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Aussie Aardvark--the General Dynamics F-111
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Above: A 1 Squadron F-111C armed with a mixed weapons load of GBU-12 Paveway LGBs and Harpoon makes a high-speed low-level pass over SE Queensland. Note the distinctive yellow '1' and unit emblem on the fin. (RAAF)

F-111.net thanks AIR International for granting permission to republish this article.

AIR INTERNATIONAL APRIL 2000

Written by John Lake.  
Graphics by Mike Badrocke

As the Royal Australian Air Force reviews its future policy, John Lake looks at the F-111 which, through a series of update programmes, is likely to remain of pivotal importance for another two decades.

AUSTRALIA is today the only operator of the General Dynamics F-111, a type it has modernised and upgraded for continued service until 2020, when it will have amassed 47 years of Royal Australian Air Force (RAAF) service. Even more incredibly, the type will by then have been out of service with its primary customer, the US Air Force, for 22 years. The US Air Force withdrew its last F-111s as part of the general post-Cold War draw-down in July 1996, and its last EF-111As in 1998.

Optimised as it was for the nuclear strike role, the F-111 was a weapons system reserved for the USA and its closest and most vital allies. In the event, the aircraft was exported only to Australia, a British order for the F-111 being cancelled before any aircraft could be delivered. In Australia the F-111, with its heavy punch, long range and all-weather capability, has always been of pivotal importance. Interestingly, the F-111C has about three times the payload/range capability of the Boeing F/A-18 Hornet, the RAAF's only other front line fast jet, and Australia's geography makes long range of crucial importance.

Developed under the US Department of Defense's TFX programme, the F-111 was planned as a multi-role tactical fighter which would replace the USAF's Republic F-105 Thunderchiefs in the nuclear strike role and also serve as a fleet air defence interceptor with the US Navy. Escalating weight soon killed off the US Navy sub-variant, while technical difficulties and cost escalation nearly killed off the USAF version.

Counter to TSR2

The US offer of the F-111 to Australia as a replacement for the RAAF's English Electric/Martin Canberras is still regarded by some as an indication of the seriousness with which the US DoD wanted to kill off the rival British BAC TSR.2. Britain itself promised to be an important customer for the F-111 if the TSR.2 was cancelled, while a successful TSR.2 threatened to be a most unwelcome competitor to aircraft like the McDonnell Douglas F-4 Phantom and North American Rockwell A-5 Vigilante, and to the F-111 itself. Australia switched its attention from the TSR.2 only when it became clear that the British official opposition (likely to form the next Government) was hostile to the aircraft, as was Admiral of the Fleet Lord Mountbatten, who personally intervened to persuade the Australians that the TSR.2 had no future. (1)

Even after the TSR.2 was rejected, many senior Australian officers favoured the A-5 Vigilante, but selection of the F-111 was finally announced on October 24, 1963, at a 'maximum cost' of $A112 (45)m for 24 aircraft. The US Australian Memorandum of Understanding (MoU) outlined that 18 of these would be F-111A 'bombers' (for delivery from late 1967) and six were planned to be RF-111A reconnaissance (recce) versions (for delivery from November 1969). Provision was made for the delivery of a further six a further six aircraft and for attrition replacements at terms 'no less favourable'.

It was proposed that the RAAF would briefly receive two squadrons of B-47Es and RB-47s as an interim loan, on a cost-only basis. This plan was soon cancelled, since the loan would have imposed massive disturbance and support costs.

Because the price to be charged to the RAAF was worked out as 24 times the average unit production and development cost at the time of delivering the 24th aircraft, it was believed that as early teething troubles were sorted out and 'economies of scale' started to 'kick in', the price would drop. Unfortunately, the aircraft was to suffer from massive and costly early problems, while orders for the USAF were reduced, relentlessly driving up the unit cost.

Delays to the USAF's RF-111 programme soon began to 'knock on' in the Australian programme, and it rapidly became clear that if the original delivery timetable was to be met, the RF-111s would have to be the extra six aircraft or would have to be returned to General Dynamics for retrofit in about 1970. The latter soon became Australia's preferred option, since there was an unwillingness to commit beyond the 24 aircraft originally ordered, with increasing costs and a rising tide of political, press and public opposition to the aircraft's procurement.

In April 1966, the configuration of Australia's F-111s was changed, and instead of receiving standard F-111As, it was decided that the RAAF would receive an F-111A-based hybrid (designated F-111C), incorporating the longer span wings and strengthened undercarriage of the new Strategic Air Command FB-111A variant, but without that version's advanced avionics.

First delivery

The first F-111C was officially handed over at Fort Worth on September 4,1968 having flown in July), but within three weeks of this ceremonial hand-over it had been decided to delay deliveries, pending modifications. This halt was prompted by the F-111's eleventh fatal accident, at Nellis AFB, in which an RAAF officer under training was killed. (2) The incident led to major repairs to the wing boxes of all F-111s, but even before these could be completed, fatigue cracking in the same area forced further modifications. In December 1969 (shortly after the new Defence Minister had asked the USAF to reactivate the stored F-111Cs for early delivery), a 15th F-111 crashed after shedding a wing. Further major modifications were found to be necessary and the F-111Cs remained in store fuselages (minus wings, engines and most equipment) at Carswell, avionics in a thermostatically-controlled hangar at Fort Worth.

Above: This view of an armed F-111 clearly shows the Pave Tack infra-red target detection and laser designation system pod in the bomb bay.  The underwing weapons are Harpoon anti-ship missile (port outer pylon), GBU-12 Paveway 500lb LGB, and on the starboard side, an AIM-9 Sidewinder and a GBU-19 2,000 lb (907kg) LGB on the outer pylon. (RAAF) (John Armstrong-Strike Publications)

It became clear that F-111C deliveries would not commence until 1974, and Australian F-111 training was suspended while an interim aircraft type was sought. Criticism intensified with accusations that the F-111 was a 'Flying Opera House' (a reference to the spiralling cost and scandalous delays to the Sydney Opera House) and that it had been involved in 'more tests than Don Bradman'. In June 1970, the lease of 24 F-4E Phantoms was finalised. The F-4Es were delivered in September and October 1970, and the 23 survivors eventually returned to the USA between October 1972 and June 1973.

In early 1973, RAAF F-111 training resumed, and on March 15, 1973, the RAAF formally accepted its first F-111C: six aircraft being delivered to Amberley on June 1, 1973. The remaining aircraft were delivered under Operation Peace Lamb in batches of six on July 27, September 28 and December 4, and re-equipped 1 and 6 Squadrons, which had traded their Canberras for the interim Phantoms. Unit markings took the form of a lightning flash running up the fin - yellow for 1 Squadron, blue for 6. Squadron badges were sometimes superimposed on these flashes. Later in the F-111's RAAF career, some 1 Squadron aircraft wore a stylised yellow '1' running up the fin leading edge, with the unit's Kookaburra insignia superimposed.

The perceived vulnerability of the F-111 to low level birdstrikes (demonstrated in 1977, when A8-133 was lost with its crew, after hitting three pelicans) was addressed by a programme to fit laminated ADBRIT windscreens. These were trialed on A8-125 and -126 in 1975, then fitted fleet-wide from 1978. Structural concerns were addressed using locally developed boron-epoxy patches around the wing pivots.


Above: Australian F-111s carry a larger range of ordnance than any of those that were in service with the USAF.  This impressive array of weapons (and more) can be carried by the F-111C. (RAAF)

When delivered, the first 24 aircraft had a (for that time) shocking US $5.95 (3.7) m unit price, though when this same price was applied to four ex-USAF (366th TFW) F-111As delivered as attrition replacements in May, July and August 1982, inflation had made it seem very reasonable. Modifications added to the cost, which rose to $A60 (24)m for all four. These aircraft (serials A8-109, 112, 113, and 114) were modified to virtually full F-111C standards, with longer span wings and strengthened undercarriages, though they retained the standard F-111A wing carry-through box. Two more aircraft were to have been included in the contract, but these failed a fatigue inspection and were returned to storage. One of the aircraft delivered (A8-109) was an ex-Vietnam veteran, and still had battle damage repair patches applied to repair damage inflicted by North Vietnamese anti-aircraft fire during Operation Linebacker II.
USAF cancels RF-111

The USAF had meanwhile cancelled the RF-111A programme in 1968 as a cost-saving measure, and the proposed RF-111D soon went the same way. US Forces had originally anticipated acquiring 110 recce-configured RF-111As and RF-111Bs to equip six squadrons within the US Air Force and US Navy, of its planned 876 aircraft total. By 1963, this number had increased to 305 RF-111As, then reduced to 60 RF-111Ds (with Mk 11 avionics) in 1967, and to the conversion of 46 existing F-111As as RF-111As in 1969. The RF-111Awas finally cancelled in 1970, which meant that Australia's requirement for a recce F-111 had become a unique embarrassment to General Dynamics. However, four of the original F-111Cs (A8-126, A8-134, A8-143 and A8-146) were finally converted to RF-111C configuration.

The RAAF awarded General Dynamics a feasibility study contract on December 31, 1974, to look at the practicality and cost of converting four F-111Cs to a recce configuration. A8-126 served as the prototype and was flown to Fort Worth for conversion in October 1978. The aircraft first flew in its new configuration in May 1979 and was re-delivered in August 1979. The three remaining RF-111Cs were converted at Amberley (using kits supplied by Fort Worth) during 1980, and entered service with an air-transportable Processing and Interpretation facility.

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Above: As can be seen here, the RF-111C's reconnaissance pack fits neatly into the former bomb bay on a pallet, taking up the space once dedicated to the M61A1 cannon pack. It contains (from front to rear) two video cameras, an infra-red line scanner, a low altitude panoramic camera, a high altitude panoramic camera and a pair of split vertical cameras. (RAAF)

The RF-111C recce pack contains a sensor suite based on that fitted to the RF-4. It fits neatly into the former bomb bay on a pallet, taking up the space once dedicated to the M61A1 cannon pack. It contains (from front to rear) two video cameras (used as vertical and forward/oblique viewfinders, via a cockpit display and also recorded onto video tape), a Honeywell AN/AAD-5 infra-red linescan (recorded on video or film) with a 60 or 120 field of view, a Fairchild KA-56E low altitude panoramic camera with a 3in (7.5mm) lens (providing 73 x 180 coverage), a KA-93A4 high altitude panoramic camera with an 18in (45.7mm) lens (14 coverage) and a pair of CAI KS-87C split vertical cameras with lenses of various lengths from 3in (7.5cm) to 12in (30cm), depending on requirements. The aircraft was also equipped to allow photography of the AN/APQ- 113 (or post-AUP AN/APQ-169B) attack radar display.

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Above: Comparison of the four F-111 variants operated by the RAAF.
1. F-111A, four ex-USAF aircraft purchased as attrition replacements, fitted with 'long-span' wings and updated to current F-111C standard.
2. F-111C, 24 aircraft originally delivered in 1973, example shown fitted with the Pave Tack pod.
3. RF-111C, four of original order converted for the reconnaissance role with camera pallet in the internal weapons bay.
4. F-111G, 15 aircraft, themselves updated FB-111As, purchased from ex-USAF stocks in the early 1990s. (Mike Badrocke/AIR International)
Pave Tack

The RF-111Cs served with 6 Squadron, which also initially used the four attrition replacement F-111A(C)s. No 6 Squadron had the same attack role as 1 Squadron, but also shouldered the burden of crew conversion and training, and, of course, reconnaissance.

For all its sophisticated terrain-following radar and navigation equipment, which allowed the F-111 to penetrate at low level and find pinpoint targets in any weather, the aircraft was originally limited to attacking targets with 'dumb' unguided bombs. Operational experience in Vietnam led to the design of a day/night laser designator pod, known as AN/AVQ-26 Pave Tack, intended for use by the F-4 Phantom. Unfortunately, the Pave Tack pod was large, heavy and unwieldy, and prevented the F-4 from carrying a centre-line fuel tank.

It was often referred to by F-4 aircrew as 'Pave Drag'. The F-111, however, had an internal weapons bay that was seldom used except for the stowage of a luggage pod or sometimes an M61A1 2Omm cannon, the latter being rendered surplus by the adoption of AIM-9 Sidewinders for self-defence. A rotating cradle was designed for the Pave Tack pod which allowed it to be carried internally by the F-111F, rotating down only when actually in use.

The RAAF immediately saw the potential of Pave Tack in giving the F-111 a genuine autonomous laser guided bomb (LGB) capability, and in 1980 ordered ten pods, while wiring all 18 surviving (non-recce) aircraft (including the F-111A(C)s) to carry the system. (Some reports suggest that 15 Pave Tack pods were eventually acquired, though this cannot be substantiated.)The first Pave Tack-capable F-111C (A8-138) was modified by General Dynamics at Fort Worth from December 1983, with the rest of the aircraft undergoing modification by No 3 AD at Amberley, starting with A8-147 in March 1985. Integration of the digital pod with the analogue equipment on the F-111C was not entirely straightforward. It necessitated replacement of the usual radar display with two separate smaller cathode ray tubes for radar and forward looking infra-red (FLIR) imagery for the navigator, as well as a pod line-of-sight hand controller. Incorporation of Pave Tack brought with it a number of new weapons for the Australian F-111s, including GBU-10 and GBU-12 2,000lb (907kg) and 500lb (226kg) Paveway 11 LGBs and the cruciform-winged GBU-15.
popeye.jpg (12908 bytes)
Above: Displayed at Nellis AFB in April 1997,for the 50th anniversary of the USAF, was F-111C A8-142 armed with an AGM-142E stand-off missile. The AGM-142E is the USAF FMS derivative of the Popeye with MIL-STD-1780 interfaces and DL frequencies, which differs from the Israeli version and the early USAF Have Nap. It is expected to enter service in 2000-2001. (Steve Fletcher / AIR International)

Another new weapon introduced to the F-111 in the mid-1980s was the AGM-84A Harpoon anti-ship missile. The Aircraft Research and Development Unit's (ARDU) F-111 deployed to the US Naval Weapons Center at China Lake for trials with the weapon in July 1982, while 20 aerodynamically-representative ballasted dummies were delivered to ARDU for further carriage trials. These tests proved successful, and the missile was procured in small numbers, though its high price tag means that live firings are extremely rare. The AGM-88 HARM anti-radiation missile was also flight-tested on the F-111C, but has not been procured, and the F-111 still requires a stand-off anti-radar missile. More recently, the AGM- 142E (Have Nap, based on Rafael's Popeye air-to-surface missile), with a unitary blast fragmentation warhead or a case-hardened penetrator, has been adopted as an F-111C Avionics Update Programme (AUP) weapon by the RAAF, and will enter service in 2000-2001.

Avionics modernisation programme

Introduction of new digital equipment and weapons underlined the anachronistic nature of the F-111C's avionics suite. The USAF's FB-111As, EF-111As and 25 F-111Es had already received an avionics modernisation programme with digital avionics, JOVIAL software, and a global positioning satellite system (GPS)-embedded ring laser gyro inertial navigation system (INS). The F-111Fs were similarly modified under the Pacer Strike programme. There was a clear threat that the analogue Australian F-111Cs would become increasingly obsolete.

Under Project AIR 5225, the RAAF therefore decided that its aircraft should undergo a similar digital avionics upgrade. Rockwell (responsible for the F-111's original avionics integration, and for Pacer Strike) teamed with Hawker de Havilland, while competitors General Dynamics teamed with Aerospace Technologies of Australia. Rockwell was awarded an update contract (covering 18 F-111Cs and four RF-111Cs) in August 1990, and began work on a prototype conversion (A8-132, painted in a new, overall grey colour scheme) at Palmdale during 1992. Subsequent aircraft were modified by Hawker de Havilland (later Boeing Australia) at Amberley.

Although there is little to distinguish an AUP aircraft from an unmodified F-111 (apart from the newly-adopted 'gunship grey' low-visibility colour scheme), and though largely based on improvements previously applied to USAF F-111s, the upgrade is an extremely ambitious and far-reaching one. This is an important point to note, since superficially the aims of AUP have been largely restricted to improving reliability and crew workload and 'spending to save' rather than dramatically improving capability. The upgraded aircraft has an improved digital Stores Management System (based on that used by the RAAF's F/A-18s) giving compatibility with a wider range of new weapons, and also has a much-improved navigation system. Although retaining many of its existing avionics systems, it has a new digital architecture which has allowed the incorporation of new items, and which will allow easier future growth and upgrading.


Above: One of the
advantages of side-by-side seating is that it promotes greater crew co-ordination compared to tandem-seating. Note the pilot's head up display, and the vertical strip airspeed indicator and altimeter either side of the attitude indicator. The hood on the starboard side of the cockpit is the  weapon system operator's display for viewing radar, Pave Tack or EOGB video. (via Gerard Frawley)

Development costs have been tightly controlled, and great emphasis has been placed on avionics accessibility, repair/replaceability and rapid fault diagnosis. An avionics mean time between failures (MTBF) of 3.5 hours has been improved to a claimed 19.5 hours as a result of the AUP programme.

The avionics system is based on dual-redundant MIL-STD- 1553B digital databuses, with de facto MIL-STD- 1760 interfaces to the pylons, albeit with lower electrical power feed to the pylons. The aircraft has a new digital computer complex with twin fully redundant MIL-STD-1750A IBM AP-102 mission computers which can each function as a databus controller and can fulfil navigation and weapons delivery functions. On the recce aircraft, camera operation is now bus-controlled via the displays, rather than a dedicated recce panel. The new computer (which replaces an AP-101F) also has a preprogrammable mission data cartridge, allowing a fully planned mission to simply be loaded into the aircraft before flight.

Improved reliability

The new navigation system is built up around dual Honeywell H423 (AN/ASN-41) ring laser gyro inertial units, augmented by an embedded Rockwell-Collins 3M five-channel MAG-R GPS.

The aircraft's original analogue flight control system has been replaced by a triple-redundant digital fly-by-wire system, using three Lear Astronics processors. This is effectively the same system used in F-111As and F-111Es upgraded by Grumman during the mid-1980s and improves reliability by a factor of about 18, particularly vital in automatic terrain-following flight. The AN/APQ-128 (which had replaced the original AN/APQ-110) terrain following radar has in turn been superseded by a new Texas Instruments AN/APQ-171, while the AN/APQ-165 real beam mapping analogue attack radar has been upgraded to AN/APQ-169 configuration.

click to download 750 Kb enlargement...
Cutaway by Mike Badrocke.
(Key here: 43Kb doc or 7 Kb zip)

The aircraft has also received a new secure voice communications system, based around KY-58 secure-voice UHF and frequency agile Have Quick II UHF radios.

The AUP programme has brought improved air-to-ground capabilities to the recce aircraft.  They are now fully compatible with the AGM-84, although they still lack provision for Pave Tack.  The internal cannon option has been deleted from all aircraft, having been deemed to be 'outside the parameters of the RAAF's operational use of its F-111s'.

In October 1992, it was announced that Australia would buy 15 surplus F-111Gs (and 12 spare engines) from the USAF, principally for spares, but also forming a possible attrition reserve.  Some reports suggest that the aircraft would replace 'high-houred' F-111Cs on a one-for-one basis, and that the F-111Cs themselves would be held in store.  The F-111Gs were redundant FB-111A strategic strike aircraft, 34 of which were converted for tactical duties and used for training by the 27th Fighter Wing at Cannon AFB until 1993, when they were replaced by F-111Es withdrawn from Europe (RAF Upper Heyford).  Australia purchased the aircraft for A$70 (28) million and a further A$74 million (30) million was allocated for logistics support.  One aircraft (68-0272) was taken from the 'boneyard', but the remainder went directly from Cannon AFB.   The first two arrived at Amberley on September 28, by which time it had been decided that some of the aircraft would be used as an 'in-use' reserve, helping to spread flying hours over a larger pool of aircraft.  This was initially achieved by giving 6 Squadron a flight of six F-111Gs.  A8-270 was the first aircraft delivered, and was used for the formal acceptance ceremony.

Compatibility

The F-111Gs were not entirely compatible with the RAAF's F-111Cs with 11% more powerful Pratt and Whitney TF30-P-107 turbofans rather than P-103s, and with different (Triple Plow II) intakes.  The new aircraft also lacked provision for Pave Tack, and had an AYK-18 mission computer which makes any real avionics synergy between the F-111C and F-111G impossible without a compatible computer upgrade. However, the F-111G did have a more accurate and more reliable navigation system installed, originally with AJN-16 INS and APN-185 Doppler, but without a GPS. Before their retirement from the USAF, the aircraft had a dual ASN-41 (Honeywell HS23 or Litton LN-39) ring laser gyro inertial navigation system fitted, together with an APN-218 Doppler. This made the F-111G a more accurate blind-bombing platform than the unmodified F-111C with its LN-14 navigation system, and some did not expect even the F-111C AUP to match the F-111G's navigational accuracy. The newly-delivered F-111Gs did feature the same extended span wing and strengthened undercarriage as the F-111C. Their earlier avionics modernisation programme had provided the same modified terrain following radar (in place of the original FB-111 APQ-134), the same multi-function displays and many of the same digital avionics as were fitted to Australia's F-111Cs under the AUP. After delivery to Australia, the F-111Gs were fitted with the same digital flight control system as was fitted to the F-111C under the AUP programme.

Arrival of the F-111G left 6 Squadron with four sub-variants, of the F-111: the F-111C, the F-111A(C), the RF-111C and the F-111G. The Squadron's Reconnaissance Flight was disbanded on July 1, 1996, passing on its aircraft and role to 1 Squadron's Operations Flight. This allowed greater opportunities for cross-training attack and reconnaissance crews, and when aircraft began emerging from the AUP it allowed 6 Squadron to be 'all-digital'. By late 1996, 6 Squadron operated six F-111Gs, six F-111C AUPs and two RF-111C AUPS.

Following the withdrawal of the USAF's F-111Fs from RAF Lakenheath, that station's simulator was sold to Australia under Project AIR 5208. It was converted by Wormald (Australia) Ltd to represent the F-111C AUP configuration and was fitted with modem visual systems before installation at Amberley in 1996.

In 1994, the Defence Science and Technology Organisation Aeronautical Research Laboratory began a major study aimed at extending the life of TF30 combustion chambers, many of which warped and cracked after as few as 750 flying hours, necessitating otherwise unnecessary engine removals. Since then, the F-111Cs and RF-111Cs have been re-engined with 20,8401b st (92,696kN) TF30-P-109RA turbofans taken from F-111Ds and EF-111As, which offer 12% greater thrust than the engines they replaced.

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Above: Line up of six Pave Tack equipped 1 Squadron F-111Cs at Nellis AFB for Exercise Green Flag in March 1999. Green Flag is a highly-realistic electronic warfare exercise, often involving a wide range of participating aircraft and nationalities. (Defence PR via Gerard Frawley)

During 1998 it was announced that the RAAF would maintain the F-111 in service until 2020, and in order to achieve this later operational service date, it was decided to reactivate the remainder of the F-111Gs, and to purchase more spares (including 130 TF30 engines!). Ten redundant ex-USAF airframes were acquired for cannibalisation, to form an attrition reserve sitting in the desert boneyard at Davis-Monthan AFB. In addition a single F-111A fuselage was acquired for use by the Defence Science and Technology Organisation. The RAAF will have the option to purchase the ten attrition reserve aircraft outright, with a US $500 (312) million price being quoted to activate, test and ferry the aircraft to Australia. If this option were ever exercised, it would make the aircraft the most expensive F-111s procured by the RAAF.

Project Echidna

Under Project Echnida (Projects AIR 5391, 5394 and 5416), RAAF F-111s were among several platforms scheduled to receive a new electronic warfare self-protection suite. They are being fitted with new indigenous (BAe Australia) ALR-2002 radar warning (RWRs), replacing the existing Dalmo-Victor ALR-62, though this is being upgraded to ALR-62V5-6 standards as an interim measure.

The project also looked at incorporating a towed radar decoy and a missile approach warning system. Some expected a directional infrared (IR) jammer to augment the Cincinnati AN/AAR-34 IR tail warning system. There are also plans to fit a radar jammer (under Project AIR 5391, Phase 7) to replace the existing Sanders ALQ-94 and ALQ-137 DECM (defensive electronic countermeasures). AN/ALE-40 chaff/flare dispensers are being fitted (to replace AN/ALE-28) under a separate programme. In 1999, the RAAF issued a formal request for proposals for a podded electronic counter measures (ECM) jammer, which would have to be already in service with another air force, making the AN/ALQ-131 and AN/ALQ-184 the key contenders. The ALR-2002 began flight trials on an F-111C during late 1999.

JDAM

Hope was soon being expressed that the RAAF might acquire Joint Direct Attack Munitions (JDAM). This GPS-guided glidebomb represents the future, offering genuine all-weather precision capability from medium altitude, without the limitations and restrictions inherent in LGBs. JDAM also promised to provide the F-111G with a genuine autonomous precision attack capability, since the type's lack of Pave Tack means that it cannot use the various GBU-10E/B, GBU-12D/B, GBU-24A/B laser and TV-guided weapons routinely carried by the F-111C. The aircraft was also unable to carry the GBU-15 (with its associated Hughes AXQ-14 datalink pod). This disparity in capability could be addressed under Projects AIR 5398 and 5418, under which a new family of stand-off weapons is to be procured for the F-111C for use from 2005. For self defence, Project AIR 5412 is likely to see the final replacement of the AIM-9M Sidewinder with the BAe ASRAAM, perhaps with a helmet mounted sighting/cueing system. In the longer term, some sources have suggested that a full helmet-mounted display might provide a direct route to single-display sensor fusion for the pilot without having to rearrange the anachronistic cockpit.

The F-111Gs possessed longer range and better ECM capabilities than Australia's original F-111Cs. However, as mentioned were unable to use the same range of weapons and lacked commonality with the existing RAAF aircraft. Consideration was briefly given to cycling the F-111Gs through the AUP upgrade, adding the necessary AP-102 computers, but this option was rejected. Some also suggested using the new aircraft as dedicated suppression of enemy air defences/electronic combat aircraft taking advantage of the type's better electronic warfare capabilities. The RAAF therefore launched Project AIR 5404 which aimed to modify the G-models in order to achieve greater commonality between the two basic types.

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Above: With its wings in the mid-sweep position and vortices rippling off the leading edge extension, an F-111G performs a re-heat fly-by at low level for the benefit of the photographer.  It is armed with 12 Mk82 500lb 'iron' bombs. Even at the end of their career with t he USAF, F-111s regularly won bombing competitions against later aircraft. (RAAF)

Under Phase 1 of this programme, modifications were made to the cockpit displays, air data computer, flight controls and wings of the F-111Gs, which also received ALR-2002 RWRS. A second (precision weapons modification) phase will add a new generation laser designator (the idea of adding Pave Tack having been ruled out), and will see upgrades to the F-111G's mission computer, stores management system, and display generator, and will add an embedded GPS. Total cost of the two-phase programme is estimated at A$200 (80) million, and will see the last fully-modified F-111G aircraft returned to service by 2007.

Re-engining

Structural considerations make it impossible for the F-111G to be re-engined with the TF30P-109 engines fitted to the F-111C and RF-111C, though the F-111G's engines have been modified to hybrid TF30-P-108 standards. The forward section of the TF30-P-109 married to the afterburner of the TF30-P-107.

In addition to being cycled through the AUP upgrade, the four RF-111Cs are also receiving a new LOROP electro-optical reconnaissance pod, developed as part of Joint Project 129. This pod is similar to the RAF's RAPTOR pod for the Tornado GR.4A and Eurofighter Typhoon, with a Raytheon DB-110 dual band sensor mounted in a converted 395 US gal (330 Imp gal/1,500 litre) supersonic fuel tank. The sensor has a range of about 36nm (60km) and can be 'pointed' by the navigator, or will point automatically at pre-planned targets. The pod has already been test-flown on an AUP upgraded RF-111C, but the RAAF has categorically denied that it was used for monitoring operations in East Timor, which were flown by standard RF-111Cs.


Above: RF-111 A8-143 taxying at RAAF Tindal, after flying the last 82 Wing sortie over East Timor on December 9,1999. Operating as part of the International Force in East Timor marked the first occasion in the Australian F-111's career that the aircraft was used operationally.
(Lenn Bayliss)

Meanwhile, the last AUP-modified F-111C was formally handed back to the RAAF at Amberley in November 1999, leaving the Air Force with an all-digital F-111 fleet which is due to remain in service until 2020. What will replace the F-111 in RAAF service remains uncertain, though it is believed that nothing has been ruled out, with unmanned combat air vehicles under consideration as well as a number of existing and planned manned platforms. Until then, the F-111 will remain a vital part of Australia's defence posture, and the type is likely to be upgraded further. The use of radar absorbent materials (RAM) skin appliques may have been considered, while internal weapons carriage, the use of FB-111A style jettisonable pylons, and even re-engining have been mooted as potential F-111 improvements.

Individual aircraft

Under the original MoU, Australian F-111As were specified as being aircraft build numbers 121, 123, 125, 127, 129, 131, 133, 135, 137, 139, 141,145,147,149,151,153 and 155, with the RF-111As being 31, 33, 35, 37, 39 and 41. The extra six aircraft on which options were held were numbers 156 to 161. In the event, however, the RAAF aircraft were given their own sequence of construction numbers as though they formed a consecutive batch, as shown in the earlier table. In the list of identities in that table, the D1 construction number prefix indicates an aircraft built for Australia, A1 an aircraft built for USAF Tactical Air Command and B1 an aircraft built for Strategic Air Command.

F-111.net thanks AIR International for granting permission to republish this article.
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(1) see www.F-111.net/aussie for recently declassified Australian Government papers on the mater.
(2) The aircraft loss involving the RAAF navigator at Nellis was caused by a fuel distribution system malfunction which eventually moved the the centre of gravity aft to such an extent that loss of control of the aircraft (F-111A 66-0040) occurred.  The crew survived ejection.

 


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