TSR2

by Damien Burke

  BAC’s first suggestion for a more impressive strategic weapon for the TSR2 was to fit their own Blue Water nuclear missile to the aircraft; the missile, with minor changes, could just about be squeezed into a semi-conformal fit under the fuselage. BAE Systems via Brooklands Museum

  A missile with improved range using Blue Water components was also proposed.

  BAC’s third suggestion was a dedicated ballistic missile, using a Polaris re-entry head and fitting entirely within the existing TSR2 weapons bay. BAE Systems via Brooklands Museum

  The final missile suggested was a high-speed cruise missile using a modified Bristol Aircraft BT3 ramjet engine, able to fly at Mach 2 at 200ft (60m) with onboard inertial navigation and terrain clearance. The length of any such design precluded weapons-bay or even semi-conformal carriage, but there was a possibility of under-wing carriage. However, the problems of the cost of development of such a weapon, and particularly its terrain-clearance system, ‘should not be underestimated’.

  BAC was unwilling to predict even basic costs or timescales, however, and the Ministry suspected it was looking at something in the region of £40 million for even the most basic of the proposals, rising to a development cost equal to the entire TSR2 project for a home-grown air-launched ballistic missile. The British Nuclear Deterrent Study Group looked at the proposals and was unimpressed. It considered every standoff weapon suggested to be ‘so unattractive on technical, financial and development time considerations that they were not worthy of further study’. The group believed that all quoted costs were too low, and all performance figures exaggerated. The planned Europe-based TSR2 strike squadrons assigned to Supreme Allied Commander, Europe, would be capable of striking Soviet strategic targets with free-fall bombs anyway, given their long-range capability. The deterrent value was already there. To give a fuller deterrent capability the easiest thing to do would be to equip the aircraft with megaton-range weapons, delivered in a low-level lay-down attack with delayed detonation to enable the aircraft to escape. The real question was whether there was any point, when Skybolt was going to be a much more capable option, and the conclusion was that ‘… this course of action would not be justified so long as the Skybolt solution to the deterrent problem remained valid. On the other hand, if the Skybolt development project failed, the development of the TSR2 weapons system would represent a real insurance.’

  Bolt from the blue

  Everything changed in November 1962, when the Americans unilaterally cancelled the Skybolt programme, leaving Britain high and dry, with the future nuclear deterrent policy in tatters. No time was wasted by BAC in responding to this, and the company issued a series of brochures in early 1963, once more pushing the TSR2 in the strategic role. The first of these, entitled TSR2 Strategic Weapons Systems, described the type’s use in the strategic role with lay-down bombs and stand-off missiles, based on the earlier study of 1960. The aircraft was already able to carry four low-yield OR.1177 weapons, and for the strategic role this was reduced to two high-yield OR.1177s with additional fuel to extend the combat radius. With space freed in the bomb bay by the carriage of just two bombs, a 330gal (1,500L) bomb bay tank could be fitted, along with a pair of underwing drop tanks of 450gal (2,045L) each and a 1,000gal (4,545L) ventral tank. A scenario was postulated in which the aircraft could return to a base 300nm (345 miles; 555km) nearer to the target than the home base from which the strike was launched (after all, it was a fair bet that home base was ground zero for an enemy strike), which in combination with the additional fuel would give a combat radius of 1,860nm (2,140 miles; 3,440km), of which 200nm (230 miles; 370km) would be flown at low level at Mach 0.9. Sticking to low level for 1,000nm (1,500 miles; 2,400km) would reduce the combat radius to a still very respectable 1,600nm (1,840 miles; 2,960km) under the same conditions of landing somewhere other than the smoking hole in the ground from which the mission had begun. The underwing and ventral drop tanks would all have to be jettisoned immediately they were empty, or the extra drag would seriously reduce the combat radius. Even with the heaviest possible load of two OR.1177 high-yield bombs and 2,230gal (10,130L) of extra fuel, the takeoff roll would still be around 1,350yd (1,235m) and required an LCN of just 44, so a large number of airfields would be suitable; over sixty within the eastern half of England, for instance. The combat radius offered would put targets such as Leningrad, Moscow, Kirov, Kazan and Volgograd (Stalingrad) within range of bases throughout England, Europe and Cyprus.

  Illustration of a TSR2 firing the first of its twin Blue Waters from the 1963 TSR2 Strategic Weapons Systems brochure. BAE Systems via Brooklands Museum

  Even more attractive was the pairing of TSR2 with a stand-off missile, specifically the Blue Water missile which had been under development by English Electric as a ground-to-ground tactical nuclear missile for the Army until the programme was cancelled in August 1962. BAC was clearly keen to see that its work on this missile was not wasted, and suggested fitting it with a megaton-class warhead to give the TSR2 a valuable stand-off strategic capability. Unlike the 1960 proposal, this was for the carriage of two missiles, to be carried under-wing on special pylons fitted at the mid-wing point and providing refrigerant to keep the missile’s guidance electronics cool before release, though no underwing drop tanks could then be carried. The original Army design for Blue Water had included the need to fire the missile at a 50-degree angle. This would entail a loft manoeuvre for the aircraft before release, and to avoid this dangerous exposure to enemy defences BAC proposed to release the missile in level flight at 200ft (60m) instead. This would reduce its range slightly, by 4 miles (6km), but still afforded a stand-off distance of 90 miles (145km), more than sufficient to keep the aircraft out of the high-density defences around most strategic targets. While the bomb bay did not have to carry any bombs for a Blue Water mission, some room would still be needed in there for an electronics pack. Even with this, however, the bomb bay fuel tank could be larger than for the OR.1177 mission, at 450gal (2,045L). Coupled with the 1,000gal (4,545L) ventral tank, this would give a combat radius of 1,580nm (1,820miles; 2,920km); not quite sufficient to hit Kirov, Kazan or Volgograd, but the aircraft would be much less vulnerable to being shot down. An alternative load, which retained the 1,860nm (2,140 miles; 3,440km) combat radius of the OR.1177 mission, was just one Blue Water in a semi-recessed ventral fit as per the 1960 study, retaining the normal under-wing 450gal (2,045L) drop tanks and a smaller bomb bay fuel tank of 350gal (1,590L). Another drawback was accuracy. Blue Water was expected to have a CEP of not more than 5,000ft (1,500m) at maximum range of both missile and aircraft. To put this in perspective, this would be like aiming the missile at 10 Downing Street and having it explode over Clapham Common. If that missile had a 1-megaton warhead, No. 10 could well have survived intact, which was not ideal, so Blue Water would have needed to have been 5 megatons or larger to guarantee sufficient destruction to include its intended target within the CEP.

  TSR2 with Blue Water, in single and long-range double carriage fit. With Blue Water having been cancelled in 1962, there was never any serious chance of it being resurrected for TSR2 use. Damien Burke

  At this time BAC was expecting the TSR2 to enter service in late 1965, and predicted that if it was given an immediate intention to proceed it could get the Blue Water fit into service by early 1967. This bold prediction was made possible only by the large amount of work that had already gone into Blue Water before its development was cancelled by the government. Total development costs of £33.9 million were predicted by BAC, of which £16.6 million had already been spent. As Blue Water had been cancelled largely on grounds of cost, this was perhaps not the attractive bargain that BAC thought it was! The brochure ended with a few paragraphs on future developments, including mention of a ballistic missile to be carried by TSR2 with a 500nm (575-mile; 925km) stand-off range but similar accuracy to Blue Water, to be in service by 1970 and costing up to £40 million; and also also an ‘air-supported missile controlled to fly a terrain-follow
ing course similar to that of TSR2’, which presumably referred to the ramjet suggestion of 1960.

  TSR2 with the proposed Grand Slam missile, a sophisticated stand-off weapon complete with its own on-board suite of decoy rockets. Damien Burke

  Grand Slam

  BAC’s final strategic brochure, entitled TSR2 Strategic Weapon System with GRAND-SLAM, described an alternative to the Blue Water fit. Grand Slam was named after the massive 22,000lb (10,000kg) HE ‘earthquake bomb’ used in the last two years of the Second World War. The Grand Slam missile was not quite so heavy, weighing a mere 7,500lb (3,400kg), of which only 600lb (270kg) comprised the warhead, but that warhead was 1.2 megatons, dwarfing its namesake. The brochure was coy about this megatonnage, mentioning no figures and only stating that the warhead was ‘that which was to be used for Skybolt’. Grand Slam’s major attraction compared with Blue Water was accuracy. Its CEP was predicted to be within 1nm (more than sufficient to reduce No. 10 to rubble even if the missile arrived on top of Buckingham Palace). Grand Slam’s chances of arriving on the target without interference by anti-missile systems was also greatly enhanced by its ballistic flight profile and a comprehensive decoy fit. On release from the aircraft (at 40 degrees in a loft manoeuvre, but at 100nm (115 miles; 185km) from the target, hopefully not putting the aircraft at too great a risk) the missile’s rocket motor would ignite three seconds later, powering it to a speed of 5,000ft/sec (1,500m/sec) and an altitude of 67,000ft (20,400m). The warhead stage would separate and continue onwards and upwards, firing radar-reflective decoys and reaching a maximum altitude of 170,000ft (52,000m) (with decoys above and below), its speed reducing to Mach 2.7. On the ballistic path back to earth the speed would increase to Mach 3.5, and in less than 4min from release the warhead would explode over or on the target. The large number of decoys and the high speed of arrival would hopefully guarantee that the warhead arrived unmolested by any of the Soviet Union’s anti-ballistic-missile systems.

  Grand Slam’s fitment on TSR2 was to be as a semi-recessed store, approximately 50 per cent buried within the bomb bay (with a 250gal (1,140L) fuel tank taking up much of the remainder of the bay). The missile’s lower and side fins were detachable, and would be fitted to it once the missile itself had been loaded in the aircraft. Combat radius with bomb bay fuel, underwing drop tanks and the aforementioned 300nm shorter return trip would be 1,600nm (1,840 miles; 2,960km), which let Kazan and Kirov off the hook, and meant Volgograd was only reachable from Cyprus. This could be increased to 1,740nm (2,000 miles, 3,220km) if a return was made to a base 600nm (690 miles; 1,110km) closer than home base – in which case, bad luck Volgograd!

  Brochure 13 from BAC was entitled TSR2 Strategic Weapon System – AIRBORNE ALERT, and recognized that an essential part of any strategic deterrent was the second-strike capability; the ability to take revenge on the Soviet Union even if it had struck first and removed all of the TSR2 bases from the world map. The solution was the standing airborne alert, as famously practised by Strategic Air Command’s Boeing B-52s and other bombers throughout the Cold War. Thus TSR2s in strategic fit would take off with maximum overload fuel and patrol over the North Sea until their fuel state was reduced to the minimum possible for a useful sortie, at which point they would refuel from Victor tankers to restore maximum fuel state. External ventral and underwing drop tanks would be retained throughout the patrol and only dropped if a live mission was begun while airborne. The length of an uneventful patrol would be limited by crew endurance, a figure of 8hr being suggested.

  The airborne alert study produced a simpler proposal involving the carriage of nuclear bombs in the weapons bay and the use of overload fuel tanks, topping up from Victor tankers whenever fuel state ran below a useful minimum. Up to ten TSR2s would be on constant airborne patrol. BAE Systems via Brooklands Museum

  With full fuel on board the bomber, the Soviet Union would be the TSR2’s oyster, with targets as far away as Kazan and Kirov reachable (assuming, once again, a return to somewhere other than ‘RAF Radioactive Rubble’; Norway, for example). Range would be successively reduced through the patrol time until the minimum sortie level was reached, which basically boiled down to being able to hit Leningrad only. With a force of sixty TSR2s, ten would need to be airborne on patrol at all times, which would require the support of fourteen Victor tankers, of which two would need to be airborne throughout. Modifications to the airframe would be minimal. Some undercarriage strengthening and brake improvements were needed to deal with the much higher AUWs when using full overload fuel, and some space for crew rations. Optionally, a tape reader could be fitted so that the navigator could programme the Verdan computer with a preset target which would be picked from those within range at any given fuel state (this was optional because it could be entered manually, given adequate time to do so).

  The two enlarged wing planforms considered in January 1963 for a possible strategic version of the TSR2. Damien Burke

  One problem of the patrol idea was that if the ventral tank could not be carried (for example, if a ventrally mounted Blue Water or Grand Slam was carried), then more frequent refuelling would be necessary. BAC suggested the addition of a ventral tank that could completely enclose the missile while still holding 1,000gal (4,454L) of fuel. The brochure did not expand upon this, but clearly a much larger ventral tank fairing would have been necessary compared with the standard 1,000gal tank, and this would have introduced ground-clearance issues. Finally, the brochure mentioned that a standard TSR2 could also carry out the airborne alert mission, but would inevitably have reduced combat radius as, without the undercarriage modifications, it would be unable to take off safely with such a large fuel load (or land in an emergency if a large amount of fuel was still on board).

  The big wing

  The Aerodynamics Department at Weybridge had also been busy looking at more-extensive changes for an airborne-alert TSR2. The most obvious thing to look at was the wing, which, understandably, had been optimized entirely towards the aircraft’s raison d’être, the tactical role. For the strategic role that small and highly-loaded wing was a drawback. Increasing its size and aspect ratio could bring useful improvements to the combat radius owing to the greater room for internal fuel and higher lift, primarily of use in the economical cruise portion of the sortie. The low-level penetration portion of the sortie would suffer. Lower wing loading meant degraded gust response, and a serious reduction in crew comfort as a result.

  Two new enlarged wings were considered, both retaining the existing wing’s root dimensions. The span of wing 1 was increased from the basic 37.14ft (11.32m) to 44.36ft (13.52m) and its leading-edge sweep was reduced from 58.5 degrees to 53.5 degrees. Its total area was 840sq ft (78.03sq m) (compared with 703sq ft (65.3sq m) for the standard wing). On wing 2 the span was further increased to 51.80ft (15.78m), the sweep reduced to 48 degrees and the wing area increased to 980sq ft (91.04sq m). The tailplane in each case was left unchanged, as the less-concentrated downwash field from the larger wing meant that it retained its overall effectiveness, even though the tailplane size remained identical. This did have a drawback, in that the increased take-off weights meant that the tailplane’s authority would be reduced, and the provision of nose gear leg-extension would almost certainly be necessary to keep the take-off roll within limits. Additionally, the tailplane’s roll authority needed to be augmented by the fitting of conventional ailerons to the larger wing 2.

  The NA.39’s designers would no doubt have been delighted to hear the suggestion that penetration speed could be reduced to Mach 0.7 to deal with the issue of reduced crew comfort owing to these larger wings! In the end, though, the study on enlarging the wing of the aircraft to help with the airborne alert proposal was a dead end, BAC rightly judging that, once again, the cost/benefit case was only going to embarrass it once more, and the Airborne Alert brochure makes no mention of changing the TSR2’s wing.

  As the RAF’s nuclear deterrent was in disarray with the loss of Skybolt, the idea of a strat
egic deterrent role for the TSR2 was of great interest to the Air Staff. They were continually fighting a battle against Treasury men aghast at the ever-increasing cost of TSR2, so the bonus of a strategic capability was not to be ignored. However, they could not justify any immediate expenditure on these expensive new strategic capabilities, so the V-force soldiered on for a few more years until the RN’s new nuclear submarines entered service.

  Trainer version

  As detailed in Chapter 10, studies of a dual-control TSR2 variant began in 1960, but serious work only began in late 1964, resulting in a brochure entitled Type 595 Pilot Trainer Aircraft being issued in January 1965. The Type 595 retained the basic tandem seating arrangement of the normal TSR2. The rear (navigator’s) cockpit would be replaced by an instructor’s cockpit with full flying controls, and the existing separate cockpit canopies were to be replaced by a single clear-vision canopy. (Initial investigation had found that the standards of view through the normal canopies would be insufficient to enable the instructor to monitor the student pilot’s flying safely.)

  General Arrangement of the Type 595 trainer version of the TSR2. The only visual difference compared to the strike version was the one-piece canopy. Damien Burke

  Three forms of aircraft were studied; a prototype trainer converted from one of the existing normal aircraft on the build line; aircraft built as trainers right from the outset and supplied to the RAF as pure trainers, and aircraft built and supplied for the strike role but capable of being converted into trainers by RAF personnel (and converted back to the strike role as required). Conversion would have been most straightforward if the aircraft included a break joint just forward of the equipment bays, but the structure had not been designed with such a joint in mind, and considerable redesign would have been necessary. Accordingly, a plan was drawn up to limit the conversion to the areas that would actually be different on the trainer; the cockpits. Converting an existing development-batch strike aircraft to a trainer would be a lengthy job, entailing the removal of most of the rear cockpit contents, cutting off the structure between the two canopies, cutting into the floor to break into the existing flying-control looms, adding a joystick and all the various consoles and panels required in the instructor’s cockpit, then repairing the cut area of the cockpit sill and introducing a new sill edge with locking mechanisms for the new canopy. The alternative, of producing aircraft that were built as trainers from an early stage in their construction, with associated interconnects and joints in areas such as the inter-canopy area, would create far less wastage and save many months of additional work. The same parts could be used to build the third type of aircraft, strike airframes embodying the capability for conversion to trainers if circumstances dictated.