by Damien Burke
Meanwhile, work continued on the joint datum design, and on the forward fuselage in particular. The nose internal layout underwent substantial revision to move items around and give a more logical arrangement, with room for control runs and air pipes that Vickers had neglected in its original draughting of the Type 571. The centre-fuselage layout also needed careful consideration, as the reconnaissance pack’s interaction with this area was an important factor. But the reconnaissance pack was a responsibility of the MoS, not of Vickers or English Electric, which complicated matters greatly. Soon leading-edge flaps were added to the wing to try to gain a bit more lift at the higher angles of attack necessary to meet the shorter-field requirements, and provision was made within the fuselage to house the electronics package necessary to carry and fire Bullpup missiles. With all this and the further addition of a braking parachute rail to improve crosswind braking capability, the weight had now risen to 80,914lb (36,727kg).
Windtunnel work had been under way for months, using models of the original P.17 and P.17 models modified to try to get close to the joint layouts as these became available, and they were now showing problems with the wing. Downwash from the wing was reducing the effectiveness of the tailplane and moving the aerodynamic centre forward. The aircraft’s c.g. was also much too far aft. With flaps down in particular, longitudinal stability was borderline. To add to the problems, BSEL’s latest specification for the Olympus 22R was showing increased fuel consumption compared with previous estimates. This would impact on the aircraft’s combat radius and its take-off performance. To try to solve these various problems, four layouts were drawn up with different fin, tailplane and wing-area combinations, tailplane root positions, fuselage lengths, undercarriage track and leg lengths, intake and engine positions, and ventral fins. None was entirely acceptable, though the smallest of the enlarged fins was kept.
This drawing, TSR2 Sheet 21 Issue 6, scheme B modified, shows the lengthened fuselage, enlarged tailplane and ventral fins; 24 June 1959. Damien Burke
At a meeting on 11 June it was decided that there was no option but to increase the wing area by 10 per cent to regain the combat radius and take-off performance lost by the new engine figures, correct the c.g. by extending the fuselage, and improve tailplane effectiveness by enlarging it once more. Two versions of this layout were tested, scheme A having the largest tailplane and scheme B having the engines moved forward to try to correct the c.g., along with an enlarged tailplane that was smaller than that in scheme A. Tailplane effectiveness was still insufficient, and the tailplane would now hit the ground with the aircraft fully flared on landing. The further enlargement of a tailplane that had already seen several increases in size was also bringing it to a critical size at which flutter could be a problem, so work continued on a combination of the two schemes: the tailplane of scheme B, but no engine shift. English Electric had also been pressing for another attempt at bringing the intake back aft of the wing leading edge and including a rearward-retracting undercarriage, and produced a drawing. The disadvantages, however, were just too many, and this configuration was finally buried for good. Along with it went a simplified main undercarriage of four wheels on each side. English Electric had considered Vickers’s draft undercarriage design ‘impossible’, and Vickers had expressed some interest in the simpler four-wheel P.17 arrangement that it claimed not to have seen previously.
By 24 June the next drawing was issued. Ground clearance for the tailplane in the landing flare was regained by reducing its anhedral to zero. Small ventral fins, as on the P.17, were introduced at the tailplane root. Frustratingly, stability still remained a problem with flaps down. A week later a drastic change had been made to try to break out of the vicious circle of main-plane and tailplane changes. The wing lost its anhedral so that it was flat on the underside, the topside taper giving a little over 1 degree anhedral along the upper surface. This was the most powerful way of reducing wing/tailplane interference, as it allowed an increase in the vertical distance between these surfaces, though it introduced some vulnerability to sideslip-induced rolling. (The Dutch roll phenomenon, an unpleasant rolling/snaking motion that can be exhibited by swept-wing aircraft with low anhedral). The situation was much improved but, frustratingly, some problems with flaps down continued. Tests showed that, with the flaps lowered to 50 degrees, the tailplane could still stall at relatively small pitch angles. To remedy this, two variations of an even larger tailplane with increased sweep were schemed. Additionally, the wing was modified to give a little more lift, the drooped leading edge being extended forward on the outer half of the wing, and notched at its own halfway point. A combination of a 30-degree drooped mainplane leading-edge extension plus the largest flapped tailplane produced the best results, including the hoped-for increase in lift, and was therefore adopted. (In later windtunnel testing the drooped leading edge would prove to be less effective than predicted, and the sawtooth extension would introduce a kink in the pitching-moment curve; the dreaded ‘pitch-up’ phenomenon that had dogged so many swept-wing designs). As a bonus, because the wing was now flat, it was found that the tailplane could be moved a little further up the fuselage side, its anhedral reintroduced, and the ventral fins deleted. To improve pilot view on approach to landing, the nose was lowered by reducing the curve along the fuselage underside.
In June 1959 contract negotiations finally resulted in a contract being placed with Vickers to cover the work that both Vickers and English Electric had been carrying out since the start of the year. This would see them through to the end of the year, by which time it was expected that they would produce a detailed technical and administrative plan for completion of the development, complete with cost estimates. Part of the deal was to produce a brochure within a month to show progress so far.
A windtunnel model similar to the aircraft depicted on TSR2 Sheet 21 Issue 6, albeit with no wing anhedral. The ventral fins, a throwback to the P.17 design, did not last long and were soon deleted from the design. BAE Systems via Brooklands Museum
Preliminary Brochure
With the stability problems continuing, the required brochure was put together. It included a general-arrangement of the TSR2 as it now was, with sawtooth extensions on a zero-anhedral wing (though windtunnel work was still going on, to see just how effective the sawtooth extensions were), large tailplanes, a relatively small fin and wedge intakes. The systems work that had been going on in parallel with the basic aerodynamic layout enabled the drawings in the brochure to be finely detailed and recognizably close to the final aircraft. The weight had continued to climb, albeit more slowly, and was now at 85,870lb (38,976kg). A detailed specification could now be put together, and this was issued as RB.192D (D for ‘development’; when the time was ripe a new specification, RB.192P, would be worked out to cover production aircraft).
As an aircraft, the brochure TSR2 was far from a practical flying machine, with some problems expected in particular areas aside from the known stability issues, notably in lateral gust response, where the effect on the crew positions of flying through continuous low-level turbulence would give a less-than-comfortable ride. However, it was a contractual obligation to produce the brochure, and, had there been any further delay, Vickers/English Electric would not have been popular with the MoS. Naturally the problem areas escaped mention in the brochure. It was also carefully described as a preliminary brochure, as there were various areas covered that neither Vickers nor English Electric wanted to end up being used as guarantee points in the production contract.
Drawing TSR2 Sheet 00/1 shows the configuration as published in the Preliminary Brochure of July 1959, with wing anhedral removed and sawtooth leading edges added. The first proposed external stores configurations are also illustrated, though these are based on drawings from October 1959. Damien Burke
An artist’s impression of TSR2 to RB.192D, July 1959. While becoming recognizably a TSR2, the configuration outlined in the preliminary brochure was far from being a practical design. Change
s to the intakes, wings, fin and rear fairing would all be required. BAE Systems via Warton Heritage Group
A windtunnel model of TSR2 with tufts attached to the starboard wing surface to aid flow visualization. The upper rear fuselage lines seen here were a short-lived variation. BAE Systems via Brooklands Museum
Only the most basic of undercarriage layouts had been drawn up to this point (unsurprisingly, given the number of changes the airframe had gone through), and there had been much argument with English Electric over each layout tried. Designing an undercarriage that could cope with poor-quality surfaces, such as Second World War airfields that had seen little use or maintenance since 1945, was going to be a challenge. It was not until August that Vickers was really able to begin detailed work in this area. The conclusions of a meeting on 25 August give some idea of the importance Vickers attached to getting the undercarriage right: ‘We are justified in putting our highest grade talent on to this area. If we are relaxed about it we shall get a heavy undercarriage, unsatisfactory performance, lose the contract and deserve it.’ Research into surface quality and its effect on existing aircraft was soon begun. Trials using a Scimitar on the grass strip at Wisley and the disused Second World War runway at Turweston were scheduled for later in the year, to give some idea of the stresses to which both airframe and undercarriage were subjected when travelling across rough surfaces.
A programme of research on variable-intake efficiencies had been instigated by English Electric in co-operation with Vickers and BSEL, looking not only at the current wedge intake, but also at a double-wedge intake and a half-cone wedge intake. No design had shown particular theoretical superiority, and the team agreed that the decision on a final choice would be based more on structural and engineering reasons than efficiency calculations. Windtunnel tests on models of wedge and conical intakes were carried out, and the results became available in September. While performance was, as predicted, much the same, engineering analysis of the designs showed that the conical intake would be structurally simpler and thus offer a small but useful weight saving, and the rectangular wedge intake had some destabilizing effect in pitch. The wedge intakes were dropped, and cone intakes drawn in. The weight was now down to 85,200lb (38,670kg).
A Preliminary Brochure windtunnel model, with large blades added to a flattened sawtooth wing leading edge in an attempt to squeeze more lift from the wing without using a cambered sawtooth. Note the simple lines of the underside of the rear fuselage. BAE Systems via Brooklands Museum
During October, work finished on the comparison of a fixed versus all-moving fin, and the all-moving fin was confirmed as part of the final configuration. This helps to illustrate part of the problem involved in designing a complete airframe. Decisions on configuration often need to be taken before there is enough information to be sure the decision is correct. In the case of the choice of fin type, the correct decision had been made early on, but in other areas, such as the wing configuration, a continual evolution resulted as more and more configurations turned out to be less than ideal after windtunnel and theoretical work.
By November 1959 Vickers/English Electric had produced some production plans and estimates, and had submitted them to the MoS. They were an unwelcome shock to the men at the Ministry; it had become clear that the magnitude of the task confronting everyone was far greater than predicted, and the estimated costs of getting the aircraft to CA release had risen from £35 million to £62 million. It was also clear that the complexity of the weapons system was going to create some very tight deadlines if the CA release date of 1965 was to be adhered to; there would be no time for vacillation. English Electric had estimated it would need 44 months from Intention to Proceed to first flight; Vickers estimated 40 months and, naturally, the lower of the two figures was quoted to the MoS.
By September 1959 the half-cone intakes had been incorporated within the TSR2 design, and BAC produced this mocked-up scene of the aircraft landing at Warton. BAE Systems via Brooklands Museum
Despite the jump in costs and concern on progress, the MoS was still behind the project, and sought Treasury approval to fund development, with a possible additional £15 million to £25 million to cover any unforeseen problems during development and flight testing. It also made it clear that time was short; an extension of the 1959 contract with Vickers would soon be necessary, along with a letter of intent to cover the development batch of aircraft, otherwise there would be an expensive hiatus in the programme.
Vickers’s financial troubles had continued to focus the management’s minds on ways out of the mess, and English Electric had been brought into discussions on the possible amalgamation of Vickers and de Havilland. English Electric was not keen on this, as it could see itself becoming a junior partner in a much larger enterprise. Various options were considered, including English Electric making a hostile takeover of de Havilland, but Vickers and English Electric could not agree on a course of action that made them both happy. English Electric, realizing Vickers’s preoccupation with civil projects, spotted an opportunity to ‘take back’ P.17 and build TSR2 on its own. Lord Caldecote of English Electric noted in August 1959 that: ‘If Vickers are really to undertake these additional responsibilities in the civil field, I think we should press very strongly indeed for the transfer of the main contract for the TSR-2 to English Electric. This no doubt would be difficult but at the stage when the specification has been agreed during the autumn it would not be impossible.’ English Electric then applied to the CA, Aubrey Jones, to take over TSR2 and leave Vickers to get on with its marriage to de Havilland. Jones would have none of it, and TSR2 continued as a joint Vickers/English Electric project. The VC10 would continue to drag Vickers’s eye off the TSR2 ball for the immediate future.
Work on the final TSR2 airframe design continued over the next few months, the issuing of general-arrangement drawings slowing down as the airframe came ever closer to the final configuration. Most of the work was related to the internals, and the English Electric members of the Joint Project Team returned home to Warton in October. A tour of the USA and several aerospace companies there had been undertaken by various English Electric/Vickers and government personnel, to study the state of the art there, and this triggered a number of changes to TSR2, such as a switch from mechanical to electrical signalling (with mechanical backup) for the flight control system.
In parallel with airframe design work, there was plenty of research and investigation going on to assist with the detail design of various airframe systems, such as the undercarriage. On this score, trials began at Vickers’s airfield at Wisley, with Scimitar WW134 carrying out three fast taxy runs on the grass at speeds from 65 to 85kt (75 to 98mph; 120 to 157km/h), and then taking off from the grass. The Scimitar’s tyres were 100psi (7.0kg/sq cm) mains with a 200psi (14.0kg/sq cm) nosewheel, and the ride was a rough one, though as soon as the nose-wheel was lifted all vibration and noise stopped. It was clear that the 100psi main wheels were not doing too badly at all on grass, though braking action was poor and the brakes overheated after sustained use. Trials then moved to Turweston, then used for agriculture and the storage and scrapping of surplus military vehicles. The runway was cleared of farm machinery, rusting tanks and other detritus, leaving just the undulations, potholes, mud and traces of oil common to disused World War Two airfields, and WW134 was flown in to begin trials on 3 December. The arrival was unexpectedly exciting, as the aircraft’s brakes disintegrated when full braking was needed, causing a violent swing to one side that the pilot corrected just in time. Having finally stopped after using 1,400yd (1,280m) of runway (800yd (730m) being the usual figure), one tyre was found to be badly cut. No spare part-worn low-pressure tyres were available, so standard 130psi (9kg/sq cm) tyres were fitted and a single taxy run was then carried out, followed by a take-off to return to Wisley. In the process the Scimitar’s efflux ripped up huge sections of the runway surface. A rethink on safety delayed further tests until 20 January 1960, when further damage was caused to the runwa
y surface, and the same happened again during two days of testing in March, when lower-pressure tyres were used. The important results, however, were that the aircraft came through the trials well, and relatively small undercarriage oleo displacements were experienced, even going over huge potholes. Braking on grass was going to be more of a problem than operating from rough strips, and it looked as though Vickers’s undercarriage design for the TSR2 would fully meet the rough runway requirement.
At about this time the RAF was finalizing the number of TSR2s it wanted. Initial thoughts were of numbers to gladden George Edwards’s heart; a front line of 170 aircraft was required. Add to that forty aircraft for the Operational Conversion Unit (OCU), plus ninety aircraft as ‘backing’ (i.e. replacements for others as they were worn out, crashed or, if the unthinkable happened, shot down), and you had a total of 300. These numbers would soon tumble downwards as the costs began to rise.