by Tom Clancy
Thanks to TACOM’s unified-design philosophy, the HMMWV is probably the most mobile and rugged wheeled vehicle ever built. Like its more deadly tank and IFV counterparts, it was designed to the same standards of mobility as all the Army’s vehicles. It climbs the same hills, fords the same streams, and has the same kind of redundancy and reliability as every vehicle of the current generation. That is the key to the Hummer’s extraordinary success.
The basic version is known as the M998, which provides the chassis for a whole family of different variants. Some of these include:• The M998 open-topped cargo/troop carrier used for general purpose operations and transport.
• The M 1026 armament carrier capable of mounting an M2 .50-caliber heavy machine gun, an M60 7.62mm light machine gun, or an Mk-19 40mm grenade launcher.
• The M966 TOW-2 missile carrier. It utilizes a light TOW launcher tripod (which can be dismounted), and has room for six TOW-2 rounds under the rear roof shell.
• The M966 mini-ambulance, and the M997 maxi-ambulance. These are the primary medevac ground assets of the U.S. Army, and proved to be extremely effective during Desert Storm.
• The M1037 shelter carrier, which is used for a variety of functions from command and control to mobile workshops.
• The M1097 “Heavy Hummer,” which may be armored against small-arms fire. These 10,000-1b/4,545.5-kg vehicles are being adapted as a squad carrier for light infantry, and as a new scout vehicle being developed by TACOM.
There can be little doubt that AM General and the Army will be developing additional HMMWV variants. They should be successful, for AM General has a successful history going back over fifty years.
The story of the HMMWV is an evolutionary one. It is produced by the same company, AM General (a direct descendent of Willys), that produced the original Jeeps. And while AM General has changed ownership more often than just about any other defense contractor (from Kaiser Jeep, to American Motors, to LTV, and finally to the Renco Group), the HMMWVs that come off of the line today are being made by the sons and daughters, and even the grand-sons and granddaughters, of the men and women who built military vehicles during World War II.
It would be nice to say that the HMMWV has the same kind of high-tech, sexy design philosophy as the M1 or Bradley. In fact, the design of the HMMWV is a marvel of engineering conservatism. The primary chassis structure of the Hummer is a pair of massive steel beams that run the entire length of the vehicle. The HMMWV rides on four specially designed wheels, each driven by a novel geared hub. The bodywork is almost entirely built of lightweight aircraft-quality aluminum alloy, so resistant to corrosion that AM General warrants the HMMWV against it for fifteen years! The Hummer is powered by an eight-cylinder, 150-hp General Motors diesel engine driving a three-speed, automatic transmission. The result of all this is a vehicle with an extremely low center of gravity, which can climb almost any hill, ford some 2.5 feet (76 cm) of water, run across ice, snow, and sand with ease, and climb steps and logs almost two feet tall.
Driving the Hummer—When you first walk up to a Hummer, the first thing that strikes you is just how incredibly boxy it is. AM General is proud of saying that not one penny of taxpayer money has ever gone into making the HMMWV stylish or attractive. In fact, it reminds one of the Air Force’s A-10A Thunderbolt II (known affectionately as the “Warthog”). Both are designed to be functional, not pretty. But to the folks at AM General and in the Army it is a thing of beauty. “Functionally elegant” is how they describe it.
The military HMMWV has little in the way of creature comforts, and the back seats of early models of the HMMWV are considered a form of torture by some passengers. If you are looking for luxury, forget this beast. As you sit down, it is vital to buckle up the safety belts. The ride of a HMMWV can be rough when crossing broken terrain, and most military HMMWVs have no doors! Only the weapon carriers and a couple of other variants have hard doors, though all other HMMWVs have the provision for canvas doors and covers. Each military Hummer is covered in the same kind of chemical-resistant CARC paint that is used on virtually every other Army vehicle being produced today. In most cases there are mountings for radios between the driver’s and front passenger seats, and many HMMWVs have dashboard mounts for the military Trimble GPS receiver.
As you view the dashboard, you will be decidedly underwhelmed if you are looking for the state-of-the-art electronics of the M1A2.,There are about the same instruments you might expect to find in an old Volkswagen: speedometer, fuel gauge, and a few indicator lights. The steering wheel is bare black plastic, with a pair of shifter knobs, one for selecting the normal gears (NEUTRAL, DRIVE, REVERSE, etc.), and a second one for selecting high or low range for the transfer case. As with most military vehicles, there is no key, just a switch on the upper left portion of the dashboard with positions for START, OFF, and DRIVE. To secure the vehicle you pull a steel cable out from the dash and padlock it to the steering wheel. Starting the Hummer is quite straightforward, and the engine quickly comes to life. For those used to the soft purr of a gasoline engine in a normal road car, the decided rumble of the HMMWV’s GM diesel may seem rather extreme. Actually, the diesel in the Hummer is quite smooth, with a very nice power curve. The key to getting the most from the powerful diesel is to think a little ahead of where you normally would driving a conventional road car: There is a slight throttle lag after you push down the accelerator pedal before the power finally begins to come on.
Unlike many off-road vehicles, the HMMWV is always in four-wheel drive (unless you put it in neutral for towing). You choose the high- or low-gear range on the transfer case. You would choose HIGH for highway driving. Surprisingly, driving the HMMWV requires a delicate touch, and not the rough kind of driving usually associated with conventional trucks and four-wheel-drive (4WD) vehicles. In feel, it is something like a Cadillac road car, with gentle steering commands and thoughtful use of power required to get the most out of it. And yet in all other respects, it does not drive like a luxury car. The best word to describe the sensation of driving the Hummer is authority. Whether it is climbing over rocks (the HMMWV has a minimum of 16”/41 cm of ground clearance) or fording streams (up to 30”/76 cm of running water), it feels capable of accomplishing any task. Of course the HMMWV can’t be driven recklessly. Rather, it is a vehicle which rewards a thoughtful, careful driver with performance that has to be seen to be believed. A major at the National Training Center at Fort Irwin, California, once told me that if you ever run into a piece of terrain that a HMMWV cannot reach or climb, you probably don’t want to own it anyway!
The Hummer is capable of several extraordinary tricks. For example, there is the matter of climbing steep hills, and then descending them! To climb almost any hill you might want to get to the top of, all you have to do is tighten your seat belt (so you don’t have to worry about falling out), drop the shifter down into the D 1 position (low range, low gear), and gently apply the accelerator. Almost like magic, you will head up the hill at a steady, albeit slow, rate. The key here is applying steady, constant power to the fat tires. (incredible as it may sound, mud, gravel, soft sand, and snow can be dealt with simply by slowing down a bit and gently applying the power.) As amazed as you will be to get to the top of a hill, getting down is even more impressive. The trick is to again put the transmission into D1 position, and head on down. The major point is to make sure that you never touch the brakes! Odd as this may sound, when descending, you are actually just hanging on the compression of the HMMWV’s diesel engine, and touching the brakes would just lock them up and might start you sliding dangerously. It is an amazing feeling to look down a slope that you frankly doubt you could climb on foot, and yet you are driving down it with a feeling of authority and confidence. This was demonstrated most convincingly by a major of the Dragon Observer/Controller team up on the live-fire range at the NTC. When he wanted to show some members of my research team the range instrumentation at the top of a mountain (a particularly tall and treacherous-looking rock p
ile), he just shoved his Hummer into D1 and headed up without giving it a thought. The “path” (if you care to call it that) was just gravel and rock shale. He later told us that the only ways to the top were via helicopter—and HMMWV!
I’ll end my discussion of the Hummer for now by describing a particularly famous photo from the Persian Gulf War (the war was filled with Hummer stories). It shows a HMMWV of the 82nd Airborne Division loaded almost to the breaking point (the wheels and axles are just jammed all the way up into the wheel wells) with ammunition and equipment, carrying a couple of airborne troopers, and towing a 105mm howitzer to boot! Later we will describe the Army’s plans for this fascinating vehicle, which has in fact become so popular that AM General sells commercial and private versions of the HMMWV. And while they are not cheap ($40,000 to $60,000 as of 1994), they are probably the finest 4WD/utility vehicles being built today. I should know since I’ve bought one for myself!
M1070/M1000 Heavy-Equipment Transporter System (HETS)
One does not just unload a battalion of M1A2s or Bradleys and run them into combat a couple of hundred miles to the front. Armored vehicles are mechanically demanding brutes which generate a lot of wear and tear on themselves for every mile they run. Thus, since it became common for armies to use heavy armored vehicles, there have been special transporters to carry them to the fighting fronts. Resembling low-boy semi-tractor-trailer rigs, these are designed so that the armored vehicle drives up a ramp onto the trailer, which then hauls it to a forward assembly area. The problem with the current HETS, known as the M911/M746 with 747 (the first number is the designator for the tractor, the second is for the semi-trailer), is that the greatly increased weight of the M 1 MBT limits it to paved roads and speeds no faster than 15 mph/25 kph.
To make up for these shortcomings, the Army is starting to field a new unit, the M1017/M1000. Produced by Oshkosh Corporation of Oshkosh, Wisconsin, it can move both on and off road with a seventy-ton payload (such as a loaded Abrams), at speeds approaching 30 mph/50 kph. And in perhaps its most important role, it will be able to maneuver on the Army’s new class of roll-on/roll-off transport ships without even having to use reverse gear. This allows the M1017/M1000s to move their vital cargo off the ships with a minimum of support equipment and dock facilities. And that can be the difference between winning a battle, and having the bad guys sunning themselves on the beaches of one of our allies.
M939 5-Ton Truck
Army units need a lot of stuff. Stuff to eat. Stuff to drink. Stuff to shoot. And all this stuff has to be moved somehow. This means trucks. Lots of them. The most common of these trucks is the classic 5-ton (this refers to the payload) M939. The newest version of this venerable design, the M939A2 is produced by the BMY Truck Company. The unique feature of the M939A2 is a new central tire-inflation system that allows the driver to alter the tire pressure, and thus the traction, with the flick of a switch from inside the cab. This improves the performance of the M939A2 in soft sand and mud.
Heavy Expanded Mobility Tactical Truck (HEMTT) Family
The Heavy Expanded Mobility Tactical Truck (HEMTT) family of trucks is designed to provide forward units with fuel, water, dry foods, and other supplies. Produced by Oshkosh Corporation, they also provide a platform for cranes and other service equipment needed to maintain other Army vehicles. With a 10-ton/9,090-kg payload and powered by a 445-hp diesel engine, the HEMTT can move at 55 mph/90 kph across a variety of terrain. There are currently five configurations, all of which gained combat experience during Desert Storm. The M977 is a light cargo carrier with a crane; the M978 is a fuel tanker with a 2,500-gallon/9,433-liter capacity; the M983 and M984 are tractor and wrecker versions respectively; and the M985 is a heavy cargo carrier with a material-handling crane. All in all, the HEMTTs are a capable series of transporters, with a great deal of growth left in the basic design. It is almost certain that the Army will be developing further variants of this excellent vehicle.
Coming Developments
In the 1980s, with the introduction of the AirLand Battle Doctrine and the institution of synchronized-maneuver warfare, the U.S. Army underwent a major revolution. And just when the bad guys are dreaming up more trouble, here comes General Gordon Sullivan, the Army Chief of Staff, with some bad news. Because the revolution of the 1980s worked so well, the Army has decided to have another one in the 1990s. By 1997, virtually all of the systems described below will be on-line and in actual maneuver units. Some of them, like the M2A3/M3A3, are upgrades of existing systems. Others, like the XM8 Armored Gun System (a powerful light tank), represent entirely new ideas. These new systems are designed to give excellent value for the limited procurement dollars that will be available in the late 1990s. And for those of you who consider defense spending bloated, consider this: Since the close of Desert Storm in 1991, the Army procurement budget (money to buy new equipment from tanks to desktop computers) has dropped by two-thirds! In spite of this, General Sullivan is still pursuing his idea of digitizing the battlefield by 1997 with passion and vision. And the way he has been going, it might just work.
The M2A3/M3A3 and Bradley Stinger Variants
By now you might be wondering when the Bradley will get the same digital makeover as the M1A2. With its onboard digital data bus and the IVIS vehicle network system, the M1A2 enjoys a tremendous command and control advantage over just about everything else on the battlefield. But the current version of the Bradley has none of these systems; it rides beside the new tank dumb and blind by comparison. Without an IVIS interface, the best Bradley commanders can do is listen for voice radio messages from their Abrams companions.
FMC is leading the effort to get some type of digital command and control system for the M2A2/M3A2. And GDLS modified some six M2A2s into IVIS-capable units for testing and evaluation at Fort Hood and the NTC. In the short term, there will be a program to upgrade the Bradley -A2 fleet with interim kits that can be installed at Army depots or bases. This will probably include the addition of a GPS receiver, a laser rangefinder, and perhaps a simple terminal for the vehicle commander. It will probably not be tied to any of the vehicle systems, and will simply feed its data through the SINCGARS radios. Thus, such vehicles would be IVIS-capable, but not really fully integrated.
Another version coming soon is the Bradley Stinger Vehicle. This variant of the Bradley is meant to fill some of the gaps in the Army’s air defense. Despite excellent performance by Army units firing the Patriot anti-aircraft missile during Desert Storm, things might have been quite different had Iraq chosen to attack forward units with their remaining ground-attack aircraft and helicopters. This is because the forward air defenses of the Army maneuver units were limited to a few obsolete systems, such as the Chaparral anti-aircraft missile, the PIVADS 20mm anti-aircraft gun (an M113 carrying a Vulcan rotary cannon), and the Stinger-RMP light anti-aircraft missile. The Stinger is the best of these, with a state-of-the-art seeker head which can see through almost any combination of decoys and jamming. The problem for the U.S. Army’s armored forces is that Stinger is currently deployed only with man-portable teams and a handful of Avenger anti-aircraft vehicles (HMMWVs with a pedestal mount for eight Stingers and a .50-caliber machine gun).
To help rectify this problem, the Army is developing a version of the Bradley designed as an anti-aircraft system to defend the armored forces. Currently in test, the Stinger Bradley has a new turret and extra stowage in the rear compartment for missiles and 25mm gun rounds. The turret has been modified with the TOW-2 launcher replaced by a four-round launcher pack of Stinger missiles. A new command and control system allows targeting data to be fed from the Forward Area Air Defense System (FAADS) early warning net. The fire-control system was modified to allow firing of the Stingers and engagement of fast-moving air targets with the 25mm chain gun. This also requires Identification Friend or Foe (IFF) interrogation gear. The exact number to be produced, as well as scheduling and fielding doctrine, is still being considered at TRADOC; but the Bradley Stinger is on
its way to becoming the best mobile anti-aircraft platform the Army has ever deployed. The only problem on the horizon is that old bugaboo of money. Somehow the Army must find a way to shoehorn the Bradley Stinger program into an already stretched budget. They probably will; they know that not every future enemy will be as ineffective as the Iraqis!
A long-term improvement to the basic Bradleys will be the M2A3/M3A3 Bradley fighting vehicle. Under this program, FMC would take existing M2/3 chassis from the early Bradley production runs, strip them down, and remanufacture a new vehicle from them, much like the U.S. Army M1A2 program at GDLS. The vehicles would be fully integrated through an MIL STD 1553 data bus, with all analog systems converted to more reliable digital ones. Some of the ideas under consideration include an independent thermal viewer for the commander (like the CITV on the M1A2) and a laser rangefinder/designator to support scouting and laser-guided weapon delivery. New thermal sights would probably take advantage of the second-generation FLIR technology used in systems like the RAH-66 Comanche scout/attack helicopter, providing much better display resolution than existing systems. There will also probably be an inter-vehicular network compatible with the IVIS system on the M1A2. This could be a second generation system that overcomes the data bottlenecks of the current IVIS system (which has a transfer rate of between 1,200 and 2,400 bits per second, about the speed of a relatively slow computer modem). On a more mundane note, FMC is experimenting with a set of inflatable floats to replace the present swim curtains. There are even some unconfirmed rumors of work on plastic fighting vehicles at FMC. Layers of plastic, Kevlar, and other composites might replace portions of the ballistic hull armor on vehicles such as the Bradley. Such a vehicle would have the advantage of being lighter, cheaper to operate (better fuel economy, less wear and tear on components), and might even be “stealthy,” due to the lower radar cross section (RCS) of a plastic upper hull.