November 16, 2004 The US Marine Corps' first 4x4 hybrid-electric tactical vehicle - the Shadow RST-V - has been tested by the Office of Naval Research (ONR) and the Defence Advanced Research Projects Agency (DARPA) and may soon challenge the Humvee as the dominant vehicle for military use. The Reconnaissance, Surveillance and Targeting Vehicle (RST-V) is a high mobility, electric drive technology demonstrator that incorporates a lightweight diesel engine coupled to a permanent-magnetic generator which drives four in-hub permanent-magnet electric wheel motors. The RST-V is ideally suited as a reconnaissance vehicle, as its lithium-ion battery pack enables silent movement for upwards of 20 miles with extremely low thermal and acoustic signatures.
The vehicle has an aluminium body with an optional armour package providing protection against small arms fire and mines, and fits a crew of four. There are two doors on the sides and a ramp at the back for entry to the internal cargo area. Bulletproof windows can be installed on the front and sides.
"The RST-V offers a tremendous amount of enhanced capabilities to the warfighter," said Jeffrey Bradel, ONR Manoeuvre manager. "This is a technology demonstrator... to show the Marine Corps leadership the potential benefits that these advanced technologies provide on the battlefield."
Four vehicles were fabricated and subjected to performance testing and operational user evaluations during the last few years, including more than 7,000 miles of field-testing and numerous demonstrations including two 1,000 mile endurance runs. In September, 2003, the Marine Corps Warfighting Laboratory organized a two-week joint service Limited Objective Experiment for the RST-V at the Army's Yuma Proving Grounds in Yuma, Arizona. The vehicle successfully completed cargo loading, silent operation, live firing and severe off road exercises. Additionally, the RST-V shattered the speed record for the Army's Rock Ledge Course at Yuma with a time of 13 minutes and 50 seconds. The previous record was over 32 minutes.
"In most cases we matched or exceeded the Humvee's capabilities," said General Dynamics' Tom Trzaska, citing improved mobility, recon ability, and providing a better platform for employing a machine gun such as the M2 .50 Cal Browning. The RST-V also has a significant edge over the Humvee in fuel economy. The average fuel usage for a deployed Humvee conducting an extended reconnaissance mission is 1,040 pounds per month, but only 440 pounds for the RST-V.
"The RST-V reduces the foot print you have to take to the field through increased fuel economy," said Trzaska.
It may also be used for light strike duties, as a battlefield ambulance, for air defence, logistics, as a personnel carrier or as anti-armour and a mortar weapons carrier once the System Design and Development (SDD) phase is completed by ONR in 2005.
The Shadow runs on a hybrid-electric drive based on a front mounted turbocharged, inter-cooled common rail direct injection diesel engine, type 2.5 litre DI-4V rated at 114kW. The diesel engine powers a 110kW Magnet Motors permanent magnet generator that drives four 50kW Magnet Motors permanent magnetic hub motors, mounted one in each of the Shadow's four wheel hubs.
The Shadow is fitted with a pneumatic suspension. It's dimensions can be reduced by allowing the tyres to be pulled in (from 79in footprint to 62in) and the height can be dropped so the base of the vehicle is 0.1m off the ground. Crucially, this will enable transport by V-22 tiltrotor.
Electric Drive System
The hybrid electric drive enables the Shadow to operate in stealth, hybrid and engine only modes. The stealth mode can be powered by battery only use, which reduces acoustic and thermal signatures.
During rapid acceleration, maximum torque, or to recharge the battery pack, the Shadow is operated in hybrid mode using power from the diesel engine and taking energy from or returning it to the batteries as needed. The Shadow is used in engine only mode to drive the vehicle.
By eliminating the conventional mechanical drive train the Shadow's interior can have the same cubic storage as a HMMWV yet fit within the V-22 envelope.
The Shadow has a maximum road speed of 112km per hour. The vehicle has a capacity of 95 litres of fuel and an unrefuelled range of 758km at a speed of 50km per hour. On battery power alone the vehicle's range is 32km.
A 3m extending mast equipped with a suite of electro-optical sensors is fitted to the Shadow, including a dual field of view day and thermal imaging sensor, operating at 3 to 5 microns wavelength, as well as a Northrop Grumman Lightweight Laser Designator and Ranger (LLDR). The sensor suite is linked to an inertial navigation and GPS with a Smiths Industries north direction finder with azimuthal accuracy of 3.6 mil. The communications systems include an ITT SINCGARS ASIIIP VHF transponder and satellite communications.
A 7.62mm, 12.7mm machine gun, 40mm grenade launcher, Objective Crew Served Weapon (OCSW), Javelin or TOW anti-tank missile systems can be mounted on the roof hatch. The Shadow can be fitted with a defensive aids suite including radar and laser warning receivers, and missile warners.
For more information see: https://www.onr.navy.mil/
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