New Defensive Avionics for the F-111

Last Updated: Fri May 16 04:19:50 UTC 2008

New Defensive Avionics for the F-111

Australian Aviation, December, 1995

by Carlo Kopp

© 1995, 2005 Carlo Kopp

The RAAF is at this time in the early phases of a major project to replace the now aging defensive avionic suite in the F/RF-111C/G aircraft. The existing defensive avionic suite dates by design to the seventies, and was optimised for defeating the Soviet IADS of the day. This equipment is however becoming dated technologically and this will, by the turn of the century, result in substantial maintainability and supportability problems.

The existing defensive avionic suite is built around the Dalmo Victor (General Instrument) AN/ALR-62(V) radar warning receiver, the Sanders (Lockheed) AN/ALQ-94 and 137 defensive electronic countermeasures (ECM), an AN/ALE-28 chaff/flare dispenser and the Cincinnati AN/AAR-34 Infrared Tail Warning system. When penetrating hostile airspace, the ALR-62 is used to detect and identify threat emitters. Where these cannot be avoided, the ALQ-94 or 137 in the G-model are then used to jam the threat, which is typically the acquisition or fire control radar for a Surface to Air Missile (SAM) or Anti Aircraft Artillery (AAA) system. Approaching missiles in the tail quadrant are detected by the AAR-34 and decoyed with flares or chaff dispensed by the ALE-28 equipment. This suite is conventional by modern standards, but in its time was the most comprehensive of its kind to be deployed in a tactical aircraft. The fact that no USAF F-111E/F aircraft were lost to hostile fire during the Gulf War reflects very favourably, but we should not lose sight of the fact the Iraqis used largely seventies generation Soviet AAA, SAM and acquisition radar systems, which the F-111 EW suite was specifically built to defeat.

The RAAF's AIR5391 project is aimed at replacing the existing defensive avionics, with a target Initial Operational Capability (IOC) around the end of the decade. AIR5391 will be split into several components, the eventual tender calling for the supply of a new Radar Warning Receiver (RWR), Defensive ECM (DECM), Countermeasures Dispenser (CMDS) and Missile Approach Warning System (MAWS). The system is expected to be highly integrated, with all components tied to a dedicated Mil-Std-1553B databus, or if appropriate, a faster bus.

Three components of the upgrade will be open to all bidders, these being the DECM, CMDS and MAWS. The RWR will most likely be the RAAF sponsored DSTO/AWADI ALR-2002 equipment. Understandably the RAAF are cautious about detailing the intended capabilities of the new defensive suite, but some aspects of the upgrade have been revealed to Australian Aviation.

The new DECM will provide fore and aft coverage against pulse mode and continuous wave (CW) SAM, AAA and airborne threats, from C band through to J band. The CMDS is expected to be an intelligent reprogrammable system, with the capability to flexibly accommodate a wide ranges of expendables. The RAAF have not discussed their preferred expendables types, but it is reasonable to assume that these will include chaff, flares and expendable jammers.

The MAWS will be either radar or optical, the RAAF have no preference in this respect. Indications are that potential bidders will be provided with a performance requirement for the equipment, and the bidders will be free to offer their preferred technical solution. It is worth noting that while radar based MAWS offer better detection and tracking performance, they are an active emitting device unlike optical MAWS which passively detect the heat and ultraviolet emissions of missile rocket motors. More complex dual mode MAWS will use passive optical techniques to detect an inbound missile threat, and then employ Doppler radar techniques to track it in bearing, elevation and range to provide optimal parameters for flare and chaff release.

The core of the AIR5391 upgrade will more than likely be the DSTO developed ALR-2002, which is currently in Full Scale Engineering Development by AWA Defence Industries (AWADI). AWADI are in the process of re-engineering the DSTO technology demonstrator (prototype) ALR-2002 design into a production Milspec item. Should the production design pass the RAAF's stringent Acceptance Test & Evaluation (AT&E) process, it will be used, if not an alternative will have to be considered.

The ALR-2002 is of particular significance because it is indigenously developed equipment, the design of which was wholly carried out in Australia. As the RWR is the most critical component of any EW suite, the use of locally built equipment is the safest strategy for safeguarding the effectiveness of the equipment in any strategic circumstances.

The ALR-2002 is intended to be a state of the art Radar Warning Receiver, built with some of the latest semiconductor technology, much of which has been developed locally. This equipment will provide coverage from the C band through to the J band, against pulse mode and CW threats. The equipment can detect, discriminate and display more than fifteen threat emitters, and is capable of cueing external DECM equipment and controlling a countermeasures dispenser where required.

Currently in Full Scale Engineering Development (FSED), the ALR-2002 installation on the F-111 will use a modern microprocessor controller, and will employ non-volatile memory which allows flightline loading of firmware updates. The F-111 installation will employ a new cockpit display, designed and built by AWADI, and the intention is to use the existing ALR-62 antenna suite, should it provide adequate performance. Grown options under consideration could include a laser warning receiver. The ALR-2002 FSED program is expected to be completed by December, 1997, and airborne performance testing is expected in early 1998.

The importance of the ALR-2002 to Australia's domestic industries cannot be understated. It is the first time in many decades that the Australian government has done what most Western nations always have done, and sponsored a domestic high technology program. The ALR-2002 will provide Australian industry with the international credibility which is necessary for the export of high technology, high value added military equipment, as well as providing our industry with an opportunity to demonstrate what can be achieved by our engineers and scientists. It is most unfortunate that many government departments preferentially source foreign built equipment, and the RAAF's commitment to the ALR-2002 project demonstrates that it has the long term strategic vision and courage to defy the self destructive "buy foreign" cargo cult mindset which has so catastrophically gripped this nation in the last decade.

There are many other practical benefits which will stem from the ALR-2002 program. From a military perspective, control of vital defensive technologies is the best guarantee that political pressure from overseas cannot be brought to bear so as to compromise Australia's position in any major dispute or military confrontation. Withdrawing access to core EW technologies is a most effective means of crippling a modern air force. A no less critical issue is cost and timeliness of software upgrades in EW equipment, as changes to internal libraries must be carried out quickly and efficiently to maintain pace with any opponent. Finally, the project will create more work for Australian scientists and engineers, hard hit by the collapse of much of the manufacturing base in the last half decade.

The ALR-2002 is hopefully the first step in the process of restoring Australia's credibility as a developer and manufacturer of cutting edge high technology military equipment. We can hope that the RAAF will be given the support it properly deserves in this matter, and the public recognition due for its contribution to enhancing Australia's long term position in this vital area of military technology.

Pic.1, 2 (AN/ALR-62)

The Dalmo-Victor AN/ALR-62 Radar Homing And Warning System (RHAWS) is the core of the existing F/RF-111C/G defensive avionic suite. This capable receiver is now verging on obsolescence and will be replaced during the F-111 EW Upgrade later in the decade. The leading candidate for this role is the DSTO developed ALR-2002 which is currently in Full Scale Engineering Development by AWADI. The nose mounted antenna suite includes the pyramidal and circular warning antennas, and the pair of unused wedge shaped homing antennas. The trailing edge of the stabilators mount the aft facing warning antennas (author).

Pic.3 (AN/AAR-34)

The bullet on the top of the vertical stabiliser houses the Cincinnati AN/AAR-34 infra-red tail warning system, which was the first ever Missile Approach Warning System (MAWS) fitted to a tactical fighter. The EW upgrade will see this obsolescent system replaced with a modern radar or optical MAWS (author).

Pic.4 (ALQ-94/137)

The dielectric fairing on the leading edge of the glove conceals the forward facing antennas of the AN/ALQ-94/137 defensive jammer, which provides E/F, G/H and I/J band coverage against fire control as well as acquisition radars. This system provides both continuous wave noise jamming, as well as a range of trackbreaking and deception jamming techniques. Subtypes with aft facing jammer coverage employ the antenna cluster in the two bullet fairings outboard of the engine nozzles. The ALQ-94/137 will be replaced with a state of the art defensive jamming system in the upcoming upgrade (author).

Artwork, graphic design and text © 2004, 2005, 2006, 2007 Carlo Kopp; Text © 2004, 2005, 2006, 2007 Peter Goon; All rights reserved.

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