The other concept proposed by the No. 601 Research Institute at the aforementioned conference of 1964 was a project designated Chengdu J-9. It was a totally different aircraft built around a single afterburning turbofan in the 8,500/ 12,400-kgp (12,790 / 27,340 lbst) dry/reheat thrust class. This was a major problem, since no engine in this class existed in China or could be sourced abroad immediately, and there was a considerable risk that powerplant development would lag behind airframe development. On the other hand, the Chengdu J-9 appeared to offer much higher performance than the Shenyang J-8, and it was decided to pursue both projects in parallel.
After an MAI conference in Beijing on 12th-17th January 1966 the Chengdu J-9 programme received official status, and a development schedule was approved on 12th April that year. The target performance figures included a maximum take-off weight of 14,000 kg (30,860 lb). Two operational concepts were explored; one was an air superiority fighter with a secondary strike role having a top speed of Mach 2.3 – 2.4 at 20,000 m (65,620 ft) and a combat radius in excess of 450 km (280 miles). The other one was a pure interceptor having a top speed of Mach 2.5 at 22,000 m (68,900-72,180 ft) and a combat radius in excesss of 350 km (217 miles).
In 1965 the No. 601 Research Institute prepared four preliminary design projects – two swept-wing designs with wings swept back 50° and 55° at quarter-chord, a version with double-delta wings swept back 50° and a pure delta with 57° wing sweep. A new operational requirement was handed down on 1st April 1966, specifying a combat radius in excess of 600 km (372 miles), an endurance of three hours and a maximum climb rate of 180-200 m/sec (35,420-39,360 ft/min). Initially the designers went ahead with the so-called Chengdu J-9 A- IV – a tailed delta with two-dimensional lateral air intakes and a large ogival radome (similar to the future J-8 II). Yet it turned out that the tailed-delta configuration did not ensure the required performance and manoeuvrability, and the Chengdu J-9 A was dropped in favour of the J-9 B-V version featuring a tailless-delta layout with 60° leading-edge sweep and a wing area of 62 sq m (666.66 sq ft).
Then came a pause caused by the ‘Cultural Revolution’; only in 1968 was it decided to resume the work on the J-9 B-V with the intention to fly the first prototype by October 1969, timing the event to the PRC’s 20th anniversary. Yet the major development problems facing the designers had not been resolved by early 1969, and the Ministry of Aircraft Industry put the J-9B-V on hold – only to revive the previously cancelled J-9A-IV! The originally selected Plant No. 112 in Shenyang had its hands full with the J-8, so the J-9 programme was assigned to the new Plant No. 132 in Chengdu and the No. 611 Research Institute, which was to complete development of the fighter. Shounan Wang was appointed project chief at this stage.
But the Chengdu J-9 was not out of the woods yet. On the contrary, on 9th June 1970 the Chinese MoD altered the SOR again, demanding high manoeuvrability and a combat radius of 900-1,000 km (559-621 miles). The Chengdu J-9 was now to have a TOW of 13,000 kg (28,660 lb) and a top speed of Mach 2.5 at 25,000 m (82,020 ft) – which, at the insistence of the PLAAF command, was amended in November 1970 to Mach 2.6 at 26,000 m (85,300 ft).
The Chengdu J-9 A-IV could not meet this new target, so it was ‘re-killed’ – this time for good. Instead, the designers reworked the tailless J-9B-V and came up with a new configuration called J-9B-VI. This aircraft bore a certain resemblance to the SAAB J-37 Viggen, utilising a canard-delta layout with lateral intakes; a single ventral intake was also considered, the high-set canard foreplanes of delta planform were all-movable, with a leading-edge sweep of 55° and a total area of 5.7 sq m (61.29 sq ft); wing sweep and wing area were 60° and 50 sq m (537.6 sq ft). The powerplant was a WS-6 (Type 910) afterburning turbofan rated at 12,490 kgp (27,530 Ibst). However, because of the ongoing development problems with this engine the Soviet Khachaturov R29-300 afterburning turbojet rated at 8,300 kgp (18,300 lbst) dry and 12,500 kgp (27,563 lbst) reheat was chosen as an alternative power- plant, to be reverse-engineered as the WS-15.
When Deng Xiaoping came to power in 1975, the SOR for the Chengdu J-9 was finalised in February, envisaging a top speed of Mach 2.5 at 23,000 m (75,460 ft), a range of 2,000 km (1,240 miles) and a climb rate of 220 m/sec (43,300 ft/min). The fighter was to be armed with four PL-4 AAMs with infrared or semi- active radar homing; the fire control system was built around the Type 205 radar with a detection range of 70 km (43.5 miles) and a tracking range of 52 km (32.3 miles).
In November 1975 the State Planning Commission allocated funds for the construction of five prototypes, the maiden flight being planned for late 1980 or early 1981. Yet in 1980 the programme was finally terminated.