bomb
User:	Fleet Air Arm. Introduced February 1943
Weight:	1,590lb (721kg). Explosive charge 209lb (95kg) Explosive D (Dunnite)
Fusing:	Delayed contact (12 seconds)
Structure:	Conical, hardened nose cone, with stabilizing fins at tail
Effect:	Armour-piercing, designed to penetrate 5in (13.7cm) of deck armour from 4,500ft (1,370m)
Note:	Of US manufacture, first introduced in US Navy in May 1942

The Fleet Air Arm also employed the 18in Mark XII torpedo, introduced before the war, which had a range of 1,500 yards at 40 knots, and carried a warhead of 388lb of Torpex explosive. This was the torpedo which crippled the Bismarck, so in March 1942 it could have done the same to the Tirpitz. However, torpedoes were only useable if Tirpitz put to sea. Once the battleship took refuge in its Norwegian lairs, torpedo attacks were pointless, as the battleship was always protected by multiple barriers of anti-torpedo netting and moored in narrow fjords which lacked the space for a torpedo run to take place.

18in Mark XII torpedo
User:	Fleet Air Arm. Introduced 1937
Weight :	1,548lb (702kg). Explosive charge 388lb (176kg) Torpex
Fusing:	Impact fuse
Power:	Burner-cycle engine
Effect:	Underwater detonation against target hull, with standard depth setting of 25ft (7.5m)
Range:	1,500 yards (1,370m) at 40 knots, 3,500 yards (3,200m) at 27 knots
Note:	Air-launched torpedo

Various types of mines were dropped during these attacks, including the Mark XIX spherical contact mine, adapted for use by the RAF. The casings of these mines were strengthened to allow them to be dropped from the air, and their horns removed. They contained 770lb of Amatol, and in theory they should have been effective. Instead they proved another disappointment, and they were only used during the spring raids of 1942. The Fleet Air Arm tried using 600lb anti-submarine (AS) Mark VIII bombs, which effectively were air-dropped depth charges. The idea was that if they hit the Tirpitz, they would inflict the same damage as a 500lb AP bomb. If they missed, they would explode in the water and inflict underwater damage. They proved another disappointment. So too did the bizarre 500lb ‘Johnny Walker’ (JW) mine-bomb. Once dropped this ‘oscillating mine’ would sink to the seabed, then repeatedly rise and fall while moving laterally, until it came into contact with the underside of a ship, when it would explode. When used during Operation Paravane they failed to inflict any damage.

600lb AS (anti-submarine) bomb
User:	Fleet Air Arm. Introduced March 1944
Weight:	550lb (249.48kg). Explosive charge 439lb (199.13kg) Torpex
Fusing:	Hydrostatic, with depth settings up to 260ft (79.3m), or delayed contact (8 seconds)
Structure:	Cylindrical, thin casing, with detachable nose cone and stabilizing fins at tail
Effect:	Anti-submarine bomb, operating like a depth charge, but also capable of being used as a conventional GP bomb of similar capabilities to a 500lb SAP
Note:	Nose cone designed to detach on entering water

JW (‘Johnny Walker’) mine Mark I
User:	Royal Air Force. Introduced July 1944
Weight:	400lb (181.44kg). Explosive charge 90lb (40.8kg) Torpex
Fusing:	Contact fuse, and self-destruct mechanism when all compressed gas was expended
Power:	Compressed CO2 gas system
Structure:	Cylindrical, with buoyancy chamber and parachute housing in tail
Effect:	Oscillating mine. On landing in water the mine would sink to the seabed, and a hydrostatic/timer switch would trigger the injection of compressed gas into the buoyancy chamber at 60ft (18.29m), raising the mine to the surface. The air would then be expelled, and the process would be repeated until the gas was expended
Note:	Designated ‘JW’ as an abbreviation for ‘Johnny Walker’, a reference both to the popular brand of whisky and to the appearance the mine had of ‘walking’ across the seabed towards its target. A parachute was attached to the tail, which was deployed when the mine was released from the aircraft. It was designed to fall away when the mine entered the water. Lateral ‘walking’ range was estimated at approximately 30ft (9.14m)

Spherical contact mine Mark XIX (mod)
User:	Royal Air Force. Introduced March 1942
Weight :	1,000lb (453.6kg). Explosive charge 700lb (280kg) Amatol
Fusing:	Hydrostatic delay pistol, mechanical delay (12 seconds)
Structure:	Specially thickened spherical steel casing
Effect:	Delayed detonation on surface, or hydrostatic detonation under water at 12–18ft (3.6–5.4m)
Note:	Originally a small naval mine, introduced in 1938. Modified for RAF use by the removal of strengthening of the casing, and the removal of the mooring fittings and the eight external switch horns

Officially designated the 12,000lb Deep Penetration (DP) Bomb, Mark I, the Tallboy was so large that it could only be carried by Lancasters which had their bomb bay doors modified to accommodate them. It was filled with 5,200lb of Torpex. When released from 18,000ft from a bomber travelling at 200mph, the bomb had a strike velocity of 1,097fps.

Finally, there was the Tallboy. Designed by Barnes Wallis, the inventor of the ‘bouncing bomb’, this huge 12,000lb MC bomb was specifically designed to attack hardened targets. It was designated an ‘earthquake bomb’, as it was designed to burrow into the earth on impact, where its explosive blast would shake the earth enough to cause fortified structures to collapse. These pointed, aerodynamically shaped bombs had a thick, hardened-steel casing, were fin-stabilized and when dropped from high altitude would reach supersonic speeds on impact. They could penetrate or undermine thick concrete structures – and could do the same to the armoured deck of a battleship. Each Tallboy was filled with 5,200lb of Torpex, and it was felt that a near miss would cause almost as much damage to the Tirpitz as a direct hit. This was certainly the case during Operation Catechism, when the hits may have caused intensive internal damage to the battleship, but it was the near misses that not only caused her to capsize, but effectively dug a grave in the seabed for her.

12,000lb Tallboy (M)
User:	Royal Air Force. Introduced June 1944
Weight:	12,000lb (5.400kg). Explosive charge 5,200lb (2,400kg) Torpex
Fusing:	Impact detonation or delayed detonation (12 seconds)
Structure:	Streamlined casing, with hardened pointed nose cone, and four stabilizing fins at tail
Effect:	Deep penetration or ‘earthquake’ bomb, designed to burrow beneath surface before exploding
Note:	This bomb could only be dropped from a specially converted Lancaster bomber. Its official designation was ‘Bomb, HE, Aircraft, MC, 12,000lb’, but Tallboy (M) was far more commonly used.