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HAL Ajeet (Invincible) - India, 1977

Detailing the development and operational history of the HAL Ajeet (Invincible) Lightweight Interceptor / Ground Attack / Advanced Trainer Aircraft.

 Entry last updated on 12/8/2016; Authored by Staff Writer; Content ¬©

The HAL Ajeet was a further evolution of the British Folland Gnat fighter by way of India.

The Indian Air Force was a primary operator of the classic British Folland "Gnat", a swept-wing, subsonic lightweight fighter which also held inherent value as an advanced jet trainer. Nearly 450 of the type, debuting in 1959, were built and India stocked the line through eight total squadrons with 200 being built locally by Hindustan Aeronautics Limited (HAL). The first all-Indian Gnat saw a first-flight in May of 1962 though the IAF had been operating Gnats for some time now. The aircraft were used to good effect during the Indo-Pak wars of 1965 and 1971 in the fighter and ground-attack roles.

Despite the success of British Gnats in Indian service, the line was fraught with reliability issues and maintenance problems during its time aloft. The various wars only served to drive the point home further under wartime conditions and this led to a new IAF initiative which sought to improve upon the existing design through an indigenous venture under the name of "Ajeet" ("Invincible"). The resulting work produced essentially an all-new derivative of the original British warplane. The last two remaining Gnat production fighters were pulled from their lines and earmarked as prototypes for the growing program.

Among the changes instituted to the Gnat were new wings plumbed for fuel delivery ("wet wings"). Four underwing hardpoints were then added - two under each wing element. The control system, one of the problem points of the original Gnat, was wholly revised as were tail control surfaces for improved handling. The avionics fit was upgraded, a new Martin-Baker GF4 series ejection seat installed, and the undercarriage modified for the better - leaving the Ajeet with nothing more than 60% commonality of parts with the British Gnat.

With these changes in place, a prototype first took to the air on March 6th, 1975. The model was powered by a TJE HAL (Bristol Siddeley) "Orpheus" 701-01 turbojet engine of 4,500 lb thrust output. The second Ajeet prototype went airborne for the first time on November 5th, 1975. A development and trials process ensued to which the project culminated with a first flight of a production-quality airframe on September 30th, 1976. Operational service involving the type began in 1977 and covered fighter, interception, ground attack and advanced training roles.

As completed, the Ajeet featured a length of 29.7 feet, a wingspan of 22 feet and a height of 8 feet. Empty weight was 5,090 lb with a Maximum Take-Off Weight (MTOW) nearing 9,200 lb. Outwardly, the series mimicked the Folland Gnat to a tee though its extra underwing hardpoints set it apart. Performance from the Orpheus engine provided a maximum speed of 715 miles per hour with a combat radius of 110 miles, and a service ceiling of 45,000 feet. Beyond its standard, fixed internal cannon arrangement of 2 x 30mm ADEN guns, the aircraft was cleared to carry conventional drop stores and rocket pods from its underwing hardpoints.

Despite the investment, the Ajeet was destined to never see combat action against neighboring Pakistan. It was withdrawn in 1991 after eighty-nine total aircraft had been built, ten of these being former Gnats upgraded to the Ajeet standard. As such, just three major production variants of the Ajeet were witnessed beginning with the Ajeet Mk.1 - originally designated by the IAF as the "Gnat Mk.2". These were the single-seat ground-attack / interceptor forms. The Ajeet Mk.2 followed as a dedicated two-seat advanced jet trainer.

Ajeets stocked the inventory of No.2 Squadron of the IAF.

HAL Ajeet Specifications

Service Year: 1977
Type: Lightweight Interceptor / Ground Attack / Advanced Trainer Aircraft
National Origin: India
Manufacturer(s): Hindustan Aeronautics Limited (HAL) - India
Total Production: 89

Structural (Crew, Dimensions, Weights)

Operating Crew (Typical): 1
Overall Length: 29.69 feet (9.05 meters)
Overall Width: 22.15 feet (6.75 meters)
Overall Height: 8.04 feet (2.45 meters)

Weight (Empty): 5,071 lb (2,300 kg)
Weight (MTOW): 9,204 lb (4,175 kg)

Power / Performance (Engine Type, Top Speed)

Engine: 1 x TJE HAL (Bristol Siddeley) Orpheus 701-01 turbojet engine developing 4,500 lb thrust.

Maximum Speed: 621 knots (715 mph; 1,150 kph)
Maximum Range: 945 nautical miles (1,087 miles; 1,750 km)
Service Ceiling: 45,013 feet (13,720 meters; 8.53 miles)
Rate-of-Climb: 6,560 feet-per-minute (1,999 m/min)

Armament / Mission Payload

2 x 30mm ADEN internal cannons

Conventional drop stores across four underwing hardpoints (two per wing).

Global Operators (Customers, Users)

Model Variants

Gnat Mk.2 - Original IAF designation for Ajeet Mk.1 models.
Ajeet Mk.1 - Single-seat attacker/interceptor
Ajeet Mk.2 - Two-seat trainer