Experimental Military Vehicles

General Motors has a long history of developing advanced vehicles for the U.S. Armed Forces, including these prototypes, which never advanced to the battlefield.

From DUKW to CUCV and everything in between, General Motors has helped design, engineer, and manufacture a wide array of vehicles for the United States Armed Forces. GM’s research and engineering teams have been involved with a number of advanced military projects in the past, including a few that never saw their way to the battlefield. Here’s a look at some of the military vehicle concepts that never were.

1956 GMC XM-157 Drake

1956 GMC DUKW 8x8 Drake ST

GMC’s amphibious DUKW proved invaluable to the Allied forces during World War II, which led in part to a post-war push for a larger version. GMC’s XM-157 prototype, colloquially known as the “Drake,” was just that. At 45 feet long, 10.8 feet wide, and 10.6 feet tall, the Drake was nearly 14 feet longer, two feet wider, and two feet taller than the DUKW. With four driven axles instead of three, the XM-157 was built to carry a payload four times greater than that of the DUKW. Power came from a pair of 5.0-liter inline six-cylinder engines, each fitted with an Allison automatic transmission and a two-speed transfer case. Portal axles provided increased ground clearance, but air suspension allowed the Drake to tuck its wheels up into the hull when on the water. The XM-157 theoretically could reach 44 mph on land and 9 mph in water, but development ended when the Army switched its focus to the LARC amphibious landing craft.

1964 GM Sidewinder

1965 circa Chevrolet Sidewinder Experimental All Purpose Military Vehicle

General Motors’ former Defense Research Laboratories (DRL)in Santa Barbara, California, worked on a number of projects, including off-road vehicle mobility. DRL’s efforts focused on different forms of articulated vehicles, including the Sidewinder prototype shown here. Developed under the auspices of off-road racer-turned-engineer Vic Hickey, the Sidewinder consisted of three segments: one housing the driver and front axle, one housing powertrain, and one housing both rear axle and cargo bed. The middle powertrain module — which housed a 215-cubic-inch V-8, a two-speed automatic transmission, and a two-speed transfer case – could theoretically be removed and replaced as a contained unit in the field. The Sidewinder never became a production vehicle, but it did influence the design of two other prototypes – including one designed for space…


1965 MOLAB Mobile Geological Lab

NASA might not be part of the armed forces, but once upon a time, it was very closely tied to them. Fittingly, what lurks beneath the surface of this rotund prototype has close ties to another GM military prototype. In the ramp-up to lunar exploration, NASA’s Marshall Flight center proposed a mobile laboratory that could provide a “shirt-sleeve” work environment for astronauts.  The ovoid vehicle looked like a prop from “Lost in Space,” but the vehicle never set foot on the moon. Instead, under the “Mobile Geological Laboratory” moniker, it was used as a geological survey vehicle by the U.S. Geological Survey.

Measuring 10’ high, 9’ wide, and 17’ long, the MGL/MOLAB was actually built upon an articulated chassis derived from the aforementioned Sidewinder. In Earth-bound form, the vehicle was powered by an air-cooled, flat-six engine pulled from the Chevrolet Corvair. With a top speed of 21 mph, the MGL/MOLAB was hardly quick, but it was capable of traversing 30% slopes and side slopes up to 45%. The lone example is on display at the U.S. Space and Rocket Center in Huntsville, Alabama.

1986 MAN-GMC 8×8 Prototype

1986 GMC MAN Experimental 8x8 Military

Both the U.S. Army and U.S. Air Force used the German MAN KAT 8×8 truck in Europe to transport cruise missiles, but GM worked with MAN to present a variant adapted for use in North America. Although this prototype from 1986 looks essentially unchanged, save for GMC emblems, the KAT was amended to utilize North American-sourced driveline components, including Detroit Diesel engines and Allison automatic transmissions. The idea was revived and updated again in 1989, when GM’s amended KAT was one of three finalists for the Palletized Load System truck contract, which was ultimately awarded to a version of Oshkosh’s HEMTT.

2003 Chevrolet Silverado Diesel Hybrid

2003 Chevrolet Silverado Diesel Hybrid
What looks like a normal Silverado LSSV fitted with the Enhanced Mobility Package actually demonstrated an advanced drivetrain. This particular prototype paired a 6.6-liter Duramax Diesel V-8 with a parallel hybrid system. Combined, the diesel-electric driveline was more fuel-efficient than conventional gasoline-fueled trucks, and also more flexible. When needed, the system could also function as a 30 kW electric generator.

The Silverado Diesel Hybrid prototype was also capable of providing silent power, thanks to a regenerative 5 kW hydrogen fuel cell. During normal vehicle operation, electricity from the hybrid system was sent to the fuel cell stack to generate hydrogen. That hydrogen was accumulated and stored for later use, when it was fed back through the fuel cell stack in order to generate electricity. This allowed the system to provide electricity without producing noise or heat.

2005 Chevrolet Silverado Hydrogen Fuel Cell

2005 Silverado Hydrogen Prototype

Military versions of the full-size C/K pickup were hardly new, but the one-off Silverado 2500HD crew cab leased to the U.S. Army in 2005 was rather advanced. This particular truck was stripped of its conventional drivetrain and fitted with a hydrogen fuel cell system. Three 700-bar compressed hydrogen storage tanks fed a pair of 94 kW fuel cell stacks, which then converted hydrogen into electricity. That electricity then drove a pair of motors – one coupled to the rear wheels, and another coupled to the front. The system provided a top speed of 93 mph and a range of roughly 124 miles.

The Silverado Fuel Cell was also fitted with four-wheel steering and custom independent rear suspension, and was rated to carry payloads weighing up to 1600 pounds. The Army primarily used it as a delivery vehicle at Ft. Belvoir in Virginia. Although this particular program came to an end, GM continues to work with the U.S. Army in advancing and developing fuel cell technologies to this very day.

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