Powering AHED

Defence Group General Dynamics has unveiled the trackless, hybrid-electric armoured vehicle that it hopes will form the basis of the UK’s future land combat fleet.

The Advanced Hybrid-Electric Drive (AHED) 8×8 is an eightwheeled vehicle that combines a powerful Mercedes diesel engine with a high-specification lithium ion battery. The vehicle was developed in the US by General Dynamics and forms the core of the group’s bid to be selected for the MoD’s Future Rapid Effect System (FRES) programme.

AHED is designed to be modular so that different add-on systems can be plugged in quickly and easily depending on specific missions. The chassis is intended to form the basis of a wider family of future land vehicles, said General Dynamics.

The hybrid-electric drive means that AHED can function in three different drive modes, while the diesel engine allows it to accelerate from 0–30 in under five seconds. It can also switch to battery only, allowing it to move quietly for stealth operations and silent reconnaissance.

Its third drive mode combines the other two, using battery power to provide an extra boost to the diesel engine for a burst of speed and increasing the vehicle’s fuel economy over long distances.

The hybrid is also used to rapidly shift power to other on-board systems such as Bowman radio.

One of the vehicle’s major innovations is the use of in-hub permanent magnetic motors to power its wheels without needing any mechanical transmission. The engine powers a direct-drive generator, which distributes power to the in-hub electric motors. This means that the wheels are able to work independently of each other, allowing AHED to produce maximum torque at very low speeds.

Steer-by-wire technology transmits information to the wheels depending on the vehicle’s speed and angle of turn, enabling it to perform extremely tight manoeuvres.

The wheels are all completely interchangeable, as are the electric motors, which fit into the front of AHED. It is designed to remain driveable even if it loses one or more wheels from, for instance, a mine.

Ray Straw, General Dynamics’ director of technology and programme development, claimed: ‘Compared to tracks, these in-hub motor-powered wheels give the AHED a huge advantage in terms of manoeuvrability, which is important for street and city-fighting.’ If the MoD makes AHED a component of FRES, it could be ready for full military operations in 2011.

FRES: Mobile, flexible and pure 21st Century

THE FRES programme was launched by the MoD last year to provide the Army with a new range of medium-weight, network-capable armoured vehicles for a variety of battlefield roles.

FRES will replace the UK’s existing fleet of Saxons and other models with new, more mobile vehicles that can operate more effectively in war zones or during peace-keeping missions. The vehicle is intended to plug the gap that exists between large, heavily-armoured tanks and smaller, less-protected personnel carriers.

Although the vehicles will be smaller and lighter than existing medium-sized vehicles, they will employ a suite of next-generation technologies such as ‘e-armour’ to keep them protected. The FRES family will range from armoured personnel carriers to reconnaissance and medical vehicles.

A key characteristic will be the units’ modular ability, whereby all components and sub-systems are interchangeable between vehicles, giving the force a complete ‘plug and play’ capability. They will have to be air-portable for rapid deployment to crisis zones and able to exchange information quickly through a digital communications network, allowing troops to reinforce and support each other more easily.

Engineering consultant Atkins is co-ordinating the initial two-year assessment phase, during which requirements will be refined and the MoD will look into all of the available alternatives.

FRES is similar in concept to the US Future Combat System (FCS), which uses advanced communications and technologies to link personnel and vehicles as part of a networked ‘system of systems’. However, where FCS is an entire programme, covering aerospace and digital communications, FRES will be confined to a suite of around 16 vehicles with separate roles.

FRES is expected to cost around £14bn, with the first units entering service early in the next decade and further variants being introduced in subsequent phases.