AN/ALE-55 Fiber Optic Towed Decoy (FOTD)

The AN/ALE-55 Fiber Optic Towed Decoy (FOTD), manufactured by BAE SYSTEMS Information & Electronic Warfare Systems (IEWS), Nashua, N.H., is an integral component of the joint U.S. Navy - U.S. Air Force Integrated Defensive Electronic Countermeasures (IDECM) Radio Frequency Countermeasures (RFCM) system.

The ALE-55's distinct dynamic fins are key to the decoy's stability. The fins adjust to changes in the air stream and help maintain continuity by minimizing the stress on the fiber optic line. Another key component to the ALE-55 is its towline's unique ability to withstand the intense heat of the F/A-18's afterburner plume. In the past, a decoy's towline would 'burn through' when exposed to a fighter jet's afterburner plume. BAE SYSTEMS worked closely with the Navy, industry, and academia to develop a thermally resistant fiber optic line that has withstood more than three times the required duration of exposure in maximum afterburner.

IDECM incorporates onboard receivers and off-board countermeasures that include the high-powered FOTD and deployment canister. IDECM provides a highly effective electronic warfare defense for U.S. military aircraft against current and future RF missile threats. Currently, the IDECM is slated for deployment on the F/A-18E/F, the B-1B, and the F-15 aircraft.

The AN/ALE-55 fiber-optic towed decoy and the AN/ALQ-214 radio frequency countermeasures (RFCM), designed by BAE Systems and ITT Avionics, were designed to improve aircraft survivability by providing an enhanced, coordinated onboard/off-board countermeasure response to enemy threats. The onboard portion of the RFCM system is designed to receive radar signals from potential threat emitters via antennas on the forward and aft sections of the aircraft and to generate an electronic countermeasures response to the threat. Jamming may use either onboard transmitting capabilities or the off-board transmitting capabilities of a towed decoy. For the off-board response, an effective jamming signal is generated by onboard RFCM equipment and provided to a decoy towed behind the aircraft for amplification and transmission. To reach the decoy, the signal is converted to light and transmitted down a fiber-optic link to the decoy. In the decoy, the light signal is converted back to RF, amplified, and transmitted using antennas integral to the decoy. The ALE-55 FOTD system is different from the operational ALE-50 towed decoy system, in that the ALE-50 has no fiber-optics and generates its own electronic response to enemy threats. Being able to use the processing capabilities of onboard RFCM equipment allows a much more robust threat response for the ALE-55 FOTD system.

In October 2002 the U.S. Navy and BAE SYSTEMS successfully completed a series of flight tests of the BAE SYSTEMS AN/ALE-55 Fiber Optic Towed Decoy on the Navy's new F/A-18 E/F Super Hornet. The success of these tests followed similarly successful test flights on a U.S. Air Force B-1B bomber in June and July 2002. The flight tests, conducted at Naval Air Station Patuxent River, Maryland, were designed to test the endurance and in-flight stability of the FOTD under extremely stressful flight conditions. During these tests, the ALE-55 was subjected to combat representative flight maneuvers. Its fiber optic towline, which connects the decoy to the aircraft, endured multiple exposures to the fighter's afterburner plume. The ALE-55 maintained fiber optic and electrical continuity throughout the entire flight profile.

In September 2002 the U.S. Air Force and BAE SYSTEMS successfully completed a series of on-going flight tests of BAE SYSTEMS AN/ALE-55 Fiber Optic Towed Decoy aboard the Air Force's B-1B bomber at Edwards Air Force Base, California. The tests included the first performance of the decoy while the B-1B was operating at supersonic speeds. During the flight tests, decoys were successfully deployed from the aircraft on four different occasions and were subjected to the most aggressive combat maneuvers attempted to date. The tests demonstrated decoy deployment, safe separation, and in-tow performance while pushing the outer regions of the decoy's flight envelope. All decoys maintained towline integrity until commanded sever during the most aggressive B-1 maneuvers to date. Signal line continuity results varied with the maximum sustained signal continuity for approximately 45 minutes. Preliminary results indicate decoy stability in the supersonic region appears to be exceptional. Supersonic test points included towing the decoys at supersonic speeds while performing multiple wing and airspeed tests.

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