Avro Vulcan B.1

The Vulcan B.1 was the first production version of Avro's delta-wing bomber and the one that took the type from prototype to the squadrons of the V-force. Forty-five were assembled at Woodford Aerodrome, and its story is one of an aircraft corrected on the move: it changed wings, went through three marks of Olympus engine, and most of the survivors were converted to B.1A standard before giving way to the B.2.

The prototypes. The first Avro 698, VX770, flew on 30 August 1952 with Roly Falk alone on board. Painted gloss white, it had the pure delta wing with a straight leading edge, a single ejection seat for the first pilot and a conventional control wheel. Because the intended Bristol Olympus engines were not ready, it flew on four Rolls-Royce Avon RA.3s of 29 kN; it had no wing tanks either, and carried temporary extra fuel in the bomb bay. In January 1953 it was grounded to receive wing tanks, Armstrong Siddeley Sapphire ASSa.6 engines of 33 kN and other systems, and it flew again in July. From 1957 it was the flying test bed for the Rolls-Royce Conway, until it crashed at a flying display at RAF Syerston in September 1958.

The second prototype, VX777, flew on 3 September 1953 and was far closer to the production standard. It was lengthened to take a longer nose undercarriage leg, which raised the wing's angle of attack and shortened the take-off run; it gained a visual bomb-aiming blister under the cabin and, at Falk's suggestion, a fighter-style control stick in place of the wheel. It was the first to fly with Olympus engines, of the 100 series, though it kept the straight-edged wing. In July 1954 it was badly damaged in a heavy landing at Farnborough; repaired and re-engined with Olympus 101s of 49 kN, it resumed trials with Avro and with the Aeroplane and Armament Experimental Establishment (A&AEE) at Boscombe Down.

The phase 2 wing. While exploring the high-speed, high-altitude envelope, VX777 showed mild buffeting near its limiting Mach number and an alarming tendency to enter an uncontrollable dive, unacceptable in an unarmed bomber. Wind-tunnel work at RAE Farnborough had already led to a redesigned leading edge, cranked and drooped and fitted with vortex generators, to delay compressibility drag; this "phase 2" wing had first been tried on the Avro 707A WD480. It came too late for the two prototypes and the first production B.1s, which were quickly retrofitted. French Wikipedia describes it as a leading-edge sweep reduced from 52° to 42° over the middle third. To counter the dive an auto-Mach trimmer was fitted, applying up-elevator as speed rose, so that the pilot had to push the column to hold level flight. According to Thunder & Lightnings, the production B.1 also received a lengthened nose to carry extra fuel and simplify the retraction of the nose gear.

The first production aircraft. The first B.1, XA889, flew on 4 February 1955 still with the original wing and joined the trials in June. At the Farnborough show of September 1955 Falk astonished the crowd by barrel-rolling the second production aircraft, XA890, in front of the SBAC president's tent, and was ordered by the authorities not to repeat the manoeuvre. Now with the phase 2 wing, XA889 went to the A&AEE in March 1956 for the type's initial Certificate of Airworthiness, granted the following month. Many early aircraft, in natural metal with the front half of the nose radome black and the rear half silver, remained the property of the Ministry of Supply for trials and development.

Engines and equipment. The first 15 B.1s had the Olympus 101; later aircraft, painted anti-flash white with type D roundels, came with the Olympus 102 of 53 kN, and every 102 was brought to Olympus 104 standard on overhaul, eventually rated at 60 kN. The original radio fit comprised two 10-channel VHF transmitter-receivers (TR-1985/TR-1986) and a 24-channel STR-18 HF set. The main electrical system ran at 112 V DC, fed by four 22.5 kW engine-driven starter-generators, with four 24 V 40 Ah batteries in series as backup.

XA897 and Heathrow. The first B.1 delivered to the RAF, XA897, left in September 1956 on a round-the-world tour of about 42,000 km to show the aircraft off: between 9 September and 1 October it flew to Australia and New Zealand, accompanied by three Avro Shackletons carrying ground crew and spares, flown by Squadron Leader Donald Howard with Air Marshal Sir Harry Broadhurst as co-pilot. On 1 October, returning from Aden with extra tanks in the bomb bay, it approached Heathrow in torrential rain. The aircraft could not use the airport's instrument landing system, and Howard was flying a ground-controlled approach for the first time. Correcting the glide path, he went too low and struck the ground about 940 m short of the runway, tearing off the main undercarriage; with the wing almost vertical, both pilots ejected. The three crew in the rear and a civilian technical adviser from Avro were killed. The court of inquiry pointed to poor visibility; in 2016 a former RAF man claimed in a book that Broadhurst had ignored orders to divert.

The squadrons. The first two aircraft reached 230 OCU (Operational Conversion Unit) in January 1957 and training began on 21 February; the first course qualified on 21 May and formed the first flight of No. 83 Squadron, the first operational unit, which flew B.1s and B.1As from 1957 to 1960. From July 1957 the Olympus 102 aircraft reached the front line, and before the year was out No. 101 Squadron had received the last of the first batch of 25. The B.1 or B.1A then served with No. 617 Squadron (1958-1961), No. 44 (1960-1967), No. 50 (1961-1966) and No. 101 itself until 1967.

Test beds. Several B.1s worked for industry: XA889 handled flight clearance of the Olympus 102 and 104; XA891 received four Olympus 200s in the spring of 1958 and crashed that July on a routine test flight; XA894 flew with five Olympus engines, the standard four plus a reheated Olympus 320 for the TSR-2 in an underslung nacelle, until it was lost in a ground fire at Filton on 3 December 1962; XA896, withdrawn in June 1964 to test the BS100 for the Hawker Siddeley P.1154, was scrapped unconverted after that aircraft was cancelled in February 1965; and XA902, rebuilt after a landing accident in 1958, replaced VX770 with four Conway RCo.11s and flew on 12 October 1961 with two Speys in the inner positions.

The B.1A and retirement. Rebuilding B.1s as B.2s was considered and rejected on cost. To extend their lives, Armstrong Whitworth upgraded the 28 survivors with Olympus 102/104 engines to B.1A standard between 1959 and 1963: electronic countermeasures in a larger tail cone like the B.2's, in-flight refuelling receiving equipment and UHF radio. They were not strengthened for low-level flying, which became the norm, and were withdrawn in 1966-1967. The last unmodified B.1s, with 230 OCU, were retired by 1966, and the last flight by any B.1 was made by the engine test bed XA903 in March 1979.