by Tom Clancy
“The best ECM in the world,” said an Israeli general famously, “is a 500 lb./ 227.3 kg. bomb down the feedhorn of the missile-tracking radar.” He was right. But how many aircraft would he lose getting into position to hit a given SAM radar? Fixed SAM sites tend to be protected by layers of optically tracked AAA guns. Thus early USAF plans to hit such sites in Cuba (during the 1962 missile crisis) with tactical fighter bombers loaded with unguided rockets and canisters of napalm would have undoubtedly exacted a high price.
Meanwhile, the U.S. Navy, long a leader in SAM technology, began to think about the problem of suppressing SAM sites. In 1961, out at the same Naval Ordnance Test Station laboratory that had developed the Sidewinder and Sparrow AAMs, an idea was born that might provide a remedy. Known as an anti-radiation missile (ARM), it was quite simply a missile designed to home in on the emissions of the SAM tracking radar, guiding in to kill the radar. By killing the radar, and hopefully its skilled operators, the SAM site would effectively be “blinded” and unable to function. The first of these missiles was known as the ASM-N-10, later designated the AGM-45 Shrike, taking its name from a predatory bird that kills its prey by impaling them on the thorns or spikes of plants or fences. Simple in concept, the Shrike took some time to perfect; the first AGM-45 Shrike missiles entered fleet service in 1963.
Along with the development of the ARM came a vital piece of equipment which was required to make it functional, the radar homing and warning receiver (RHAW), or radar warning receiver (RWR) as it is known today. Amazing as it may sound, no U.S. tactical aircraft sent to Southeast Asia in 1965 went with any sort of warning system to tell the aircrew they were being tracked by enemy. Thus, when President Lyndon Johnson began the systematic bombing of North Vietnam, with Operations Flaming Dart and Rolling Thunder, USAF, USN, and USMC aircraft began to fall in numbers that were more than just disturbing.
Interestingly, the USAF took a different approach to suppressing SAMs than the Navy or the Marine Corps. The Navy/Marine policy on SAM suppression was just that: prosecute to suppress just long enough for the strike force of attack aircraft to hit their targets, and then run for the safety of the aircraft carrier or home base. In fact, the policy of avoiding duels with air defense sites is at the foundation of USN/USMC strike warfare doctrine even today. Thus, from early 1966, USN defense suppression efforts centered around A-4 Skyhawk attack aircraft equipped with an early RWR and a pair of the new ARMs.
The USAF doctrine is completely different. For the Air Force, it was not enough to scare the operators of the SAM and AAA radars. In the view of the Air Force leadership, those individuals, and their machines of war, were there to be killed. Thus, the Air Force formed a small force of specially configured aircraft and handpicked highly trained aircrews to do the critical job of radar hunting. These were the famous “Wild Weasels,” initially flying two-seat versions of the famous F-100 Super Sabre, configured with RWR gear, rocket pods, and napalm canisters. Although they were successful in lowering losses from SAMs to the aircraft of the strike forces going “up north,” their own losses were prohibitively high. Thus, integrating the new AGM-45 Shrike became a “crash” priority with the USAF. When this was done, losses among the Wild Weasel F-100Fs began to drop, and the crews began to have a future. Not much of one, though. Being on a Weasel crew was statistically suicidal in the early years of the Vietnam conflict.
However, the Shrike had significant tactical limitations and shortcomings. One big one was range. At high altitudes, the Shrike could hit radars some 21.7 nm./40.3 km. distant, while low-altitude launches could be up to 15.6 nm./ 29 km. away. But in practice, launch ranges were usually less than half of the maximum, because certain functions necessary to targeting the missile had to be performed. Most dangerous of these was a maneuver known as a “Shrike pull-up.” The launching aircraft had to go into a 15° climb just before launching the ARM; otherwise it would not successfully hit the target radar van. And if the enemy radar shut down while the Shrike was streaking down onto the target, the ARM was likely to miss, lacking as it did the necessary radar emissions for it to home in on. It was, as they say, a very tough business.
From the very beginning of its use, the Navy and Air Force were unhappy with the Shrike’s performance. In 1969, the U.S. Navy conducted a Tactical Air Armament Study which looked into shortcomings of Shrike and the whole range of USN/USMC air-launched weaponry. From this study came a whole set of requirements which led to the beginning of a development program for a new ARM program. The new missile would be small, with the same general weight and shape as the Shrike, but with greater range, speed, accuracy, and lethality. Also, it would operate from the full range of USN/USMC tactical aircraft, both planned and in service, and would both outrun and outsmart the SAMs and radar operators for every Soviet and other potentially hostile SAM system, even those still under development. It was a tall order for the program engineers at NWC China Lake, California, when they began the new program in 1972. Called the High Speed Anti-Radiation Missile, or HARM, the new missile, designated AGM-88, would take over a decade to bring into service, and would undergo many of the same trials and problems suffered by other advanced missile systems, such as the AIM-120 AMRAAM.
HARM was the first really “smart” air-to-ground missile developed by the United States, using for the first time the new technology of microprocessors and computer software. In other words, HARM was a technical “stretch”—betting that a number of immature technologies ranging from high-impulse rocket motors to a new generation of RWRs would come together all at once, some years in the future, within some sort of cost ceiling. Not everything went as planned. Still, by 1974 Texas Instruments was selected as the prime HARM contractor, and advanced development was under way. And by 1978 the first test firings were under way at NWC China Lake. By FY-1981, the first eighty missiles were under contract, and they headed into fleet service in 1982.
The new missile was called the AGM-88A. And the AGM-88C1 (Texas Instruments) variant is the most common version produced today. The basic -C model missile weighs in at 798 lb./362.7 kg., is 164.2 in./417 cm. long, and is based on a 10.5 in./26.7 cm. diameter airframe with a forward (guidance) fin wingspan of 44 in./112 cm. At the front of the missile is the radome for the Texas Instruments Block IV seeker, which has vastly more capability than even the -B model birds of just a few years ago. Behind the bullet-shaped seeker dome are a series of broadband antennas, which are designed to provide all the functions of an aircraft RWR system, as well as providing passive targeting for the missile guidance system. When we use the term “broadband,” we’re talking about everything from .5 to 20 GHz; this covers everything from UHF radio transmissions to short-wavelength fire control and ground-mapping radars. These antennas feed into a microprocessor-controlled digital signal processor, which is capable of breaking down all the incoming signals and translating them into a prioritized target list. This is accomplished via the reprogrammable onboard threat library, which can be used “as is” by an aircrew or customized for a specific threat or situation. With the new seeker, even rotating air traffic control and phased array radars (like those used on the Aegis and Patriot SAM systems) can be effectively targeted and attacked.
A cutaway drawing of the Texas Instruments AGM-88C1 High speed Anti-Radiation Missile (HARM). Jack Ryan Enterprises, Ltd., by Laura Alpher
Just aft of the seeker section is the warhead section. This is a 145 lb./65.9 kg. blast fragmentation-type unit, with a laser ranging proximity fuze, similar to that of the Sidewinder and the AMRAAM, which spews its twelve thousand tungsten cubes into the heart of the target radar. Behind the warhead section is the guidance/control section, which flies the missile during flight. This is accomplished by a digital autopilot equipped with a strapdown inertial guidance system, driving a series of electro-mechanical actuators which control the large guidance fins mounted along the mid-body of the AGM-88 airframe. Like the Paveway III, the autopilot allows the missile to fly the most energy efficient flight profi
le and make the most of the “smash” provided by the HARM’s rocket motor. Located just aft of the guidance section is a TX- 481 dual-grain (two-stage), low smoke (to prevent observation), solid fuel motor supplied by either Thiokol or Hercules. It is this motor that generates the incredible speed that gives the missile the first letter in its designation. The top speed, while classified, is probably greater than Mach 3, possibly as high as Mach 4 or 5. This allows it to outrun almost any SAM system in a “quick draw” contest, should that occur. It also provides for a vast increase in range over the Shrike, probably up to a maximum of perhaps 80nm./ 146.3 km. from high altitudes (say 30,000 feet/9,144 meters), and 40 nm./ 73.2 km. when launched as low as 500 feet/152.4 meters. Normally, these ranges would probably be halved, to maintain a performance advantage over any SAMs that might be counterfired against the launching aircraft. The AGM-88 is normally carried on an LAU-118 standard launcher.
From the very beginnings of the HARM program, the Air Force maintained an interest in the new ARM. They too wanted the benefits of such a weapon, and joined in the program at their first opportunity. Initially, their participation included the development and integration of the APR- 38 (later upgraded to the APR-47 standard) RWR suite on the F-4G Wild Weasel variant of the Phantom, which was the primary USAF aircraft assigned to the suppression of enemy air defenses (SEAD) mission at the time. The APR-38/47 is a group of RWR systems, tied together to allow the F-4G WSO (technically called an Electronic Warfare Officer or EWO, but known traditionally as the “bear”) to accurately plot the positions and characteristics of hundreds of enemy threat emitters. By integrating HARM with this system, the F-4G became a radar hunter of amazing lethality, taking only one loss during Operation Desert Storm—and that happened because an Iraqi AAA round punched a hole in the aircraft’s fuel tank; it wasn’t able to land before running out of fuel. The crew survived the mishap without injury.
In addition to the dedicated Wild Weasel aircraft, the Air Force made several of their other new aircraft designs capable of carrying and firing the new ARM. Both new variants of the F-15 and F-16 can do so, given the right RWR systems, launch hardware, and software. And the F-16C has been extensively used to augment, and now replace, the aging F-4Gs that are on their last legs of service. As the last of the precious F-4Gs are going to the boneyard for a well-earned retirement, the F-16 is taking over all of the SEAD/HARM mission, thanks in part to the introduction of the ASQ-213 HARM Targeting System (HTS) pod. By combining the HTS pods with data exchanged from other F-16s via the Falcon’s IDM, a rough approximation of the F-4G’s SEAD capabilities can be reconstituted, without a gap in this badly needed resource.
So how would a pilot fire such a weapon? Well, let’s imagine that we’re flying a Block 50/52 F-16C, equipped with an ALR-56 RWR and an ASQ-213 HTS pod attached to the Station 5 (right) pod mount point. You and your wingman each have two HARMs on LAU-118 launchers at Stations 3 and 7. The two of you are flying a loose hunting formation ahead of a strike force, with a lateral separation of about 5 nm./9.1 km. You have been briefed about hitting a pair of Buk-1M/SA-11 Gadfly SAM sites on the ingress route of the strike force, and told to look out for possible mobile SAM launchers, which may have been moved into the area. The two of you have set up your IDMs to exchange HTS data and are flying subsonic at about 350 kt./640 kph into the target area. Down on the multi-function display at your right knee is the readout for the HTS pod data, showing a rotating acquisition radar of the type used to pass targeting information to SAM transporter erector launcher and radar (TELAR) vehicles. At approximately 30 nm./54.9 km. to the target area, the two of you set up a pair of diagonal racetrack-shaped patterns and wait for the action to begin.
As the strike force begins to come up, you see a pair of symbols titled STA 11 come up on the MFD, with indefinite range indications. You call a warning to the strike force to go “heads up” for a possible SA-11 threat, and go to work. In a matter of seconds, your and your wingman’s HTS pods have worked out approximate range and bearing to both sites. This done, the two of you each set up a HARM in RK MODE (RANGE KNOWN) and get ready to launch. Within a few seconds, the range to both SA-11 TELARs has settled down, and been fed automatically to the HARM, and you see the two vehicles going for a lock-on with their radars on your RWR. You select MASTER ARM ON and pull the trigger once to launch the missile from Station 3. As the missile flies off, you turn to keep on the edge of the TELAR’s maximum range. Thirty seconds later, you see the symbology from both TELARs go off the air as they are destroyed by the two AGM-88s. The two of you now move out in front of the strike force to continue escorting them to the target area. About 10 nm./18.2 km. to the target, you get a sudden warning alarm from your RWR, indicating that a missile-tracking radar has just locked up your Viper. A quick look at the RWR shows the STA 8 symbology indicative of an SA-8 Gecko TELAR somewhere off to the right front. You quickly select the SP MODE from the HARM options, the azimuth setting being automatically sent to the remaining HARM at Station 7. You squeeze the trigger one more time, call a warning to the force, and begin evasive maneuvers, punching out chaff as quickly as you can. Within a matter of seconds, the SA-8 TELAR goes off the air, another victim of the superior speed of the AGM-88. Meanwhile, the one missile it launched at you goes “stupid,” flying off to self-destruct somewhere else. The force is safe for now, and you move to a covering position to make sure no wandering MiG tries to hassle your wingman or the rest of the force. Just another day’s work.
Today the Texas Instruments AGM-88 production line is going strong, continuing to build the 2,018 replacement HARMs that were contracted to replenish the stock fired during Desert Storm, as well as the foreign orders that are being serviced. There are no known plans to replace the AGM-88 at this time; and there will probably be none in the near future, given the general stagnation in the worldwide SAM development market and the remaining growth potential in the HARM airframe. As for the AGM-88 HARM, it should remain the premier ARM in the world for at least the next ten years.
THE FUTURE: TSSAM AND BEYOND
The future of U.S. long-range air-launched standoff weapons is, to put it mildly, in disarray. This is the unhappy result of the cancellation of a weapon that the USAF and USN had bet the farm on—the Northrop Grumman AGM-137 Tri-Service Standoff Attack Missile. TSSAM was to have been a stealthy, superaccurate, long-range (180 nm./300 km.) guided missile with versions for the Navy and Air Force, and even a ground-launched version for the Army. Unfortunately, development and program management problems drove up the cost of the program. And it took a severe hit when the Army dropped out several years ago.
Since the TSSAM program was canceled, the Air Force has been scrambling to figure out how to provide their combat aircraft with a viable precision standoff missile. The current plan has the USAF buying more of what they already have, ALCM-Cs. Several different options are under consideration to fill the gap left by the cancellation of TSSAM. Some of these include:• Buying the clipped-wing version of the AGM-142 Have Nap, and fitting it to the B-1B, the F-15E Strike Eagle, and the F-16C. This would provide a large part of the capability promised by the original TSSAM program.
• Retrofitting the IIR seeker developed for TSSAM to existing missile airframes like the AGM-86C/ALCM-C or the AGM-84E SLAM/ SLAM-ER, which is a development of the Navy Harpoon anti-ship missile.
• Producing a reduced-cost version of the AGM-137 TSSAM, with the stealth features installed only on the frontal surfaces of the airframe. This is probably the least likely option, given the current budget climate and the general lack of funding for new weapons systems.
Whatever the decisions reached in the halls of Congress, the Pentagon, and the USAF Material Command, there will have to be new gopher zappers, which will undoubtedly be joint programs with the Navy, and perhaps even foreign partners. That is perhaps the greatest impact of the New World Order on the worldwide weapons market—only through cooperation will the industry survive.
Air Combat Command: Not Y
our Father’s Air Force
ONCE upon a time in America, there was an Air Force. It was created in 1947 as a separate service (from the U.S. Army), with a simple set of goals: to deter our primary Cold War enemy, the Soviet Union, from expanding beyond its borders, and, if deterrence failed, to successfully fight the Soviets with the other armed services and achieve victory. For over forty-five years, the United States Air Force stood up to the challenge and outlasted its opponents. This is not to say it did so in the most efficient, economical, or even acceptable way. Its bitter turf battles with the U.S. Navy are legendary around Washington, D.C. Also, like all large organizations, the USAF was prone to internal conflicts. Throughout the Cold War, there were continuous squabbles between the primary commands of the USAF. The bomber pilots and ICBM missileers that made up the leadership of the Strategic Air Command (SAC) were always at odds with the fighter pilots who led the Tactical Air Command (TAC). If this was not divisive enough, the “combat” fliers at SAC and TAC scorned those who flew the transports for the Military Airlift Command (MAC), whom they considered “trash haulers.”
And in 1991, the U.S. Air Force suffered the greatest disaster (save defeat in battle) that can befall a military force. Its primary enemy, the Soviet Union, collapsed as a result of the failure of the August Coup. Of course, only a truly sick and cynical observer of world events would have wished the Cold War to continue indefinitely. Yet scarcely anyone foresaw the end of the conflict between the U.S. and the USSR and the end of the bipolar world we’d known for half a century. Now, if you think you were surprised, you should have seen the shock of the armed services leadership!
