Profile Publications Number 004 - The Hawker Hunter F.6

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Marcus Antonius

Marcus Antonius

Per Ardua Ad Astra
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Marcus Antonius #8887
I had the pleasure of working on these aircraft whilst carrying out my technical training in the Royal Air Force.

I was always wary of the under wing undercarriage area, for the mainwheels, there was a big locating spike for the mainwheel.

I was always careful not to suddenly stand up underneath it! :lol:
 
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Spike circled in red.

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Now...Here's the interesting bit.

No. 4 of the 'Aircraft in Profile' series, launched by British company, Profile Publications, in the mid 1960s.

Detailed description of the design, development and operational history of the Hawker Hunter F.6, a British transonic jet developed in the 1950s.

Well illustrated with colour drawings by P. Endsleigh Castle and R. Ward, also many black and white photos.

"Representing the design and production climax of the basic Hawker P.1067 Hunter concept, which had originated in the F.3/48 Specification for a transonic interceptor, the Hunter Mark 6 was built in larger numbers than any other version."
 
A standard Armstrong Whitworth-built Hunter F6 with 100-gal. drop tanks and 24 rocket projectiles. Wing leading edge extensions, extended cartridge case chutes, gun blast deflectors and store jettison guns are fitted (note absence of drop tank fins). (Photo: Cynl Peckham)

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Representing the design and production climax of the basic Hawker P.1067 Hunter concept, which had originated in the F.3/48 Specification for a transonic interceptor, the Hunter Mark 6 was built in larger numbers than any other version.

Following the Avon-powered Hunter Mark 1 and Sapphire-powered Mark 2—which had both suffered Service criticism for their limited range and endurance—the Mark 4 and 5 (also with Avon and Sapphire respectively) introduced increased internal fuel capacity and external store provision, including the carriage of up to four 100-gallon drop tanks.

While production of these early Hunters had been getting under way, Hawker Aircraft had been pursuing the development of a “second generation” Hunter, a re—heated Avon-powered version with a 50° swept wing.

Designated the P.1083, this version carried high hopes and boded well to become the first truly super-sonic fighter in R.A.F. service, and construction of a prototype (WN470) was well advanced by mid—1953.

At the same time the original P.1067 prototype (WB188) was flying with a re-heated Avon R.A.7R engine as part of the powerplant development programme.

(This aircraft established an Absolute World Speed Record in September 1953 at 727.7 m.p.h.).

Radical changes however, were seen in 1953 in Air Staff fighter policies.

Believing the air-to-air missile-armed supersonic fighter to be no more than four years away, the Air Staff saw in the Hunter a promising interceptor and ground attack fighter which would remain at operational status for a further six to eight years.

Almost overnight the only-marginally super-sonic P.1083 was abandoned, and with it went the re-heated Avon in the Hunter context.

Greater emphasis was to be laid on the new generation of Avon 200-series turbojets which were initially rated at 10,000 lb. thrust Without reheat.

During the late summer of 1953 the Hawker design team prepared proposals for a “straight” Hunter, powered by the Avon 203, but in most other respects similar to the Hunter 4 and 5 (which were not due to fly until the autumn of 1954).

Designated the P.1099, the project was accepted and a prototype completed within three months by the simple expedient of using the centre fuselage sub-assembly of the defunct P.1083 to match the new Avon.
 
The prototype Hunter 6, XF833, was first flown by Sqdn. Ldr. Neville Duke on January 22nd 1954 from Dunsfold and, after preliminary flight trials, was delivered to the A. & A.E.E. at Boscombe Down the following month.

After blade failures in the engine had led to a couple of forced landings, the Avon 203 was down-rated to 10,000lb. thrust, and Service and manufacturers’ trials—including handling, gun firing and
performance measurement—proceeded satisfactorily.

The aircraft was subsequently painted glossy pale green for an appearance at the 1954 Farnborough display and was eventually delivered to Rolls-Royce for trials with a thrust reverser in the tailpipe.

The 30% greater power from the Avon 203 of course permitted a considerable increase in take-off weight as well as reduced take-off runs and times to height.

Promise of early deliveries of Avon 203s prompted the issue of production contracts for the Hunter 6, and, to meet the inevitable demand for development and trial installation aircraft, Contract No. 7144 (which had originally called for ten Hunter 4s) was changed to include seven Mark 6s (WW592— WW859).

The first of these was flown by A. W. (“Bill”) Bedford on March 25th 1955 and commenced a series of trials at Dunsfold in parallel with those being conducted on XF833 at Boscombe Down.

By the end of 1955 all seven development aircraft had flown and embarked on the CA. release programme in the hands of Neville Duke, Bill Redford, Hugh Merewether, Frank Bullen, Duncan Simpson, David Lockspeiser and Don Lucey.
 
The first true production aircraft, XE526, was flown by Merewether on October 11th 1955, and although deliveries to R.A.F. Maintenance Units started in the following January, acceptance for
Squadron service was delayed by the R.A.F. for a further nine months.

The delays were occasioned on three counts:

(i) The investigation of aerodynamic “pitch-up” tendencies at high altitude and high indicated Mach numbers;

(ii) The investigation of “pitch-down” when firing the guns at high altitude, and

(iii) the development of a full-power elevator.

(In connection with the last of these, there was a proposal to fit later Hunter 6s with slab tailplanes and although flight trials with the associated ram air turbine commenced during 1956, the plan was dropped in favour of the fully-powered elevator with spring-feel.)

To overcome the pitch-up tendency, Hawker had already preposed the addition of an extended wing leading edge (increasing the wing area from 340 sq. ft. to 349 sq. ft.) to the outer sections of the wings.

On the gun-firing pitch-down problem, a concentrated programme of trials—in which one Hunter fired 40,000 rounds in flight at full throttle—led to the development of muzzle blast deflectors.

Though both these expedients brought solution to their respective problems, the first hundred or so production Hunters were delivered to the M.U.s without modification, and by the autumn of 1956 the R.A.F. had agreed to accept the aircraft, albeit with temporary restrictions.

In the meantime, modification kits were produced and issued to the Service.

Thus, although the existence of the powerful new Hunter had been known since 1954, the first R.A.F. Squadron was not so equipped until late in 1956.

It is a point worth recording here that the Maintenance Unit principally concerned with the Hunter was No5 M.U. at Kemble, assisted to a lesser extent by Nos. 19 (St. Athan), 33 (Lyneham) and 45 (Kinloss).

First Squadron to receive the Hunter 6 was No. 74(F) Squadron at Horsham St. Faith, Norwich.

This airfield had also been the location of a field working party responsible for the preparation of Hunters to full R.A.F. standard and handed over the first Hunter 6s (most of them built by Sir ‘W. G.
Armstrong Whitworth Aircraft Ltd., Coventry) to No. 74 before the Squadron’s move to nearby Coltishall.
 
By March 1957 the build-up of Hunter 6 squadrons had achieved the planned rate of two per month, Nos. 43, 54, 63, 65, 66, 74, 92, 247 and 263 either equipped or completing delivery of their new aircraft.

By the end of the year No. 111 Squadron had converted and the initial deliveries to home-based Fighter Command squadrons were complete.

With production of the new aircraft reaching around forty per month from the factories early in 1957, it was also possible to commence replacing the Hunter 4s on the 2nd Tactical Air Force Squadrons based in Germany.

The Hunter 6 gained immediate popularity with the Squadrons and in tactical exercises proved itself an excellent ground support aircraft.

There was a short period towards the end of 1957 when 2nd T.A.F. Squadrons found that the serviceability of the Hunter 6 left something to be desired—at least when compared with the Hunter 4—but this was found to be due to the non—arrival of modification kits from the U.K.
 
The Hunter 6 arrived in R.A.F. service too late to participate in “hostilities” during the Suez Crisis of late-1956 and it was left to the Hunter 5s of Nos. 1 and 34 Squadrons to reinforce the Middle East fighter force.

Nevertheless 1957 saw the start of Hunter 6 squadron “rotation” to bases in the Mediterranean and the Middle East.
 
Also a product of 1957 was the Duncan Sandys’ White Paper on Defence which purported to foreshadow the end of the manned interceptor, and which brought cancellation of the last 150 Hunter 6s on order for the R.A.F.

The result was that Hunter 6 production for the R.A.F. was completed on July 9th 1957 with the flight of XK156 by Duncan Simpson.

This aircraft was in fact the very last single-seat Hunter built for the R.A.F., all subsequent versions being converted from aircraft built before that date.

By December 1957, 210 Hunter 6s were at first line strength with the R.A.F., the remaining 159 being held in reserve at the M.U.s.

Fourteen had crashed and been written off.
 
R.A.F. Hunter. XF418 of No. 111 Squadron (“The Black Arrows”). This aircraft was part of the Squadron’s initial equipment and was not fitted with extended wing leading edges.
(Photo: J. M. G. Gradidge)

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HUNTER 6s OVERSEAS

Ever since the early nineteen-fifties foreign interest in the Hunter had been Vigorous and in 1953 negotiations had resulted in its choice to equip the N.A.T.O. air forces of Holland, Belgium and Denmark.

The two former countries had arranged to manufacture the aircraft under licence and thirty Mark 4s were delivered to Denmark.

Production of the Mark 4 commenced at Fokker and Avions Fairey during 1956 and in 1958 transferred to the Mark 6.

In the meantime other countries evinced interest in the Hunter 6.

N.A.T.O. pilots evaluated early production aircraft in 1956, but in view of plans to introduce the Lockheed F-104G Starfighter into European air forces it was considered unnecessary to replace the Republic F-84 Thunderjet and Hunter 4.

Moreover, the Fiat G-91 represented new ideas on the subject of battlefield support aircraft.

Switzerland, on the other hand, being uncommitted to N.A.T.O. policies, issued a fighter requirement to which the Hunter seemed ideally suited.

Preliminary evaluations eliminated such aircraft as the Canadair Sabre, the Folland Gnat and the Swiss P-16, with the result that it only remained to decide on a standard of preparation for the Hunter 6 and the size of the order.

Demonstrations of bombing and gun-firing were performed by XE587 and 588 during 1957 in Switzerland (XE587 being equipped with a tail parachute) and in January 1958 an order for 100 aircraft was signed with the Swiss Government.

In order to speed deliveries, the first twelve aircraft were to be released from R.A.F. stocks.

Subsequently termed Hunter Mark 58s and equipped with tail parachutes, the Swiss Hunters were nonetheless basically Mark 6s—rather than Mark 9s—and seem likely to remain in service in Switzerland until towards the end of the nineteen-sixties.

After the commencement of the Swiss negotiations, but before their conclusion, an Indian defence delegation had visited Britain and showed interest in the Hunter 6.

In the course of three. short months during the summer of 1957 Indian pilots evaluated the Hunter and an order was signed for 160 aircraft on September lst that year.

Once again the British Government released aircraft to speed deliveries, twelve Hunters being returned from M.U.s and thirty-two of the cancelled R.A.F. order (XK157-176 and XK213-224) being completed to the Indian standard, in Indian insignia.

After having completed a short conversion course at Benson, Indian Air Force pilots started ferrying their Hunters (equipped with four l00-gallon drop tanks each) out to Karachi, thereafter joining
Nos. 7, 14, 17, 20 and 27 Squadrons of the I.A.F. at Poona and Ambala.

Some of these aircraft subsequently went into action against ground targets during the brief campaign against Portuguese Goa.
 
In the R.A.F., Hunter 6s of Fighter Command demonstrated their control precision through the medium of formation aerobatics, their greater reserve of power making them obvious and worthy successors to the Hunter 4.

Without doubt the most famous R.A.F. aerobatic team of all time was that of No. 111 (F) Squadron—the Black Arrows, so named after their all-black Hunters—led by Sqdn. Ldr. Roger Topp.

Year after year this team performed with more and more aircraft in the formation, culminating with a formation roll with twenty-two Hunters.

When 111’s turn came to re-equip with Lightnings, its place was taken by No. 92 Squadron’s team, the Blue Diamonds.
 
Turning now to the Middle East (for it is likely to be in this theatre that the Hunter will eventually serve longest), it was in 1958 that the RAF. started trials to select a replacement for the aging Venom fighter-bomber.

Under the general direction of the Central Fighter Establishment and A. & A.E.E., Folland Gnats, Percival Provosts and Hunter 6s were subjected to “eliminating trials” to decide on the R.A.F.’s future standard tropical ground attack fighter.

Considerable experience in warm climates had been achieved with the Hunters in Cyprus, and it was not a surprising that the Hunter was selected from the trials at Aden.

The first squadron, No. 208, was in fact formed and equipped at Tangmere under Sqdn. Ldr. John Granville-White, before being transferred to the Middle East.

When, a year or so later, Iraq threatened the sovereignty of Jordon, No. 208 Squadron flew escort flights for the Blackburn Beverley carrying supplies from Cyprus into the blockaded country.

Prior to the coup which had overthrown King Feisal of Iraq, that country had received from Britain a present of fifteen Hunter 6s (five in April and ten in December 1957) from R.A.F. Middle East stocks.

It is almost certain that these aircraft, in the hands of rebel pilots flying from Mosul, were the first Hunters ever to fire their guns in anger, being used in rocket attacks on royalist encampments in
South Iraq.

Shortly afterwards further presents of Hunters were given to the Governments of the Lebanon and Jordon.
 
The Hunter 6 remained the R.A.F.’s principal first-line fighter until, in 1960, its place at home started being taken by the English Electric Lightning.

Nevertheless as late as 1964, Hunter 6s remained on strength with two squadrons of No. 38 Group, while many others, modified as Ground Attack Mark 9s and Fighter Reconnaissance Mark 10s are likely to remain in service until towards the end of the nineteen-sixties.
 
Of course, Hunter 6s came to be used by a host of non-operational R.A.F. units, among them Nos. 229 and 233 Operational Conversion Units at Chivenor and Pembrey respectively, the Fighter Weapons School, the Central Flying School, the Central Fighter Establishment and the Empire Test Pilots School.

Numerous trial installations were performed on Hunter 6s, perhaps the most important being the application of de Havilland Firestreak infra-red-seeking air-to-air missiles.

This, the Hawker P.1109, resulted in considerable lengthening of the nose to accommodate the associated radar, deletion of two ofthe four 30mm. Aden guns and mounting of two Firestreaks on the inboard underwing pylons.

Two versions were built; the 1109A was no more than an aerodynamic “shape”, and the 1109B with full weapon installation.

Four such aircraft were completed, one of which took part in firing trials (and proved entirely successful), and although the project was abandoned one aircraft, WW598, was subsequently used by the
RAE. for high-speed low-altitude gust investigation in the Middle East in preparation of gust data for the BAC. TSR-2 project.

Another project involved the carriage of wing-tip fuel tanks on XG181 in connection with a two-seat night/all-weather fighter version of the Hunter (the P.1114 and P.1115).

This project remained still-born and the tip-tanks, although demonstrated at the 1956 Farnborough display, produced quite unacceptable buffet conditions, and the aircraft was returned to standard for delivery to the Service.
 
Perhaps the most important development carried out on the Hunter 6 was that of the Hawker 230-gallon steel drop tank, although this was not introduced into service until much later.

Originally proposed by Hawker Aircraft shortly before the Suez Crisis, the 230-gallon tank was intended to enable the Hunter 6 to reinforce Middle East units, flying non-stop from the U.K.; dummy tanks were flown on a Mark 4, and on October 2nd 1958 Hugh Merewether flew XF374 from Dunsfold to El Adem, Libya, non-stop in 3 hours 19 minutes—a distance of 1,588 naut. miles.

His aircraft carried the prototype pair of 230-gallon tanks and two 100-gallon tanks outboard.

Two other versions of the Hunter 6 should be mentioned.

The first is the Mark 6/Interim Mark 9; the full-standard Hunter 9 (with which we are not concerned here in detail) was a developed version equipped with braking parachute, gun blast deflectors
removed, provision for 230-gallon tanks and an associated increased pilot oxygen capacity.

The Mk.6/Interim Mk.9 did not include the tail parachute, but, for reinforcement purposes only, could accommodate the large drop tanks.

By 1961 almost all the interim aircraft had been advanced to full Mark 9 standard.

The final version was the Jordanian F.R. Mark 6, of which only one was delivered.

This aircraft, 712 of the Royal Jordanian Air Force, was a standard Mark 6 but equipped to mount three cameras in the nose.

In this respect the aircraft was similar to the R.A.F.’s F.R.Mk.10 Hunter, but the Jordanian example lacked the tail parachute.

By 1961 Hunter 6s in Belgium and Holland were being replaced in service and in anticipation of further export orders from Britain, the parent company acquired about 30 ex-Belgian aircraft, most of them being flown to Dunsfold with SBAC registration numbers and Belgian insignia removed.

Minutely overhauled and brought up to Mark 9 standard, some of these were re-exported to Kuwait and Iraq in 1963—64.
 
THE HUNTER DESCRIBED

The Hunter structure was conventionally built in five main sections: front fuselage, centre fuselage, rear fuselage with tail unit, port and starboard wings.

The nose section contained the radar ranging equipment, cockpit, gun armament and magazine and nosewheel gear.

The centre fuselage, incorporating the wing stubs, contained the powerplant, engine intakes and main fuselage fuel tanks, the rear fuselage, detachable to expose the engine for maintenance, supported the tailpipe, included the tail controls and surfaces, and the ventral airbrake.

The wings incorporated the mainwheel units, the wing fuel tanks, ailerons, flaps and provision for a pair of store pylons on each side; these were built up on a front and rear main spar which attached through heavy forgings to the main spar frames in the stub wings.
 
Armament.

The fixed armament consisted of four 30-mm Aden guns each with up to 150 rounds.

The gun barrels remained fixed to the aircraft structure, and the gun bodies and magazine tank were incorporated in a removable pack which could be winched down to facilitate re-arming.

External weapons could be carried on detachable wing pylons, up to 1,000-lb. bombs or 230-gallon drop tanks on the inboard pylons, and 100-gallon tanks on the outboard pylons.

Alternatively up to twenty-four rocket projectiles could be attached under the outer wings in place of the pylons.

Equivalent loads of Napalm tanks, practice bombs, rocket batteries or target-towing gear could be carried.
 
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