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.

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