Kingdom of Sweden (1991)
Infantry Fighting Vehicle – 345 Built
Early in the development of the CV90, it was decided that the CV 9040 version should be developed into a family of vehicles comprising four additional variants:
- CV90 FCV (Forward Command Vehicle)
- CV90 FOV (Forward Observer Vehicle)
- CV9040 AAV (Anti-Aircraft Vehicle)
- CV90 ARV (Armored Recovery Vehicle)
The basic design philosophy of the CV9040 emerged from the few overarching requirements given by the Swedish Defence Materiel Administration (Försvarets materielverk, FMV) in a priority list, with mobility in northern Sweden being at the top. This emphasized the necessity to reduce the vehicle’s weight without negatively affecting the armament and protection. As the armored hull took up most of the weight, the philosophy was to make the vehicle “big on the inside and small on the outside” or, otherwise said, the vehicle layout had to be as volume efficient as possible.
Any increase in weight and volume lead to a negative feedback spiral, as a heavier or larger vehicle requires the upsizing of many subsystems, which in turn lead to more weight and more occupied volume. During the development of the CV90, the designers realized that every useful feature that could be added to the design or its subsystems had a price to be paid in terms of useful volume and weight.
Terramechanic simulations undertaken during the development stage led to the conclusion that the track ground contact length should be as long as possible in order to ensure a low ground pressure and high mobility even on soft terrain. At the same time, the number of road wheels should be as large as possible and they should be arranged close together in order to create an even distribution of the vehicle’s weight.
In order to have good steering performance, the ratio between the track ground contact to the distance between centerlines of the two track center lines should not exceed 1.7. This put an upper limit on the vehicle length, as the width was already limited by external limitations for road and rail transport.
In order to ensure that the vehicle would not get stuck on obstacles, the armored hull should not protrude too much in front or behind of the track assembly. These mobility concerns more or less determined the maximum possible length of the armored hull and, thus, the maximum size of the role-specific volume. The role-specific volume is the internal vehicle volume left after subtracting the volume needed for the armor, suspension and automotive components.
Chassis Layout
The CV 9040 has a three-man crew consisting of a driver, a commander, and a gunner, with the commander and gunner operating the turret. In the rear of the vehicle, a rifle squad with eight fully equipped soldiers is carried, who can disembark through the rear doors. This was later reduced to seven men in order to free up space for more equipment.
It was preferred to have the load area rectangular in shape and as long as possible. It was also decided that no other vehicle systems, such as the transmission or fuel tanks, should intrude in the role-specific area in order to provide a common base within the vehicle family. The length of the role-specific volume was increased by the use of a short power-pack. For this, the natural engine choice was the Swedish Scania DSI14 V8 diesel giving 550 hp.
By placing the cooling system in the rear of the right-side sponson, the driver´s station and the engine compartment could be efficiently placed side by side at the front of the vehicle, without any other ergonomic compromises. The CV 9040 turret has a shallow basket offset to the left side and above the bottom of the track sponson.
The dimensions and volume needed for the rifle squad were determined during early mock-up tests made by the Swedish Army. In comparison with the American M113 APC, the troop area in the CV9040 is taller and approximately 200 mm wider.
The space needed for a sitting soldier is directly linked to the vehicle’s internal volume and the sitting position is also closely related to the vehicle’s width and height. In the CV 9040, the soldiers’ seats have a “relaxed” position that lowers the required height of the compartment and of the vehicle. Mine tests with instrumented test dummies have shown that the seats gave good and well-distributed support for the backbone which reduced the risk of severe injury from explosion shocks from underneath.
Early full-scale complete-vehicle mock-ups showed that an inclined hull rear wall was optimal for exiting the vehicle. This also gave a shortened the hull bottom, and it eliminated any issues related to the lower hull protruding beyond the track assembly.
The roof above the rifle squad has a 1° inclination with the purpose of increasing the height of the rear door. Two large, rectangular hatches are located on the roof, allowing for close fire support from two soldiers on each side.
Size of the CV 90 Compared With Other IFVs
The low frontal height of the CV 9040 was made possible by having the radiators in the rear part of the right sponson instead of above the engine. Due to this placement of the radiators, all of the major systems in the vehicle’s front are at the same height, an important factor for high volume efficiency.
By having a focus on weight and volume, the CV 90 is approximately three tonnes lighter than other vehicles in a comparable role.
Power-Pack
The CV90’s 550 hp power-pack consists of a Scania DSI14 engine built together with the X-300-5 transmission originally developed by Detroit Diesel Allison for the M2 Bradley.
The basic Scania truck engine was modified for a dry sump lubrication system to reduce the engine height and allow for operation at large vehicle inclinations.
The X-300 transmission was first used in the British Warrior IFV under the X-300-4B designation. It is a fully automatic cross-drive transmission offering four forward and two reverse gears driven through a torque converter with a lock-up clutch.
Steering is continuously variable (meaning the vehicle can turn with any turning radius) with true pivot turn in neutral (meaning it can turn on the spot) which is achieved with hydrostatically controlled double differentials. Service and parking brakes are incorporated into the transmission and they are hydraulically applied with mechanical back-up.
The Swedish version has the designation X-300-5. The main difference is that the transmission oil filter is inclined to enable a direct assembly to the engine.
During cold chamber tests, excessive oil pressure occurred, leading to transmission damage, a significant problem for a Swedish IFV given the harsh winter climate. Modifications to the transmission were introduced to limit pressure build-up. The cold start problems were solved by these modifications together with the use of synthetic oil with better low-temperature viscosity.
The power-pack is designed with a minimized number of connections in order to enable a fast exchange of the complete unit without drainage of fluids. The hydraulic system’s reliability is closely linked to oil cleanliness and it is therefore important to avoid opening the system at a power-pack lift.
The complete hydraulic system is located in the chassis, there is no power-pack hydraulics. The pump unit is located in the rear part of the engine compartment and the pumps are mechanically driven from the engine crankshaft. A disconnect of the drive shaft is the only action at power-pack lift.
Maintenance and repair are also possible without a power-pack lift as most subunits are accessible from inspection hatches in the engine compartment walls.
CV 90 Suspension and Tracks
As with the CV90 in general, the suspension was designed with efficiency in mind. Besides being weight-efficient, the suspension also has a low height in order to allow as much volume as possible inside the hull sponsons.
Stridsfordon 90 är även bra på att klättra. pic.twitter.com/zjTlZj8OdO
— Ulf Lundberg (@stora_norrland) March 13, 2020
The Infanterikanonvagn 91 was the first armored vehicle in the Swedish Army that met the mobility requirements for use in northern Sweden due to low ground pressure in addition to a favorable suspension and track design from a mobility standpoint. This vehicle was the natural starting point for the design of the CV90 track and suspension system.
The Ikv 91 had six road wheels. Each was 670 mm in diameter and had 220 mm of travel. The bottom of the sponsons acted as a stopper for the road wheels, preventing the torsion bars from being overloaded. The large road wheel diameter, in combination with the limited road wheel travel, made it possible to use conventional linear shock absorbers.
The road wheel diameter of the CV90 is smaller than that of the Ikv 91 in order to enable the installation of seven wheels in a densely packed configuration. The M2 Bradley’s tracks and 610 mm road wheels were a natural choice to use, with the additional benefit of ease of production. The increased road wheel travel in the CV90, together with these smaller wheels, means that there is no room for conventional linear dampers.
The CV90 rotary dampers exist in two versions, the first one is designed to cope with the high gun recoil at salvo firings, being lockable. The introduction of a stabilized turret in the CV9040B upgrade opened the possibility of introducing a new damper which did not have to support locking in place for firing.
CV9040 Turret
The 40 mm gun in the CV9040 is based on a modified 40 mm L/70 towed anti-aircraft gun, but inverted with the ammunition feed from below. The gun can fire single shots or salvos of 4 or 8 rounds, with an automatic rate of fire of 5 rounds/sec. The spent cartridge cases are ejected upwards and forwards through a hatch in the turret roof.
Additional armament consists of a 7.62 machine gun and two banks of Galix smoke dischargers that fire IR concealing smoke grenades. The 7.62 mm coaxial machine gun is linked to the 40 mm gun and aimed from the main gun’s UTAAS sight. The turret can be rotated 360 degrees and has an electric gun drive system with a manual back-up in both elevation and traverse. The turret houses two crewmembers, the commander and the gunner, sitting on either side of the Bofors 40 mm L/70B gun system.
The commander has seven fixed periscopes for all-around visibility. The hatch can be locked in an “umbrella” position enabling the commander to have direct observation with overhead protection.
The gunner has the UTAAS IR-sight in front. The top module of the sight has an armor protection cowl that can be opened from inside the turret. The gunner is provided with three periscopes for observation to the right of the turret.
CV9040 Ammunition
The ammunition magazines are divided into three eight-round compartments. Each compartment is loaded with one type of ammunition. The change from one compartment to another is done by sliding the magazine sideways. With those three compartments, different ammunition combinations can be fired in the same salvo.
One basic requirement was that all types of existing L70 ammunition should be usable by the CV90’s gun. In addition to the existing types of High Explosive (HE) ammunition, a new Armor Piercing Fin Stabilized Discarding Sabot (APFSDS) ammunition was developed.
In order to further enhance ammunition performance, the new programmable 3P ammunition was introduced (3P ammunition – Prefragmented Programmable Proximity fuzed ammunition). A video of the 3P ammunition in use can be found HERE.
The 3P bursting munition has a programmable multi-function fuze that can be set in one of six modes in order to achieve the best effect on target. Each 3P fuze is automatically and individually programmed by a Proximity Fuze Programmer which continuously receives data from the Fire Control Computer. Immediately before firing, the fuze is programmed to the selected mode.
Reloading the gun is done by a rotatable carousel that is easily accessible by both the gunner and the commander. This carousel can store 48 rounds and is a part of the turret basket.
UTAAS Sight and Fire Control System
The basic requirements for the fire control system come from the seven-point priority list. Namely, it has to be effective against land targets and, at the same time, be effective against low flying aircraft and helicopters.
UTAAS is short for Universal Tank and Anti-Aircraft Sight and it is designed to be effective against both ground and air targets. The design of the top module allows for large lead angles in both azimuth and elevation that are essential for effectiveness against fast aircraft.
The sight is of a modular design with an integrated fire control system that includes both a ballistic calculator and a variable repetition frequency laser rangefinder for both ground and air target capability.
UTAAS has an independent line of sight that enables the operator to retain the target in the center of the reticule during the entire aiming and laser range-finding sequence. No re‑aiming is needed. Gun-laying is automatically controlled by the fire-control computer.
Night and all-weather operations are enabled by a thermal camera integrated to the sight. A monitor at the commander’s station gives access to the IR picture from UTAAS.
CV9040 Variants in the Swedish Army
The first 9040 serial vehicles were delivered in 1994, with the last deliveries being completed in 2002. Originally, these vehicles did not have a fire on the move capability due to the lack of a gun stabilization system.
The later produced CV9040A version can easily be recognized by the addition of a damping cylinder on the turret front that reduced gun oscillations during movement.
A number of modifications were introduced during production, primarily to improve firepower and to allow for firing on the move. All the first series of Strf 9040’s were later rebuilt to the same standard, named CV9040A. In addition to turret modifications, more storage and better emergency exits reduced the number of seats in the troop compartment to seven.
In total, 209 Strf 9040A have been produced or converted. Of these, one vehicle was rebuilt to an electronic warfare vehicle. All the remaining Strf 9040A vehicles are still in service with the Swedish Army as of the writing of this article.
The 146 remaining CV9040 were all produced to the CV9040B standard. The Strf 9040B turret has an improved stabilization system for firing and observation on the move and the external damping cylinder was removed.
Important inputs for the suspension redesign of the Strf 9040B variant came from the Norwegian testing of the CV9030, where early tests of firing on the move clearly showed the necessity for an improved suspension system. These tests included firing at different vehicle speeds on an obstacle track representing extreme rough terrain. During these trials, it was recognized that the performance of the suspension system was an essential part of achieving a good hit accuracy.
With the fully stabilized 9040B turret, the suspension dampers could be redesigned to only account for mobility aspects. Above the dampers, a new set of torsion bars was introduced having lower spring resistance, leading to better crew comfort and improved hit probability at high vehicle speeds.
146 CV9040Bs were produced and 55 vehicles of those are upgraded primarily for peacekeeping missions. The Strf9040B1 and Strf9040C versions are upgrades to already produced CV9040B´s.
- Strf 9040B1: 13 Strf 9040B vehicles were modified for international peacekeeping missions, having a 3P ammunition programmer, climate control and anti-spall liner.
- Strf 9040C: 42 vehicles were upgraded for international peacekeeping operations. This version has add-on armor, laser filtering in all periscopes and tropical grade air conditioning. Due to the bulk and weight of the upgrade, only six soldiers are carried.
The Strf 9040 were deployed with combat units spread all over Sweden for home defence and training. The Swedish Strf 9040, 9040A, and 9040B did not see any combat action. Only the Strf 9040C version saw action in Liberia and in Afghanistan. The CV90 platform also saw action with other countries, but the Strf 9040, A and B were not tested in actual operations.
Conclusion
The Strf9040 was a success for the Swedish army, which not only acquired hundreds of vehicles for its own use, but is also planning to upgrade them in order to keep them in service for the foreseeable future. The Swedish army also uses other variants of the CV90 chassis for other roles.
The Strf9040 did undergo a series of improvements during production and upgrades after its entry into service, mainly dealing with gun stabilization and mobility aspects.
The true claim to fame of the Strf 9040, however, is the fact that the CV90 platform has been a worldwide commercial success, with six other European nations operating hundreds of CV90 vehicles. The CV90 is also proposed to several other countries looking to replace their obsolete IFV fleets.
At this point, the CV90 is the most common Infantry Fighting Vehicle used by the nations of the European Union and will probably play an important role if a common EU army ever comes to fruition.
A Swedish Strf 9040A in a usual Swedish three-tone camouflage scheme. Illustrated by Tank Encyclopedia’s own David Bocquelet.
Strf 9040A |
|
| Dimensions LxWxH | 6.55 x 3.17 x 2.77 m |
| Weight | 23.5 tonnes |
| Crew | 3 (driver, gunner, commander) + 7 passengers |
| Powerpack | Scania DSI14 8-cylinder Diesel engine giving 550 hp (404 kW) with a Perkins automatic 4+2 gearbox |
| Suspension | Torsion bars |
| Maximum speed | 70 km/h |
| Maximum range | 320 km |
| Armament | Bofors 40 mm L/70 autocannon 7,62 mm ksp m/58C machine-gun Galix grenade launchers |
| Total built | 345 built |
Sources
Video presentation of CV9040 prototype
FMV presentation of the CV90 project
Swedish Armour Historical Society SPHF: CV 90 Photo guide, 2010
Sources for further information in Swedish
Svantesson, C.-G. & Lindström, R.O.: Svenskt Pansar – 90 år av svensk
stridsfordonsutveckling, 2009
Presentation of the CV90 project by Rickard O. Lindström
Swedish Armour Historical Society SPHF
About the Author
Alfons Falk graduated in 1967 from the Royal Institute of Technology (KTH Stockholm), majoring in aircraft engineering. In 1975, he started his employment at BAE Systems Hägglunds and became the head of armor vehicle design in 1979, later to include test and verification. Being the head of all armored vehicle design, he has been responsible for the development of the CV90 for Sweden and thereafter for CV90 export versions.
In 2005, The Society for Swedish Mechanical Engineers (SMR) presented him with the Ljungström Medal, an award given only once every three years. The medal was given with the following commendation:
“CV90 – today the most modern IFV in the world – has been a great success in Sweden and internationally. Alfons Falk’s wide knowledge, commitment and ability to transfer operational requirements to excellent technical solutions from system level to detailed design have been decisive for the success of all BAE Systems terrain vehicles. His systematic way of working has changed the development culture within the company.”
