Print friendly version of this article (text only)

The Convair B-58 Hustler was USAF’s ultimate in nuclear delivery systems in 1958. The sleek four-engine, delta-wing aircraft was designed to penetrate Warsaw Pact defenses, outrun the defending fighters, and deliver its payload with stellar-navigated accuracy. The Hustler also employed an unproven and sophisticated electronic countermeasure system made by Sylvania to confound enemy radars as the aircraft made its way to its intended target. "Sylvania had tested the system in its somewhat primitive simulator," recalls Bernie Falk, then a Convair electronics engineer. "But we wanted to see how the system was going to work in the real world." Their answer was to build a lab in Fort Worth, Texas, where the Hustler was designed and developed, to evaluate the ECM equipment. This lab, originally called the Electronic Warfare Evaluation Simulator, was renamed the Air Force Electronic Warfare Evaluation Simulator when the Air Force assumed ownership in the early 1960s.

With AFEWES, as it is now called, Convair engineers investigated ways of thwarting ground-based radars and other defensive systems. They also validated the B-58’s radar-jamming system and its track-breaking system. "More importantly, though, the lab allowed us to test in hours on the ground what would have taken us months to test in the air," Falk continues. "In the process, we simulated the first accurate representation of threat radar antenna patterns. We also simulated the first accurate representation of conical scan-tracking radar, including radar track loops."

Today, AFEWES simulates most known threats in the world to fully evaluate defensive systems. It even simulates newly discovered threats to evaluate new defensive systems. For example, AFEWES was used to test a new electronic warfare technique in 1993 on the Rockwell B-1B bomber when field tests proved ineffective. "We had scheduled another field test in six months with a revised technique," explains Warren Lee, now technical advisor for modeling and analysis at the Air Force Operational Test and Evaluation Center. "But we were hard-pressed to come up with something before we were to repeat that test." When Lee and his staff learned that AFEWES could simulate the threat in question, they used characteristics of the B-1 and its countermeasures in the AFEWES threat simulator to test several possible techniques. During the simulation, one of the AFEWES engineers suggested another technique besides the one being simulated. "We tried the technique right then and there," Warren recalls. "We had never considered the technique before and we would probably never have considered it without the ability to simulate it." The significance of the technique was later verified in a field test. Even better, Warren estimates the cost of simulation at AFEWES was about $5 million less than comparable tests at a flight test range.

AFEWES is also noted for its quick reaction time to short-term requirements. When a surface-to-air missile shot down Capt. Scott O’Grady’s F-16 over Bosnia in June 1995, the Air Force had to determine on short notice how the SAM was able to penetrate O’Grady’s ECM system. Before O’Grady was even rescued, AFEWES was determining how to correct the radar-warning system.

"We programmed the radar-warning receivers like those on the aircraft O’Grady and his wingman were flying," relates Lt. Col. Linda Palmer, former AFEWES director. "Then we put the radar-warning system into the dynamic situation of the battle area and transmitted the same signals that the two aircraft actually saw. With the same electronic order of battle, we ‘flew’ the aircraft in the same scenario that existed over Bosnia. As a result, we could say with confidence what the radar-warning receivers on those two aircraft actually saw." The correction worked; no more F-16s, or any other aircraft, have been lost in the area since.

Earlier in its history, AFEWES was put to use to counter SAM threats in the skies over Vietnam. Craig Johnson, then with USAF’s Special Communications Center at Kelly AFB in San Antonio, recalls that AFEWES and Calspan Corp., of Buffalo, New York, studied new tactics for future air attacks on targets in North Vietnam. Calspan used its large REDCAP simulator to investigate how an air defense system network functioned. That information was then used to spot targets for electronic countermeasures.

"Calspan ran a simulated attack on the air defense system until the attacking aircraft neared the point of launching defensive missiles," remembers Johnson. "Then we loaded that data into the AFEWES simulators and worked out exactly what the defensive systems would be doing on the ground. AFEWES simulations showed exactly what would happen. And it happened just as we predicted. From this information, we could successfully counter the air defense system.

"During the Vietnam conflict, we developed measures to disrupt enemy defenses," continues Johnson. "These tactics worked until the enemy came back with countermeasures. We then devised counter-counter measures. And so on. Vietnam was also the first conflict in which we applied human factors engineering to simulations to find out what a potential threat would do in a given situation. Based on those evaluations, we derived what information a particular threat needed to make a critical decision."

Many of the ECM devices used on US aircraft today were developed with AFEWES during the Vietnam conflict. In the early 1960s, AFEWES was used to help develop an ECM system for the Lockheed U-2 reconnaissance aircraft. "Before that, the U-2 hadn’t bothered with an ECM system," says Jerry Little, a retired AFEWES test manager. "The aircraft flew so high that no one considered such a system necessary." But the Cuban missile crisis convinced USAF that the U-2 was no longer safe against radar-guided defensive systems. Accordingly, AFEWES was used to evaluate candidate ECM suites for the airplane. Then AFEWES engineers also supported the planning of each U-2 mission over Cuba during the missile crisis.

Today, AFEWES is a major link in USAF’s electronic combat test process, which is administered by the 412th Test Wing at Edwards AFB. The Fort Worth facility provides the first point in the electronic combat test process in which hardware is challenged to demonstrate its effectiveness against hostile threats. This capability, rare if not unique at a single site, has drawn the attention of many US allies who come to Fort Worth frequently to test their own electronic warfare designs and concepts. These international visitors take advantage of a high-fidelity realtime test as well as the complex background signal environments, clutter, fully dynamic maneuvering target engagements, and operator interaction of the simulation. AFEWES tests the actual hardware of a system, not just its theoretical or calculated performance.

Originally, AFEWES could simulate only a limited number of threat radars. Through the years, however, USAF has invested $350 million and developed more than thirty different threat simulators to bestow AFEWES with unparalleled capabilities in electronic warfare system test, evaluation, and development. Many of the threat signal generators are not simulations but real equipment that has been acquired and placed at AFEWES. If actual equipment is not available, such as on some newly discovered threats, accurate simulations are provided and updated as more data become available.

Among the threats AFEWES can represent in the test laboratory are Russian-built SAMs from the SA-2B up through the SA-18, Redeye, and Stinger Basic; air-to-air missiles from the AA-6 through the AA-11, the AIM-9L, and AIM-9M; airborne radar interceptor systems of Russian-built combat aircraft, such as the MiG-21, MiG-25, MiG-29, MiG-31, and Su-27; and antiaircraft artillery, such as the Russian ZSU-23-4 and RPK-1.

Housed in a 42,000 square-foot secure facility, AFEWES is a hardware-in-the-loop test laboratory with a wide range of high-fidelity radio frequency and infrared threat simulators. These simulators are sufficiently accurate to permit the developers of electronic combat systems to test their devices in a controlled, ground-based environment with great fidelity. Within this realistic environment, simulated engagements can be fought with electronic warfare systems operating in realtime at the proper frequencies or wavelengths. These engagements can include the effects of "hostile" operators acting within the loop and affecting the actual progression of the test.

AFEWES played a major role in the development of towed decoys, now used on US military aircraft, by proving the concept feasible in the early 1980s. Gene Starbuck, today a section head and program manager at the Naval Research Laboratory in Washington, notes that the basic concept for a towed decoy had been developed in the late 1970s as a potential counter to monopulse radar. "We proved the effectiveness of the towed countermeasure concept at AFEWES, which led to the integrated defense selectable countermeasures concept," explains Starbuck. "We still go to AFEWES, where both the Air Force and the Navy are working, to find the best tactics to use with towed decoys and to evaluate their potential against new threats."

In addition to simulating threats, AFEWES uses various environmental simulators to provide a realistic battle environment for these simulated threats. A large part of this capability comes from the facility’s multiple emitter generator, an open-loop simulator that evaluates radar-warning receivers or power-managed ECM systems. This system can simulate all hostile, friendly, and neutral signals in any specific theater, just as they would be encountered in actual combat. Foreign signals that can be simulated include the Russian Slot Back, Flashdance, Billboard, and Grill Pan; the French-developed Crotale; the British Fox Hunter; and the German Super Fledermaus. Virtually all US-developed signals can also be represented, right up to the AN/APG-66 in the F-16.

The multiple emitter generator affords seventy-three physical RF sources that can represent seventy-three simultaneous emitters or more than 200 emitters when time multiplexing is employed. Realistic features, such as terrain masking effects and the capability of being integrated with an external manned flight simulation cockpit, provide highly realistic evaluations.

AFEWES has two infrared test laboratories that can operate independently, together, or with one of the radio frequency simulation systems. The older of the two labs began operation in 1965; the newer lab began operation in 1992 to keep AFEWES in step with the rapidly developing infrared countermeasure technologies.

Both labs are closed-loop systems that can develop specific countermeasure systems, such as flares and jammers. Both labs use a free-space, folded optical path transmission system to present true wavelengths of target signature, infrared countermeasures, and flare effects to infrared seekers mounted on a moving flight table that accurately simulates dynamic flight conditions. These air-to-air seeker simulations can link directly to airborne interceptor radar simulations for more realistic battlefield scenarios. The newer lab can evaluate passive missile warning systems as well as infrared countermeasure systems.

Both the IR and RF laboratories at AFEWES generate vector components for both the target and the threat missile throughout the complete simulated engagement. These components provide true position and attitude data necessary to calculate Probability of Kill and Reduction of Lethality, two measures that quantify the effectiveness of a defensive system.

To achieve the ultimate in testing defensive electronic combat systems in a real-world environment, AFEWES can be tied to any manned flight simulator cockpit operating in a domed dynamic visual simulator. A pilot in the cockpit of the visual simulator can see the realistic flash of a missile launch and then decide whether to evade it by maneuvering, by employing electronic countermeasures, by employing infrared countermeasures, or by employing any combination of reactions. This interactive testing provides the best means of evaluating the overall ability of the aircraft to evade attacks by guided missiles or guns.

AFEWES facilities have also been electronically linked to other research facilities in the United States and in Europe. These links include digital computer models, system integration laboratories, hardware-in-the-loop labs, installed system test facilities, and open air ranges. Other facilities linked to AFEWES are at Patuxent River, Maryland, and at Spangdahlem AB, Germany.

Despite the facility’s impressive historical record and the extensive government investment in both equipment and experience, AFEWES is not guaranteed a bright future. It will have to continue to show that it can do the job of supporting the warfighter better than any other facility. All three services have facilities that can do part of the job that AFEWES is now doing, but none of them can match the entire AFEWES capability at a single location.

"We are trying to be realistic and believe that the facility in greatest demand and that best supports the fighting team will be the one that survives," says Lt. Col. Jaime Silva, the current USAF director at AFEWES. "Because of this realization, all capabilities added to AFEWES will be those needed to meet modern warfighter needs.

"We are often asked how representative the results are that come out of this laboratory, and we continue to say that they compare favorably to the results we get in live test firings," Silva adds. "Part of our job is to convey the value AFEWES continues to add to our nation’s warfighting abilities."