TSR.2

Flight International 31 October 1963

Britain's New Weapon: An Assessment by the Technical Editor

During the past decade the persistent reluctance of the British Government to come to or maintain any decision regarding major programmes in the fields of aircraft, guided weapons or space has resulted in a situation in which any all-British programme representing a truly substantial advance on existing practice is to be regarded as an exception, and an achievement to be proud of. It is against this vacillating background that TSR.2 must be assessed, and any objective appraisal leads to the conclusion that this big and versatile aeroplane is something of which its creators may indeed be justly proud.

TSR.2 is more than a new aeroplane; it is a comprehensive weapon system developed to meet a stated and far-ranging need of the Royal Air Force, and to produce it, British Industry has had to fill in a number of gaps in the supply of all kinds of airborne equipment from advanced radars to microswitches. Opponents of the programme have often suggested that TSR.2 was about to be cancelled; but such abandonment would tantamount to emasculating the Royal Air Force on one hand, and seriously weakening British industry on the other. TSR.2 is virtually a complete generation of aircraft technology, all wrapped up in one package with a wing span no bigger than a Spitfire's.

Since 1949 the Canberra has been progressively improved to enable it to stay in the front line of air forces all over the world as a standard tactical bomber, strike and reconnaissance aircraft. But by 1955 it was clear that the Canberra could not go on forever. At that time surface-to-air missile systems were just beginning to become an effective factor in the argument, and despite the shortcomings of the first-generation weapons it was evident that weapon systems then on the drawing-board would be capable of destroying with a very high degree of certainty any aeroplane coming within range and capable of being acquired and tracked.

It was this realization which practically eliminated the traditional high-level role of jet bombers, except over relatively undefended areas. On the one hand, this meant increased emphasis on the development of stand-off weapons such as Hound Dog and Blue Steel, and on the other it resulted in the design of strike aircraft able to fly at transonic or supersonic speed so low that they cannot be detected by normal, conventionally sited radars. The first of these low-level attack aircraft was the Royal Navy's Buccaneer, the story of which was published in our issue of April 4 last [1963]. The NA.39 specification to which the Buccaneer was built was a singularly farseeing one but in no way meets the requirements of the Royal Air Force. Although equipped with largely automatic systems for low-level navigation and target strike, it is designed primarily for missions against discrete radar obvious ships in the middle of the ocean; and its range, although very good, is short of what the RAF require.

During 1956 the Air Staff conducted a survey into their future operational requirements in the general tactical field. At home, the problem of interception of enemy aircraft is adequately handled by the Lightning, and at no time was an interception capability for the Canberra-replacement regarded as a prime necessity. In the European theatre a new aeroplane was needed to equip the Bomber Command force committed to SACEUR, which was formed with Canberras and has since 1960 been equipped with Valiants (today Bomber Command is a itself an "assigned" force, but this agreement is hedged about with shoals of footnotes). Outside Europe the United Kingdom has firm commitments to CENTO, SEATO and to many dependencies and friendly nations, as well as other less precisely defined moral obligations. The Air Staff began to formulate a requirement for an aeroplane able to fulfil every commitment.

From the outset the programme to produce the new aeroplane exceeded in magnitude all that had gone before it in this country. In order to bring the maximum number of brains to bear on the project, the General Operational Requirement procedure was adopted, with the number 339. Usually a Draft Operational Requirement is formulated by the Air Staff, and then referred to specialist staff, at the RAE and elsewhere, who study the technical feasibility of the demands before inviting manufacturers to tender.

In this case, however, GOR.339 was circulated direct to the industry as well as to Ministry establishments in the second half of 1957, and the companies approached were asked to submit feasibility studies. At least half a dozen submissions resulted (about three times as many as one might expect today), and these provided a sufficient number of interesting ideas to keep the evaluation teams at the Air Ministry and MoS [Ministry of Supply] extremely busy throughout 1958. Towards the end of that year, the Minister of Supply, Mr Aubrey Jones, told the industry that the project would not be awarded to any one firm, and thus hastened "rationalization".

On December 26, 1958, we wrote of the GOR.339 evolution, "The optimum solution has yet to be evolved, and it will certainly be reached only by a consortium of our most capable manufacturers." By this time two of the companies who had made submissions, Vickers-Armstrongs and English Electric, told the Minister of their willingness to share the contract, and on January 1 1959, the Ministry of Supply announced that the aircraft would be called TSR.2, and that the main contract would be placed with Vickers and the work shared with English Electric.

The immediate task facing the management at Vickers-Armstrongs (Aircraft) Ltd at Weybridge, where the design authority was established, was to form a joint project team. The original Vickers study had been handled by the former Supermarine design organization at Hursley Park, near Winchester. It was thus logical for this team to make a permanent move to Weybridge, but for the design staff of English Electric Aviation at Warton it meant keeping a home in Lancashire and spending their working hours 200 miles further south.

During the early part of 1959 this combined design team, under the general control of Mr H. H. Gardner and Mr F Page, carefully re-explored the proposals of GOR.339, undertook a detailed study of the technical problems and design philosophies involved and hammered out the basic design of the optimum weapon system to meet the needs of the RAF. In close parallel, the Air Staff were engaged in turning GOR.339 into OR.343 related to this aircraft.

Powerful forces continued to lobby against the new programme. One group believed that most of the tasks for which TSR.2 was being designed could be performed better by a missile, such as Blue Water. Another group saw no reason why the RAF's needs could not be met by the Buccaneer. Politicians were naturally concerned at what the TSR.2 programme might eventually cost; and to the Government in general it was hard to disguise the fact that the new aircraft meant a complete reversal of policy, for they had stated in April 1957 "The Government have decided not to go on with the development of a supersonic manned bomber."

TSR.2 survived these political storms for the simple reason that the RAF had a very real need for it, and critics of the aircraft are found today only among those who do not appreciate the problems involved.

The Ministry Of Supply regarded an advanced version of the Olympus turbojet as the optimum choice. This engine has been designed to give a sea-level static thrust of 33,000lb, which is more than that of any other powerplant in production in the western world. It is this great thrust and the adoption of high-lift devices on the wing which enable the aircraft to take off from what Mr Harold Watkinson, when he was Minister of Defence, described as "a short, bulldozed strip." Mr Watkinson also mentioned that the TSR.2 has "a unique undercarriage which allows it to land on very short airfields." In fact this latter ability stems more from the Weybridge insistence on slow circuit and approach speeds, coupled with excellent handling; the "unique undercarriage" serves to bring the LCN (footprint loading) down so low that the aircraft can operate from plain grass or compacted earth in normal conditions.

For at least a decade, many British Observers (including the author) have inclined the view that modern weapon systems demand a system management structure of the type pioneered in the United States from 1950 onwards. Had such a management structure not been adopted, it is doubtful if TSR.2 could have been accomplished at all; the programme would certainly have taken much longer and been more costly. On the Government side the Ministry of Aviation set up a permanent TSR.2 management board on which sit various senior Air Staff officers, directors-general and manufacturer representatives, and an extremely comprehensive and detailed plan was drawn up for the development of the weapon system. It may perhaps be as well to reiterate what the Americans have known since Korea; that the weapon system consists of the aircraft, everything that goes in it and everything that supports it, right down to the fuse cartridges for the simulator. One still occasionally finds Englishmen who think that the term means the armament carried by the aircraft.

In previous British military aircraft, many of the vital subsystems---especially the mission electronics---would be supplied not to the airframe constructor but direct to a MoS or MoA department who would then have it installed in the aircraft. The development of all such equipment was carried out under contract to a Ministry establishment, and when a new aeroplane came along, it was the custom to fill it up with whatever equipment happened to be available. When GOR.339 was being drafted, a list---a long list---of existing mission equipment was drawn up as a guide to what the new aeroplane would have to carry. If this policy had been pursued, TSR.2 would have been weighed down with rack after rack of devices culled from V-bombers and even Shackletons and all identified by colourful code-names, but in no way tailored to the new requirement. Much of the equipment would undoubtedly have required very extensive development for it to function at all over the whole range of TSR.2 flight conditions.

It was obvious to the Air Staff and the prime contractor that the weapon-system principle had to be applied ruthlessly, and Sir George Edwards appointed the Vickers guided-weapon division, under Brig John Clemow, to undertake a detailed study of the requirement for mission electronics and to devise form scratch a fully integrated system tailored to the TSR.2 requirement.

This led to much of the airborne equipment coming into a new category in which, for the first time, a British aircraft manufacturer could write both the specification and choose the subcontractor, who would henceforth be responsible not directly to the Ministry but to the prime contractor. The relevant Ministry departments would, however, exercise an essential consultative and advisory function, and meet as referee where appropriate. This procedure represented a considerable administrative revolution and realignment of traditional responsibilities, and that the system was set up quickly and made to work is a testimony to the co-operative spirit of everybody concerned.

Before the summer of 1959 TSR.2 had taken shape. To some extent it was an amalgam of the best features of the separate submissions by Vickers and English Electric. The design team at Warton under Freddie Page was the only one to have extensive experience of Mach numbers up to two, and they accordingly concentrated upon the aerodynamic, stability and control aspects of the design. Their feasibility study had the better wing, which during 1958 had been subjected to extensive tunnel testing yielding desirable results. Vickers, on the other hand, had instituted the far-reaching study into electronic systems and airborne equipment, and in consequence had a more refined fuselage. As far as manufacture was concerned, the aircraft split cleanly near the trailing edge of the wing box and English Electric being responsible for the wing, rear fuselage, powerplant installation, and tail. Design of the tail surfaces was actually handled at Weybridge.

This arrangement satisfied the 50-50 split demanded by the minister, and must have provided valuable experience carried across to the Concorde programme, where a similar 50-50 split is working successfully between two different nations. From the administrative point of view, the position was greatly simplified by the formation in February of 1960 of British Aircraft Corporation Ltd, which today embraces the aircraft interests not only of Vickers and English Electric, but also of Bristol and Hunting. From January 1 next [1964] the names of the former companies will disappear, and the TSR.2 programme will be shared by BAC Weybridge Division and BAC Preston Division.

Up to October 7 1960, the company operated with a design contract, but on that date the Minister of Defence, then Mr Harold Watkinson, announced the placing of a full development contract, involving the construction of nine aircraft. A pre-production batch was placed under contract at a later date. Both batches are being constructed in production jigs, so that most of the enormous tooling outlay has already been paid for. The second batch follows the first without a break, and will lead directly into production of aircraft for operational service. Production aircraft are now also under contract, and BAC have for several months been cleared to spend a substantial sum on long-term materials for aircraft No 21 and beyond.

The initials TSR stand for tactical strike and reconnaissance. In this context, the word "tactical" covers a considerable spectrum of mission ranges, including penetrations of enemy territory to a depth of far beyond 1,000 miles. The "cab-rank" type of close support of troops in a battlefield could certainly be performed by this aircraft, but is best left to cheaper machines. TSR.2 has three primary missions: all weather day and night strike against any surface target with various nuclear weapons; all-weather day and night strike against any target with a full range of conventional weapons; and all-weather day and night high-grade reconnaissance by all available means.

Generally it is true to assert that too great an increase in aircraft versatility tends to result in degradation of mission performance, and in some cases in a reduction in safety of the aircraft. TSR.2 would undoubtedly suffer in its primary role if it were to be given in addition an interception capability. Such a role would demand a wing of considerably increased area in order to obtain the desired manoeuvrability at all altitudes. Space would have to be found for the parent-aircraft components of the Red Top weapon system, and racks for the missiles themselves would need to be installed. Even the seemingly simple matter of designing the nose radar to operate in AI mode would probably degrade the system integrity and performance.

In fact, so demanding is the prime requirement of being able to fly supersonically along the surface of the Earth for several hours at a time that this largely dictates the design. Such a mission requires a wing of minimum span and area. Not only is the TSR.2 wing relatively very small, but it has been carefully designed to have minimum gust response. In a normal aeroplane flight through a gust or "air pocket" results in appreciable vertical acceleration. This is mildly unpleasant at low speeds, but at supersonic speeds in dense air the vertical accelerations are of intolerable violence. Several years ago the Air Ministry conducted trials with a Canberra in Libya and maximum-speed runs at low levels in the heat of the day were as much as the airframe or crew could stand. TSR.2 is designed to fly at the same height roughly twice as fast.

English Electric's careful tunnel testing at Warton has led to a wing which is not only of small area but also has a flat lift curve. Fairly constant lift slope is a characteristic of a delta, and in this case refinement of the profile has resulted in a wing giving sensibly constant lift over a wide range of angles of attack, and therefore relatively insensitive to gusts.

In order to meet the requirement for a flight Mach number greater than 2 at altitude, the wing must obviously be of very low thickness/chord ratio; and this, coupled with the extremely high wing loading, militates against the design objective of STOL performance.. The answer is the employment of very large blown flaps over the full span of the wing out to the turned-down tip. Take-off distance is also improved by the excellent thrust/weight ratio. There is every reason to believe that TSR.2 will be able to fly circuits slower, and under better control than any aircraft resembling it now flying. Approach speed will be of the same order as that of the VC-10--around 130kt--and the landing roll will be shortened by an enormous braking parachute and powerful wheel brakes.

Supersonic aircraft generally require anhedral to prevent Dutch roll at low speeds. Simple anhedral on the TSR.2 would have placed the tailplane in undesirable flow-patterns, and would probably have led to severe aerodynamic coupling resulting from the powerful vortex trailing behind the wing tips. Since the wing cannot be mounted any higher, nor the tailplane any lower, the answer has been to keep the wing straight and tilt the outermost portions sharply downwards. There are no fences, sawcuts or vortex generators, but subtle variation in contour, especially over the leading edge at the root and tip, has resulted in a wing with excellent characteristics and linear derivatives about all three axes over the entire performance envelope.

V/STOL techniques were studied very closely during the project's early days, but the debits of jet lift appeared to outweigh the credits, just as they did three years later with the American TFX programme. A few doodles will confirm the apparent impossibility of accommodating the engines, main wing box and weapons bay (and possibly the retracted main gears) all on the centre of gravity. In the present aircraft the fuel and weapons are presumably disposed evenly fore and aft of the c.g., but the engines place themselves further aft.

There are no movable surfaces on the wings apart from the flaps. Control is effected by an all-moving slab vertical tail and by a rolling tailplane (or "taileron") similar to the arrangement employed on the A-5 Vigilante. The surfaces are naturally fully powered, and both they and their actuating systems have great power and stiffness. High-strength steel is employed in the landing gear. Each main unit has tandem wheels with low pressure tyres carried on a long-stroke leg. The steerable nose unit can be extended to rotate the aircraft to the take-off attitude; this extension may be done before or during the take-off, and flight trials will show whether or not this is preferable to conventional rotation.

Bristol Siddely Power

Engines are a pair of developed Bristol-Siddely Olympus 22R turbojets with full reheat and infinitely variable nozzles. Officially stated to have a development potential of 33,000lb static thrust, these engines have an excellent specific fuel consumption and have been designed to meet all requirements posed by the TSR.2's arduous operating environment; although all choices in aircraft design are compromises, and to deign an engine to ingest a tropical vulture at low level at over 1,000 m.p.h. would appear to pose unacceptable penalties. During development several TSR.2 powerplants have been flown beneath a Vulcan and run both on the bench and at the NGTE at Pyestock under the full range of environmental conditions.

Fuel is carried in integral tanks everywhere that there is space available. It is believed that the fuel weight is a higher proportion of the maximum gross weight than in any previous British military aircraft. There is provision for flight refuelling.

Pilot and navigator are seated in tandem on the centreline. Martin-Baker rocket-assisted ejection seats are expected to permit safe escape at any point in a mission, including the take-off run. The seats may be ejected independently, although pilot ejection causes the navigator the be shot out first. No "capsule" is employed, although special partial-pressure clothing is being designed for TSR.2 crews to provide, inter alia, a new standard of blast protection during high-speed ejection.

Mission equipment is complex, varied, highly flexible yet closely integrated, and almost entirely new. Basic navigation system is Doppler/inertial DR, progressively updated by the radars. The nose radar is for weapon delivery and terrain-clearance, and its output is continuously fed into the navigation system. The side-scan radar appears to occupy almost the full depth of the fuselage, in contrast to the slender axial aerials previously used. The new arrangement enables the scanner to rotate and lock-on to ground targets to give better definition. Output from this radar may be matched against maps by the navigator to provide co-ordinates for further refinement of the Doppler/inertial position.

Navigation outputs are all fed into a central computing system to govern the flight of the aircraft via the autopilot and control system. The computer memory can store commands for the execution of an entire mission; if this is done, the aircrew have to perform little more than a monitoring function, albeit an important one. At the same time, it must be emphasised that the TSR.2 is no mere missile, and the unique facility of the human brain to cope with the unexpected is utilized to the full. At any time the pilot can break into the automatic control loop and take over manually.

Both pilot and navigator have a moving-map presentation driven off the computer. The pilot has an OR.946 panel of instruments, as well as a head-up display of basic flight data on the windscreen. The latter facilitates transition to a visual attack, and relieves the pilot of the critical decision of when he should look up. Very detailed attention has been paid to cockpit instrumentation and controls, and also to the air-conditioning system, in order to reduce crew work-load and discomfort. Moreover, every system fails safe; for example, any malfunction in the terrain-following system causes the aircraft to go into a climb (with a bold warning signal on the pilot's panel).

In the reconnaissance role, the TSR.2 can be equipped with a crate of equipment supplementing the cameras permanently carried . The TV cameras can transmit pictures for projection at Army command posts.

In theory, TSR.2 requires no outside support from a forward base apart from supplies of fuel. All on-board systems can be run at dispersal from an onboard a.p.u., and their self-checking capability is exceptional. Moreover, TSR.2s have inter-theatre ferry range enabling them to reach "the scene of the crime" in a matter of hours, and then to operate for a period with no support equipment other than can be readily flown in by a 748MF.

BAC are well advanced with the manufacture of 20 development and pre-production aircraft, and are negotiating with the MoA for an initial batch of 30 for squadron service with the RAF. The development machines will be retained by BAC, but the pre-production TSR.2s will be shared between the MoA and an RAF development squadron. Most pre-production aircraft may ultimately be converted to operational use.

Air Ministry have a planning team which has already done its best to ensure that the aircraft, crews, ground equipment and supporting services all come together at the right place and time. No particular problems are foreseen in bringing the aircraft into service, although first-tour aircrew will not be posted to TSR.2 squadrons for a year or two. Studies are in hand to ascertain the possibility of fitting dual controls into squadron aircraft.

This weapon system is far more than just a replacement for the Canberra. It is likely to prove the only one of its generation able to hit the correct enemy bridge, and the correct span of the bridge, after a deep penetration of any type of territory equipped with the best defences. It will provide the Royal Air Force with a full range of options to react effectively and economically to any military situation anywhere. Application of a Pentagon style cost/effectiveness study to TSR.2 and all available alternatives drives home the fact that this all-British aircraft is one item of equipment we cannot afford not to have.