leFH 97
General Characteristics:
- Type: Towed howitzer
- Weight: 2,500 kg
- Length (towed position): 6.9 m
- Width: 2.0 m
- Height: 2.1 m
- Crew: 4-5
Armament Characteristics:
- Caliber: 105 mm
- Barrel length: 52 calibers (57 w/ muzzle brake)
- Rifling twist: 1:22
- Breech: Semi-automatic sliding wedge
- Muzzle brake: Pepperpot, 60% efficient
- Recoil system: Hydropneumatic, 1 meter recoil
- Firing range: 24 km (hollow base), 30 km (base bleed), 36 km (rocket-assist/base-bleed)
- Dispersion: <0.3% range, <0.1% deflection
- Rate of fire: 6 rounds/minute
Traverse and Elevation Equipment:
- Type: Electrohydraulic w/ manual backup
- Elevation range: -5° to +75°
- Traverse range: +/- 40°
Maneuverability:
- Onroad towing speed: 100 km/h
- Offroad towing speed: 50 km/h
- Ground clearance: 0.3 m
- Fording Depth: 0.6 m
Overview:
The leFH 97 is a lightweight towed howitzer designed by SDI Armament Systems. The leFH 97 is intended primary to equip airborne and other light infantry forces and can be transported by helicopter and towed by 4x4 utility vehicles such as SDI's GdW 30 Lynx or any other 5-ton type of utility vehicle.
Armament:
The leFH 97 employs a 52 caliber barrel constructed from swage-autofrettaged electro-slag refined (ESR) steel with a 1:22 rifling twist and a chrome plated bore and chamber. The end of the barrel features a high-efficiency pepperpot muzzle brake 5 calibers long with convergent-divergent nozzles which is rifled on the inside, adding an additional 5 calibers to the effective barrel length. The recoil system is a conventional hydropneumatic recoil system with a fixed recoil length of 1.0 meter. The breech mechanism is a semi-automatic vertical sliding split-wedge mechanism which provides obturation and contains a primer magazine containing 12 primers. The loading system consists of a hydraulically powered flick-rammer which can load both the projectile and propellant charges at any elevation angle. The howitzer is designed to use SDI's family of 105 mm artillery ammunition along with SDI's five-zone AM21 modular charge system which employs modular propellant charges with cool-burning non-toxic propellant contained in a rigid combustible case which ensures a barrel life of more than 5,000 EFC rounds.
Sighting & Laying:
The gun's sights include a 3x magnification, 10° field of view direct-view telescopic sight for direct fire out to ranges of 3,000 meters and a 4x magnification, 10° field of view trunnion-mounted panoramic telescope with trunnion cant compensating mechanism used for indirect fire which is mounted to the left side of the weapon. Indirect fire is further assists by an SDI Artillery Digital Fire Control System (ADFCS) which includes a muzzle velocity radar, ring laser gyroscope inertial navigation system with GPS, gunner's display and control unit (GDCU), and portable data terminal unit which provides continuous and accurate 3D gun self location with or without GPS, continuous determination and display of gun barrel traverse and elevation, and automated gun laying and fire control computation. The INS/GPS system consists of a shock-hardened inertial measurement unit (IMU) mounted directly above the gun trunnions which contains a 3-axis ring laser gyro and 3-axis accelerometer which provides 0.20% of distance traveled horizontal CEP and 0.15% of distance traveled vertical CEP position determination along <1 mil RMS heading and <0.5 mil RMS pitch and roll determination. The IMU is also coupled to a 12-channel selective availability/anti-spoofing module (SAASM) compatible GPS receiver which provides <5m CEP position determination. The muzzle velocity radar system consists of an X-band (10.4 - 10.6 GHz) unmodulated continuous wave radar unit with a microstrip antenna array which is contained in a housing measuring 19 x 19 x 10 cm which is mounted ahead of the INS/GPS unit. The muzzle velocity radar unit is activated by an acoustic trigger upon gun firing and measures projectile muzzle velocity to within +/- 0.05% accuracy with the ability to store up to 1,000 muzzle velocity measurements using its onboard non-volatile memory. The gunner's display and control unit (GDCU)consists of a 20 centimeter touchscreen display with an internal 1.6GHz dual-core processor with 2GB RAM and 16GB solid state drive with interfaces to the INS/GPS unit, muzzle velocity radar, and tactical radio and is used to control all local fire control and gun laying operation. Finally the portable data terminal unit (PDTU) consists of a handheld tablet computer which can be mounted to the gun or mounted inside the cab of the gun towing vehicle which through an interface to the howitzer's radio acts to link the battery command post (BCP) with the howitzer's mission computer for transmission of ballistic target data and for transmission of gun location information to the battery command post.
Traverse & Elevation Control:
The traverse and elevation gear used on the leFH 97 is an electro-hydraulic drive system which employs a hydraulic motor driven mechanical gearbox for traverse and twin hydraulic elevation cylinders coupled to a pneumatic equilibrator for elevation. The traverse gearbox is also fitted with a clutch which when engaged allows for rapid traverse of the gun barrel from the travelling to the firing position. The Hydraulic system fitted with proportional control valves and is controlled using a joystick controller on the left side of the gun. The hydraulic system allows for traverse at speeds from 0.03° to 6.75°/s and elevation at speeds from 0.03° to 8.4°/s. Hydraulic pressure is provided by an electrically driven hydraulic pump with hydraulic hand pumps for manual elevation and traverse of the gun provided as a backup. The hydraulic control system is also fitted with an SDI Automatic Gun Laying System (AGLS) which through an interface to the howitzer's Digital Fire Control System (DFCS) is used to automatically lay the weapon onto the target after receiving a fire mission from the battery command post. Power for the hydraulic system and other electrical systems is provided by two 12 volt batteries which power the howitzer's onboard 24V electrical system.
Carriage:
The leFH 97 features a fairly conventional split trail carriage with a bottom carriage constructed from forged ultra-high-strength steel (UHSS) with twin box trails constructed from welded 7075 aluminum alloy. Two wheels are mounted to the carriage on a trailing arm suspension with ground clearance adjustable up to 0.3 meters. Brakes include an inertia brake activated by the tow hook along with hydraulic disc brakes on each main wheel. Maximum towing speed when the gun is locked in the travelling position is 100 km/h on roads and 50 km/h offroad. When deployed in the firing position the howitzer is supported by a jack with a stabilizing platform which is manually lowered underneath the forward part of the carriage and by spades located on the ends of each trail. For towing by 4 × 4 vehicles the carriage is provided with an adjustable tow hook and features removable lifting hooks for transposition by sling-loading under helicopters. The left split trail also carries a barrel clamp which is used to clamp the barrel when the gun is towed in the travelling position.
