Although the Hummer continues to be popular with civilian car buyers (regardless of the cost to fill the gas tank), its military counterpart, the high mobility multi-wheeled vehicle (HMMWV) is already 20 years old and approaching the end of its service life. More importantly, its ability to be upgraded through incremental improvements is severely limited. While still an outstanding vehicle, a replacement is needed with the latest technology optimally integrated into an original design rather than added to a dated one.
Designed during the Cold War, the Humvee has a light, aluminum body for high speeds in hilly European terrain. It is not the best vehicle for protection against ballistic, land mine, and improvised explosive device (IED) threats such as those experienced in Iraq. Armor has been added to the Humvee to increase protection, but it slows down the vehicle, thus reducing its effectiveness and increasing vulnerability. Also, the lack of air conditioning is a major discomfort in desert environments.
When the U.S. military is deployed in combat, up to 70% of its supplies by tonnage is fuel. If you think $3-per-gallon gasoline is outrageous, JP-8 can cost $400- to 600-per-gallon by the time its gets into the field. Like the civilian world, the U.S. military wants better fuel economy to reduce cost and logistics while extending the range so vehicles can stay engaged in combat longer.
Today's military takes much electric powered gear into battle-computers, GPS, communications, surveillance systems, and air conditioning. Ever greater electrical power demands will come with emerging technologies like electro-static armor, beamed weapons, and bunker-busting rail guns. While these demands can be met with towed generator trailers, as is the case currently with the Humvee, its replacement will supply this power without the trailer.
Ultra AP and 3T
The Ultra AP (armored patrol) was developed under Office of Naval Research (ONR) sponsorship by a Georgia Tech research team and automotive industry experts, including those with NASCAR racing expertise. Not destined for mass production, the Ultra AP is a concept vehicle. It will be used to evaluate various advanced technology options that could be used in future vehicles including any HMMWV replacement.
The three-ton Ultra AP is slightly larger than the Humvee and is built on the Ford F-350 chassis with features including four-wheel disc brakes with ABS, power steering, tilt steering wheel, and modern suspension system. Power comes from a Powerstroke 6.0-liter turbo diesel engine mated to a five-speed automatic transmission. One version could feature four-wheel steering.
The Ultra AP has a survivable crew capsule mounted on the chassis. Based on NASCAR experience, this egg-shaped "blast bucket" provides ballistic, blast, and enhanced roll-over protection. The four occupants are seated in a diamond configuration with backs to one other-driver facing forward and three passengers, one facing each side and one facing to the rear. This allows for a 360-degree field of view and moves the soldiers as far away from the source of a blast as possible. The blast bucket is also designed to deflect the force of a blast away from the occupants. An internal roll cage protects those inside should the vehicle tip over.
Though currently not a funded development, the research team has looked at a more advanced vehicle, the Ultra 3T, as well as developing technologies such as fuel cells, batteries, and hybrid engines that could make a vehicle like the Ultra 3T possible. The ONR wants the Ultra 3T to provide up to a megawatt of exportable power. The Ultra 3T could use a hybrid diesel/electric power plant that would not only generate electric power, but also offer a silent electric mode for stealthy operation.
Shadow RST-V
While hybrid electric vehicles are popular today due to spiraling fuel prices, for the military they offer important benefits beyond just more miles-per-gallon. They can operate with reduced infrared and acoustic signatures. Many military experts believe that stealth running is more important on the battlefield than better milage. A hybrid can also provide a power source to complement or replace trailered or portable generators.
The Marine Corps could be the first to have a hybrid combat vehicle, the Shadow RST-V (reconnaissance, surveillance, and targeting vehicle). The RST-V is being developed by General Dynamics Land Systems sponsored by the ONR, the Defense Advanced Research Projects Agency (DARPA), and Marine Corps Warfighting Laboratory (MCWL).
This hybrid uses a lightweight, 2.5-liter diesel engine coupled to a generator that provides electric power to motors in all four wheels. Excess electrical energy is stored in lithium-ion batteries. Other battery types or even ultra capacitors could be used to store electric energy. The Shadow can supply up to 30 kilowatts exportable power generated by its hybrid electric propulsion system.
The four ton Shadow, powered only by batteries, can travel about 20 miles with extremely low thermal and acoustic signatures. When rapid acceleration or maximum torque for climbing a steep hill is called for, the Shadow operates in the hybrid mode with energy from both the diesel engine/generator and batteries. The RST-V can run on the diesel engine alone. With 25 gallons of fuel, the Shadow has a range of 470 miles at 30 mph. Top speed is 70 mph.
The Shadow was designed for transport in CH-53 or CH-46 helicopters as well as V-22 Osprey or C-130 aircraft. The narrow Osprey requires the RST-V to have a pneumatic suspension system that pulls the wheels in 13 inches to reduce the width to a mere 62 inches. The height can be dropped so the clearance is only about 3 inches. The bottom is arched to move over an aircraft ramp and obstacles. Without a conventional mechanical drive train that takes up much interior space, the RST-V has the same carrying capacity as a HMMWV.
The Marine Corps sees the Shadow as a replacement for both the M151-A2 Fast Attack Vehicle and the HMMWV. Besides RST-V it could be used for C3I (command, control, communications, and intelligence) missions, as a battlefield ambulance, or to carry anti-armor and mortar weapons. It can be armed with a 7.62-mm or 12.7-mm machine gun, 40-mm grenade launcher, Objective Crew Served Weapon, Javelin or TOW anti-tank missiles. The Shadow can be fitted with defensive aids including radar and laser warning receivers, and missile detectors.
The Shadow carries a crew of four. There are two doors and a rear ramp for access to the cargo area. While the RSTV has an aluminum body, an optional armor package is available. This includes steel and ceramic sandwich bolt-on armor and bulletproof windows on the front and sides. Four prototype RST-V vehicles have been successfully tested at the Aberdeen Proving Ground, Yuma Proving Ground, and other locations. In early 2006, two Shadows will be sent to Iraq for testing.
The Humvee has been a dependable vehicle for more than two decades. It is time for a new generation of utility vehicles specifically designed for the battlefields American troops are likely to find themselves on in the 21st century.
Colonel Siuru retired after 24 years in the Air Force. His assignments included command of the research laboratory at the U.S. Air Force Academy, and Director of Engineering at Wright-Patterson AFB. He has a PhD in Mechanical Engineering and is currently the technical editor for the Green Car Journal and Diesel Progress.