Aermacchi MB-326

The Aermacchi or Macchi MB-326 is a light military jet trainer designed and produced by the Italian aircraft manufacturer Aermacchi. It is one of the most commercially successful aircraft of its type, being bought by more than 10 countries and produced under licence in Australia, Brazil and South Africa.

The MB-326 was developed during a period when "all-through" jet training was considered by many air forces to be the most cost-effective model for training of military pilots. Accordingly, Aermacchi designed it as a single type of aircraft that could readily perform both elementary and advanced training right through to a near combat-ready standard. After it was proposed during the 1950s, the Italian Air Force (AMI) quickly became interested in the MB-326, and an initial contract to produce three prototypes was issued following a competition. Several design refinements were made prior to the AMI, giving its official approval of the project during 1956. On 10 December 1957, the first prototype performed its maiden flight. On 15 December 1958, the Italian government ordered 15 pre-series aircraft; further orders soon followed.

During February 1962, the MB-326 formally entered service with the AMI. Operational experience with the type demonstrated that the advantages of operating just one type for all training purposes, being simplicity and economy of scale, were usually outweighed by the disadvantages, namely the higher purchase and operating costs of a large all-jet training fleet. Many operators therefore soon switched to operating the MB-326 in conjunction with a cheaper piston-engined type for basic training purposes. Over time, the MB-326 found its primary role as a lead-in trainer to prepare pilots for transition to very high performance fighter aircraft. It set many category records, including an altitude record of 56,807 ft (17,315 m) on 18 March 1966. While the majority of operators were military, some civil organisations also flew the type; Italy's national flag carrier Alitalia conducted pilot training using a handful of MB-326s.

In excess of 800 MB-326s were built between 1961 and 1975. Brazil was the biggest export customer for the MB-326, which included its produced under license by Embraer. Licensed production of the type was also performed by Atlas Aircraft Corporation of South Africa. While the MB-326 had been originally conceived as a two-seat trainer, multiple single and two-seat light attack versions were also developed. Armed MB-326 saw combat, the South African Defence Force opting to employ the type during the South African Border War against the People's Armed Forces for the Liberation of Angola (FAPLA) and Cuban expeditionary troops in Angola between 1975 and 1989.

During the 1950s, a number of countries began to operate compact jet-powered trainer aircraft that possessed similar performance to frontline operational aircraft, often having been produced as two-seat adaptions of these aircraft. Recognising the potential to better fulfil this role, several different companies independently chose to commence the development of purpose-built aircraft to serve as trainers; these included the French Fouga Magister, the American Cessna T-37 Tweet, the British Jet Provost, and the Czechoslovak Aero L-29. In the aftermath of the devastating Second World War, Italy spent a number of years recuperating and reestablishing its economy; as such, the nation found itself unable to prioritise the necessary financing for the independent development of high-end combat aircraft that would be competitive with the upcoming generation of supersonic interceptors or bombers; accordingly, Italian aviation company Aermacchi elected to instead focus its resources and development efforts upon the production of a line of light fighters and trainer aircraft.

What would become the MB-326 had its origins in a private venture project by Macchi; it was developed by a team headed by Italian aeronautical engineer Ermanno Bazzocchi, the company's technical director and chief engineer. Reportedly, Bazzocchi had considered many different configurations for the tentative trainer before the design team chose to proceed with a single-engined design. In accordance with its intended primary use, the airframe was a robust and light all-metal structure, being relatively simple and cheap to construct and to maintain. The design was also to be powered by the British Armstrong Siddeley Viper turbojet engine, an efficient powerplant for the time. The Viper engine had been originally designed as a short-life unit destined for use upon disposable target drones, however, the engine had shown itself to be far more reliable and useful in other roles. During 1954, initial representations by Bazzocchi were made to the Italian Air Ministry. During 1953, the designed airframe and engine combination led to Macchi formally launching the MB-326 programme.

Around the time of the programme's launch, the Italian Air Force took interest in the proposed aircraft. The service was considering options for the potential replacement of its existing trainer fleet, thus, upon the commissioning of a competition to select a suitable successor, the MB-326 was an obvious early entrant. A detailed specification was released for the competition, the requirements stated included a maximum load of 7 g when flown at the maximum weight, a lifespan of 5,000 flight hours, an interval of at least 50–60 hours between servicing, ample warning in advance of stalls (to be at least 15 km/h (9 mph) above the aircraft's stall speed), the ability to take-off at maximum weight in 800 m (2,625 ft) over a 15 m (50 ft) high obstacle (or 500 m (1,640 ft) when flown at a light weight), being able to land within 450 m (1,480 ft) at minimum weight, a minimum speed of 110/130 km/h and a maximum speed of 700 km/h, a rate of climb at least 15 m/s (2,950 ft/min), and an endurance time of at least three hours at 3,000 m (9,840 ft).

Interest in the proposed MB-326 led to the award of the development contract for three prototypes. The programme was subject to significant refinement around this stage, leading to several modifications being made. Amongst these changes was the elimination of the negative dihedral angle previously present on the horizontal tail surfaces and the substitution of a pair of wing-based airbrakes into one located at a ventral position. During 1956, the AMI gave its official approval of the project and issued a request for the production of a pair of prototypes (later designated as MM.571 and MM.572) as well as a single airframe for static tests. These prototypes were not intended to include several features, such as the ability to equip and deploy armaments or refinements such as cabin pressurization, however, Bazzocchi chose to introduce them regardless.