Rolls Royce Thrust Measuring Rig (Flying Bedstead) (XJ314)Rolls Royce Thrust Measuring Rig (Flying Bedstead) (XJ314)

Rolls Royce Thrust Measuring Rig (Flying Bedstead) (XJ314)  [@ London Science Museum]

Made of tubular steel and powered by two opposed Nene 101 engines the Flying Bedstead was purely a test rig.   With 92% of the available thrust directed downwards and the remainder being directed forwards and backwards, the first rig, later designated XJ314, first flew in the tethered hovering mode on the 9th July 1953 and in the free flight mode on the 3rd August 1954.   By December 1954 XJ314 having completed 224 tethered and 16 free flights was transferred to the Royal Aircraft Establishment (RAE) at Bedford for additional trials.  Following an accident on the 16th September 1957 when the artificial stability control failed while hovering XJ314 struck the ground inverted but fortunately the pilot escaped.  Written off, XJ314 was rebuilt for display at the Science Museum.  A second rig, XK426, flew on the 12th November 1956 but crashed on the 27th November 1957 on a tethered hovering flight killing the pilot.

XJ314 was first flown in the tethered hovering position on the 9th July 1953 and in the free flight mode on the 3rd August 1954.

Short SC.1 (XG900)Short SC.1 (XG900)

Short SC.1 (XG900)  [@ London Science Museum]

In 1952 the Air Ministry issued specification ER.143D for a conventional aircraft which would be capable of vertical and horizontal flight.  In 1954 Short Bros was awarded a contract for the manufacture of two prototypes, XG900 and 905.  Powered by five RB.108 engines of which four supplied the lift.   XG900 was completed and shipped to Boscombe Down for initial trials on the 2nd April 1957 with only the propulsion engine fitted while XG905 was fully fitted by the September when the lift engines were run.  The first tethered hovering flight was on the 23rd May 1958 with the first free flight taking place on the 25th October.  Unfortunately XG905 crashed killing the pilot but after a rebuild joined XG900 at the RAE.  Although vector thrust technology had overtaken the dual engine approach the two aircraft remained on trials tasks until retired in 1971.

XG900 was first flown on the 2nd April 1957 and retired to the Science Museum in June 1971.

The Harrier traces its lineage back to 1957 when Hawker Siddeley Aircraft Limited launched the concept of the P.1127 V/STOL aircraft.  Prior to the P.1127 project Hawker Aviation had been working on a replacement for the Hawker Hunter, the Hawker P.1121, however the P.1121 was cancelled shortly after the 1957 Defence Review.  The P.1127 design began in 1957 and was designed around the Bristol BE.53 vectored thrust engine, the forerunner of the Rolls Royce Pegasus.  In this revolutionary turbofan, air from the fan and the low- pressure compressor is divided is diverted to the front pair of vectoring nozzles, while remaining engine thrust is directed through the rear pair of rotating nozzles.  By 1960 the Ministry of Supply had issued ER.204D for the funding of two prototypes.  Hawker Siddeley had also undertaken considerable development work on a supersonic version of the P.1121, the P.1154, for use with both the RAF and Royal Navy. 

A BS100 engine for the P.1154  

The P.1154 would replace the Hawker Hunters of the RAF and the de Havilland Sea Vixens of the Fleet Air Arm Following a Government Defence Review in 1964 the P.1154 project was also cancelled leaving the Royal Navy to acquire the McDonnell Douglas Phantom II and the future BAC TSR.2 for the RAF.  The photograph above shows a  BS100 engine that was been developed for the P.1154.  Derived from the British Siddeley Pegasus engine, the BS100 was first test run in 1964 and uses after-burning to raise the thrust to 35,000lbs.  Designed and built in Bristol the BS100 was never developed beyond the prototype stage and only a few were built.  In the photograph the engine is mounted upside down.  This was done during the test programme to simplify support requirements for the engine.

Hawker Siddeley P.1127 (XP831)Hawker Siddeley P.1127 (XP831)

Hawker Siddeley P.1127 (XP831)  [@ London Science Museum]

The first prototype P.1127, XP831, was delivered in July 1960 powered by a Pegasus 1 engine.  Testing began straight away and by the end of the year the aircraft had achieved both vertical take-off and horizontal flight.  The first tethered flight took place at Dunsfold Aerodrome on the 21st October and free flight hover was achieved on the 19th November.  The first conventional take-off was on the 13th March 1961 and transition from vertical to horizontal flight was achieved in the following September.  A second prototype, XP836, made its first take off conventionally on the 7th July 1961 also powered by the Pegasus 1 engine.  The test program also explored the possibility of use upon aircraft carriers with XP831 performing the first carrier vertical landing on HMS Ark Royal in 1963.  Four more prototypes (XP972 - Pegasus 2 engine, XP976 - Pegasus 3 engine, XP980 – Pegasus 3 engine, XP984) were ordered.  Apart from improvements in the Pegasus power-plant the first four prototypes were quite similar.  However, the fifth, XP980, introduced the taller fin and tail-plane anhedral (as seen later seen on the Harrier).  While the last P.1127, XP984, introduced the swept wing and the Pegasus 4 engine to became the prototype Kestrel FGA.1 The first three P.1127s crashed, XP831 during the Paris Air Show in 1963 but was fully repaired and resumed development flying and the second and third during development.  Fortunately all the pilots involved survived.

The first prototype P.1127 to be built, XP831 was first flown in the tethered hovering mode on the 21st October 1960 and in the free flight mode on the 19th November 1960.  First placed on display at RAF Hendon on the 13th November 1972 and later move to the Science Museum.

Hawker Siddeley Harrier P.1127 (RAF) (XP980)Hawker Siddeley Harrier P.1127 (RAF) (XP980)Hawker Siddeley Harrier P.1127 (RAF) (XP980)

Hawker Siddeley Harrier P.1127 (XP980)  [@ Fleet Air Arm Museum]

Based upon the P.1127/Kestrel XP984 prototype nine Pegasus 5 engined evaluation aircraft were ordered as the Kestrel FGA.1 with the first, XS688 flying on the 7th March 1964.  The Kestrel was evaluated in 1965 by pilots of the RAF, U.S.  Air Force, U.S.  Navy, US Army and the federal German Luftwaffe.  A special Tripartite Evaluation Squadron (TES) within the Central Fighter Establishment was formed on the 15th October 1964 at RAF West Raynham, Norfolk.  The evaluation was completed by November 1965 and during the testing one aircraft was lost.  After the trails one of the aircraft, XS693, went to Blackburn for modification to take the up-rated Pegasus 6 (Mk 101) engine, one was attached to the Blind Landing Experimental Unit (BLEU) at RAE Bedford and the remaining six were transferred to the USA for evaluation by the Army, Air Force, and Navy as the XV-6A Kestrel.  In 1969 the US Marine Corps (USMC) received approval to buy the first of 102 Pegasus 10 (Mk 102) powered aircraft with the designation AV-8A.

The fifth prototype P1127, XP980, was built at Kingston-upon-Thames and first flown on the 24th February 1963.  After flight trials with the A&AEE and pilotless crash barrier trials at RAE Bedford, XP980 was used from August 1975 at Royal Aircraft Establishment Bedford for Sea Harrier restraining hook trials.  On the 9th October 1980 XP980 was transferred to the School of Aircraft Handling at RNAS Culdrose as A2700 for dummy deck training.  Repainted in 1981 to look like a Sea Harrier XP980 was moved to the Fleet Air Arm Museum on the 9th March 1989 for display.

The RAF began looking at a simple upgrade of the Kestrel, and issued Requirement ASR 384 for a V/STOL ground attack jet known as the P.1127 (RAF).  This variant was closely based on the Kestrel and became world's first operational V/STOL ground attack and reconnaissance fighter.  Six evaluation aircraft were built with the first flying from Dunsfold on the 31st August 1966.  Orders for 60 production aircraft were formally received by Hawker Siddeley Aviation in early 1967 and were given the designation Harrier GR.1. 

Hawker Siddeley P.1127 (RAF) (XV277)Hawker Siddeley P.1127 (RAF) (XV277)

Hawker Siddeley P.1127 (RAF) (XV277)  [@ RAF East Fortune]

The GR.1 (XV276) first flew on the 31st August 1966 and the first six development aircraft went to the manufacturer and Boscombe Down for intensive trials, development and weapons work.  While the GR.1 first production variant (61 built) first flew on the 28th December 1967 and entered RAF service with the Harrier Conversion Team at RAF Wittering, Lincolnshire, on the 18th April 1969 and was followed into RAF service by the GR.1A with both variants being used in the close support role (CAS).  1 Squadron who were now based at RAF Wittering, Lincolnshire, became the world’s first operational V/STOL squadron in 1970.  Whereas the Kestrel embodied about 50% of the structure of the P.1127, the Harrier was in many respects a new aircraft re-engineered around the more powerful Pegasus 6 engine.  The aircraft were built at either Kingston upon Thames, southwest London, or at Dunsfold Aerodrome, Surrey.  The GR.1 was powered by the Pegasus 6 (Mk 101) engine while the GR.1A (17 built plus 41 GR.1s upgraded) was powered by the Pegasus 10 (Mk 102) version and entered service in 1971.  The GR.1 was fitted with four under-wing and one fuselage pylons to accommodate a total of 5,000 lbs of bombs or rockets together with a pair of Aden 30 mm cannon that could be carried in detachable under-fuselage pods.

XV277 was the second evaluation P.1127 (RAF) aircraft to be built by Hawker and was first flown on the 9th November 1966.  Later transferred to the Fleet Air Arm at RNAS Yeovilton on the 30th November 1988 as A2600.  Sold on to the private market, XV277 arrived at RAF East Fortune during April 2000.

A prototype T.2  two-seat tandem trainer variant, XW174, flew for the first time on the 24th April 1969 powered by the Pegasus 6 (Mk 101) engine and the type (16 built) was issued to 233 OCU as well as squadrons.  With nose and tail extensions and an extended under-fuselage strake and variant was later retro-fitted with taller fins.  The T.2A variant (11 T.2 conversions) had a Pegasus 10 (Mk 102) power-plant fitted and like the T.2 was fully combat capable.  Originally powered by the Pegasus 10 (Mk 102) engine the T.52 was an export variant of the T.2.  Only one of this variant was built and was used as a company demonstrator.  First flown on the 15th September 1971 the power-plant was upgraded to a Pegasus 103 engine following an accident.

Hawker Siddeley Harrier P.1127 (RAF) (XV278)Hawker Siddeley Harrier P.1127 (RAF) (XV278)

Hawker Siddeley Harrier P.1127 (RAF) (XV278)   [@ Luftwaffenmuseum der Bundeswehr, Berlin]

In 1969 Hawker Siddeley and McDonnell Douglas formed a partnership to enable the building of the Harrier in the USA for the American military.  However, it was decided it would be cheaper to have the aircraft built in the UK on the existing production lines.  Between 1971 and 1976 the United States Marine Corps (USMC) received 102 AV-8As and 8 two-seater TAV-8A trainers.  In general the AV-8A variant was similar to the GR.1 but was powered, in the main, by the more powerful Pegasus 11 (Mk 103) engine.  Due to the possibility of corrosion by sea air all of the magnesium components were replaced and the variant was fitted American radios and Identification Friend or Foe (IFF) system and the Stencel SEU-3A ejection seat instead of the Martin-Baker type.  Unlike the GR.1 this variant was factory fitted with self-defence AIM-9 Sidewinder heat-seeking air-to-air missile system.  The AV-8S Matador was an export version of the AV-8A variant that was built for the Arma Aérea de la Armada (Spanish Navy designation VA-1 Matador).  Similarly the TAV-8S Matador (VAE-1 Matador) was the export version of the TAV-8A for the Spanish Navy.  All were later sold by the Spanish to the Royal Thai Navy.

XV278 was the third evaluation P.1127 (RAF) aircraft to be built by Hawker and was first flown on the 13th December 1966.

Hawker Siddeley Harrier GR.1/GR.3 (XV748)Hawker Siddeley Harrier GR.1/GR.3 (XV748)

Hawker Siddeley Harrier GR.1/GR.3 (XV748)  [@ RAF Elvington]

Following on in RAF service was the GR.3 variant powered by the Pegasus 11 (Mk 103) [photograph - below] engine and entered service in 1974.  A number of upgrades were included such as the Ferranti LRMTS target seeker and marker in a revised nose and a passive warning radar receiver on the fin and tail boom.  Forty new aircraft were built but 62 of the GR.1 and GR.1A fleet were upgraded to this standard during major services and were used in the close support role. 

First flown in April 1969 XV748 was originally built as a GR.1 and served at RAF Wittering with the Conversion Unit and later 1 Squadron.  Converted to GR.3 standard by 1976 XV748 was used as a test aircraft with the Royal Aircraft Establishment at Bedford.  The museum acquired the aircraft from Cranfield University on the 21st September 2000.

Pegasus 11 (Mk 103)

Similarly the T.2 was upgraded along the same lines as designated the T.4 variant (11 built + 14 T.2 or T.2A conversions) but reverted to the original lower fin of the early T.2 and was fully combat capable.  By deleting the laser nose, hence saving weight, the T.4A variant (1 built + 4 T.4 conversions) achieved a much greater range.  The last GR.3 was delivered in December 1986.  During the Falklands War in 1982 10 RAF GR.3s of 1 Squadron operated from the aircraft carrier HMS Hermes.  Although not designed for navel service the aircraft were modified against corrosion and a new deck-based inertial guidance aid was devised to allow the RAF Harrier to land on a carrier as easily as the Royal Navy Sea Harrier.  In addition transponders were fitted to guide the aircraft back to the carrier during night-time operations as well as flare and chaff dispensers.  The main role of the GR.3 was to provide close air support to the ground forces and was also used in ground-attack missions against the main airfield and runway at Stanley.  By modifying the outboard weapons pylons to take air-to-air Sidewinder missiles the RAF GR.3 was also used to support the Sea Harrier in fleet air defence and combat air patrols against Argentine fighters.

Hawker Siddeley Harrier GR.3 (XZ133) 

Hawker Siddeley Harrier GR.3 (XZ133)  [@ RAF Duxford]

First flown on the 4th May 1976 XZ133 was delivered to 233 Operational Conversion Unit at RAF Wittering on the 9th July 1976.  Transferred to 1(F) Squadron on the 29th March 1982, XZ133 was deployed to the British Fleet during the Falklands War.  Operating from HMS Hermes XZ133 flew ground attack missions against Argentine forces.

Hawker Siddeley Harrier AV-8AHawker Siddeley Harrier AV-8A

Hawker Siddeley Harrier AV-8A (159233)  [@ Imperial War Museum - Manchester]

The Harrier used 1950s technology in the airframe design and construction and in systems.  So by the 1970s, despite systems updates, this was restricting the further development of the aircraft's potential.  As a result of pressure from the USMC for a more capable aircraft the McDonnell Douglas was contracted in 1978 to develop the Harrier II.  In the meantime the RAF required a more capable aircraft and BAe designed a variant with a larger wing to specification ASR409.  By 1981 an agreement was reached for a common type to become the Pegasus 11-21 (Mk 105) powered AV-8B/GR.5.  A prototype AV-8B Harrier II first flew in November 1978 and was followed by the first development aircraft in November 1981 with production deliveries to the USMC beginning in 1983.  Spain became the first international operator by signing an order for 12 AV-8Bs in March 1983 and was designated the VA-2 Matador II by the Spanish Navy.

Constructed as an AV-8A by Hawker Siddeley, 159233 entered service with the United States Marine Corps.  Presented to the Fleet Air Air Museum at RNAS Yeovilton, 159233 is displayed at the Imperial War Museum North.

Hawker Siddeley Harrier GR.3 (XZ997)Hawker Siddeley Harrier GR.3 (XZ997)Hawker Siddeley Harrier GR.3 (XZ997)

Hawker Siddeley Harrier GR.3 (XZ997)  [@ RAF Hendon]

Powered by the Pegasus 11-21 (Mk 105) engine the GR.5 (43 built) had a new composite wing of much larger area and a revised forward fuselage and cockpit for improved visibility as well as significantly improved avionics.  The wing had large slotted flaps linked with nozzle deflection at short take-off unstick to improve control precision and increase lift.   Leading-edge root extensions (LERX) were fitted to enhance the aircraft's air combat agility by improving the turn rate, while longitudinal fences (LIDS, or Lift Improvement) incorporated beneath the fuselage and on the gun pods to capture ground-reflected jets in vertical take-off and landing, gave a much greater ground cushion and reduce hot gas recirculation.  With eight underwing hard-points and one under the fuselage this variant could carry 9,200 lbs of armaments plus two 25 mm cannon.  The prototype, ZD318, first flew on the 30th April 1985 and the variant entered service in July 1987.   1 Squadron based at RAF Wittering became operational from the 23rd November 1988.  Due to problems with production of the GR.5 the variant was seen only as an interim before the introduction of the GR.7.  The GR.5A variant (19 built) was similar to the GR.5 but with the GR.7 standard fitments and was immediately placed into storage for full conversion later; the first being ZD432. 

A Falklands veteran, XZ997 was first flown on the 21st January 1982 and entered RAF service with 4 Squadron at RAF Gütersloh on the 12th February 1982.  Transferred to 1 Squadron at RAF Wittering, Lincolnshire, on the 12th February 1982 and prepared for Falklands War service.  On the 4th May XZ997 was flown from RAF St.Mawgan, Cornwall, to Wideawake Airfield on Ascension Island - a tip 4,600 miles in 9 ¼ hours which was achieved with the use of additional fuel tanks and Handley Page Victor refuelling tankers.  Transferred on the 6th May to the “Atlantic Conveyer” for transportation to the Falklands but unfortunately was transferred on the 18th May to HMS Hermes.  From the 21st May (initial British landings at San Carlos Water) until the 14th June (Argentine forces surrender) XZ997 was involved in daily sortie operations with 1 Squadron flying from HMS Hermes.  XZ997 had returned to RAF Wittering by the 6th October and was then transferred back to 4 Squadron at RAF Gütersloh on the 21st February 1984.  However, XZ997 returned to the Falklands on the 14th June 1984 to provide air defence with 1453 Flight.  Upon completion of the new airport at Mount Pleasant on the 12th May 1985 1453 Flight was disbanded and so XZ997 returned to the UK.  XZ997 continued in RAF service with 233 Operational Conversion Unit at RAF Wittering, 1 Squadron also at RAF Wittering before returning to 4 Squadron at RAF Gütersloh on the 6th December 1988.  The last flight was on the 21st August 1990 when XZ997 flew to RAF St. Athan, Glamorganshire, for storage before finally entering the museum on the 4th December 1991.

Hawker Siddeley Harrier GR.3 (XZ968)Hawker Siddeley Harrier GR.3 (XZ968)

Hawker Siddeley Harrier GR.3 (XZ968)  [@ Muckleburgh Collection]

Basically the GR.7 variant (53 built including the GR.5A conversions and 30 converted GR.5s) was similar to the GR.5 including the armament and power plant but had night attack capability.  This resulted in a slight change in the nose profile to accommodate forward-looking infrared imaging system (FLIR) in a fairing above the nose and two smaller bulges below the nose to house the forward Zeus ECM (Electronic Counter Measure) antennae.  The GR.7A variant was a GR.7 upgrade but with the more powerful Pegasus 11-61 (Mk 107) engine fitted.

XZ968 first flew on the 31st October 1980 and enter RAF service on the 10th December 1980.  Later used as a ground instructional airframe at RAF Marham, Norfolk, XZ968 was delivered by RAF Chinook to the museum 1st February 1995.

Hawker Siddeley Harrier GR.5A/GR.7/GR.9 (XD461)

Hawker Siddeley Harrier GR.5A/GR.7/GR.9 (XD461)  [@ Imperial War Museum - London]

The Pegasus 11-61 (Mk 107) powered GR.9 was the designation for the mid-life upgrade of the GR.7 but now with a terrain referenced navigation system and provision for the AIM-120 (Advanced Medium-Range Air-to-Air Missile, or AMRAAM).  ZD402 was the first GR.9 to be flown in 1989.  While the GR.9A variant was the avionics and weapons upgrade of the GR.7A.

Following on from the T.4 was the Pegasus 11-21 (Mk 105) powered T.10 tandem trainer (13 built).  Built to accompany the GR.7 this variant, unlike its American counterpart the TAV-8B, was fully combat capable.  The prototype, ZH563, first flew on the 7th April 1994.  Under the designation T.12 nine T.10 airframes were upgraded to act as trainers for the GR.9 but the variant retained the original less powerful Pegasus 11-21 (Mk 105) engine.  T.8 was the designation for two RAF T.4 trainers that were transferred to the Royal Navy when the T.10 became available. 

ZD461 was built at Kingston-upon-Thames and first flew on the 10th October 1989 as one of twenty-one GR.5A airframes.  Delivered to 1 Squadron RAF on the 16th November 1989, ZD461 was upgraded to a GR.7 standard during March 1992 and then to GR.9 standard in October 2008.  ZD461 later flew with the Harrier Operational Conversion Unit at RAF Wittering and with the Royal Navy Naval Strike Wing based at RAF Cottesmore.  Having saw active service in Afghanistan, ZD461 suffered a CAT 3 (repairable) damage in January 2010 when a fire started after taxying onto the ramp at Nellis AFB, Nevada, USA, during exercise "Red Flag 2010-2".  Freighted back to the UK ZD461 arrived at RAF Cottesmore on the 19th March 2010.  Due to budgetary cuts and the demise of the Harrier fleet ZD461 was struck off charge on the 15th December 2010 and declared a Cat.5 i.e. damaged beyond economical repair.

Hawker Siddeley Harrier GR.5

Hawker Siddeley Harrier GR.5 Trainer  [@ Midland Air Museum]

The second generation Harrier IIs saw action in Bosnia, Iraq, and Afghanistan.   In 2006 the Sea Harrier was retired from Fleet Air Arm service and the RAF Harrier fleet were tasked with the missions that it used to share with those aircraft.  The former Sea Harrier squadron 800 NAS reformed with ex-RAF Harrier GR7/9s in April 2006 and was later-joined by the re-formed 801 NAS in 2007.  These squadrons were later expanded to become the Naval Strike Wing.  On the 31st March 2010 20 Squadron RAF, the Harrier Operational Conversion Unit (OCU), was disbanded while 4 Squadron was also disbanded and reformed as 4 (Reserve) Squadron at RAF Wittering.  All RAF GR.7s were retired by July 2010.  On the other hand the GR.9 was expected to stay on in service until at least 2018.  However, to the dismay of many, the British government announced on the 19th October 2010 that the remaining GR.9s would retire by April 2011.  In December the GR.9s made their last operational flights and at the end of November 2011 the British government announced the sale of the final 72 Harriers to the USMC for use as spare parts. 

Hawker Siddeley Harrier GR.9

Hawker Siddeley Harrier GR.9  [@ RAF Waddington]

Following the agreement with McDonnell Douglas in 1982 four AV-8B full scale development aircraft were and were, in turn, followed by 162 production aircraft between 1983 and 1989.  The TAV-8B was a two-seat trainer variant with 23 being built between 1986 and 1992.  As well as for the USMC the AV-8B Harrier II+ was built for the Spanish Navy and Italian Navy.  Similar to the Night Attack variant but with the addition of APG-65 radar 72 were converted from existing AV-8Bs together with 43 newly builds from 1993 to 1997.  In total 12 EAV-8B Matador IIs were built between 1987 and 1988 and were followed by 19 EAV-8B Matador II+ aircraft (including 11 EAV-8B conversions) between 1995 and 1997 for the Spanish Navy.  For the Italian Navy two TAV-8B Harrier II+ two-seat trainers were built between 1990 and 1991 and these were followed by an order for sixteen AV-8B Harrier II+ aircraft.  The last 13 aircraft were assembled in Italy by Alenia Aeronautica from kits delivered from the USA.

ZG501 was first flown 13th December 1990 and entered RAF service on the 20th December 1990.  Withdrawn from use at RAF Cottesmore on the 15th December 2010.

The Royal Air Force will eventually replace the Harrier GR.9s with the Lockheed Martin F-35B Lightning II which is the short takeoff and vertical landing (STOVL) variant.  This will give the RAF a multi-role all weather, day and night capability fighter. 617 Squadron will be the first operational Royal Air Force Squadron to receive the F-35B.  The photograph below shows a full sized model of a F-35A, which is the is the conventional takeoff and landing (CTOL) variant.

Lockheed Martin F-35A - a full scale model

Lockheed Martin F-35A  [@ RAF Hendon]