CHALLENGES Dual Power Source results in low Power Plant power density

1. CHALLENGES • Dual Power Source results in low Power Plant power density • Silent Propulsion with electric drive motors requires greater chassis weight • As Power plants get larger AND Chassis get heavier – • Payload capacity will suffer • Power Requirements can be reduced by compromising • Payload weight • Speed • Terrain Severity • ANY REDUCTION IN CAPABILITY DECREASES MILITARY USEFULNESS

2. Basic Vehicle Power Design Considerations for Propulsion V F Motion Resistance Neglecting Acceleration, Aerodynamic Drag Forces and Auxiliary Power

3. POWER DENSITY (HP/ton or Watts/kg)

4. 4 .025 = Hallway .06 = Low psi tires .15 = Tracked vehicle .3 = Easy Off-Road .8 = Complex Terrain

5. 4 mph Silent Propulsion Design Point Terrain Severity Index = 0.3 Wheel vehicle motion resistance in soft soils OR 30% Slope NEED Vehicle Power Density = 5.85 W/kg Power Source Density = 39 W/kg Assuming 90% Transmission Efficiency and Power Source = 15% GVW

6. 4 mph Silent Propulsion Design Point Power Source Needed = 11.7 kW JUST TO PROPEL VEHICLE, NOT INCLUDING ANY ACCESSORIES OR AUXILIARY EQUIPMENT

7. ALTERNATIVE FUEL OPTIONS Power Density Methanol Fuel Cell 6.2 w/kg SOFC 14.4 w/kg Sunpower Sterling Engine 27.2 w/kg Ballard Hydrogen Fuel Cell 52.7 w/kg Zebra Batteries 150 w/kg

8. Design Point - GOAL Off-Road Speed = 6 mph Terrain Severity Index = 0.8 Motion Resistance of 30% AND 60% Slope Vehicle Power Density = 21 W/kg = 29 HP/ton Power Source Density = 159 W/kg Assuming 90% Transmission Efficiency and Power Source = 15% GVW Power Source Needed (min) = 64 HP = 48 kW JUST TO PROPEL VEHICLE, NOT INCLUDING ANY ACCESSORIES OR AUXILIARY EQUIPMENT

9. DESIGN POINT GOAL cont. • By satisfying the low speed difficult terrain design point, • The vehicle will also satisfy: • 30 mph on pavement • 0 – 30 mph in 7.5 seconds