Tactical Aircraft Directed Infrared Countermeasures System Overview

K.A. Sarkady, H.A. Romero, D.M. Cordray, J.G. Lynn, and R.M. Mabe
Optical Sciences Division

K. Strothers, J.A. Schlupf, and R.C. Cellucci
Raven, Inc.

An Emerging Weapon of Choice: Shoulder-fired surface-to-air missiles (SAM) are widely proliferated, relatively inexpensive, and easy to conceal. An emerging market now exists making these weapons available to numerous insurgency and terrorist organizations. In November 2002, al-Qaida claimed responsibility for firing two SAMs at an Israeli civilian aircraft during take-off in Kenya, raising concern throughout the Western world about the safety of civilian air travel. By contrast, military aircraft have long been susceptible to infrared (IR) guided SAMs and air-to-air missiles (AAMs). Results of a worldwide survey, shown in Fig. 1, indicate that these missiles are responsible for well over 50% of all military aircraft losses. These three factors (availability, price, and record of performance) make IR SAMs and AAMs an emerging weapon of choice.

TADIRCM: The Tactical Aircraft Directed Infrared Countermeasures (TADIRCM) system has been designed to provide Navy and Marine Corps fixed and rotary wing platforms with covert, highly effective protection against even the most advanced IR-guided SAMs and AAMs. The system uses a suite of two-color IR sensors to passively detect the afterburning signature of a threat missile plume. Judicious choice of the operating wavelengths and system optics allows for the detection of these missiles' boost ignition signature well beyond their maximum kinematic launch range, even if operating in severe (measured) urban clutter conditions. An onboard digital processor provides the system with the capability to autonomously cue a directed jamming system that can establish a precision track on the approaching missile using a high-resolution IR camera. A modulated laser beam is then used to create false targets in the missile seeker, causing optical break-lock (OBL) of the targeted platform. The use of an onboard laser provides for essentially unlimited platform protection. This constitutes an extremely desirable capability since the protection currently available to Navy platforms is severely limited by the number of countermeasure assets that can be carried onboard.

Live-Fire Testing of the TADIRCM System: Figure 2 shows the TADIRCM system components. These components were installed on an aircraft pod mounted on a QF-4 drone aircraft (Fig. 3). System performance was tested on the QF-4 from the spring of 2001 to November 2001. Testing resulted in OBL in each one of an advanced SAM and AAM fired against the QF-4. The ability of the TADIRCM system to rapidly declare the onset of boost ignition resulted in very large miss distances in each of these live-fire exercises.

Confidence in the capabilities of the TADIRCM system was established in a number of intermediate tests conducted at the Navy's weapons test range in China Lake, California. The ability of the system to reliably declare a threat missile was conducted (frequently) with the help the of the Optical Beam Evaluation and Wander (OBEWAN) instrument. This instrument generates an IR signature whose intensity, spectral content, and temporal properties closely resemble NRL's large database of exploited threat missile signatures. For this portion of the test, the OBEWAN signature needed to correspond only to that seen in the missiles' boost motor ignition phase.

Testing of the TADIRCM system then focused on evaluating its ability to deliver laser beam energy at the desired target. To this end, a number of seekers of the two selected live-fire missiles were placed in the vicinity of the OBEWAN instrument. While flying in a racetrack pattern, TADIRCM was repeatedly stimulated and the OBEWAN instrument was used to measure the spatial and temporal properties of the laser beam. Simultaneously, the missile seeker electronics were monitored to determine OBL of the QF-4 target. This portion of system testing was very successful and resulted in OBL of all tested seekers in every pass of the QF-4. In all cases, OBL was measured to occur on very fast time scales. This portion of the test also confirmed the favorable power levels and spatial properties of the laser beam at all launch ranges of tactical interest.

At this point, all checks of system performance were successfully achieved and testing proceeded by firing one advanced SAM and AAM at the drone QF-4. In each case, the missiles were equipped with special telemetry packages that monitored the internal state of the missiles' seeker electronics. Timelines for all of the system events (missile launch, missile threat declaration, time to slew and establish track by the fine pointer-tracker, time to deliver laser energy, and time to OBL) were carefully monitored and cross-correlated. In each case, system performance was excellent and corresponded closely to that established in all preliminary tests of the TADIRCM system. The ability to rapidly declare the onset of boost motor ignition resulted in timelines for laser energy on target prior to the missile achieving a guided proportional navigation flight pattern. Hence, the miss distances in each of these tests well exceeded those needed for aircraft self-protection. In the case of the AAM, this test constitutes the first time that such a threat has been successfully countered in a live-fire scenario. For completeness, Fig. 4 is a graphic illustration of a TADIRCM live-fire engagement.

Conclusions: The Navy has successfully tested TADIRCM, resulting in a great deal of interest in establishing a production program for this system. Current planning calls for the production of several pod units to be delivered to the Fleet to establish configurational and operational procedures for this electronic warfare system.

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