by Tom Clancy
With the dawn of the 1960s came the first helicopters designed from the start to take advantage of turbines. The most notable of these was the Bell Model 204, or UH-1, which became famous as the UH-1 lroquois, or “Huey.” Thousands of these versatile choppers were produced and sent to fight in the Vietnam War. So durable was the UH-1 design that new versions and derivatives were still being produced in 1993. One of those offspring was the AH-1 Cobra Attack helicopter, which first saw combat in 1967 and continues in service with the Army and Marine Corps to this day.
These new helicopters allowed the Army and Marines to develop new tactics: For the Marines, who had lost so many thousands of men storming the beaches of Tarawa, Iwo Jima, and other Pacific islands, it was the concept of vertical envelopment—enabling a Marine landing force to come ashore behind the enemy without warning. For the Army, it meant the resurrection of the 1st Cavalry Division (which had been disbanded after the Korean War), and making the entire unit moveable by air-or “air mobile”-on a mix of different helicopter types. The new troops—called “air cav”—were the most effective force that fought in Vietnam. Able to swoop down on an enemy without warning, their mobility unimpaired by swamp or jungle, the air cav became a nasty surprise to the Communist forces. This surprise did not come without a price to the Americans, though. The Hueys and other helicopters of their generation had virtually no protection against small-arms fire or the man-portable SAMs that appeared in the late 1960s. Thousands of helicopters were shot down in Vietnam, so many, in fact, that the Army cannot give an exact accounting to this day. And then there was the human cost. The early turbine choppers lacked ballistic or crash protection for the crews or fuel tanks, which resulted in high casualties and terrible burns and injuries to crash survivors. Though fixes and new designs were on the way, they never reached units in Vietnam before the end of the conflict in the early 1970s.
The end of the war in Vietnam and the re-emergence of the Soviet Union and the Cold War as the Army’s key focus meant that Army Aviation had to adapt to the new roles and missions of the late 1970s and 1980s. There had been plans to develop a dedicated second-generation attack helicopter to replace the Cobra, but the cancellation of the Lockheed All-56 Cheyenne program in the early 1970s put an end to these plans. The Cheyenne program suffered from a number of problems, as well as from Air Force complaints that it violated existing agreements on what missions the Army was allowed to fly. The final nail in the coffin of the Cheyenne may have been its very performance. Because of its high speed, and the fact that it derived lift from stub wings, the AH-56 was seen by the Air Force as a technical violation of the Key West agreement. (This agreement, a virtual “treaty” between the Army and Air Force, stated that only the Air Force can own armed fixed-wing aircraft.) But above all, Cheyenne was killed by the changing nature of the threat. Designed to attack from medium altitudes in a steep dive, and protected only against heavy machine-gun fire, it would have fared poorly against the radar-controlled automatic cannon and infrared-homing missiles that the Soviets and their clients were fielding in growing numbers in the late ’70s and early ’80s.
Nevertheless, like the Armor branch, Army Aviation recovered from the stillborn programs of the 1960s and moved on with improved ideas for the future. Around 1974, they initiated a pair of new programs, the Advanced Attack Helicopter (AAH, which became the AH-64) and the Utility Tactical Transport Aircraft System (UTTAS, which became the UH-60) to replace the venerable but aging AH-1 and UH-1 choppers that made up the bulk of the Army’s helicopter fleet at that time. Systems that had been planned for inclusion in the AH-56 attack helicopter, notably the TOW missile system, were grafted onto modified versions of the AH-1, to provide an interim anti-armor capability while the Army waited for new chopper designs to reach service. Finally, the Army began to try out new tactical formations and ideas to make use of its growing aviation assets. These included parceling out aviation brigades to all of the Army’s divisions, and not just to dedicated air cavalry formations like the 1st Cav. Also, the aviation community began to integrate their tactics and operational plans with those of the ground forces, so that the overall war-fighting objectives of the Army could more effectively be carried out.
By the early 1980s, these initiatives were beginning to pay off. Army Aviation became a separate branch within the Army in 1983. (Previously, attack helicopter crews belonged to Armor, heavy transport helicopter crews belonged to the Transportation Corps, and scout helicopter crews belonged to the Artillery!) In this way, the Army was saying to its aviators that they were the equals of their Armor, Infantry, and Artillery colleagues. While this may not seem like a big deal, to the aviators it was a special recognition of their combat role. It has also eliminated the kind of infighting that led the Army Air Corps to divorce itself from the Army in 1947. On a more practical level, a whole new generation of helicopter types arrived to enhance the Army Aviation force. Some, like the AH-64A Apache and the OH-58D Kiowa Warrior, opened up whole new capabilities for the Army, like deep-strike and night operations. Others, like the UH-60A Blackhawk and the CH-47D, expanded existing capabilities with improved range and load-carrying capacity. The new helicopters were capable of dishing out awesome firepower and taking punishment that would have destroyed earlier choppers.
Proof of this capability came in Operation Just Cause, the invasion of Panama. And in Operation Desert Storm, Task Force Normandy opened the war, and the mass movement of the 101st Air Assault Division (the only division-sized helicopter unit) to the Euphrates River was one of the war’s final acts. So powerful had the Army Aviation units become that General Franks, the commander of the U.S. VII Corps during Desert Storm, had over 800 helicopters under his command.
Let’s take a look at some of the tools that have allowed them to compile such an impressive record in the past few years.
The AH-64A Apache Attack Helicopter
It’s a nasty-looking beast. I mean, just looking at it, you know you will never see a civilian version as a Traffic-Copter over the city during rush hour. It hardly looks like an aircraft at all. As you walk around it, this monster looks different from every angle. A flying machine, even a helicopter, is supposed to have smooth lines to assist the airflow over its airframe. Not the AH-64 Apache. It has all the direct, in-your-face brutality of some predatory insect spawned on a faraway planet. Except that this one eats tanks, not aphids.
The AH-64 is currently the ultimate expression of the attack helicopter. Its firepower and armor make it the equivalent of a heavy tank flying about the battlefield, day or night, in adverse weather, finding and killing targets at will, almost immune to enemy weapons.
An AH-64A Apache in your face. Note the windshield wiper on the gunner’s front window and the deployed position of the nose-mounted sensors and optics: TADS/PNVS above, laser range finder/ designator and direct-view optics below.
MCDONNELL DOUGLAS HELICOPTER COMPANY
Like the M 1 Abrams, the Apache has its roots in a canceled program. In the case of the AH-64, this was the Lockheed AH-56 Cheyenne. The Cheyenne based its performance more on raw straight-line speed than agility and stealth. Looking for all the world like an angry hummingbird, the AH-56 was designed on the mold of the World War II Russian I1-2 Shturmovik (“storm fighter”), an armored dive-bomber built around tank-killing cannons. Shturmovik’s twin 23mm guns could rip through the roof armor of most Nazi Panzers. Some Shturmovik aces racked up hundreds of tank kills.
In addition to the main rotor, the Cheyenne was equipped with a tail-mounted pusher propeller and stubby wings to achieve high speeds (for a rotocraft—over 300 mph/480 kph). The AH-56 was designed to make high-speed dives on its targets, using a combination of TOW missiles (it was the first helicopter designed to fire the TOW system), 2.75”/70mm rockets, and 20mm cannon fire. The performance of the Cheyenne was impressive, but behind the performance lay some fatal problems. For one thing, the cost of the AH-56 escalated during the years of double-digit inflation in the early 1970s. For
another, a structural flaw caused the loss of one of the prototypes during testing. Worst of all, the high-speed diving attack of the AH-56 put it in the heart of the weapons envelopes of a number of Soviet-designed weapons (such as the SA-7 Grail and SA-8 Gecko SAMS, and ZSU-23-4 Shilka mobile air-defense gun).
Thus, the stage was set for the cancellation of the Cheyenne. When that happened, there were two major results. First, the Air Force initiated the development of a dedicated close-air-support (CAS) aircraft called Attack-Experimental (shortened to AX), which eventually became the A-10A Thunderbolt II. Second, the Army was given permission to start up a replacement program for the AH-56. That program was known as the Advanced Attack Helicopter (AAH). And this became the AH-64 Apache attack helicopter.
The AAH program was designed to provide the Army with a helicopter capable of day and night, adverse-weather operations against enemy armor and other hardened targets. The Army selected a pair of contractors, Bell Helicopter-Textron of Forth Worth, Texas (the maker of the classic AH-1 Cobra), with their YAH-63 design, and Hughes Helicopter of Culver City, California, and Mesa, Arizona, with their YAH-64, to build prototypes for a competitive “fly-off.” Both were excellent designs. The evaluation was long and arduous, and both machines were tested to the limits of their capabilities. In the end, the Army judged the Hughes Helicopters (as of mid-1993 McDonnell Douglas Helicopter Company) entry to be superior in flight performance, cockpit layout, and systems integration. The Army then moved ahead to full-scale development of the Hughes design, now designated the AH- 64A Apache. In 1982, the Apache was deemed ready for production, and the first unit was fielded in 1986. The Army has ordered 811 Apaches from McDonnell Douglas Helicopter, with additional units sold to Israel, Egypt, Saudi Arabia, the UAE, and Greece.
The AAH specification made no compromises in the areas of sensors, weapons, agility, and survivability. Unlike the AH-56, where raw speed was the goal, the AAH design emphasized the ability to sneak along at low level, survey the battlefield, sort out the targets, and launch weapons from long range, outside the enemy’s anti-aircraft range.
Like the Tank Automotive Command (TACOM) with its common mobility specification for all new vehicle designs, the Army Aviation Center at St. Louis, Missouri, has mandated that all new helicopter designs meet certain standards of maneuverability, ballistic tolerance against enemy gunfire, and load-carrying. For example, the AH-64 is invulnerable to 7.62mm projectiles, tolerant against 12.7mm/.50-caliber projectiles, and survivable (able to get home if hit in the power plant/drivetrain/flight-control systems) against 23mm high-explosive projectiles.
The airframe structure is designed to take a 20-G (twenty times the force of gravity) crash without killing the crew, and the fuel tanks are crash-resistant and self-sealing.
New U.S. helicopters have infrared (IR) signature suppression designed in from the start. Infrared-homing missiles are a major threat to low-flying aircraft. The seeker head on an enemy IR-homing missile is looking for the hot exhaust pipe of a gas-turbine engine. One way to reduce the missile’s effectiveness is to mix the hot exhaust gases with a large volume of cooler air, deflect them away from the aircraft, and insulate the exhaust pipes, so that the missile does not “see” hot metal. The AH-64A Apache’s “Black Hole” IR suppressors accomplish this very effectively.
Helicopters also need electronic countermeasures (ECM) to survive on the modern battlefield. ECM is a secretive, ever-changing field; and the technical perfomance specifications of particular systems are usually classified, but a typical “suite” of these black boxes includes:• A radar-warning receiver, to alert the crew when they are being tracked by an enemy radar, so they can take evasive action.
• A radar jammer that transmits signals that drown out or confuse hostile radars.
• Chaff dispensers that release a cloud of metal-coated strips that strongly reflect particular radar frequencies, to clutter up the enemy’s radar screen, concealing real targets.
• Flare dispensers that can “decoy” infrared-homing missiles.
• An infrared jammer—typically an electrically heated “brick” on the tail boom of the helicopter that radiates so strongly in a particular IR wavelength that the sensitive seeker head of an incoming missile is saturated and confused. The current model is the ALQ- 144, nicknamed “disco ball” because of its distinctive shape.
All this makes the current generation of U.S. helicopters the most survivable in the world. Not invulnerable, but very tough indeed as compared to their Vietnam-era predecessors. As for load-carrying, the experience of the Southeast Asian jungles has made hot-climate operations a requirement for all new helicopter designs. The magic number “4,000/95” is used as the measure of helicopter performance. This number represents the vertical flight performance that a particular helicopter can achieve while carrying its standard payload in an ambient temperature of 95° Fahrenheit/35°Celsius at a 95% throttle setting. This approximates the worst possible engine conditions (gas turbines generate their greatest horsepower in cold temperatures; their least in hot, humid climates) that might be encountered in places like the Persian Gulf and Panama. Considering the geography of the world’s trouble spots, this specification makes good sense.
A cutaway of the McDonnell Douglas AH-64A Apache attack helicopter.
JACK RYAN ENTERPRISES, LTD., BY LAURA ALPHER
An Army CWO shows series illustrator Laura Alpher one of the avionics bays on an AH-64A Apache attack helicopter.
JOHN D. GRESHAM
As you walk around the Apache, you get the feeling that nobody actually designed it, but that a group of guys with blindfolds stuck together a bunch of components with glue and sticky tape. The rotor blades droop, the fuselage sits at an almost absurd upward angle, and stuff juts out of the thing this way and that. But all that is misleading; the Apache is one of the most impressively integrated weapons systems in the world.
The outer skin is mostly aluminum semi-monocoque (i.e., the skin and its underlying ribs are formed into a single load-bearing structure); and much of this consists of access panels. The engine covers are designed to support the weight of service personnel and be used as work platforms. In addition, the entire aircraft is designed to be folded, packed up, and carried in a variety of Air Force transport aircraft.
The two engines are General Electric T-700-GE-701Cs with a rated output of 1,800 shaft horsepower (shp) each. They are coupled into a common main transmission, with the tail rotor being driven by a long shaft running the length of the tail boom. This tail rotor, like those on all conventional single-main-rotor helicopters, is used to counteract the rotational torque of the main rotor to maintain the proper flight attitude. The main rotor head, which is above the transmission, carries a four-bladed main rotor, which is designed to be more efficient than the two-bladed UH-1 and AH-1 designs of the 1960s. More blades give you more lift and a smoother, quieter ride—provided that you have the engine power to drive them at sufficient speed, and the engineering skill to design a rotor head that keeps them balanced, controlled, and firmly attached to the aircraft. Some Russian designs have as many as five or six blades.
In fact, the first real sign that most folks have that a helicopter has four blades instead of two is when the familiar “whomp-whomp” sound of the twin rotor is replaced with an aggressive “growl.”
Most of the avionics and other “black boxes” are housed in a pair of fairings along the sides of the forward fuselage, and these provide steps to climb into the cockpit of the Apache. The cockpit itself is separated into forward (for the copilot/gunner) and rear (for the pilot) positions by a thick, bulletproof transparent plate. All of the canopy windows are “flat” panels, which are specially shaped to minimize sun glint (reflections), which can show an enemy the position of the helicopter. The cockpit structure is armored to withstand a direct hit by high-explosive 23mm cannon shells. Both positions in the AH-64 have the standard flight controls (cyclic to control forward/aft pitch, and collective to control power
to the main rotor) and displays to pilot the aircraft, though each has instruments for the specific task of each operator.
The most important of these are the readouts for the Martin Marietta Target-Acquisition Designation Sight and Pilot Night-Vision Sensor (TADS/PNVS) system, which is mounted in the nose of the Apache. The PNVS portion of the system is located in the top turret of the system, and is composed of a thermal-imaging sight (similar to the technology on the Abrams and Bradley) whose movement is tied to the movement of the pilot’s helmet. The helmet is a remarkable item. Individually fitted and adjusted to each crew member, it allows him or her to aim the aircraft’s weapons and sensors with a simple turn of the head.
This system is used whenever the Apache is operated under adverse weather, in heavy fog or dust, or at night. The pilot’s view is displayed on a small round screen attached to the helmet that snaps down directly in front of the pilot’s right eye, above the cheek. This eyepiece also displays other navigational and fire-control data so that the pilot always has the information needed to get around the battlefield.
