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Hawk - Frontline Trainer

The following article appeared in the 2004 edition of The Royal Air Force Yearbook, a highly recommended read for all those interested in the RAF.

Many thanks to the editor of the Yearbook (Peter March) for permission to use this piece.

The article was written by Gordon G. Bartley.

RAF Yearbook
As we approach the 30th Anniversary of the Hawker Siddeley Hawk's maiden flight, Gordon G. Bartley ARPS looks back at the origins of this outstanding jet trainer, and forward to the entry into service of its 'digital' successor, the BAE Systems Hawk 128.
Since the start of the jet age, the Royal Air Force has operated a number of thoroughbred aircraft in the Advanced Flying Training role, most notably the Gloster Meteor, de Havilland Vampire and Hawker Hunter, all of which were ordered in large numbers. To this list, some would add the diminutive Folland Gnat, even though the aircraft's handling characteristics, particularly on take-off and landing, required super-human agility on the part of the student pilot or Instructor.

By the late-1960s. however, it was becoming increasingly apparent to the RAF that it urgently needed to replace both the Gnat and the Hunter, which were operating in the Advanced Flying Training and Tactical Weapons Training roles respectively. At that time, student pilots undertook Elementary Flying.

Training on the DHC Chipmunk and Basic Flying Training on the Hunting/BAC Jet Provost. They were then streamed into either Multi-Engine Pilot Training or Fast Jet for the Advanced Flying Training portion of the training syllabus.

It was against this background that the RAF Operational Requirements Board (ORB), influenced by developments in the United States (most notably the supersonic Northrop T-38 Talon advanced jet trainer) initially issued Air Staff Target (AST) 362. This called for a twin-engined aircraft capable of Mach 1.5 in level flight and able to operate from wet runways of just 6,000ft in length. The aircraft would also be required to display excellent handling qualities, so that stall characteristics (but not spinning) could be safely demonstrated to student pilots. In addition, cost and international collaboration on design and production of the new aircraft, were considered to be key elements of the overall requirement. The eventual outcome of AST 362 was the Anglo-French SEPECAT Jaguar, which was produced both as a two-seat operational trainer and as a single-seat ground attack and reconnaissance aircraft.

Hawks replaced Hunters with No 1 Tactical Weapons Unit at RAF Brawdy from January 1978.

The two key players in Britain's rapidly consolidating aircraft industry, the British Aircraft Corporation and Hawker Siddeley, then turned their attentions to designing a successor to the Jet Provost. Their belief was that RAF's future flying training fleet would consist of the new Scottish Aviation Bulldog for Elementary Flying Training, a new 'Basic Jet Trainer' for Basic Flying Training, and the two-seat SEPECAT Jaguar for Advanced Flying Training.

By early 1968, both companies had completed extensive surveys of the global jet trainer market, and had embarked on detailed design studies. However, the RAF Central Flying School had also produced a draft specification for a Jet Provost replacement and by October 1968 this had become the basis of Air Staff Target (AST) 397. This called for a medium-sized, single-engined jet trainer in the 10,000lb gross weight category, as this would allow adequate space for a modest avionics fit and provide greater operational flexibility. The new aircraft would also feature a tandem seating arrangement, with the rear seat raised for enhanced forward visibility, and would be required to demonstrate a circuit speed of 130kts, a seven minute climb to 30,000ft, and a maximum level speed of 500kts at sea level, Mach 0.85 at altitude. The aircraft had to have sufficient fuel for a one-hour general handling sortie at sea level, or 1.5 hours at altitude, and underwing hardpoints to permit tactical weapons training or light ground attack capability.

For its part, Hawker Siddeley considered a substantial number of both single and twin-engined design configurations before arriving at its preferred solution, the HS1182AJ. This design proposal was based around an unreheated version of the new Rolls-Royce/Turbomeca Adour turbofan engine, giving a measure of commonality with the new SEPECAT Jaguar. The HS1182AJ featured a tandem seating arrangement, with a low-set wing and shoulder-mounted air intakes, a design that promised good all-round performance and operational flexibility. The HS1182 design team at Kingston-upon-Thames, was also mindful of a potentially large export market that existed for a |et trainer in this category, and was confident that its design solution would carry the day. In late 1969, the MoD surprised both BAC and Hawker Siddeley by openly referring to a new 'Intermediate' jet trainer that would be required, in sizeable quantities, from the mid-1970s onwards. Both companies suspected that any new advanced jet trainer submission would have to be far more than just a Jet Provost replacement. Their suspicions were confirmed early in 1970. when the RAF announced that the two-seat Jaguar would be used for operational conversion only, owing to its complexity and operational costs. At around the same time, the ORB finally issued AST 397 to industry. Both companies then embarked on a final round of design refinements, before submitting their respective proposals. After detailed consideration of both the P59 and HS1182AJ proposals, on 1 October 1971 the MoD announced that the HS1182AJ had been selected to fulfil the requirements of AST 397. In March 1972, Hawker Siddeley was awarded a fixed-price contract for 176 HS1182 aircraft, there being no prototype aircraft as such, and with production standard tooling being used from the outset.

At the insistence of the RAF. Hawker Siddeley was also obliged to incorporate Martin Baker Mk 10 ejection seats, in place of the originally proposed lightweight Folland-designed seats, and this in turn necessitated a ten-inch increase in fuselage length. The RAF also required the installation of a gas turbine starter to help with in-flight engine relights, as the Adour was known to be slow to spool-up in such circumstances. Hawker Siddeley had also tried to find a suitable name for the new aircraft by holding a competition amongst its employees, but was ultimately overruled by the RAF which, on 3 August 1973, announced that the name 'Hawk' had been selected. By early 1974, production of the first Hawk (XX154) was progressing well at Kingston. The front fuselage section had been produced in-house at Kingston, while the rear fuselage, canopy and windscreen were fabricated at Hamble, with the wing, tailplane and tail fin being produced at Brough. The Hawk became the first British aircraft to be manufactured entirely using the metric system of measurement. By the summer of 1974, major sub-assemblies of XX154 had been transferred to Hawker Siddeley's flight test and development airfield at Dunsfold, and it was there that it underwent final assembly and painting.

The first Hawk T1 XX154 (1) accompanied by the second (camouflaged), third and fourth aircraft on an early test flight from Dunsfold.

On 12 August 1974, XX154 was formally rolled out at Dunsfold, sporting the distinctive red and white gloss paint scheme that was characteristic of all RAF training aircraft at the time. The aircraft then passed to the Flight Test Department at Dunsfold, where it became the responsibility of Chief Test Pilot Duncan Simpson and Hawk Project Pilot Andy Jones to prepare the aircraft for its maiden flight. Duncan Simpson elected to go for a maiden flight late on 21 August and shortly after 1900hrs. XX154 lifted off from Dunsfold. at the start of a comprehensive flight test programme. Flight testing progressed smoothly, and by 28 August 1974, some nine test flights had been completed. Confidence in the aircraft was such that a move to Farnborough for the duration of the SBAC show in September was approved. Following display clearance, XX154 flew on each day of the show, sometimes in appalling weather conditions, and impressed everyone with its performance. The aircraft's display routine was confined to gentle manoeuvring, as it was still an unknown quantity. The aircraft remained serviceable throughout the show -no mean achievement for an aircraft still in the initial stages of flight test and development.

As a product of the late-1960s and the 1970s, the new Hawk T1 utilised proven materials technology and traditional manufacturing techniques, which resulted in a rugged and reliable airframe, requiring only the most basic skills to maintain. For ease of maintenance, approximately 30 per cent of the surface area of the Hawk is made up of access panels.

A further plus point for the Hawk is its Adour Mk 151 turbofan engine, which is of modular construction for ease of maintenance and repair. This develops 5,200lb st. and gives considerable fuel economy and excellent reserves of power. The engine drives two hydraulic pumps for the dual hydraulic systems. which operate the aircraft flying controls. In addition, the No 1 system operates the flaps, undercarriage, airbrake and wheel brakes. In the event of total engine failure, or failure of the No 2 hydraulic pump, a Ram Air Turbine located in the fuselage spine just ahead of the tailfin extends into the airstream and provides emergency power to the flying controls. Compressed nitrogen accumulators are then used to lower the undercarriage and flaps.

The Hawk T1 flight test and development programme was relatively uneventful, but minor design changes were made to the aircraft to improve control response, directional stability and aircraft stall warning/wing stall characteristics. Later in the flight test programme, Duncan Simpson uncovered a further stalling problem, when the aircraft was flown with flaps fully extended, but with the undercarriage retracted. In essence, downwash from the Hawk's double slotted flaps was adversely affecting airflow over the tailplane, causing it to stall. The problem was ultimately rectified by removing a section of the inboard flap vane, thereby restoring adequate airflow over the tailplane.

In parallel with the flight test programme, Hawker Siddeley had also conducted a comprehensive weapons clearance programme. In the summer of 1975, XX156 underwent a series of hot weather flight trials in Malta, during which performance of the aircraft, engine and systems were monitored during typical operational sorties. Some of these sorties were flown with maximum external stores. Such was the confidence in the new aircraft that by ate 1976, the centreline 30mm Aden gun pod, Matra 155 unguided rocket pod. and CBLS (Carrier Bomb Light Store) unit had all been cleared for use on the Hawk, In October 1976, a Release to Service was granted for the Hawk T1. allowing Hawker Siddeley to begin deliveries to the RAF.

Flown from RAF Leeming, this Hawk T1A carries the distinctive markings of No. 100 Squadron.
BAE Systems.

The RAF took delivery of its first Hawk T1s on 4 November 1976, at RAF Valley. These aircraft, and several others that arrived soon afterwards, were initially used by the Central Flying School detachment at the station, to train Instructors of No 4 Flying Training School, also based there. It was not until early 1977 that the first student pilots began to train on the Hawk, undergoing a 22-week Advanced Flying Training course. This involved 75 hours of dual and solo flying, supplemented by over 20 hours of Hawk simulator experience. These students graduated from No 4 FTS on 11 November 1977, moving to RAF Brawdy, home of No 1 Tactical Weapons Unit (TWU), to become the first Hawk-trained TWU graduates.

RAF Brawdy had begun to receive its first Hawk aircraft in January 1978, and by the middle of that year was operating 26 Hawk T1s. The TWU course covered a 16-week period, during which the students flew 18 hours of dual instruction, and 36 hours solo. At Brawdy, the Hawk T1 s, resplendent in a grey/green camouflage scheme, initially operated in the guise of No 234 (Reserve) Squadron, but from October 1981 onwards, tactical weapons training at the base was divided equally between No 234 (Reserve) Squadron and the newly Hawk-equipped No 79 (Reserve) Squadron. Hawk operations continued at RAF Brawdy until August 1992, before transferring to RAF Valley.

A second Hawk-equipped Tactical Weapons Unit, No 2 TWU, formed at RAF Chivenor on 1 April 1981, being redesignated No 7 FTS on 1 April 1992. The unit was made up of two squadrons. No 63 (Reserve) Squadron and No 151 (Reserve) Squadron, but, in September 1992, these squadrons assumed the mantle of Nos 19 and 92 Squadrons. The existence of No 2 TWU/7 FTS ended in the early 1990s following a UK Government Defence Review in 1993, when it was announced in December that year that RAF Chivenor would cease operations in October 1994, and its Hawk assets would then transfer to RAF Valley. In fact, operations at Chivenor continued until the spring of 1995, as weapons training detachments from RAF Valley frequented the base until that time.

Possibly the most significant allocation of Hawk T1 aircraft within the RAF occurred in August 1979, when the Red Arrows began to receive the first of its initial allocation of nine Hawk aircraft. Based at RAF Kemble, the team had been flying Gnat jet trainers, and the arrival of the Hawk brought a number of benefits, most notable amongst these being greater operational flexibility, range and endurance, and enhanced aircraft reliability.

In 1999, the solo Hawk display aircraft was painted in special markings to celebrate the 25th anniversary of the type's first flight from Dunsfold in 1974.
Neil Dunnidge.

The Red Arrows Hawks were converted for display use by British Aerospace at its Bitteswell factory, and, in addition to the distinctive red and white paint scheme, featured a number of operational refinements. The most visible of these was the 70 gallon ventral fuselage tank, which contains diesel fuel and red and blue dyes for smoke generation. The only other significant difference between the team's aircraft and the standard Hawk T1 is the engine. The Red Arrows' aircraft are equipped with the Adour Mk 151X engine, which features a fuel accelerator system for improved throttle response - essential for formation flying. The first public display by the team with its new Hawks was in 1980, and this year the Reds will be celebrating their 40th anniversary as a team.

Throughout its operational career with the RAF, British Aerospace (latterly BAE Systems), has supported the Hawk fleet with a number of life extension programmes. Between 1983 and 1986, 88 Hawk T1s were upgraded to enable them to launch the AIM-9 Sidewinder missile, and to operate in the secondary Air Defence role. These aircraft were subsequently redesignated as Hawk T1As and were repainted, with the exception of the Red Arrows aircraft, in a light air defence grey paint scheme. Since that time, over 40 Hawk T1/1AS have been rewinged, and more recently, 80 were the subject of a Fuselage Replacement Programme (FRP) that involved the replacement of the aft-centre and rear fuselage sections with new sections built to the higher Hawk 60 Series export standard. Virtually all of the aircraft involved in these modification programmes were ex-TWU aircraft, which had been extensively operated in the punishing high-speed, low-level, operational environment, and were consequently running low on fatigue life.

Today, the RAF's Hawk T1/1A fleet, now in an overall gloss black paint scheme, is concentrated at RAF Valley with Nos 19 and 208 Squadrons, and at RAF Leeming with No 100 Squadron, continuing to provide sterling service in the Advanced Flying and Tactical Weapons Training roles. But for how much longer? There are those who believe that the Hawk T1/1A, with its analogue 'clocks and dials' cockpit environment, is irrelevant to the future training needs of the RAF, given that the cockpits of both current (and future) front line combat aircraft are dominated by state-of-the-art 'digital' displays.

However, the Hawk T1/1A still has an important role to play in introducing student pilots to the high­speed, high workload environment of the front line combat pilot. To the student pilot, the turboprop-powered Shorts Tucano may appear to be fast, covering the ground at over 250kts, but at low level, the Hawk T1/1A can comfortably achieve speeds of up to 500kts, so things happen much more quickly. In the circuit too, the Hawk is much faster, with the initial downwind leg being flown at around 190kts, base leg at around 150kts, and final approach at around 130kts - decaying to around 110kts on touchdown. Precise engine management is critical in this phase of flight, and because the Adour takes a full eight seconds to accelerate from flight idle to full power, the approach is always flown with a minimum power setting of 70 per cent.

So how will the existing Hawk T1 /1A fleet fit into the RAF's future flying training syllabus? At present, it seems likely that selected aircraft from the T1/1A fleet will operate in parallel with the recently-announced Hawk 128 Advanced Jet Trainer (AJT) fleet. No 19 Squadron at RAF Valley is earmarked to become the first operator of the new Hawk 128 when the type enters service in April 2008.

So what will the Hawk 128 offer? The new aircraft will introduce student pilots to the digital cockpit environment that they will experience in front line operational service. Externally, the aircraft will be similar to many other Hawk 100 Series export variants, but in addition will be equipped with the latest Rolls-Royce/Turbomeca Adour Mk 951 turbofan engine, rated at 6,500lb St. and incorporating a Full Authority Digital Engine Control (FADEC) system. This new engine provides 25% more thrust than the Adour Mk 151 in the current Hawk T1/1A fleet, so student pilots should notice a significant difference in overall performance. They can be safe in the knowledge that the engine's FADEC system will prevent them from mishandling the engine, and will ensure optimum performance in all phases of flight.

The front cockpit of the BAE Systems Hawk 128 will be dominated by a wide-angle Head-up Display (HUD) and three prominent Active Matrix Liquid Crystal Displays (AMLCDs).
BAE Systems

The most significant differences between the Hawk T1/1A and the Hawk 128 will be found in the cockpit and 'under the bonnet'. The Hawk 128 cockpit will be equipped with three Active Matrix Liquid Crystal Displays (AMLCDs), each controlled by 'soft keys', and each able to display a comprehensive range of navigation, sensor, weapons and systems data. The front cockpit will also be dominated by a wide-angle Head-Up Display (HUD) which will feature symbology that is fully compatible with front line combat aircraft types. Data from this unit will normally be repeated on the central AMLCD in the rear cockpit. Ail cockpit instrumentation will be fully compatible with the use of Night Vision Goggles (NVGs) for enhanced situational awareness, particularly during night operations.

To ease pilot workload during critical phases of flight, and potentially in combat situations, the cockpit of the Hawk 128 will feature Hands-On-Throttle-And-Stick (HOTAS) controls, and here again the moding and switching functions of this system will be fully representative of front line combat aircraft. In addition, the Hawk 128 will feature Open Architecture Mission Computers (OAMC) for future growth potential, an enhanced Stores Management System (SMS), Inertial Navigation/Global Positioning System (IN/GPS) for greatly enhanced navigation and weapon aiming accuracy, and a Health and Usage Monitoring System (HUMS) for improved monitoring of aircraft fatigue life. From a systems perspective too, the Hawk 128 will offer significant advantages over the existing T1/1A. The new aircraft will incorporate an upgraded Electrical System, an Auxiliary Power Unit (APU) for greater operational autonomy and to assist with engine start (and engine relight in flight, should that become necessary), an On-Board Oxygen Generation System (OBOGS) - that replaces the limited duration, bottled oxygen supply of the T1/1A-and provision for air-to-air refuelling. This latter capability was successfully demonstrated, for the first time, on a Hawk 100 series aircraft in December 2002, utilising a Hawk 127 LIF and Boeing 707 tanker of the Royal Australian Air Force (RAAF). On the subject of fuel, the Hawk 128 will be able to carry two external 130 Imp gal fuel tanks for long range and endurance, but consideration is also being given to a 100 Imp gal centreline conformal fuel tank, similar to the one that was developed for the Canadian Hawk 115/CT-155 aircraft. The Hawk 128 will be cleared to carry a comprehensive range of weaponry but future enhancements to the aircraft may, in some cases, dispense with the need to carry weaponry altogether, as synthetic sensor and weapons capability - including radar and EW simulation, and DataLink - is introduced. Other enhancements may include a Digital Moving Map (DMM), Ground Proximity Warning System (GPWS), Traffic Alert and Collision Avoidance System (TCAS), and an Autopilot for compliance with Reduced Vertical Separation Minima (RVSM) in controlled airspace.

BAE Systems' new generation Hawk 100 series demonstrator.
BAE Systems

Production of the first two Hawk 128 aircraft (RT001 and RT002) is already underway at BAE Systems' Brough facility, and both aircraft are set to fly in mid-to-late 2005. These aircraft will then be flown as just one component in the overall flight test and development programme.

With the Hawk 128, the RAF will acquire another thoroughbred trainer, with an impeccable pedigree. Having 30 years of global experience under its wings, and an increasingly potent operational capability, the Hawk seems set to remain as the RAF's principal advanced flying training asset for many years to come.