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BAC TSR-2

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The BAC TSR-2 was an ill-fated Cold War strike aircraft developed by the British Aircraft Corporation (BAC) for the Royal Air Force (RAF) in the early 1960s. The TSR-2 was designed to penetrate a well-defended forward battle area at low altitudes and very high speeds, and then attack high-value targets in the rear with close-in bomb runs and precision drops. The TSR-2 included a number of advanced features that made it the highest performing aircraft in this role, yet the programme was controversially cancelled in favour of the General Dynamics F-111, a procurement that itself was later cancelled.

All modern aircraft have four dimensions: span, length, height and politics. TSR-2 simply got the first three right.

— Sir Sydney Camm

Development

Background

Prior to the TSR-2 effort, the British Royal Air Force had deployed the English Electric Canberra bomber, capable of flying at high altitudes and relatively high speeds. Like the de Havilland Mosquito before it, the Canberra carried no defensive weapons and relied on its high performance to allow it to avoid defenses. Fighters could approach the speeds of the Canberra, but doing so while climbing to its altitude was by no means a trivial task. Nevertheless, as the performance of the Soviet interceptors grew, the Canberra grew increasingly vulnerable. English Electric had been studying higher performance designs, otherwise similar to the Canberra, since even before the Canberra entered service.

The introduction of the radar-guided surface-to-air missile (SAM) significantly upset this balance. SAMs attacked in a straight line from below, and had speed and altitude performance much greater than any contemporary aircraft. The Canberra, and other high-altitude aircraft like the Avro Vulcan or B-52 Stratofortress, were extremely vulnerable to these weapons. The solution was to fly lower. As radar is line-of-sight, an aircraft flying at 200 ft (60 m) only becomes visible at about 25 miles (40 km) distance. An aircraft traveling just under Mach 1, say Mach 0.85 or 650 mph (1046 km/h), will cover this distance in a little over two minutes, giving the SAM site very little time to prepare for an attack. This also assumes a perfectly smooth Earth; trees, hills, valleys and any other obstructions reduce this range even more, making an attack extremely difficult.

The Canberra was designed for high-altitude flight and could not be easily flown at lower altitudes. In particular its large wings would result in high loads due to turbulence. Additionally, navigation at low altitudes is a demanding task, one that the 1940s era electronics of the Canberra was simply not up to. Low-level strike fighters, or "interdictors" as they became known, grew into a new class of their own through the late 1950s. They generally featured high wing loading to reduce the effects of turbulence, some form of high performance navigational radar to allow them to fly very low at high speeds, and large fuel loads to offset the higher fuel use at low altitudes.

GOR 339

Aware of these issues, the Ministry of Supply started work with English Electric in 1956, attempting to define a new interdictor. Originally the designs concentrated on a smaller aircraft more similar to a fighter, and there was some discussion of developing the P.1B project (soon to become the English Electric Lightning) in this direction as the P.18, while adaptations of the earlier developments of the Canberra were gathered under the P.17 designation. These early studies eventually settled on an aircraft with a 2,000 nm (3,700 km) ferry range, Mach 1.5 speed "at altitude", and VTOL or STOL performance. The latter requirement was a side-effect of common battle plans from the 1950s, which suggested that nuclear strikes in the opening stages of war would damage most runways and airbases, meaning that aircraft would need to take off from improvised sites, or even fields. As the project continued, the requirements continued to grow. A crew of two was required, one operating the advanced navigational and attack equipment, and bombload was six 1,000 lb (450 kg) bombs. This basically eliminated the P.18 design as a suitable approach, and further work concentrated solely on the delta-wing P.17A.

The requirements were eventually made official in March 1957 with GOR (General Operational Requirement) 339. This specification was exceptionally ambitious for the technology of the day, requiring a supersonic all-weather aircraft that could deliver nuclear weapons over a long range, operate at high level at Mach 2+ or low level at Mach 1.2, with a short takeoff ability from rough and ready airstrips.

Specifically the requirement included:

  • deliver tactical nuclear weapons at low level in all weathers.
  • photo-reconnaissance at medium and low levels day and night
  • electronic reconnaissance
  • deliver tactical nuclear weapons day and night at medium altitudes blind bombing if necessary
  • deliver conventional bombs and rockets

Low level was stated to be under 1,000 ft (300 m) with an expected attack speed at sea-level of Mach 0.95. The operational range was to be 1,000 nautical miles (1,850 km) operating off runways of no more than 3,000 ft (900 m).[1]

Political changes

As this specification was being studied by various manufacturers, the first of the political storms that were to dog the project reared its head, when Defence Minister Duncan Sandys stated in the 1957 Defence White Paper the era of manned combat was at an end and ballistic missiles were the weapons of the future. Within a decade, this philosophy became thoroughly discredited, but at the time, and in the climate of the Cold War and "mutual deterrence", it doubtless appeared to make some sense, especially as it seemed missiles would offer significant cost savings over manned aircraft. Debate over the need for GOR 339 in light of the White Paper continued for some time, but it was eventually allowed to continue as one of the projects that was "too far along" to cancel.

Along with this was the uncertainty caused by the House of Commons Select Committee on Estimates' report of the year prior. This report suggested that contracts should only be accepted from teams consisting of more than one company, in order to force the companies to merge. Although the large number of companies in the UK at the time was a problem, the Committee's solution to the problem led to various problems when teams that had never even spoken before were forced to work together for no reason other than to have a chance of winning work.

Another political matter that did not help was the mutual distrust between the various services. At the time GOR 339 was being defined the Royal Navy was in the midst of their NA.39 project, which would eventually become the Blackburn Buccaneer. The Buc was also a low-altitude high-speed attack aircraft, but designed for overwater as opposed to overland use. The savings involved in both forces using a common aircraft would be considerable, and Blackburn offered the RAF a supersonic version of the NA.39 as a fit for the GOR 339 requirements. However, the RAF rebuffed the proposal, stating that anything under Mach 2 performance was unsatisfactory, and S/VTOL performance was mandatory. As one RAF official put it, "If we show the slightest interest in NA.39 we might not get the GOR.339 aircraft."[2]

Submissions

Work on GOR 339 continued, with a deadline for submissions on 31 January 1958. A large number of proposals were entered; EE's P.17A along with designs from Avro, Hawker and Vickers-Armstrong (through their Supermarine division). Short Brothers also sent in the P.17D, a flying platform that was to be used in concert with the P.17A, lifting it into the air so that the P.17 did not have to have VTOL performance on its own. The Air Ministry eventually selected the EE P.17A and the Supermarine 571 for further development. The Ministry was particularly impressed with the Vickers submission, which included not only the aircraft design, but a "total systems concept" which outlined all the support facilities and logistics needed to support the aircraft in the field.

GOR 339 was revealed to the public in December 1958 in a statement to the House of Commons. Under pressure by the recommendations of the Committee on Estimates, the Air Ministry examined ways that the various project proposals could be combined, and in January 1959 the Minister of Supply announced that the TSR-2 would be built by Vickers-Armstrong working with English Electric; the initials coming from "Tactical Strike and Reconnaissance 2".[1]

On 1 January 1959 the project was given an official go-ahead under the new designation OR (Operational Requirement) 343. OR 343 was more specific and built upon work from the various submissions to GOR 339 specifically stating that the low level operations would be at 200 ft or less, and that Mach 2 should be attained at altitude.

The mission

The envisioned "standard mission" for the TSR-2 was to carry a 2,000 lb (900 kg) weapon internally for a combat radius of 1,000 nautical miles (nm) (1,850 km). Of that mission 100 nm (185 km) was to be flown at higher altitudes at Mach 1.7 and the 200 nm (370 km) into and out of the target area was to be flown as low as 200 feet (60 m) at Mach 0.95. The rest of the mission was to be flown at Mach 0.92. If the entire mission were to be flown at the low 200-ft altitude, the mission radius was reduced to 700 nm (1,300 km). Heavier weapons loads could be carried with further reductions in range.

Extensions to the TSR-2's range were planned to be made by fitting external tanks — one 450-Imperial gallon (2,000 L) tank under each wing or one 1,000 Imperial gallon (4,500 L) tank carried centrally below the fuselage. If no internal weapons were carried, a further 570 Imperial gallons (2,600 L) could be carried in a tank in the weapons bay.

It was also planned to be able to equip the TSR-2 with a reconnaissance pack in the weapons bay which, coupled to the aircraft's capable sideways looking radar (SLAR), would have turned the aircraft into a formidable "recon" asset not unlike the contemporary North American RA-5C of the United States Navy.

Design

File:SmallTSR-2.jpg
TSR-2 prototype XR219 on its maiden flight

English Electric, manufacturer of the Canberra, and Vickers-Armstrongs had been judged to have made the best submissions for GOR 339. The two companies combined their ideas for the specification and put forward their joint design with a view to an aircraft flying by 1963. No order was forthcoming and by the time the Ministry had made a decision the various companies had been amalgamated as the British Aircraft Corporation in 1960. EE had put forward a delta winged design and Vickers a swept wing on a long fuselage. The EE wing, born of their greater supersonic experience, was judged superior to Vickers, while the Vickers fuselage was preferred. In effect, the aircraft would be built 50/50: Vickers the front half, EE the back.[1]

The design was a large aircraft to be powered by two Bristol-Siddeley Olympus afterburning turbojets, with a large shoulder-mounted slab-wing with down-turned tips, an all-moving swept tailplane and a large all-moving fin. The engines were a variant of those used in the Avro Vulcan, and would later be developed further for Concorde. It is often stated, incorrectly, that the leading designer of the TSR-2 was Vickers' Barnes Wallis, the legendary aeronautical engineer famous for his Wellington bomber design and contribution to the Dambusters raids. Wallis was not involved in the TSR-2, but his son, who also worked for Vickers, was involved with it to a small extent. In fact Wallis was quite critical of the TSR-2, and stated that a "swing-wing" design (a concept that he championed, having done much work on it) would be more appropriate.

The design featured blown flaps to achieve the short takeoff and landing requirement, something that later designs would achieve with the technically more complex swing-wing approach. The aircraft featured some extremely sophisticated avionics for navigation and mission delivery — far ahead of anything else available at the time — which would also prove to be one of the reasons for the spiraling costs of the project. Some features, such as ground-following terrain radar, FLIR cameras, side-looking airborne radar and the sophisticated autopilot, only became commonplace on military aircraft later.

The wing loading was high for its time, enabling the aircraft to fly at very high speed and low level with great stability without being constantly upset by thermals and other ground-related weather phenomena. This in turn made the innovative ground-following radar and autopilot system feasible. To improve the ride quality at low levels further, the cockpit had a degree of "float" to help damp out turbulence and reduce crew fatigue.

There were considerable problems with realizing the design. Some contributing manufacturers were employed directly by the Ministry rather than through BAC, and the Ministry itself took on design tasks, with the usual long deliberations and meetings typical of civil servants.[3]

Operational history

Testing

Despite the increasing costs (which were inevitable, given the low original estimates), two prototype aircraft were completed. Test pilot Roland Beamont made the first flight on 27 September 1964. In the course of testing, the TSR-2 was found to meet easily the demanding GOR 339 performance specification. Aerodynamically the aircraft was trouble-free, but there were continual problems with the engines and the undercarriage. Indeed, the engines delivered for the first aircraft did not fit, leading to delays for the first flight which meant that the TSR-2 missed the opportunity to be displayed to the public at that year's Farnborough Air Show.

Initial flight tests were all performed with the undercarriage down and engine power strictly limited. Only on the tenth test flight was the landing gear successfully retracted, but vibration problems on landing persisted. The aircraft's nosegear vibrated at the resonance frequency of the eyeball, causing the pilot and navigator to suffer double vision during taxiing. The problem was dealt with by adding damping into the already extremely complex landing gear. The second prototype (XR220) incorporated additional dampers in the main gear legs (fixed dampers having been flight tested on XR219).

The first supersonic test flight (Flight 14), was achieved on the transfer from the Aeroplane and Armament Experimental Establishment at Boscombe Down to BAC Warton. Surprisingly, the aircraft achieved Mach 1 on dry power only (supercruise). Following this, test pilot Beamont lit one of the afterburners only (because of problems with the other engine's afterburner fuel pump), with the result that the aircraft accelerated away from the chase Lightning despite its engaging full afterburner on both engines.[3]A speed of Mach 1.2 was reached on that occasion.

Over a period of six months many test flights were conducted. None of the complex electronics were fitted to the first prototype, so these flights were all concerned with the basic flying qualities of the aircraft, which according to the test pilot involved, were outstanding.

Project cancellation

The United States had developed the swing-wing General Dynamics F-111 project as a follow-on to the F-105 Thunderchief, a fast low-level bomber designed in the 1950s with an internal bay for a nuclear weapon. As a cost-saving measure over developing a duplicate aircraft, the RAF considered the F-111 as an alternative. In response to suggestions of cancellation BAC employees held a protest march, and the new Labour government, which came to power in 1964, issued strong denials. But in the budget speech of 6 April 1965, the cancellation in favour of the F-111 was announced. A week later the Chancellor defended the decision in a debate in the House of Commons, saying that the F-111 would prove cheaper.

One of the surviving airframes at the RAF Museum, Cosford

The TSR-2 tooling and partially completed aircraft were scrapped. Two finished but unflown aircraft eventually survived, though with substantial internal damage inflicted; XR220 at the RAF Museum, Cosford near Wolverhampton, and XR222 at the Imperial War Museum Duxford. A number of unfinished airframes were hastily scrapped, with very few parts retained intact. Along with two unfinished frames (XR221 and XR223), the only airframe ever to fly, XR219, was taken to Shoeburyness and used as a target to test the vulnerability of a modern airframe and systems to gunfire.[3] The haste with which the project was scrapped has been the source of much argument and bitterness since.

To replace the TSR-2 the Ministry decided on two aircraft, one would be the swing-wing American General Dynamics F-111K for the strike reconnaissance role with a longer-term replacement being a joint Anglo-French project for a variable geometry strike aircraft, dubbed AFVG.[1] However, the F-111K itself suffered enormous cost escalation, far exceeding that of the TSR-2 projection, and many technical problems before its successful deployment in combat. Coupled with a poorer than projected performance and the devaluation of the pound, the order for 50 F-111Ks for the RAF was cancelled and instead they took on the F-4 Phantom II and the Blackburn Buccaneer, some of which were transferred from the Royal Navy.

These were the very same aircraft that the RAF had apparently derided in order to get the TSR-2 go-ahead, but the Buccaneer proved capable and was still in service into the early 1990s. The TSR-2 nonetheless remains a lingering "what if?" of British aviation, like the CF-105 Arrow interceptor in Canada. The Phantom and Buccaneer were eventually replaced by the variable-geometry Panavia Tornado, a much smaller design than either the F-111 or the TSR-2. Experience in the design and development of the avionics, particularly the terrain-following capabilities, were used on the later Tornado programme. The Soviet Union also developed swing-wing fighters and strike bombers in the late 1960s and 1970s. The Royal Australian Air Force adopted the F-111, and continues to fly them.

A government study into the feasibility of resurrecting the TSR-2 project was carried out during the early 1980s when Margaret Thatcher was Prime Minister.[citation needed] There was, briefly, some speculation that TSR-2 might yet see the light of day in an updated form.[citation needed] But after the study concluded that it would be far too expensive (the previous destruction requiring a complete start from scratch), and that the technology was no longer cutting edge, the TSR-2 was cancelled forever.

Survivors

Specifications

Data from [4]

General characteristics

  • Crew: 2

Performance

Armament

  • or 4 x 37 rocket packs or nuclear weaponry on inner pylons only.


Maximum of 20,000 lbs (9,000 kg) of bombs. Avionics

  • Autonetics Verdan autopilot modified by Elliot Automation
  • Ferranti (terrain following radar and navigation/attack systems)
  • EMI (sideways looking radar)
  • Marconi (general avionics)
  • Cossor (IFF)
  • Plessey (Radio)

References

Notes

  1. ^ a b c d Buttler 2005
  2. ^ The BAC TSR.2
  3. ^ a b c Thunder and Lightnings TSR-2 History
  4. ^ Thunder and Lightnings, Survivors

Bibliography

  • Buttler, Tony. British Secret Projects: Jet Bombers Since 1949. London: Midland Publishing, 2003. ISBN 1-85780-130-X
  • Forbat, John. TSR2: Precision Attack to Tornado. Stroud: Tempus Publishing Ltd., 2006. ISBN 978-0-7524-3919-8
  • Thornborough, Anthony. TSR2. (Aeroguide Special) Suffolk, UK: Ad Hoc Publications, 2005. ISBN 0-946958-46-7
  • Winchester, Jim. "TSR.2." Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft. Kent, UK: Grange Books plc., 2005. ISBN 1-84013-309-2

See also

Aircraft of comparable role, configuration, and era

Related lists

Wikimedia Commons has media related to BAC TSR-2.
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