Designation:

Ikv-91

Info
Manufacturer: BAE Systems Land Systems Hagglunds AB  
Product type: Armoured Vehicles  
Name: Light tank  

The first of three prototypes of the Ikv-91 (Infanterikanonvagn 91) tank destroyer was completed in December 1969 with the second two following in 1970. After extensive trials, Hägglunds was awarded a production contract for the Infanterikanonvagn Ikv-91 in March 1972. The first two preproduction vehicles were completed in 1974 with the first production vehicle complete in 1975. Production of the Ikv-91 was completed late in 1978 for the Swedish Army.

It is believed that total production of the Ikv-91 amounted to 210 systems. It was never exported and is no longer being marketed.

Late in 1997, Hägglunds Vehicle was taken over by Alvis of the UK although the company still trades under its former name.

Description

The hull of the Ikv-91 tank destroyer is of all-welded steel and divided into three compartments with the driver's at the front, fighting in the centre and the power pack at the rear. The vehicle has complete protection against attack from 20 mm armour-piercing rounds over its frontal arc. Above the tracks the sides of the hull are double skinned, with the main armour inside the tracks. The space is used for stowing accessories and diesel fuel, giving increased protection against HEAT and HE penetration.

The driver is seated at the front of the hull on the left side and has a single-piece hatch cover opening to the left. Three day periscopes are mounted forward of the hatch cover and there is a hull escape hatch to the right and slightly to the rear.

The other three crew members are seated in the all-welded steel turret with the commander and gunner on the right and the loader on the left. The commander's cupola is fitted with M17 day periscopes and a ×10 periscopic sight is mounted on the front of the cupola. The cupola, which has a single-piece hatch cover opening to the rear, can be traversed through 240 and operated either locked to the turret or counter-rotating. Superimposed in either mode is an electric servo system which provides accurate power traverse of the cupola. The loader's cupola has a single-piece hatch cover and a day periscope.

The engine compartment is at the rear, separated from the fighting compartment by a bulkhead. The complete power pack consists of the engine, gearbox with torque converter, bevel gear and steering clutch. The power pack is mounted diagonally in the engine compartment to shorten the length of the hull. The gearbox is fully automatic but a selector enables the driver to restrict the upshift within any desired range. Engine exhaust is used to drive the turbocharger as well as to induce a flow of cooling air over the steering brakes by passing it through an ejector.

The Ikv-91 has the same clutch-and-brake steering system as the Hägglunds Vehicle Pbv 302 APC, designed to permit continuous slip-steering. The steering clutch is of the double dry plate type operated by a hydraulic servo. The steering brakes at each end of the drive shafts are also used as main brakes.

The torsion bar suspension consists of six dual rubber-tyred roadwheels with the drive sprocket at the rear and the idler at the front. There are no track-return rollers. Shock-absorbers are provided at the first and last roadwheel stations.

The Ikv-91 is fitted with the Hägglunds-designed M70 track which is a single pin, rubber-bushed link with the rubber bushings confined to one link at each joint, the pin being fixed at the other.

The track shoes can be fitted with the same type of studs that are commercially used on trucks. For increased traction when driving cross-country in deep snow, the track shoes can be removed and, if necessary, the track links can be fitted with conical spikes protruding 50 mm below the surface of the link.

The vehicle is fully amphibious, being propelled in the water by its tracks. Before entering the water a trim vane is erected at the front of the hull and low screens are raised around the air inlets and the exhaust and air outlets. Four bilge pumps are provided.

The Ikv-91 has been designed for operations in the northern part of Sweden and preheating the engine with a built-in blowtorch permits engine starts from -35C (-31F). A built-in electric preheater for the combustion air permits immediate engine starts under less severe conditions.

An electric fan creates a slight overpressure by sucking air from the air inlet through a dust filtration system and blowing it through an NBC filter fitted into the fighting compartment which also has a heater. The Ikv-91 is not fitted with night vision equipment.

The gun fires the following types of fixed ammunition developed by Bofors: fin-stabilised HEAT with the complete round weighing 10.7 kg, projectile weighing 4.5 kg and a muzzle velocity of 825 m/s; fin-stabilised HE with the complete round weighing 12.3 kg, projectile weighing 6.7 kg and a muzzle velocity of 600 m/s. The HEAT round, developed by Bofors, utilises a piezoelectric fuze to reach full-calibre sensitivity and is capable of penetrating all NATO targets with substantial effects behind the plates. The HE round, which is used against personnel, has a mechanical time fuze.

Of the 59 rounds of 90 mm ammunition carried, 16 are stowed in ready racks at the loader's station, 18 to the right of the driver and the remaining 25 in the chassis on the left side to the rear of the turret.

More recently the Ikv-91 has been retrofitted with a thermal sleeve for the 90 mm gun, Bofors Lyran launchers on the turret roof at the rear, external stowage for Lyran flares and an external stowage bin on the turret rear.

Fire-control system

The commander has no direct access to the computer but a mechanical linkage from one of the trunnions transfers gun elevation to a collimator. When the cupola is aligned with the turret the collimator is in front of the commander's sight. The collimator then projects an image of a ballistic graticule into the commander's field of view.

The gunner has a Jungner Instrument AB monocular periscopic sight TP-1050L with a day magnification of x10 and a 6 field of view. It also incorporates a Bofors laser range-finder. Gun elevation is transferred from the top prism by a mechanical linkage from one of the trunnions to a differential in the gunner's sight. Electric servos deflect the line of sight in azimuth and elevation according to the actual ballistic solution determined by the computer.

The transmitter/receiver of the neodymium-type laser range-finder is attached to the right side of the gunner's sight and the path of the laser beam is incorporated in the optics of the sight. The range of up to two objects within the laser beam can simultaneously be displayed in the left eyepiece of the gunner's sight. The measured range is fed automatically into the computer and in the case of two echoes, the shortest range, which is usually the correct one, is fed into the computer. Ranging is triggered from the gunner's control handle as well as shifting between two simultaneously displayed echoes.

The laser beam leaves the top prism of the sight parallel to the gunner's line of sight, which means that ranging can be made instantaneously, regardless of the superelevation and lead angles introduced into the system. If the computer fails, the electric servos of the gunner's sight are mechanically zeroed and the firing sequence can be completed by using a ballistic graticule.

The basis of the fire-control system of the Ikv-91 is a hydraulic system for turret traverse and elevation, fed through a hydraulic accumulator from an intermittently working electrohydraulic pump in the turret.

For the hydraulic system, AGA Aerotronics AB developed an electric gun control system which includes a ballistic computer and electric servos to control the gunner's line of sight. The power traverse and power elevation velocities are normally controlled from the gunner's control handle with an override capability from the commander's control handle. If there is a power failure the gunner can hand-crank the turret in traverse and the gun in elevation with hydraulic pumps working directly on the traverse motor and the elevation jack assembly.

The computer determines the ballistic solution for the 90 mm HE and HEAT rounds as well as the 7.62 mm coaxial machine gun as chosen by the gunner. Range is fed automatically from the laser range-finder or, if desired, from a manual range input at the gunner's station.

The computer depends on preset values for non-standard muzzle velocities, powder temperatures and ambient conditions. These values are manually introduced by turning potentiometers on the computer panel. Trunnion cant and tracking rates are introduced from sensors, and lead angles in azimuth and elevation due to target movements are continuously calculated. When superelevation and lead angles in azimuth and elevation are introduced into the system the gunner's line of sight is counter-rotated at exactly the same controlled rate. Thus the gunner's line of sight remains undisturbed on the target, reducing reaction time and increasing accuracy.

Variants

  • Ikv-91 with 105 mm gun

Details of this version, which is no longer being marketed, were given in Jane's Armour and Artillery 1993-94 page 445. Hägglunds Vehicle is now teamed with Giat Industries of France and is offering the CV 90105 TML which is covered in the Light tanks section under International. As of early 2001 this remained at the prototype stage.

  • AMOS 120 mm mortar system

Details of this twin 120 mm self-propelled mortar system, which for trials purposes has been fitted to the Ikv-91 chassis, are given in the Self-propelled mortar systems section under International. Possible production applications of the AMOS include the Hägglunds Vehicle CV 90, Russian BMP-3 and Patria Vehicles XA series of 6 × 6 light armoured vehicles. The Finnish Defence Force have ordered one AMOS system on a 6 × 6 chassis.

  • Road mineclearing vehicle

The Road MineClearing System is also called the Hurricane and has been designed and built by BOA Defence to clear air delivered mines and submunitions from roads, light terrain and runways. It is expected that an initial batch of 40 vehicles will be ordered, followed by two further batches each of 40 vehicles.

The Hurricane system uses two horizontally rotating high tensile steel blades which are tipped with non-magnetic striking tools. Rotating at 1,200 rpm just above the surface, the tools strike the mines at a typical speed of 420 km/h.

This high impact destroys the mine's fuzing system and disintegrates the mine within 2 ms. The normal reaction time for any electrical fuze system is 10 ms. The system clears a path 3.5 m wide.

The modifications carried out to the Ikv-91 chassis include the following:

  • Turret has been replaced by a power pack to provide hydraulic power

  • The mineclearing unit is installed at the front of the vehicle

  • Second crew position is created to the right of the driver.

Specifications:
Property Value
Crew
4
Weight (kg)
16400
Length (mm)
8835
Width (mm)
3000
Height (mm)
2355
Main weapon caliber (mm)
90
Barrel length (calibres)
73
AA gun caliber (mm)
7.62
Auxiliary gun calibre (mm)
7.62
Traverse arc (degree)
360
Elevation (degree)
15
Depression (degree)
-10
Ammunition of the main gun
59
Ammunition of the auxiliary gun
4560
Engine power output (h.p.)
350
Max. road speed (km/h)
70
Max. road range (km)
550
Max. water speed (km/h)
7
Vertical obstacle (mm)
800
Trench (mm)
2800



Ikv-91 quantities:
Country Qnt
SWEDEN SWEDEN
210
Qnt:
210

   
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