K
Hybrid Fuel Efficiency
In addition to Army internal hybrid studies, there have been a number of hybrid studies initiated with some completed by the major defense industry suppliers. Some of those efforts are summarized below.
Oshkosh Defense presently offers in production a series hybrid diesel-electric powertrain system called ProPulse® on its Heavy Expanded Mobility Tactical Truck (HEMTT-A3) and Medium Tactical Vehicle Replacement (MTVR) (see Figure K.1). Reportedly, this system increases the HEMTT fuel economy by up to 20 percent versus the non-hybrid version. The system also is capable of providing up to 120 kW of electrical power to external users.
BAE Systems recently received a $32 million agreement to develop a 35-ton series diesel-electric hybrid Bradley Fighting Vehicle. QinetiQ, a partner on this project, is developing the electric cross drive transmission (Modular E-X-Drive).
As another example, General Dynamics Land Systems completed a drive evaluation in 2009 of a series hybrid “E-Drive Stryker,” part of an internal research and development (R&D) project. Using independent electric hub-drives, it leveraged the existing architecture and hardware of the Advanced Hybrid Electric Drive (AHED) vehicle, developed by GDLS from 1999 to 2007. It was subsequently dropped as the integration of braking, motoring, and gearing into the independent wheel hubs proved to have problematic reliability.
Overseas suppliers have also been active in military vehicle hybrids as shown below by the hybrid power pack (civilian rail; Figure K.2) and land defense marketing materials from MTU Solutions (Figure K.3).