The Commonwealth Aircraft CA-15

Nicknamed Kangaroo, the Commonwealth Aircraft Corporation CA-15 was an advanced warplane designed in Australia during War II, but as a result of its lengthy development, it was not completed until after the end of the war. With turbojet-powered fighters coming rapidly to the fore during this period, the CA-15 was cancelled after the sole prototype had undertaken flight trials.

After its success in the design and rapid production of the Boomerang fighter-bomber, in 1943 Commonwealth and its chief designer, Fred David, embarked on the design of the CA-15 as an interceptor, fighter-bomber and long-range bomber escort. The CA-15 bore some similarity to the North American P-51 Mustang, but was not derived in any direct fashion from the Mustang and possessed different performance priorities and dimensions. Evidence of this independence from the Mustang can be found in the fact that David, impressed by trials of captured Focke-Wulf Fw 190 fighters, initially intended for the CA-15 to be powered by an air-cooled radial engine rather than the liquid-cooled inline engines used in most British and US fighters at the time. Development of the CA-15 was slowed by a recommendation of Lawrence Wackett, Commonwealth’s head, that the company should construct the Mustang under licence rather than shoulder the financial and time considerations of designing and testing its own fighter. It’s worth noting that by the later stages of its development, it was generally believed that the CA-15 would offer capabilities sufficiently great that it could succeed the P-51.

Radial or inline engine?

The Commonwealth design team initially planned for the CA-15 to be powered by the turbocharged Pratt & Whitney R-2800-10W Double Wasp, an air-cooled 18-cylinder two-row radial unit rated at 2,000 hp (1491 kW) or 2,300 hp (1715 kW) with water injection. When it was learned that this engine might not be available in the numbers which might be needed, the programme was considerably delayed as the design team reworked the fuselage to carry an altogether slimmer powerplant, the Rolls-Royce Griffon 61 liquid-cooled V-12 unit rated at 2,035 hp (1517 kW). The company leased two engines from Rolls-Royce for the prototype, and it was planned that the engines for any production aircraft would be fitted with a three-speed supercharger.

The protracted design and construction of the CA-15 prototype was further slowed by the end of World War II in August 1945, and the prototype recorded its maiden flight on 4 March 1946 on the hands of a Commonwealth test pilot, Jim Schofield. The prototype revealed viceless handling characteristics, and possessed a maximum level speed of 389 kt (448 mph; 721 km/h) at an altitude of 26,400 ft (8045 m). Only comparatively little test flying had been completed by 10 December 1946, when the prototype met an early end: the prototype suffered a hydraulic failure on approach to the Royal Australian Air Force’s airfield at Point Cook, and the pilot had to remain in the air to burn off fuel before risking a landing. The main landing gear units were only half lowered, with no way to extend them fully or to retract them, but the tailwheel was fully extended and locked. As the prototype landed, it was the tailwheel struck the runway first, and the prototype then porpoised before its air inlet dug into the ground.

The prototype settled onto its fuselage and skidded to a halt in severely damaged condition. After repairs, the prototype was returned to the Royal Australian Air Force’s Aircraft Research and Development Unit in 1948. The pilot reported that the repaired prototype had reached 436.4 kt (502.2 mph (808.2 km/h) after levelling out of a dive of 4,000 ft (1220 m) on 25 May 1948. By this time it was clear that jet aircraft had far greater potential, however, and work on the CA-15 prototype was terminated. The prototype was scrapped in 1950, and the engines were returned to Rolls-Royce.

Specification

Commonwealth CA-15

Type: single-seat interceptor, fighter-bomber and long-range bomber escort

Powerplant: one Rolls-Royce Griffon 61 liquid-cooled V-12 piston engine rated at 1,540 hp (1148 kW) for take-off , 2,305 hp (1719 kW) at 7,000 ft (2135 m) and 1,820 hp (1357 kW) at 21,000 ft (6400 m)

Wing: 36 ft 0 in (10.97 m) with area of 253.00 sq ft (23.50 m²)

Length: 36 ft 2.5 in (11.04 m)

Height: 14 ft 2.75 in (4.34 m)

Empty weight: 7,540 lb (3427 kg)

Normal take-off weight: 10,764 lb (4883 kg)

Maximum take-off weight: 12,340 lb (5597 kg)

Maximum level speed: 389 kt (448 mph; 721 km/h) at 26,400 ft (8045 m)

Climb: initial climb rate 3,650 ft (1113 m) per minute; climb to 20,000 ft (6095 m) in 5 minutes 30 seconds

Service ceiling: 39,000 ft (11890 m)

Range: 2,206 nm (2,540 miles; 4088 km) with drop tanks; typical 1,000 nm (1,150 miles; 1851 km) with standard fuel

Armament: six 0.5-in (12.7-mm) fixed forward-firing machine guns with 250 rounds per gun, and up to 2,000 lb (907 kg) of disposable stores carried on two hardpoints (both under the wing with each unit rated at 1,000 lb/454 kg) and generally comprising two 1,000- or 500-lb (454- or 227-kg) free-fall bombs or 10 air-to-surface unguided rockets

The pioneering guided bomb: the German Fritz-X

The name Fritz-X was one of several applied to the German guided anti-ship bomb which was the world’s first precision-guided weapon, and the first to sink a ship in combat. Other names for this important weapon were Ruhrstahl SD-1400 X, Kramer X-1, PC-1400X and FX-1400. Together with the similar Azon weapon developed for the US Army Air Forces during the same period of World War II, it is one of the precursors of today’s anti-ship missiles and precision-guided weapons.

The Fritz-X was a development of the PC-1400 armour-piercing HE bomb, which the Germans had nicknamed Fritz. This was a penetration weapon for use against strongly protected targets such as heavy cruisers and battleships, and was a 3,086-lb (1400-kg) weapon of standard bomb configuration with a 661-lb (300-kg) filling of TNT and wax inside a tapered cylindrical casing of forged steel construction with walls 32 mm (1.75 in) thick, increasing 320 mm (12.6 in) in its nose section. The bomb was stabilised by a ring tail, 150 mm (5.9 in) deep, carried by four low-aspect ratio fins.

The Luftwaffe had come to appreciate the difficulty of hitting a moving and possibly manoeuvring warships during its involvement in the Spanish Civil War (1936/39). Dipl. Ing. Max Kramer, who worked at the Deutsche Versuchsanstalt für Luftfahrt, had been experimenting since 1938 with remote-controlled 250-kg (551-lb) free-fall bombs, and in 1939 the definitive layout emerged with a nose of more refined aerodynamic shape, four stub wings (not indexed at 90° to each other), and a box-shaped tail unit comprising an approximately 12-sided annular set of fixed surfaces, and a cruciform tail with thick surfaces within the annulus, which themselves contained the aerodynamic controls in the form of radio-controlled spoilers. In 1940, Ruhrstahl was invited to join the development effort as the company already possessed considerable experience in the development and production of unguided bombs.

Radio command guidance

Guidance was based on the Funkgerät (FuG 203) Kehl, which was a dual-axis package controlled by a single joystick. This radio-control transmitter was carried by the bomb-carrying aeroplane and used to send control signals to the Fritz-X, which was fitted with the FuG 230 Strassburg receiver. This sent the guidance signals to the movable solenoid-operated spoilers in the Fritz-X’s thick vertical and horizontal tail fin surfaces within the annular fin structure. The Strassburg receiver’s antennae were aerodynamically integrated into the trailing edges of the fin’s annular surfaces within a quartet of bulged trailing-edge sections. A dive brake assembly round the fins limited the terminal velocity to 1000 km/h (621 mph).

Trials confirmed that a minimum launch height of 4000 m (13,125 ft) was required to allow the weapon to accelerate to its maximum speed and to provide the weapon operator to acquire and guide the missile, but an altitude of 5500 m (18,045 ft) was preferable. A stand-off range of 5 km (3.1 miles) was also necessary. The operator had to keep the bomb in sight at all times (a tail flare was provided) and the launch bomber had to hold its course from the time of the bomb’s release to its impact, which made any evasion of anti-aircraft fire or fighters impossible.

The Fritz-X was controlled by surfaces on its tail unit, using three sets of aerodynamic control spoiler systems: inboard horizontal spoilers and vertical spoilers provided control in pitch and yaw, operating differentially and constantly oscillating under direct control of the Kehl/Strassburg radio-control link. Control in roll was independent of the guidance system, and used outboard spoilers which oscillated similarly to those of the guidance system: these spoilers were controlled by an internal gyroscope in the tail’s central housing to keep the ordnance level during its trajectory. The inboard set of spoiler surfaces in the tail’s horizontal surfaces, which incorporated a set of flat fences for airflow separation from the autonomous roll control spoilers, controlled the pitch angle after release and were controlled by the radio control link, giving the Fritz-X’s controller in the bomber the ability to control the range of the drop. The yaw-control spoilers housed in the vertical tail surfaces were also under control through the radio link, and had similar fences to guide airflow over them. All three spoiler surface sets, when deployed, barely protruded from the surface during operation, and the pitch- and yaw-control pairs of spoiler systems possessed some ‘proportionality’ in their operation by varying the dwell time spent on one side or the other during their rapid rate of oscillation from side to side when a control input was sent to them.

Delayed service entry

It was intended that the Fritz-X be used with the Heinkel He 177 bomber, but problems with the development of this bomber delayed its introduction to operational service, and the Dornier Do 217K-2 was therefore modified to take the Fritz-X. The Do 217K-2 could carry two of the bombs, one under each wing, as a maximum load, but its range was severely limited in this condition and the bomber normally carried one bomb only, mounted under the fuselage, to permit the use of a greater fuel load. The bomb was dropped conventionally, using the Lofte 7D sight, but after launch, the bomber pilot reduced his speed and climbed to enable the bomb aimer to follow the fall of his missile with the bomb sight. From the normal dropping altitude of 7000 m (22,965 ft), the bomb took 42 seconds to reach its target, the bomb aimer having it under control for all but the first 15 seconds. The task of the bomb aimer was to steer the bomb so that the image of the flare in its tail and the image of the target, as seen in his sight, always coincided. The maximum correction of course with this system was 500 m (545 yards) in range and 350 m (385 yards) in bearing.

The only Luftwaffe unit to deploy the Fritz-X was the III Gruppe of Kampfgeschwader 100. This unit used the Do 217K-2 medium-range bomber on almost all of its attack missions, though in a few cases toward the end of the Fritz-X’s operational career, the Do 217K-3 and Do 217M-11 variants were also used. A few special variants of the troublesome He 177A long-range bomber were equipped with the Kehl transmitter and racks to carry the Fritz-X, and it is believed that this combination might have seen limited combat service.

The Fritz-X was first deployed operationally on 21 July 1943 in a raid on Augusta harbour in Sicily after the Allies’ ‘Husky’ landing on that island. A number of additional attacks around Sicily and Messina followed, though no confirmed hits were made and it appears the Allies were unaware that the large bombs being dropped were radio-guided weapons. On 9 September of the same year, however,, the Luftwaffe achieved their greatest success with the weapon after the signature of an armistice between Italy and the Allied powers. Under the terms of this armistice, the Italian fleet had to surrender its ships, and several major units steamed from La Spezia toward Malta and Tunisia. To prevent the ships from falling into Allied hands, six Do 217K-2 bombers, each loaded with a single Fritz-X, took off from a base in the south of France. The Italian battleship Roma, flagship of the Italian fleet, received two hits and one near miss, and sank after her magazines exploded, and while her sister ship, Italia, was also damaged, although she eventually managed to reach Tunisia.

Production of the Fritz-X, including development examples, reached some 1,400 bombs, and these were responsible for the sinking or damaging of many Allied warships and transports when about 100 were used operationally in the Mediterranean Sea, Atlantic Ocean and North Sea in an active career between 21 July 1943 and 30 April 1944.

The other data for the Fritz-X included a weight of 1650 kg (3,638 lb) including 320 kg (705 lb) of Amatol explosive, length of 3.30 m (10 ft 10 in), maximum width of 1.50 m (4 ft 11 in), diameter of 0.85 m (2 ft 9.5 in) and operational range in the order of 5000 m (5,470 yards).

The Raduga Kh-22

Succeeding the turbojet-powered Raduga KS-1 Komet and K-10S (AS-1 ‘Kennel’ and AS-2 ‘Kipper’) subsonic and supersonic missiles in the stand-off role against major surface forces, especially those centred on an aircraft carrier, the Raduga Kh-22 is known to NATO as the AS-4 ‘Kitchen’. This substantial long-range missile is still in service, and in an air-launched weapons which can carry either a conventional HE or nuclear warhead.

After undertaking and completing a major analysis of World War II’s naval battles and encounters (especially those involving the US Navy in the Pacific theatre), during the late 1940s and early 1950s Soviet military planners came to the conclusion that the era of the large naval battle had ended, and that the optimum method for the defeat of large naval task forces was the stand-off attack by missiles carried by large warplanes. In this manner, the planners decided, that the US Navy’s superiority in major offensive warships could be neutralised without the USSR having to build, equip, man and train a comparable capability.

Although the major powers in World War II had used aircraft, either land-based or carrierborne, to attack their opponent’s fleet, this meant that the aircraft had to undertake their tasks at very close proximity to their targets, and thus to come under attack by the fighters of the opponent’s combat air patrols, or otherwise have to penetrate the curtains of light, medium and heavy anti-aircraft fire, generally controlled by radar, lofted by the defending ships. Such attacks often suffered heavy losses, and the Soviets decided that the use of the stand-off or cruise missile would remove the need to approach the target task force to a dangerously close range. Thus the Soviets embarked on a major programme to adapt numbers of their heavy bombers into raketonosets (missile carriers) for deployment against approaching naval fleets and task forces from coastal or island airfields.

The Kh-22 was developed by the Raduga design bureau specifically for this task as the primary armament of the Tupolev Tu-22M-2 ‘Backfire-B’ supersonic strike bomber. The new missile was designed to provide altogether superior performance, especially in speed, than its predecessors, and was thus based more closely on ‘missile’ rather than ‘aeroplane’ thinking, with much cleaner aerodynamic lines (although still of basically aeroplane configuration) and rocket propulsion.

Rocket propulsion

The Kh-22’s propulsion system is based on the Isayev rocket engine burning a hypergolic liquid mixture of triethylamine/xylidine and inhibited red fuming nitric acid to yield an almost hypersonic maximum speed and a considerable stand-off range. The missile is carried semi-recessed into the launch aeroplane’s lower fuselage, and can be launched in either the high- or low-altitude mode. In the case of the former, after launch the missile climbs to 88,585 ft (27000 m) and then makes a steep dive at Mach 4.6 onto its target, and in the case of the latter, the missile climbs to 39,370 ft (12000 m) and then makes a shallow dive onto its target at about Mach 3.5 before making the final approach at an altitude of less than 1,640 ft (500 m). The missile is guided by an inertial platform (gyro-stabilised autopilot in conjunction with a radio altimeter), and has active radar terminal homing.

The missile can be fitted with either a 2,205-lb (1000-kg) RDX conventional explosive warhead or a nuclear warhead possessing a yield of between 300 kilotons and 1 megaton. Trials revealed that the detonation of the shaped-charge conventional warhead created a hole almost 16 ft 6 in (5.0 m) in diameter and 39 ft 4 in (12.0 m) deep.

The first operational examples of the Kh-22 became available in 1962 and equipped with the Tu-22M-2, although the type can also be used by the Тu-22K and Tu-95K-22. The two initial production models with the baseline Kh-22 with the conventional warhead and the Kh-22N with the nuclear warhead, but in the middle of the 1970s these were supplemented by Kh-22P, which is an anti-radiation missile optimised to home onto and destroy radar installations. In the 1970s the Kh-22 variant was upgraded to the Kh-22M and Kh-22MA standards with new attack profiles, speed of up to Mach 5, range increased to 375 miles (600 km), a launch weight of 26,455 lb (12000 kg) and a data-link allowing mid-course updates of the guidance system.

The Kh-22E is the conventionally armed version for the export market, and the Kh-32 is a development for the Tu-22M-3 bomber with major improvements, alternative HE and nuclear warheads, an improved rocket motor and a new terminal guidance package.

The Kh-22 had a weight of 12,830 lb (5820 kg), body diameter of 1 ft 0.25 in (0.92 m), length of 38 ft 2.67 in (11.65 m) and wing span of 9 ft 9.75 in (3.00 m).

Soviet nuclear stand-off missile – the Raduga Kh-20

Where the first US stand-off nuclear missile to reach operational status, the Bell GAM-63 Rascal, was a rocket-powered weapon of typical ‘missile’ configuration, an early Soviet counterpart was of turbojet-powered aeroplane layout. This was the Raduga Kh-20 which, in the absence of firm intelligence data about its real designation, received the NATO reporting designation/name AS-3 ‘Kangaroo’.

As such, the Kh-20 was a cruise missile, and was created under the supervision of Mikhail I. Gurevich, known primarily as the designer of manned fighters, for carriage by and launch from the Tupolev Tu-95 ‘Bear’ turboprop-powered strategic bomber. Development of the weapon started in 1954, and the missile’s design drew heavily on the designer’s experience with the MiG-17 ‘Fresco’ high subsonic and MiG-19 ‘Farmer’ supersonic fighters, and in 1955 two Tu-95 bombers were converted into Tu-95K missile carriers to support the missile effort. Initial testing of the missiles was undertaken with the use of four modified MiG-19 fighters designated as the SM-20/I and SM-20/II for launch aeroplane/missile interface and air-launch testing purposes, and the SM-K/I and SM-K/II for guidance system and ground-launch testing purposes.

The first launch of the SM-20/I from a Tu-95K took place in the autumn of 1956, and one of the most difficult problems to overcome in the early phases of development was how to start the missile’s Lyul’ka AL-7F turbojet engine after prolonged passive carriage in the very cold air of the atmosphere at high altitude. Flight trials of the Kh-20 began on 17 March 1958, the first launch was not successful, and the missile’s range and accuracy failed to reach the required figures. This resulted, at least in part, from the fact that the weights of the warhead and guidance system were considerably greater than the missile design team had been told to expect: the guidance system was of the inertial type with provision for radio upgrade, and the thermonuclear warhead, with a yield of between 800 kilotons and 3 megatons, weighed something in the order of 5,070 lb (2300 kg).

Aeroplane configuration

The weapon was of aeroplane configuration with a tapered cylindrical fuselage, an anhedralled  swept wing and swept tail surfaces, the latter including a short vertical fin (to facilitate semi-internal carriage in the lower fuselage of the Tu-95) and a low-aspect-ratio ventral fin. The missile’s official trials were undertaken between 15 October 1958 and 1 November 1959. There were 16 launches, and of these 11 were deemed successful (though accuracy still inadequate), allowing the Kh-20 to enter service in 1960 in the initial form of the Kh-20M with an improved nuclear warhead. Production amounted to some 130 missiles, which was sufficient for two missiles for each of about 40 Tu-95K-22 and 25 Tu-95KD aircraft. The load was later reduced to one missile per aeroplane.

The Kh-20 had been created as an instrument of retaliation against major US targets. Then, given the fact that it took 22 hours to arm a Tu-95 with the Kh-20 and that it was difficult to store the missile’s early-generation nuclear warhead, it was decided that the missile was not suitable for the first-response role, and it was relegated to secondary strikes on targets which had survived an initial strike, and also against naval task groups centred on an aircraft carrier. The time required to arm a Tu-95 with a Kh-20 was later trimmed to four hours and reliability was markedly improved. However, the poorest feature of the Kh-20 was its guidance system, and a high degree of targeting accuracy required manual guidance, which was vulnerable to jamming.

An attempt to adapt the Myasishchev M-4 ‘Bison’ turbojet-powered bomber for the carriage and launch of the Kh-20 was unsuccessful as a result of the missile’s considerable size.

By a time late in the 1970s it had been recognised that the Kh-20 was no longer capable of penetrating modern air defences, and by the mid-1980s the Kh20 had been replaced by the Raduga Kh-22 (NATO designation/name AS-4 ‘Kitchen’).

The data for the Kh-20 included the powerplant of one Lyul’ka AL-7FK axial-flow turbojet engine aspirated via a nose inlet and rated at 15,100 lb st (67.1 kN), span of 30 ft 0.125 in (9.15 m), fuselage diameter of 5 ft 11.25 in (1.81 m), length of 49 ft 0.625 in (14.95 m), height of 9 ft 10.875 in (3.02 m), empty weight of 12,959 lb (5878 kg, launch weight of 26,455 lb (12000 kg), cruising speed of Mach 2.0, cruise ceiling of up to 65,615 ft (20000 m) depending on the target, and range of between 235 and 370 miles (380 and 600 km) depending on the specific cruise altitude.

The North American AMG-28 Hound Dog

The North American AGM-28 Hound Dog was an air-launched stand-off missile developed from the late 1950s, and was created primarily to attack Soviet ground-based air defence installations and thereby open the way for Boeing B-52 Stratofortress manned bombers to attack the USSR. The missile was allocated the initial designation B-77, then GAM-77 and finally AGM-28. It was conceived as an interim stand-off missile pending development and production of the Douglas GAM-87 Skybolt air-launched ballistic missile, but the latter’s development was cancelled and the AGM-28 remained in service for 15 years until its replacement by two Boeing missiles, the AGM-69 SRAM and AGM-86 ALCM.

During the 1950s the USA became aware of great strides being made by the USSR in the development of surface-to-air missiles, which was a cause for great concern as the USA’s current nuclear deterrence capability was vested in manned strategic bombers. The solution adopted to overcome this problem was an ‘extended-range bomb’ of either the glide bomb type or more practically the air-launched short/medium-range missile.

As the Soviet air defence sites were static and therefore easily detectable air or satellite reconnaissance imagery, the concept was to use a long-range cruise missile to destroy these air defence sites before the bombers approached them. The current S-75 Dvina (SA-2 ‘Guideline’) surface-to-missile had a maximum range of about 18.5 miles (30 km), but as the bombers would be approaching S-75 sites their own missiles would have to be launched some time before the bombers entered SAM range. If the US missile was also to be used to attack Soviet air bases, a considerably greater range would be required. A missile with these capabilities was demanded in General Operational Requirement 148, which specified a supersonic air-to-surface cruise missile with a loaded weight of no more than 12,500 lb (5670 kg) and capable of being carried in pairs by the B-52 Stratofortress. Each bomber would carry two such missiles, one under each wing, on a pylon located between the fuselage and inboard pair of engines.

Vought and North American Aviation submitted GAM-77 proposals to the USAF in July 1957. Each submission was based on the company’s earlier work on long-range ground-launched cruise missiles: the Vought submission was for an air-launched version of the Regulus missile developed for the US Navy, and the North American offering was adapted from the Navaho missile. On 21 August 1957, North American was contracted to develop Weapon System 131B, which included the Hound Dog missile.

Navajo origins

The airframe of the Hound Dog exploited technology developed in the SM-64 Navaho missile in a form revised for air launching from the B-52. The Hound Dog’s design was based on that of the Navaho G-38 missile, which featured small delta wings and forward canard surfaces. Power was provided by a Pratt & Whitney J52-P-3 turbojet engine in place of the Navaho’s ramjet engine. This engine was nacelle-mounted beneath the rear fuselage and, unlike the J52 engine installed in manned aircraft, was optimised to run at maximum power during the missile’s flight. Thus the Hound Dog’s J52 variant had an operating life of only six hours, reflecting the fact that the missile was expected to self-destruct in less than six hours.

The N5G derivative of the Navaho’s N-6 inertial navigation system, developed by North American’s Autonetics Division, was used in the Hound Dog, and a Kollsman star-tracker located in the B-52’s launch pylon was used to correct INS orientation errors with celestial observations while the Hound Dog was being carried by the bomber. The INS could also be used to fix the bomber’s position after the initial calibration process, which took about 90 minutes, and gave the Hound Dog a circular error probable of 3,800 yards (3475 m), which was deemed acceptable for a weapon equipped with a nuclear warhead.

The Hound Dog’s thermonuclear warhead was the W28, which could be preset for a yield between 70 kilotons and 1.45 megatons, and could also programmed for ground burst or air burst at a preset altitude; the former was intended for use against ‘hard’ target such as a missile site or command and control centre, and the latter against a large ‘soft’ target.

Three attack profiles

The Hound Dog was designed for launched at any altitude down to 5,000 ft (1525 m), and initially three flight profiles for the Hound Dog were available for selection by the launch bomber’s commander and bombardier: high-altitude attack, low-altitude attack, and dog-leg attack.

In the high-altitude attack, the missile flew at an altitude of up to 56,000 ft (17070 m), depending on the amount of fuel carried by the missile, all the way to the target area, whereupon the missile dived to its warhead’s pre-set detonation altitude. In the low-altitude attack, the missile flew at a pressure-determined altitude of less than 5,000 ft (1525 m) to its target, where its warhead detonated. In this mode, the missile had a range of only 400 miles (645 km), did not use terrain following, and had to be set on a course uninterrupted by major terrain obstructions. A variant of this low-altitude available to the GAM-77B (later AGM-28B) was a low radar-set altitude at any altitude between 100 and 3,000 ft (30 to 915 m) above the ground. The range was again shorter than that of a high-altitude attack, but the missile could fly in radar ground clutter and remain nearly invisible to radar detection. Eventually, all GAM-77A missiles were upgraded to this GAM-77B standard. In the dog-leg attack, the missile flew a pre-designated heading, at either high or low altitude, to a preset location, then turned to port or starboard and headed to its target. The object of this flight profile was to draw defending fighters away from the missile’s target.

The first air-drop test of a dummy missile was carried out in November 1958, and 52 GAM-77A missiles were launched for testing and training purposes between 23 April 1959 and 30 August 1965. The weapon’s development was completed in only 30 months. North American had received a production contract on 16 October 1958, and the first production missile was delivered to the US Air Force on 21 December 1959. Some 722 missiles were manufactured before production ended in March 1963.

Reduced radar cross section

In May 1961 an improved GAM-77A missile, with improvements to reduce its radar cross section, was test flown for the first time. The missile already possessed a small head-on radar cross section because of its slender fuselage and highly swept delta wing, and this cross section was now lowered still further by the replacement of the original nose cap, engine inlet spike and engine duct with new components fabricated of radar-absorbent materials which scattered or absorbed radar energy. The GAM-77A also included a Kollsman KS-140 star-tracker integrated with the missile’s INS, and this unit replaced the celestial navigation star-tracker originally located in the B-52’s wing pylon. The fuel capacity of the GAM-77A was also increased during this upgrade, and a radar altimeter was added to provide a vertical terrain-following radar capability. Some 428 GAM-77 missiles were upgraded to this GAM-77A standard.

A total of GAM-77A missiles was launched for testing and training up to April 1973. In June 1963 the GAM-77 and GAM-77A were re-designated AGM-28A and AGM-28B respectively.

In 1971, a Hound Dog missile was test flown with the newly developed TERCOM (Terrain Contour Matching) navigation system, and it is probable that the designation AGM-28C would have been used for any production version  of this upgraded missile had development continued. No TERCOM-fitted development of the Hound Dog was ever deployed, but the technology, upgraded with improved electronics and digital computers, was later used in both the USAF’s AGM-86 Air-Launched Cruise Missile and the US Navy’s General Dynamics Tomahawk cruise missile.

In 1972, Bendix was contracted to develop a passive anti-radar seeker to guide the Hound Dog missile toward antennae transmitting radar signals. Such a combination was test flown in 1973, but the variant did not enter production.

It was in July 1960 that the Hound Dog reached initial operational capability with the B-52, and the missile was used on airborne alert for the first time in January 1962. In 1962, SAC activated missile maintenance squadrons to provide maintenance for both the Hound Dog and the ADM-20 Quail decoy missile. Full operational capability was achieved in August 1963 when 29 B-52 bomber wings were operational with the Hound Dog. In 1960 the Strategic Air Command developed procedures whereby the B-52 could use the engine of the two Hound Dogs for additional thrust while the missile was located on a bomber’s two pylons: this helped heavily laden bombers depart their bases more rapidly and therefore, it was hoped, clear them before they were obliterated by Soviet nuclear weapons.The Hound Dogs could then be refuelled from the B-52’s wing fuel tanks.

On 22 September 1966, Secretary of Defense Robert McNamara recommended that all remaining Hound Dog missiles be retired within a few years, the missiles being retained pending the outcome of TERCOM guidance system development, but this recommendation was not approved and the Hound Dog remained in service. After 13 years of service, the last Hound Dog missile was removed from alert deployment on 30 June 1975 and, after being kept in storage for a number of years, the last Hound Dog was retired for scrapping on 15 June 1978.

The Hound Dog variants were the XGAM-77 (25 prototype missiles), GAM-77 (697 production missiles), GAM-77A (452 missiles upgraded from GAM-77 to GAM-77A standard), AGM-28A (GAM-77 redesignated in June 1963), and AGM-28B (GAM-77A redesignated in June 1963).

The data for the Hound Dog included the powerplant of one J52-P-3 axial-flow turbojet engine rated at 7,500 lb st (33 kN), maximum weight of 10,147 lb (4603 kg), span of 12 ft 2 in (3.71 m), length 42 ft 6 in (12.95 m), height of 9 ft 4 in (2.84 m), maximum fuselage diameter 2 ft 4 in (0.71 m), maximum speed 1,385 mph (2230 km/h) or Mach 2.1 at high altitude, maximum ceiling 56,200 ft (17130 m), and range of 785 miles (1265 km).

British anti-tank guns of WW2: the Ordnance QF 17-PDR

The Ordnance QF 17-pdr was a British anti-tank gun developed during World War II to succeed the Ordnance QF 6-pdr in the same role. Though the weapon was used primarily as an anti-tank gun on its own carriage, it was also used as the main gun of several British tanks and was also used to ‘up-gun’ some foreign-built vehicles in British service – most notably, the US M4 Sherman medium tank in order to create the Sherman Firefly. Accurate and hard-hitting, this weapon was the most effective Allied anti-tank gun of the war and, when firing APDS (Armour-Piercing Discarding Sabot) shot, was able to defeat all but the thickest armour of Germany’s late-war tanks.

Even before it entered service, the British predicted that the 57mm 6-pdr anti-tank gun would soon become redundant, as the Germans were at the same time increasing the armour thickness of their tanks. Late in 1940, the British therefore started the process of creating a replacement, and the design of the new 76.2-mm (3-in) weapon had been largely completed by the end of 1941.

A prototype production line was created, and when the PzKpfw VI Tiger I heavy tank appeared in North Africa, the first 100 prototype weapons were quickly shipped to North Africa to counter this new threat. So highly expedited was this process that the guns were despatched before proper carriages had been developed, and the guns were therefore mounted on the carriages of 25-pdr gun/howitzers to create a type known as the 17/25-pdr Pheasant. This first saw action in February 1943. The fully developed 17-pdr started on its own carriage entered production in 1943 and saw its first operational use in the Italian campaign of 1943/45.

Carriage and tank mountings

Given the fact that it offered a level of performance superior to all other Allied armour-piercing guns, the 17-pdr was a natural candidate for adaptation as a tank-mounted weapon. Few current tanks were capable of carrying such a large a gun because of the small diameter of their turret rings: it was planned that a 75-mm (2.95-in) gun under development by Vickers would be used for tanks, but this did not enter service.

The British also planned a tank to carry the 17-pdr. Based on the Cromwell which was then under development, it soon ran into problems in the modification process meant that the result, the Cruiser Tank Mk VIII Challenger, was delayed and relatively few were produced. However, the British devised a conversion for the M4 medium tank to take the 17-pdr and the resulting Sherman Firefly was rushed into service in time for the ‘Overlord’ invasion of Normandy in June 1944.

The ordnance was a modified design produced specifically for the Sherman Firefly, with the carriage-mounted weapon rotated 90° to lie on its side in the Sherman Firefly’s turret. An additional box was welded to the back of the turret to accommodate the radio equipment, which had to be relocated to provide clearance of the ordnance’s breech and recoil. Eventually about half of Sherman tanks in British service were of the Sherman Firefly pattern.

The British also converted some of their US M10 tank destroyers, replacing the original 3-in (76.2-mm) gun with the 17-pdr to create the 17-pdr Achilles (otherwise 17-pdr M10). The 17-pdr gun was also successfully trialled on the Australian Sentinel tank, though no tanks equipped with this gun entered Australian service.

The 17-pdr variants were the Mk I initial production variant; Mk II for tank use with no carriage mountings and the muzzle brake replaced by a counterweight, though the muzzle brake was reintroduced in March 1944 with the introduction of the APDS shot; Mk III Royal Navy adaptation intended for landing craft use and generally similar to the Mk I but with an automatic loader; Mk IV tank adaptation for the Sherman Firefly with a different breech with the block opening to the side rather than down to take up less room; Mk V version of the Mk IV with different mounts to allow it to replace the US 3-in (76.2-mm) in the 17-pdr Achilles; Mk VI adaptation of the Mk IV; and Mk VII similar to the Mk VI but with a revised breech.

More compact tank variant

The British also created a gun of the same calibre but small enough to be accommodated in the current generation of tank designs, most especially the Cromwell cruiser tank which was currently being designed. The gun was designed to fire US 75-mm (2.95-in) AP shot and HE shell but at higher velocity. This L/50 gun, firing a 75-mm (2.95-in) projectile attached to a necked down 3-in (76.2-mm) anti-aircraft gun cartridge by means of a modified breech, was the Vickers HV 75 mm. This achieved a higher muzzle velocity, and hence improved armour penetration, through the use of a greater propellant charge. Although the 75 mm HV was a promising weapon, it proved to be too big for the Cromwell tank, which was fitted with the normal 75-mm (2.95-in) gun as other British tanks. When the Comet, schemed as the Cromwell’s successor, was being designed, the 75 mm HV was reworked to fire the same projectiles as the 17-pdr through a shortened 17-pdr barrel, but retaining the 3-in (2.95-in) cartridge firing from a standard 3-in (76.2-mm) breech. This has the benefit of greater ease of use on tanks, many of which would not have sufficient turret space to accommodate the breech length and recoil distance of the 17-pdr. To prevent confusion over ammunition supplies, the revised weapon was given the designation 77 mm HV, and was used in the Comet tank.

The 17-pdr fired either of two anti-tank ammunition types. The APCBC (Armour-Piercing, Capped, Ballistic Capped) type could penetrate 130 mm (5.12 in) of armour at 500 m (545 yards) and 119 mm (4.69-in) at 1000 m (915 yards) at a 30° impact angle. The APDS (Armour-Piercing Discarding Sabot) type could penetrate 204 mm (8.03 in) of armour at 500 m (545 yards) and 185 mm (7.28 in) at 1000 m (915 yards) at a 30° impact angle, giving it a theoretical capability to penetrate the armour of even the Tiger II heavy tank. However, the sub-calibre tungsten penetrator of the APDS ammunition was deemed less accurate than APCBC ammunition at ranges beyond 1,000 yards (915 m): this was the result of the fact that shot which fell short of the target created far less of a visible impact, and thus it was harder for the gunner to spot the fall of shot and correct his aim. Moreover, the APDS type was also considered to cause less damage to its target tank, should it not penetrate the armour, but the penetrator tended to destabilise after penetrating armour and ricochet around inside the target, causing crew casualties. The APCBC ammunition was standard, and the APDS shot was used for about 6% of the average load of British tank armed with the 17-pdr gun.

A HE shell was initially developed for the 17-pdr, but this lacked power because the use of a high-powered cartridge meant that the shell walls had to be thicker to stand the stresses of firing, which reduced the volume left available for explosive. Reduction of the propellant charge for the HE shell allowed the use of a thinner-walled and more powerful shell carrying 15.4 lb (6.99 kg) of explosive.

Impressive data

The data for the 17-pdr on its split-trail carriage with a gunshield included an L/55.1 length of bore, weight of 2,923 lb (1326 kg) in action, elevation arc from -6° to +16.5°, traverse arc of 60°, muzzle velocity of 3,115 ft (949 m) per second with the APCBC ammunition, 3,950 ft (1204 m) per second with the APDS ammunition and 2,900 ft (884 m) per second with the HE ammunition, rate of fire of 10 rounds per minute, and detachment of four men.

A considerably bulkier and heavier weapon than the 6-pdr, the 17-pdr had to be towed by a tractor such as the Morris Quad, M3 Half-track or the Crusader, as it could not effectively be moved by its gun crew alone, especially on poor ground. When used on soft ground, the 17-pdr had often to be pulled out of the ground as the recoil buried the trail spades.

British anti-tank guns of WW2: the Ordnance QF 6-PDR

The Ordnance QF 6-pdr was a British 57-mm (2.24-in) gun which was the British army’s mainstay in the anti-tank role during the middle of World War II, and was also used as the main armament in several armoured fighting vehicles. It was first employed operationally in the North African campaign during April/May 1942, and quickly replaced the 2-pdr in the anti-tank role, allowing the 25-pdr to revert to wholly to its primary artillery role.

The tactical and technical limitations of the 2-pdr were evident when it entered service in the mid-1930s, and work of a replacement began as early as 1938 at the Woolwich Arsenal, which selected a 57-mm calibre for the new gun. Guns of this calibre had been used on British warships from a time late in the 19th century, so manufacturing equipment was available. Design work on the ordnance had been completed by 1940, and that of its associated carriage in 1941. Production had been authorised, but was then delayed by the needed to maintain the 2-pdr in production and service to offset the almost total losses suffered in the Battle of France. Thus production of the 6-pdr was delayed until November 1941.

Unlike the 2-pdr, the new gun was mounted on a conventional two-wheeled carriage of the split-trail type. The first mass-production variant was the Ordnance QF 6-pdr Mk II, which differed from the pre-production Mk I in having a shorter L/43 barrel as a result of the shortage of lathes for the manufacture of longer barrels. The later Mk IV had an L/50 barrel fitted with a muzzle brake. The equipment was fitted as standard with a forward shield but, while issued, the optional side shields seemed to have been little used.

Tank use

The 6-pdr was used where possible to replace the 2-pdr in the current generation of British tanks, which thus required work on their turrets, pending the introduction of a new generation of tanks designed to take the 6-pdr. The Churchill Mks III and IV, Valentine Mk IX and Crusader Mk III, the latter two with the turret crew reduced by one man to allow the installation of the 6-pdr, began to enter service during 1942. The tanks designed to take the 6-pdr were the Cavalier, Cromwell and Centaur: when the Cromwell entered combat in 1944, however, it was armed with the Ordnance QF 75-mm gun, which was a redesign of the 6-pdr to take US 75-mm (2.95-in) ammunition and more useful against general targets. The 6-pdr was also fitted to the AEC Armoured Car Mk II.

The 6-pounder was kept competitive, at a steadily reducing level, through World War II, but in reflection of the fact that the Germans were steadily upgrading the protection of their tanks, and would no doubt continue to so so, work commenced with objective of developing a weapon with the same general dimensions and weight as the 6-pdr but providing improved performance. The first attempt was an 8-pdr L/59 weapon, but this was too heavy to be used in the same role as the 6-pdr. A second attempt was made with a shorter L/48 barrel, but this proved to have performance only marginally superior to that of the standard 6-pdr and the programme was cancelled in January 1943. The 6-pdr was followed into production and service during February 1943 by the next-generation 17-pdr, but as a smaller and more manoeuvrable gun, the 6-pdr in fact remained in British service not only for the rest of World War II, but also for some 20 years after the war.

Other production

In addition to the UK, the gun was also produced in Canada, South Africa where the Combined Ordnance Factories built 300 such weapons, and the USA. The notion of manufacturing the 6-pdr first found favour in the US Army Ordnance branch during February 1941 though, as at that time the US Army still preferred the 37-mm Gun M3, production was planned for Lend-Lease export. The US 57-mm Gun M1 was based on the 6-pdr Mk II, of which two examples were provided by the UK as patterns. As there was sufficient lathe capacity in the USA, however, the longer barrel could be produced from the start. Manufacture began early in 1942 and continued until 1945 for a total of 15,637 such weapons. The M1A1 variant used US Combat tyres and wheels, and from September 1941 the M1A2 introduced the British practice of free traverse (effected by the crew pushing and pulling on the breech) instead of solely geared traverse. The M1 was made standard issue in the spring of 1943. Once the M1 had entered US service, a modified towing point design was introduced to create the M1A3 for US service.

Some two-thirds of US production went to US Army divisions in Europe, about one-third was delivered to the UK, and 400 guns were sent to the USSR through Lend-Lease. When the USA rearmed Free French forces for the ‘Overlord’ and ‘Dragoon’ landing in Normandy and the south of France, their anti-tank units received US-fabricated M1 guns.

Like the British army, which trialled a 57-mm/42.6-mm) squeeze-bore variant for a higher muzzle velocity, the US Army also experimented with a squeeze-bore adaptor (57-mm/40-mm T10), but the programme was likewise cancelled. US ammunition design and production was slower than those of the gun, so at first only armour-piercing shot was the only type of ammunition was available. The HE shell was not available until after the Normandy landings and UK stocks were procured to cover its absence. Regular service in the US Army’s front-line units ended in the 1950s.

Widespread service

The 6-pdr and M1, of which 4,242 examples were received, were initially issued to the Royal Artillery anti-tank regiments, each of four 12-gun batteries, in infantry and armoured divisions for service in the western theatres, and later in the war to the six-gun anti-tank platoons of infantry battalions. An air-landing battalion had a combined anti-aircraft and anti-tank company with two four-gun anti-tank platoons. Formations and units in the Far Eastern theatres had a lower priority and different organisation reflecting lower tank threat posed by the Japanese forces. The gun was also employed by commonwealth forces. Initially the anti-tank ammunition was a basic armour-piercing (AP) shot, but by January 1943 an Armour-Piercing, Capped (APC) shot and an Armour-Piercing, Capped, Ballistic Capped (APCBC) shot was supplied. An HE shell was produced so that the gun could also be employed against unarmoured.

Variants of the 6-pdr anti-tank gun included the Mk I limited-production initial model with an L/50 barrel, the Mk II first mass-production version with a shortened L/43 barrel, the Mk 3 tank version of the Mk 2, the Mk 4 with an L/50 barrel and single-baffle muzzle brake, the Mk 5 tank version of the Mk 4, the Molins Class M 6-pdr gun fitted with automatic loader built by the Molins company and carried by some motor torpedo boats and de Havilland Mosquito warplanes, and the 57-mm Gun M1 US version based on the Mk II but with the L/50 barrel.

The British carriage types were the basic Mk I, the Mk IA with a different axle and wheels, the Mk II of  simplified design, and the Mk IV modified for use by airborne troops, while the US carriage types were the basic M1, the M1A1 with US wheels and tyres, the M1A2 of 1942 with an improved traverse mechanism allowing free traverse, the M1A3 of 1943 with a modified towing hook and the first version to be adopted by the US Army, the M2 of 1944 with a caster wheel added to the right trail, relocated trail handles and a new utility box, and the M2A1 of 1945 with improved elevation gear.

As well as the UK and its commonwealth partners, the 6-pdr was used by Brazil, France, Ireland, Israel, Netherlands, Pakistan, South Korea, USA and USSR.

The data for the 6-pdr with the L/43 barrel included a vertical sliding block breech mechanism, weight of 2,471 lb (1121 kg), elevation arc between -5° and +15°, traverse arc of 90°, maximum range of 5,000 yards (4570 m), effective range of 1,650 yards (1510 m), and detachment of six men.

The standard AP shot weighed 6.3 lb (2.86 m) and was fired with a muzzle velocity of 2,800 ft (853 m) per second from the L/43 barrel to penetrate 2.7 in (69 mm) of armour at a 20° impact angle at 1,000 yards (915 m) and 2,925 ft (892 m) per second from the L/50 barrel, while the AP discarding Sabot Mk 1T round used from March 1944 was fired from the L/43 barrel with a muzzle velocity of 3,775 ft (1151 m) to penetrate 5.12 in (130 mm) of armour at a 20° impact angle at 1,000 yards (915 m) and at 4,000 ft (1219 m) per second from the L/50 barrel to penetrate 5.59 in (142 mm) of armour at a 20° impact angle at 1,000 yards (915 m).

The first piece of modern artillery – the ‘French 75’

In the final stages of World War I, the ‘French 75’ or, as it was more formally designated, the Canon de 75 modèle 1897, became legendary in France as the piece of artillery which made it possible for the French army to win the war.

Its real fame, in historical terms, rests in the fact that it was the first of all field artillery designs of what may now be regarded as the ‘modern type’, as it combined a very efficient recoil mechanism – removing the need for the piece to be reloaded between shots – with a rapid-action breech design and a carriage in a package – which made feasible rates of accurate fire that, until the end of the 19th century, were the subject of fantasy rather than military reality.

The ‘75’ was designed between 1891 and 1896 by Lieutenant-colonel Albert Deport, Capitaine Etienne Ste Claire Deville and Emile Rimailho on the basis of an experimental 57mm weapon of 1891. This was based on what were, at the time, the most advanced artillery technologies of the period, namely Paul Vieille’s nitrocellulose-based smokeless propellant, which had been introduced in 1884; fixed (self-contained) ammunition in which a brass case contained the propellant and primer as well as the shell; an early hydro-pneumatic short recoil mechanism designed by Major Louis Baquet; and a rotating screw breech built under licence from Thorsten Nordenfelt. The only major technical change between the 57- and 75-mm pieces was the latter’s long recoil mechanism.

Long service in time and space

Before 1914, the ‘75’ was essentially a state secret. However, once it was put into action, it more than proved its worth – to the extent that the French army depended on its high rate of fire to make up for deficiencies in the availability of heavier artillery weapons.

Such was the success of the ‘75’ that more than 21,000 were manufactured between 1897 and 1940 by the French national arsenals at Puteaux, Bourges, Tarbes and St Etienne, and under licence in Mexico, Poland and the USA. The weapon served in the armies of France, the Baltic states, Belgium, Bulgaria, Eire, Finland, Germany, Poland, Portugal, Romania, Serbia, Spain, UK and USA, and later in Cameroon, Cambodia, Greece, Haute Volta, Laos, Mexico and Morocco. The ‘75’ saw service in a host of French colonial wars, as well as the Boxer Rebellion, World War I, Polish-Soviet War, Riffian War, Spanish Civil War and World War II.

By 1939, the ‘75’ was rather past its best. Comparable weapons of other origins had surpassed it in technological terms, and it was outranged by more modern field gun designs. However, the French still had more than 4,500 of them in front-line service at the start of World War I. The ‘75’ of 1939 was in many cases very different from the ‘75’ of 1918. The USA and Poland had introduced split trail
carriages in place of the original pole trail, and many nations, including France, had introduced 
solid or pneumatic rubber-tyred wheels for motor traction in place of the original metal-tyred spoked wheels which had been deemed adequate for traction by a team of six horses.

The ‘75’ has also undergone some changes in role. Before 1918, many ‘75’ barrels had been placed on simple carriages to provide an anti-aircraft capability, both static and mobile, and despite their limited value, many such pieces were still in service in 1939. The ‘75’ has also undergone some adaptation as a form of tank weapon, but it was to be left to the Americans to make the most effective evolutionary development of this possibility with their adaptation of the type as the main gun for their M3 Lee/Grant and M4 Sherman medium tank series. In France the ‘75’ had been updated to Canon de 75 modèle 1897/33 standard with a new split-trail carriage, but by 1939 there were only a comparatively small number of these in service.

A new lease of life

In the catastrophic French defeat of May and June 1940, large numbers of ‘75’ guns were taken by the Germans and pressed many of them into their own service with the designation 7.5-cm FK 231(f)
 or, more commonly, the 7.5-cm FK 97(f). The weapons were initially allocated to occupation garrisons and second-line
formations, but later on, many others were incorporated into the beach defences of 
the so-called Atlantic Wall.

The Germans also stockpiled large number of the weapon pending the time when
 some use could be found for them. This happened during 1941, when the Germans discovered that the armour of
the Soviet T-34/76 medium tank was effectively invulnerable to the shot fired by almost all German anti-tank
guns. As a stop-gap measure, therefore, ‘75’ guns were taken out of storage to be revised with strengthening bands around the barrel and 
placed on the carriages of obsolete 5-cm PaK 38 anti-tank guns: a muzzle brake was fitted 
to reduce the recoil forces and special armour-piercing ammunition was hastily produced, and the
 resulting weapons were deployed to the Eastern Front, where they proved capable, though only just capable, of penetrating the armour of Soviet medium tanks. This improvisation was known
 to the Germans as the 7.5-cm Pak 97/38, 
and operational experience revealed that it was really too powerful for the light anti-tank gun carriage, but it provided a limited capability until the Germans could field more potent anti-tank guns.

The data for the original ‘75’ included a calibre of 75 mm (2.95-in), length of piece of 2.72 m (107.08 in) of L/36, weight of 1970 kg (4,343 lb) in travelling order and 1140 kg (2,514 lb) in firing order, travelling dimensions of 5.577 m (18 ft 3.57 in) in length, 2.011 m (6 ft 7.17 in) in width and 1.402 m (4 ft 0.05 in) in height, elevation arc of -11° to +18°, traverse arc of 6° on its carriage, muzzle velocity of between 530 and 575 m (1,739 and 1,886 ft) per second, maximum range of 11100 m (12,140 yards), effective range of 6800 m (7,435 yards) with the shrapnel shell and 8550 m (9,350 yards) with the HE shell, shell weight of 7.24 kg (15.96 lb) for the shrapnel round and 5.4 kg (11.9 lb) for the HE round, rate of fire of 12 to 15 rounds per minute, and detachment of six men.

Amphibious Warfare – Salvage & Repair Craft

By its very nature, amphibious warfare presents the men and equipment involved not just with the hazards of any military undertaking, but also with the possibility of destruction or damage as a result of the particular nature of the operation milieu. The most obvious problem faced by landing craft is that of becoming stranded as a result either of hitting the assault beach too fast and driving farther than intended onto the sand, or of being left high and dry by the ebb of the tide. In this circumstance, many of the smaller types of landing craft required only a comparatively gentle push by a bulldozer to be restored to the water, and even tank landing craft and other larger landing craft might be saved by such action after being stranded by the falling tide or an onshore wind, or even by being wedged against a rock outcrop. In the ‘Avalanche’ landing at Salerno in western Italy during September 1943, each engineer beach battalion was equipped with six bulldozers and 12 men so as to be able to perform salvage work of this type.

When a craft had suffered an engine failure, or lost its steering or had been badly holed, it had either to be hauled out of the water by the appropriate shore party or or to be taken in tow when eased off the beach and back into the water. If the the craft had been holed to a more severe degree, it would also require support by slings between two dedicated salvage craft so that it did not take in the volume of water that would cause it to sink before it reached the attack cargo ship allocated the task of lifting it from the water.

When there was surf during an assault landing, any minor craft which broached while beaching probably filled with water, and this was also a frequent result of the holing of the craft by rocks or enemy fire. In this circumstance the craft had to be patched and have the water pumped out of it before it was towed off the beach. In ‘Avalanche’ each attack transport carried a dedicated LCM Mk 3 outfitted for this task with a trailer pump able to shift 500 gallons of water per minute, a length of hose sufficient to reach stranded craft, and beefed-up towing cleats for the lines needed to tow a stranded craft off the beach. This provided a useful capability, but the commander of the US 8th Amphibious Force believed that improved salvage arrangements, offering greater flexibility among other things, could be created, and suggested the use of supply ships carrying with tank landing craft and other spares. Such an arrangement was already under active consideration by higher command echelons.

Size a factor

The re-floating of a beached tank landing ship, with a mass of more than 3,000 tons by comparison with tank landing craft’s figure of less than 750 tons, was an altogether more daunting proposition, but major landing craft such as an LST could in most circumstances be towed off the beach by companion craft or by the tugs which were no standard in amphibious assault forces. A beached LST could have become completely dried out between tides, but on a reasonable beach would generally not have suffered any structural damage unless the beaching was in a location that caused the LST to hog or sag. In the ‘Iceberg’ landing on Okinawa during April 1945, and indeed in the course of other landings, in the situation in which a beached LST blocked a berth and thereby imposed a major delay on the unloading programme, recourse was provided by tugs specially equipped with 3,000-lb (1360-kg) anchors by which they secured themselves to seaward of stranded medium craft and ships which had to be towed forcible off the beach: this practice allowed the tug to use her powerful winch most effectively to heave the stranded craft or ship off the beach.

Many different types of craft were used for the salvage role: these included large infantry landing craft and mechanised landing craft at Salerno, while in many of the island landings in the Pacific theatre vehicle/personnel landing craft moved forward in the wake of the assault waves for the specific task of salvaging craft and rescue men from any boats, craft and amphibian which foundered as a result of the sea conditions or damage. The steadily increasing use of amphibian vehicles meant that specialised equipment had to be carried and landed for damage to be repaired by welding: in this capacity, the recovery of an amphibian vehicle was comparable to that of the salvage of an armoured vehicle.

Hard knocks

Minor craft were designed for beaching, but as increasing reliance was placed on pontoon and other jetties to speed ferry work, many of these minor craft had to come alongside ever more frequently, inevitably suffering hard knocks. Such events could spring plywood sides, and once its frames had been broken – a craft was in need of a difficult repair. For major craft on a beach, the combination of factors such as runnels in the sand where there had been LSTs, pits left after coasters had floated off, and the accumulation of military jetsam along the tide line could impose severe but more importantly uneven strains on hulls, rudder and propellers. As a result, at Arromanches after the ‘Overlord’ landing in north-western France during June 1944, a floating dry dock for tank landing craft was in fact used to change bent rudder stocks, replace broken propellers and undertake a host of comparable repairs on craft up to the size of the LCT Mk 4.

The often extended nature of amphibious operations and the land campaign which followed them created the need for a servicing capability as well as a salvage facility, and this need was satisfied, in part at last, by work which minor craft maintenance teams could undertake on board infantry landing ships: this came to include many instances of remarkable running repairs on larger landing craft and ships. At other times the men of flotilla flagship landing craft could provide additional capability.

In the event of major task such as the replacement of heavy equipment, the work required was too long for ‘front-line’ repair unless appropriate lifting and other gear was available, and specialised auxiliary landing craft repair ships were equipped with such lifting gear in the form of a 44.5-ton derrick, and two 8.9-ton king-post booms. The auxiliary landing craft repair ship was a modified LST Mk 2 with the bow sealed and outfitted with electrical, pipework, sheet metal and other workshops (including a blacksmith’s forge) for repair work. The embarked stores of such ships included replacement parts for craft and probably also for LSTs. The ships also carried 10 balsa rafts to keep damaged minor craft afloat until they could be lifted from the water. The first six auxiliary landing craft repair ships came into service during 1943: 39 such ships were built or converted from LSTs while under construction, and two were allocated to the British as emergency repair landing ships.

Damage control

As on every other type of warship, the crews of LSTs and major landing craft were organised and trained to become damage-control parties able to effect temporary repairs in order to keep a craft or ship from sinking after being hit by bombs or shells. However, in combined operations there was little chance to provide men and junior officers with much of the specialised training provided to the damage-control parties of larger ships, though plugs for shot holes were carried, and on major craft a typical outfit of damage-control equipment might be six baulks of timber and a few hundredweight of quick-drying cement. Major damage was rendered sea-proof (not completely watertight) by being stuffed with hammocks, mattresses and other material to fill a gaping hole and allow the ingress of water only at a rate which could be handled by the craft’s or ship’s pumps. What cannot be argued, however, is the fact that the feature which made it possible for most landing ships and craft to survive heavy damage was their design with large numbers of separate watertight compartments sealed for each other by doors and hatches with heavy clamps, of which six to eight were turned against wedges to seal any door or hatch before the ship or craft entered action. The sill of the doors and hatches were set about 1 ft (0.305 m) above the level of the relevant deck, and this contained any moderate ingress of water within a compartment until the door could be closed.

Tank landing ships could survive enormous damage, though in their enclosed cargo spaces fire was the biggest hazard. In US service 12 LST Mk 2s were converted into auxiliary battle damage repair ships. These could effect temporary repairs to major damage suffered by any warship and LST, and operated with salvage vessels (converted minesweepers and other small ships) off amphibious assault areas to make it possible for damaged ships to make the passage back to a forward base.

Amphibious Warfare – The Landing Vehicle Tracked (I)

Widely known as the amphtrack and amtrak (or amtrac), the LVT (Landing Vehicle Tracked) was a type of vehicle optimised for the amphibious warfare role, and was a small amphibious landing craft used initially by the US Navy, US Marine Corps and US Army during World War II. The vehicle was initially intended to carry cargo in the ship-to-shore role, but was swiftly developed into a type for the delivery of assault troops and then with the capability to deliver fire support. As such, the LVT was a decisive piece of equipment in the USA’s arsenal of amphibious assault weapons in Admiral Chester W. Nimitz’s Pacific Ocean Areas and General Douglas MacArthur’s South-West Pacific Area.

The LVT had its origins in a civilian rescue vehicle, the Alligator conceived, designed and developed in Florida by Donald Roebling during 1935 as a vehicle capable of operating in swampy areas, such as the Florida everglades, inaccessible by standard wheeled vehicles and boats. Roebling’s vehicle was rendered buoyant by its watertight hull, and was propelled in the water by its tracks, which were cleated and whose submerged sections scooped water to the rear in a sort of paddling action. Two years later, Roebling built a redesigned vehicle with greatly improved water speed, and the US Marine Corps, which was currently undertaking a radical upgrade of its amphibious warfare doctrines, developed an interest in the vehicle after it had been featured in a Life magazine article. The USMC and Roebling discussed the service’s requirement and Roebling agreed to design a more seaworthy model for military use. After more improvements to meet US Navy requirements, the vehicle was adopted as the Landing Vehicle Tracked.

A contract for the manufacture of an initial batch of 200 LVTs was awarded to FMC (Food Machinery Corporation), which had built some of the parts for the early civilian Alligators. These pioneering 200 vehicles were manufactured FMC facility in Dunedin, Florida, which was the site at which most of the improvement work had been undertaken. During World War II, LVT production was extended by FMC and the US Navy to another three factories at Lakeland, Florida, Riverside, California, and San Jose, California. (It is interesting to note that Roebling Construction received the construction contract for the Lakeland factory, and this was the only profit Roebling received from his invention as he refused to accept any royalty or commission from the government for what he considered his personal duty in support of the war effort.)

Extensive and widespread production

The first LVT-1 came off the production line in July 1941, and by the end of World War II in August 1945 the Roebling factories in Florida and California, supplemented by Borg Warner of Kalamazoo, the St Louis Car Company and the Paige Motor Corporation, had completed 18,621 examples of the LVT, 11,251 of them from the four Roebling factories, in several forms.

The LVT-1 was not fitted with any ramp to facilitate loading and unloading, and could carry 4,500 lb (2041 kg) of cargo. Originally intended to ferry supplies and men from ships to the shore after an assault landing and as the beach-head was consolidated into a larger lodgement in which standard wheeled vehicles could be used, the LVT-1 had no armour protection, and its tracks and suspension proved to be unreliable when the vehicle was operated over hard terrain. Built to the extent of 1,225 vehicles, the LVT-1 was capable of 15 mph (24 km/h) on land  and 4 kt in water, the LVT-1 could alternatively deliver some 20 to 24 fully equipped assault troops to the beach, and supply supporting fire using its armament of two 0.3-in (7.62-mm) M1919 Browning air-cooled machine guns. The USMC soon came to appreciate that the LVT-1, despite its limitations, could be used as a viable assault transport vehicle, and before the ‘Galvanic’ assault of Tarawa atoll in the Gilbert islands group during November 1943, many of the vehicles had been revised with two 0.5-in (12.7-mm) Browning M2 heavy machine guns forward above the enclosed driving compartment, and the two M1919 medium machine guns relocated farther to the rear. Even so, the LVT-1 was limited by the fact that it was not armoured and its thin steel hull offered almost no protection even against smalls arms fire, although before ‘Galvanic’ some of the vehicles had received 9 mm (0.35 in) of armour plating to the driving compartment. As noted above, the tracks performed well on sand, but not on hard and rough surfaces, the rigid suspension tended to throw the tracks, and roller bearings corroded rapidly in salt water. Adequate maintenance of the new machine was often a problem as few marines were trained to work on the new type, and as a result the early vehicles were prone to frequent failures.

By this time the USMC was well aware of the potential of the LVT in the assault role, and this led to the introduction in 1942 of the LVT(A)-1 armoured and fire support version, dubbed the ‘amtank’. Some 510 examples of this variant were produced with a hull carrying armour 6 to 12 mm (0.24 to 0.47 in) thick, the modified turret of the M3 Stuart light tank with a 37-mm M6 gun in an M44 mount, and two rear-mounted machine guns.

Into action

One of the first LVT actions was fought by five LVT-1 vehicles of the 3rd Platoon, A Company, 2 Amphibious Tractor Battalion of the USMC. Involved in the first wave ashore in the USMC’s ‘Ringbolt’ landing on Tulagi island, across ‘Ironbottom Sound’ from Guadalcanal island, these five vehicles beached 09.00 on 7 August 1942, only eight months after the Japanese ‘Ai’ raid on Pearl Harbor had drawn the USA into World War II. One of these unarmoured LVTs used the fire of its single 0.5- and 0.3-in (12.7- and 7.62-mm) machine guns to destroy a Japanese strongpoint while protecting wounded infantry before evacuating them to a tank landing ship lying offshore.

The data for the three-crew LVT-1 included a weight of 16,900 lb (7666 kg), length of 21 ft 6 in (6.55 m), width of 9 ft 10 in (3.00 m), height of 8 ft 2 in (2.49 m), payload area measuring 8 ft 6 in (2.59 m) in length, 7 ft 9 in (2.36 m) in width and 3 ft 11 in (1.19 m) in depth, and a powerplant of one Hercules 146 water-cooled petrol engine supplied with 80 US gal (302.8 litres) of fuel for a range of 75 miles (120.75 miles) on land and 50 miles (80.5 km) on water.