The Lvkv m/43 (Luftvärnsvärnskanonvagn modell 1943) or "Anti-Aircraft Gun Carriage Model 1943" is a Swedish self-propelled anti-aircraft weapon developed by AB Landsverk and Bofors in 1943 out of the need for a tracked anti-aircraft vehicle to protect armored columns from air attack. Based on an elongated version of the hull of a Landsverk L-60 tank and mounting dual Bofors 40 mm L/60 guns, the vehicle was adopted into service with the Swedish Army in 1947.

Development and design

Due to the Swedish Air Force's limits for air superiority in a possible war by 1942, and a reorganization of the armored brigades that same year, the need arose for a vehicle capable of covering armored vehicles underway from air attacks. At the time the concept of SPAAG was quite new (tracked and armoured), as the Germans would develop their own from 1942 onwards as well. An order was given to AB Landsverk to create forty two of such Gun Carriages, mounting a 20mm anti-aircraft gun. However many issues arose and eventually no prototype was delivered.



In between, the Swedish Army reevaluated its needs and wanted a more potent AA asset. There was formal order for 17 new anti-aircraft vehicles, this time mounting a pair of 40mm Bofors Automatic Cannons. Indeed by 1944 it was clear that this piece of ordnance was the best AA on the allied side, and providing it in 1944 made sense. An order was placed by the Royal Armed Forces Administration (Kungliga Armeförvaltningen) to AB Landsverk and Bofors for them to collaborate on the project, the first on the chassis and the second on the dual mount. Development was restarted by late 1945.

The war ended as the first prototype was tested, and after a year of testings, adopted in 1946. Production was setup and started in 1947. Yet still this was a first pre-serie experimental batch, hence its designation of Luftvärnkanonvagn fm/43, with fm being an abbreviation of "försöksmodell", meaning "experimental model". The turrets were assembled in Karlskoga, by Bofor. They were then sent to Landskrona by rail, to Landsverk, and married with the chassis available for last assembly. The first full batch of 17 retained its "experimental" title but not further orders were made. In 1950 the concept of Bofors-armed SPAAG, not radar-assisted, was already obsolete.

Chassis

The chassis of the Luftvarnsvärnskanonvagn M/43 was based on the Landsverk L-60 tank, heavily modified and lengthened with an extra axle and new roadwheel, so stretched out. The tracks and engine however were the same as the L-60, without change. The added weight degraded performances compared to the original L-60, but the extra free space was used to store 40 mm ammunitions. The configuration remained thus the same, with a driver which sat forward to the left, engine at the rear, but transmission forward, for tractor front sprockets. Idlers remained at the rear. Amm roadhwheels were doubled and rimmed with rubber, for single pin tracks. There were an additional pair of return rollers as well.

The remainder of the crew (commander/gunner, 2 loaders) were located in the turret. The forward part of it was sloped, with a light armour of just 15 mm (0.6 in) forward on the nose to 9 mm (0.4 in) at all angles, notably on the hull support for the turret and the turret itself, so proof against small arms fire and not immune to shrapnel as the roof was open. The vehicle was of course not protected NBC either. It was the equivalent of the US M42 Duster, or the Soviet "Sparka" (ZSU-57-2). These were first gen. SPAAGs lacking radar control and stabilized mounts. They needed to stop to fire and were mostly efficient at close range, less than 500 m.

Turret

The turret was based on the previous paper projects for 1942 and 1942 Landsverk L62 Anti I and Landsverk L62 Anti II designs. The turret was an enlarged and modified version of the previous conical roof-less turret, enlarged to mount the twin Bofors 40 mm L/60 mount. It was, unlike most WW2 Bofors mounts, hydraulically powered, and this enabled a full 360° traverse in only 7 seconds. The rate of fire was 120 rounds per minute. 326 rounds were stored between the turret and the hull. The system was still fed by 5-round clips. There were an ascess door on the right side for easier access.

Armament

The pair of 40mm Bofors L/60 cannons derived from th army/naval variants accepted already in 1936, from which derived the numerous allied variants. The mount, due to space limitations had the two cannons solidary, but to avoid fire dispersion, they fired at intervals, provided the loaders were coordinated. Due to the limited space inside the turret, the commander was alsothe gunner, spotting, aiming and firing. He was assisted by the tow loaders, either side, picking and dropping 5-rounds canisters by gravity feed for a nominal rate of 120 rounds per minute per barrel, 240 combined, so at best four rounds every second. It was faster with the barrels at ground level. There was an interruption every five shots. Cooling was liquid and air.

The shells were AB 40 mm L/60 HE-T - 2.05 lbs. (0.93 kg) HE types, 1936 HE - 4.63 lbs. (2.1 kg) complete rounds. They had HE-T 7a - about 0.150 lbs. (0.068 kg) TNT busting charges, 0.661 lbs. (0.300 kg) propellant charge, complete 1936 HE - 17.60 in (44.7 cm) in lenght. Muzzle velocity was 2,789 fps (850 mps) and range (max) up to 11,019 yards (10,076 m) at 42° and above a max ordinate 22,800 feet (6,949 m). Practical range was 1,500 yards (1,372 m) and below. It was also pretty decent against lightly protected vehicles up to 2,000 yards (1,829 m) by 1.20" (30 mm) RHA. At point blank, horizontal fire, they could even defeat 2.70" (69 mm) of RHA.

The Lvkv m/43 in In service

Performance

It was clear from the start these vehickles were problematic, with narrow tracks, high ground pressure on snow and mud, not compensating for the additional 7 tons and extra axle, compared to the L-60. Vehicles sank into the ground and got bogged. There were issues with track breakages and excessive suspension wear and tear. Moreover as the engine was the same, these vehicles were badly underpowered, performances degraded so much they could no longer follow an armoured unit in combat, as they were observed at barely 36 kilometers per hour (22 Miles per Hour) on flat and solid ground. The Lengthening of the hull caused additional steering issues, as the commands were very heavy. the Luftvarnsvärnskanonvagn M/43 was hard to steer given its higher lenght to width ratio. It had a large turning circle and lacked agility, climbing performances were poor. On the armament side, given the use of old school optical sights, it performed poorly in bad weather.

Upgrades (Lvkv fm/43 (1957))

In 1948 all the vehicles had been delivered, tested, and already modified. To alleviate the ground pressure problem they were given wider tracks, the last one on the production line. In 1950-1951 the engines were replaced by newly purchased 300 hk Maybach HL120 TRM from Germany. Being twice as powerful they enabled these vehicles to reach 55 Kilometers per Hour (34 Miles per Hour). Smaller upgrades and changes were made until 1958 such as a protective armored box on top of the turret for better protection and mounting an Ra 400 Radio set, as well as attachments for spare wheels placed atop. To weight rose to 17 Tonnes.

End of service

Despite these upgrades the army was never satisfied with it. Many initial problems could not be solved. In addition, too few were produced to fulfill an organic role in a sufficient way. Plans were made in 1949 to replace these by 275 new vehicles. These remained at paper stage however due to budget restrictions and the fact that Sexeden was already well advance in missiles and worked on SAM defence already. With the reorganization of brigades in 1963, all the Luftvarnsvärnskanonvagn M/43s were taken out of service, stored, then scrapped in 1969 without successor. In 1955 they were already helpless against modern jets. Bofors remained popular in many navies to this day however, in the new 40 mm/70 M1953. Ducussions floated around to replace the M1936 L/60 by those, along with brand new stabilized mount radar assisted and automated, but the added weight would have imposed a brand new chassis anyway.

specifications
Dimensions	5.79 x 2.31 x 2.26 m
Weight	15.9 Tonnes
Crew	4 (driver, cdr/gunner, 2 loaders)
Propulsion	Scania-Vabis L 603/3 120 hp
Transmission	GBX Volvo VL-220
Suspension	Torsion bars
Speed (road)	36 kph (~22 mph)
Range	c250 km
Protection	9-15 mm
Armament	2x 40 mm/60 (1.57") Model 1936
Total production	17

Gallery

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Front view, guns at high elevation, camouflaged vehicle as modernized in 1949.


Profile, same.

Sources

sphf.se
landskrona.se
ointres.se
navweaps.com/
www2.landskrona.se