Chengdu J-7 II
The Chengdu J-7
II was developed from J-7 I. It was powered by an improved WP-7B turbojet offering a 12.8% higher dry thrust, a 70% higher afterburning thrust – 6,100 kgp (13,450 lbst) versus 5,100 kgp (11,240 lbst) – and a TBO doubled to 200 hours. The aircraft reverted to the fixed-geometry air intake – apparently the Chinese version of the variable intake proved unsatisfactory A larger drop tank holding 720 litres (158.4 lmp gal) was developed for the J-7 II, replacing the original 480-litre (105.6 Imp gal) model. Changes were also made to the equipment and armament; in particular, the PL-2 AAM became a standard fit at last. Also, the brake parachute container was modified, allowing the parachute to be deployed at higher speed and reducing the landing run to less than 800 m (2,640 ft).
The Chinese Chengdu J-7 II prototype performed its maiden flight on 30th December 1978 with Yu Mingwen at the controls. The Chengdu J-7 II became the first member of the J-7 family to be produced in significant numbers, entering PLAAF service in the early 1980s. Yet the production rate remained low; also, even though the PLAAF and the PLANAF were in urgent need of a modern fighter to replace the ageing J-5s and J-6s, foreign customers seemed to enjoy priority. Apparently the Chinese defence industry was eager to earn hard currency for a technology upgrade.
In parallel with the development of the J-7 II M Airguard, in 1981 the Chengdu Aircraft Corp. joined forces with the Guizhou Aircraft Industry Corp., another manufacturer of the J-7/F-7 family, to create a true all-weather version of the fighter. The project entered full-scale development in the late 1970s. The aircraft received official designation Chengdu J-7 III (later renamed J-7C).
This was essentially an attempt to reverse- engineer the Soviet MiG-21SM – or rather its export equivalent, the MiG-21MF. China succeeded in obtaining at least one MiG-21MF from Egypt, which was on friendly terms with both nations, in February 1979. Serialled ‘150 Red’, this fighter became the pattern aircraft for the Chengdu J-7 III.
The development and production responsibilities were shared between CAC, which was responsible for the fighter’s fuselage and final assembly, and GAIC, which would supply the wings and landing gear.
Outwardly the Chinese J-7 III was almost identical to the MiG-21MF, featuring the same large air intake with a large dielectric centrebody of pure conical shape, the two-piece cockpit canopy opening to starboard, the fat fuselage spine housing a fuel tank, the broad-chord vertical tail and the ventral cannon installation. The wings featured blown flaps. The brake parachute container, however, was closed by a J-7 I/II style upward-opening hemispherical cover instead of the MiG-21 MF’s vertically split doors.
The Chengdu J-7 III was powered by a WP-13 afterburning turbojet equivalent to the Tunnanskiy R13-300; the engine was rated at 4,100 kgp (9,040 lbst) dry and 6,600 kg (14,550 lbst) reheat. The WP-13 was reported as an indigenous product jointly developed by the Guizhou Engine Connpany and the Chengdu Engine Company As compared to the WP-7, it had substantially higher surge resistance, higher reliability and a longer service life.
The armament included a 23-mm (.90 calibre) Type 23-111 twin-barrel cannon (a copy of the Gryazev/Shipunov GSh-23L) with 200 rounds. Like the F-7M, the J-7 III had four wing pylons; these were used for carrying four PL-2 or PL-5 IR-homing short-range AAMs, free-fall bombs, or rocket pods with 57-mm, 90-mm or 130-mm FFARs. The outer pylons were ‘wet’, permitting the carriage of 480-litre drop tanks.
In 1987 the Chengdu Aircraft Corp. (CAC) began development of a further version designed to supersede the J-7II/F-7B. Designated Chengdu J-7E, the aircraft introduced a host of improvements concerning aerodynamic performance and avionics.
The most important change was the new wings of double-delta planform. The leading- edge sweep was reduced from 57° to 42° on the cambered outer wing portions, which incorporated leading-edge flaps. The trailing edge was also kinked, with forward sweep outboard of the flaps, and the boundary layer fences were deleted. The wing span increased from 7.15 to 8.32 m (from 23 ft 5 in to 27 ft 3 in), while gross wing area was increased 8.17% – from 23.00 to 24.88 sq m (from 247.6 to 267.8 sq ft). This design offered much- enhanced manoeuvrability and field performance. In addition, the wings were ‘wet’, incorporating integral tanks; this doubled the internal fuel load as compared to the J-7 HA.
The J-7E was powered by a WP-13F engine delivering 4,500 kgp (9,920 lbst) dry and 6,600 kgp (14,550 lbst) reheat. (Some sources, though, state the slightly less powerful WP-7F with an identical dry rating and a 6,5G0-kgp (14,330-lbst) afterburner rating.)
The built-in armament was restricted to a single Type 30-1 cannon with 60 rounds on the starboard side. The four wing pylons could carry up to 2,000 kg (4,410 lb) of ordnance – AAMs, bombs and FFAR pods. The two outboard wing stations could carry 480-litre drop tanks.
The designers made large-scale use of new technologies, including computer-aided design and computer-aided manufacturing (CAD/CAM), numerical control processing, laser/electromagnetic tests, composite materials, and high-pressured water cuts when developing the J-7E.
The J-7E prototype made its first flight in May 1990. Flight tests showed that the rate of climb at sea level had increased from the J-7 IIA’s 155 m/sec (30,500 ft/min) to 195 m/sec (38,380 ft/min); the ferry range increased from 1,500 to 2,200 km (from 931 to 1,366 miles), and the operational G limit was increased from +7 to +8.
According to CAC, the J-7E’s overall performance was improved 43% as compared with the J-7B, while combat effectiveness was increased by an impressive 84%. The J-7E demonstrated that Chinese aeronautical engineering had reached a certain level of maturity and was now able to produce innovative and effective designs on its own instead of simply copying existing foreign machines.
The Chengdu J-7MF projected export model revealed in 2002 was an extensive redesign of the J-7E featuring a forward fuselage strongly reminiscent of the Eurofighter EF2000 Typhoon II – or the CAC J-10, with a large ogival radome and a two-dimensional variable ventral air intake positioned well aft. Another new feature was the small all-movable canard foreplanes for aerodynamic performance improvement. As distinct from the J-7FS, the nose gear unit had twin wheels and retracted aft, not forward.
The cockpit had a bubble canopy and a frame- less curved windshield. There were three pylons under each wing.
The new forward fuselage design permitted installation of a modern pulse-Doppler radar with a detection range in excess of 80 km (50 miles). The cockpit featured an HUD and two multi-function displays, plus HOTAS controls. The project did not reach the hardware stage.