TSR2

by Damien Burke

  A fuselage breakdown. BAC Weybridge built everything forward of station 644; English Electric built the wings, tail surfaces and rear fuselage. BAE Systems via Brooklands Museum

  The wood-and-metal TSR2 mockup at Weybridge in October 1961. This dimensionally accurate complete mockup of the entire aircraft was used for a variety of purposes. BAE Systems via Brooklands Museum

  Forebody construction in the stage 1 jig at Weybridge. BAE Systems via Brooklands Museum

  The port camera bay of XR220. On this aircraft the bay was used to house flight-test instrumentation instead of a camera. Damien Burke

  The equipment bay and Vickers Electronic Racking. BAE Systems via Brooklands Museum

  The starboard equipment bay of XR220, restored to a representative fit. The braces between shelving were necessitated by vibration and resonance problems. Damien Burke

  The port equipment bay of XR220 has not been restored, and the severed cables to the missing equipment are evident against its rear wall. Damien Burke

  Alternative intake designs for improved auxiliary air supply. The existing twin auxiliary intake doors proved insufficient in both efficiency and actuator strength, limiting take-off performance in the process. The initial 25-degree opening had to be increased to 40 degrees. Damien Burke

  Filling the space between the forward edge of the main equipment bay and the navigator’s rear bulkhead was a triangular-shaped compartment in which the side-facing reconnaissance cameras were to be mounted. (The first five development-batch aircraft were not so fitted, this compartment being used for flight-test instrumentation.) Below this, at the bottom of the fuselage, was a bay earmarked to house a down-and-forward-looking camera, though this was later deleted.

  Forward centre-section

  The forward centre-section comprised the area of the fuselage from the nose undercarriage bay back to the forward part of the intake assemblies. Along the bottom of this section (from forward to aft) ran the nose-gear bay, the Doppler and inertial platform bay and the Cumulus airborne auxiliary powerplant (AAPP) bay. Housed above all of these were the No.1 and No.2 fuel tanks. The No.1 tank was made up of three rectangular units of integral machined stringer skin panels around dividing bulkheads, the tank sides forming the fuselage sides. The No.2 tank was made up of two rectangular units tapering to the rear (situated between the intake tunnels) and two saddle-shaped units (sitting on top of the intake tunnels and extending through into the aft centre-fuselage section). The forward fuel collector box sat below this tank. Access to fuel pipes, collector box and associated pumps was via access panels on top and below the fuselage, and also via the Cumulus AAPP bay roof.

  The air intakes extended from a position forward of the wing root, and comprised half frames braced by longitudinal stringers and diaphragms, with internal and external chemi- etched stressed skins broken by auxiliary intake doors to provide additional airflow at low forward speeds and high throttle settings. Intake frontal area was controlled by hinged cones within the intake mouth; a fore-aft pair on each side, with hinges at the points and jacks extending the cone bases outwards when required, varying the cone angle from 17 to 25 degrees. The automatic intake control units were delayed and were never fitted to the only TSR2 to fly, which had the cones locked at the 17-degree mark. Even manual operation was prevented, as clutch slippage was experienced on early tests.

  Upper and lower boundary-layer air bleed ducts cut through the intake frames, the lower bleed also supplying air to a heat exchanger which exhausted below the intakes. Windtunnel tests showed that the intake walls needed to be thickened because of poor subsonic-cruise drag, which reducing efficiency by 10 per cent and imposed a fuel penalty of 300lb (135kg) on the 1,000nm sortie. The RAF was eventually presented with a pair of slightly altered intake designs, one of which would perform slightly better in the supersonic cruise, while the other worked best at subsonic speeds. As the aircraft would spend most of its life subsonic, the latter intake design was chosen for incorporation on production aircraft. The auxiliary intake doors proved highly susceptible to problems in early ground testing, with required jack pressures far in excess of predictions and the surrounding structure unable to deal with the required loading. As a result, on XR219 the doors were locked fully open for the first flight, and then a simplified mechanism was put in place so that they were fully open when the undercarriage was down, and fully closed when it was retracted. In contrast, XR220’s auxiliary intakes were locked closed, and a reduction in maximum permissible take-off weight was imposed as a result. While a temporary modification to incorporate a stronger auxiliary intake door mechanism was in progress at the time of cancellation, several alternative auxiliary intake designs were also suggested at a late stage. The favourite entailed deletion of the auxiliary doors and the introduction of a translating intake lip that would move forward on tracks to give additional airflow at low speeds and bring intake efficiency up to 91 per cent. Work on this was halted by the project’s cancellation, as was analysis of windtunnel results on a version of the intake that re-energized the boundary layer and thus dispensed with the drag penalty of having to bleed it away.

  A forward centre fuselage in the stage 1 jig at Weybridge, early 1962. These two open bays formed No.1 fuselage fuel tank, with cut-outs to accommodate the nosewheel tyres visible in the forward bay. BAE Systems via Brooklands Museum

  The nose gear bay housed the rearward-retracting nose undercarriage, which was attached to a longitudinal beam in the roof of the bay by integrally machined spherical bearings. The fuel tanks forming the roof of the bay were dished to accommodate the nose-gear tyres. Four doors covered the gear bay, the two largest opening only during the extension/retraction sequence and normally remaining closed. They could also be opened for ground servicing access to the various components within the bay.

  In this photo the aft centre fuselage has been married to the forward centre fuselage in the stage 3 jig at Weybridge. BAE Systems via Brooklands Museum

  Rear fuselage construction. This area was as complicated as the rest of the fuselage, with the added difficulties of sealing the engine tunnels against fluid and hot-gas leaks. BAE Systems via Brooklands Museum

  Rear centre section

  The fuselage rear centre-section comprised the remainder of the air-intake tunnels, the main undercarriage bays and most of the bomb bay. The air-intake tunnels formed the majority of the structure in this section, composed of frames braced by integrally machined stringer skin planks and inner skins formed by longitudinal stringers and chemi-etched panels. The rear saddle-shaped portion of fuel tank No. 2 sat above the intake tunnels. The bomb bay extended throughout the entire length of this section of fuselage and into the next section, and was constructed in a similar fashion to the intake tunnels, with doors hinged to the bottom longerons. The shape of the bay was dictated by the available space between the intake tunnels; thus the bay narrowed towards its roof, with the lower portion of the tunnels forming the corners of the bay. The sidewalls incorporated several clip-in boxes, used to attach various stores release units or complete role packs, such as the reconnaissance pack.

  The internal shape of the main undercarriage bays was decided in part by the intake tunnel arrangement, and in part by the bomb bay walls. The framework within the bay was largely vertical, and the frames bearing the main undercarriage pintle bearings were angled to match the outward and trailing angles of the extended main undercarriage legs. The outer edge of the bay was formed by the bay doors, the smallest rear-most door remaining open whenever the main undercarriage was extended, and the two large forward doors remaining open only during the extension/retraction sequence to avoid the loss of longitudinal stability experienced when these large doors were in the open position. They could, however, be sequenced open on the ground to provide access for ground crew.

  The top of this section of fuselage also included cut-outs in the transverse frames to accommodate the wing assembly, with attachments for the wing front spar, drag and vertical links
and auxiliary attachments for the wing apex.

  Rear fuselage

  The final fuselage section, the rear section, primarily comprised ventilated engine and jetpipe tunnels. The fuselage here was constructed of machined and plate-work transverse frames, the engine tunnels being built up as the core of the section, formed of stringer skin panels and ‘T’ booms with a lower vertical shear web and an engine thrust beam running along the top. Rails also ran along the top and bottom of the tunnels to facilitate removal and insertion of the engines and jetpipes. Each engine tunnel had a large cut-out near the forward end, leading to the engine accessories bays, and large doors hinged on the side longerons gave access to the bays and their equipment. Each tunnel was a load-carrying structure in itself, and was surrounded by a heat shield which also acted as a secondary fuel tank wall, designed to contain a fire in the engine tunnel for 5min. The Nos 3 and 4 fuel tanks were located in between and around the engine tunnels, extending rearward to a machined frame forming the rear fuel tank bulkhead, which incorporated integral spigots for the tailplanes and an attachment point for the fin spigot. A fuel collector box was located at the bottom rear of No. 3 tank. A water tank also sat between the engine tunnels, extending down to the roof of the bomb bay.

  The rear-fuselage mockup at Warton. Different colours were used for particular functional zones, for example, red for fuel. BAE Systems via Brooklands Museum

  The rear fuselage of the first pre-production aircraft, XS660, at Preston in early 1965. BAE Systems via Warton Heritage Group

  The rear fairing, made by BSEL, was blighted by design and production problems, and both tasks were to be taken back in-house by BAC for production aircraft. BAE Systems via Brooklands Museum

  The rear fuselage section also included a cut-out at the forward edge to accommodate the rear part of the wing assembly, and incorporated attachments for the rear spar, along with drag and vertical links. Aft of the wing trailing edge were two airbrake recesses, the upper airbrake doors being hinged at their forward edges. A further pair of airbrakes was mounted on the underside corners some distance further forward than the upper pair, with a linkage between all four to synchronize their operation. Finally, the rear fairing, a removable aft portion of the rear fuselage (constructed primarily of Waspaloy, a nickel-based superalloy with excellent strength properties at high temperatures), housed the rearmost portion of the jetpipe tunnel and reheat nozzles plus a brake-parachute bay. This bay was closed off by an aft ‘beak’ door hinged at the top. The fabrication of this rear fairing was the responsibility of BSEL, but work on it was dogged by costs and stressing problems, and early flights were limited to 400kt (460mph; 740km/h) to keep the pressure differential between the parachute box and engine tunnel walls within acceptable limits. Modifications were in hand in early 1965, but by then BAC had had quite enough of the rearfairing fiasco, had sorted out its own temporary fix and was determined to redesign the fairing so that it could be produced inhouse faster, cheaper and to a better standard. Just a week before the project was cancelled BAC decided to manufacture production fairings at Weybridge, and to inform BSEL the next week; it never had to do so.

  Wing skin panels, ribs and spars; primary wing box. BAE Systems via Warton Heritage Group

  The wing structure. BAE Systems via Warton Heritage Group

  Typical structural details of the wing. The integrally machined ‘egg box’ spar construction was later judged to be too complex and costly, and was a candidate for simplification on production aircraft. BAE Systems via Warton Heritage Group

  Wing, tailplanes and fin

  The wing’s primary structure consisted of a multi-spar/rib torsion box with port and starboard forward apex extensions. Built in separate halves and joined at the centre-line, the box was sealed to form a fuel tank on each side. Leading-edge pieces and wingtip structures were built as separate units and attached, along with two-piece blown flaps, to complete the overall wing. There were seven spars within the torsion box, swept at an angle of 17 degrees and extending from the centreline to the wingtip joint, with the exception of spar 1 (the forward spar), the centre portion of which formed the straight leading edge of the torsion box between the apex extension sections. Each spar was machined from a single light-alloy billet, and formed a solid web with integral vertical and horizontal stiffeners. Interspar ribs, twelve on each side, were either machined from solid billets (in high stress areas) or formed from weband-post construction. The centreline rib acted as a baffle between the port and starboard fuel tanks. The next two ribs, 1 and 2, ran fore and aft, and rib 2 incorporated the wing-fuselage attachment points on the underside and slinging attachments on the upper surface. The remaining ribs were at right angles to the spars, with the exception of rib 12 at the wingtip joint. The apex extensions were composed of eight open-girder spars.

  The port wing of XR220. The flaps are down slightly, and the dark areas are unpainted titanium around the flap-blowing slits. Damien Burke

  The starboard wingtip of XR220 under construction at Samlesbury in March 1963. Visible running through the root area is the fuel vent pipe. This doubled as a basic fuel-jettison system on the development-batch aircraft and, after an RAF request, was likely to have been accepted on production aircraft, as the budget was unlikely to stretch to the development of a faster fuel-jettison system. BAE Systems via Brooklands Museum

  The flaps on each side were manufactured as two separate subassemblies joined by a spigot, and constructed in a similar manner to the mainplane itself, on a smaller scale. The trailing edges were filled with aluminium honeycomb and covered with chemietched light-alloy skins. The leading edges were constructed from titanium to cope with the high-temperature engine bleed air directed through ducts (also titanium) in this part of the flap, which exhausted through slits over the top surface of the flap. The flaps were operated by a powered flying-control unit within the fuselage, connected via a driveshaft to screw jacks on the wing undersurface that were covered by fairings.

  The HF radio aerials were mounted within cut-outs in the apex sections of the wing, covered by dielectric panels, though performance in flight testing was poor and a redesign was on the cards for production aircraft. Navigation lights were mounted in cut-outs in the wingtip leading edges, and the wingtips also housed ILS aerials (there was a proposal in being at cancellation to relocate the ILS aerials from the wingtips to the nose radome), the fluxgate compass (starboard) and a missile warning receiver (there was originally to be one in each wingtip trailing edge, but interference with the compass meant that this was reduced to a single installation on the port side only). Stores pylons pick-up points were incorporated on the underside of the wing at stations 120 and 155 (120 and 155in (305 and 394cm) outboard of the aircraft’s centre-line). A fuel venting/jettison gallery passed along the leading edge and was then directed through the wingtip to a vent/jettison outlet in the tip’s trailing edge.

  The starboard wingtip of XR220 forty-seven years later, with the fuel vent and jettison pipe now evident. Damien Burke

  Skinning of the torsion box, apexes and wingtips used tapered panels of light alloy (X2020 on the development batch), machined from planks with integral spar booms and spanwise stringers. Each plank was joined to the next by a lap joint and riveted and bolted to attachment brackets on the torsion-box ribs. After the concerns about X2020’s strength arose, and the static-test example’s wing failed during testing, an alteration to the tips was made so that they would include stiffening patches. Production wings would probably have included redesigned tips skinned with an alternative light alloy.

  Tailplanes

  The all-moving, cropped-delta tailplanes were operated differentially for roll control (the wing having no ailerons) and in unison for pitch control. Each tailplane comprised a multi-web box with stringer-stabilized skins and chordwise ribs. Both the upper and lower skins were taper-machined from a single piece of X2020 alloy (again likely to be changed on production units to an alternative alloy such as L73). Mass-balances we
re attached to the root of the forward closing web of the primary box. Each tailplane was mounted on a spigot protruding from the rear fuselage section, rotating about it on bearings supported by the root and first outboard ribs. Both of these ribs were made from steel, while the remainder of the tailplane, excluding skins, was of light alloy. Tailplane actuation was via hydraulic jacks within the rear fuselage, acting on a bracket on the root rib close to the rear-fairing/rear-fuselage interface.

  The tailplane structure. This illustration predates the finalization of the tail-flap actuator configuration – an oval fairing was added to cover the screw-jack mechanism used on the aircraft. BAE Systems via Brooklands Museum

  The port tailplane of XR219 in final assembly at Accrington in early 1963. The tail-flap mechanism fairing can be seen on the workbench in the foreground, along with the associated drawing. BAE Systems via Brooklands Museum

  The port tailplane of XR220. The fairing for the tail-flap actuators is evident, along with the blue lines denoting the walkway area and a ‘bonker’ plate outboard of the fairing. Damien Burke

  For additional pitch authority at low speeds the tailplanes had trailing-edge flaps of light alloy honeycomb construction. The tailplane flaps were operated by mechanical gearings housed within upper-surface fairings, linked to the tailplane angle, but only when the wing flaps were down. For higher-speed flight, when the wing flaps were retracted, the tailplane flap gearing would be disengaged and the tailplane flaps would be locked in the neutral position.