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 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 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 and Cuban expeditionary troops in Angola between 1975 and 1989.
Development
Origins
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, the ability to take-off at maximum weight in 800 m over a 15 m high obstacle, being able to land within 450 m 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, and an endurance time of at least three hours at 3,000 m.
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 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.
Into flight
On 10 December 1957, the first prototype performed its maiden flight, flown by Macchi's chief test pilot Guido Carestiato. This prototype, designated as I-MAKI, was first publicly demonstrated over France. During its flight test programme, the MB-326 prototypes demonstrated highly favourable flight characteristics of the design; however, several of the modifications made had negatively affected the overall weight of the aircraft; allegedly, at one stage, the excess weight was 400 kg greater than that given in the initial estimates. The original Viper 8 engine was capable of producing 7.8 kN of thrust; to address the increased weight, the more powerful Viper 9 model was adopted instead, which was capable of generating 0.7 kN more thrust.On 22 September 1958, the first prototype was joined by the similarly configured second prototype. It did feature some differences from the earlier aircraft; chiefly, it was powered by a newer model of the Viper engine, the Viper 11, which had been rated to produce 11.1 kN thrust. The Viper 11 would be the same standard of engine used on subsequent production standard aircraft. Direct competition to the MB-326 came in the form of the Fiat G.80; this aircraft was both more powerful and was the first real Italian jet, having flown five years earlier. However, the G.80 had several disadvantages, including being heavier, considerably larger and more expensive than its rival; as such, it ultimately lost the trainer contest and remained without a market.
On 15 December 1958, having been suitably impressed, the Italian government placed an order for a batch of 15 pre-series examples on behalf of the AMI. A production line was established at Macchi's facility in Masnago, Varese, Northern Italy. Shortly thereafter, the AMI issued its first order for the MB-326 for an initial group of 50 production standard aircraft. During 1960, a larger follow-on order for 100 aircraft was received by Macchi; this sizable commitment was viewed as being a major step towards establishing the company's supremacy in jet trainer market.
Design
The Aermacchi MB-326 was a low-wing monoplane with an all-metal structure composed of light alloys. It was one of the first jet trainers to be developed with the aim of catering to both for ab initio and advanced instruction. As originally developed, the MB-326 functioned as a refined but simple aircraft capable of covering the considerably wide range of performance characteristics required to cover both ab initio training and advanced instruction alike; other major characteristics of the type included the capacity to deliver a high rate of utilization in conjunction with minimised servicing and maintenance requirements. According to Flight International, the type was suitable for the teaching of the majority of advanced flying techniques. In addition to being relatively easy to fly, a high degree of safety was also intentionally built into it, including adoption of new Martin-Baker-built ejection seats.The MB-326 was powered by a single Rolls-Royce Viper non-afterburning turbojet engine, initial production aircraft were powered by the Viper 11 model, capable of generating up to 2,500 lb of thrust. The engine possessed multiple favourable attributes, including its general simplicity and robustness, relatively low revolutions per minute and turbine entry temperature, rapid acceleration, ease of installation, and its somewhat forgiving nature to mishandling in the air by students. Air was provided to the engine via a pair of low-profile intakes set into the wing roots. The Viper was produced under licence by Italian aviation company Piaggio following an agreement established with its original manufacturer, the British engine firm Bristol Siddeley, during 1959.
In a structural perspective, the MB-326 was relatively straightforward. Both the fuselage and the wing were constructed in three sections; of these, the centre section of the wing was integral to the fuselage. The fuselage was divided into a forward, central, and rear section; the forward section contained the nose wheel and radio systems; the centre part, accommodated the cockpit, fuel tanks and the engine; and the rear section which comprised both the tail unit and jet pipe. The fuel system had one large tank in the middle-fuselage and two in the wingtips; a single-point pressure-fuelling system is located on the starboard side of the aircraft to provide a total refuelling time of around five minutes. The rear of each wing had flaps, and ailerons with a trim surface; each wing had 22 ribs and two spars. Wing fences were added mid-wing to increase the lift characteristics. Accordingly, the MB-326 was readily capable of performing relatively slow speed take-off and landing while retaining an excellent rate of climb.
The MB-326 was outfitted with a tandem cockpit configuration, this arrangement had been chosen to result in a slimmer and more aerodynamically efficient fuselage in comparison to the more usual side-by-side arrangement. It was covered by a bubble canopy for excellent external visibility; it featured a windscreen anti-icing system powered by the engine compressor using bleed air. The cockpit was also pressurised, enabling the MB-326 to conduct high-altitude flight. The ability to fly at higher altitudes was favourable for multiple purposes, including during the execution of aerobatic and navigational training, as well as improving fuel efficiency for long-distance flights. The onboard systems were typically pre-manufactured units which were easy both to access and to remove; several elements were also intentionally interchangeable. The exterior of the aircraft was covered by a total of 80 inspection panels and doors; in-situ engine inspection could be performed via a pair of large access panels set above and below the engine bay while another pair of doors allowed access to the intake duct's interior for the inspection of the first-stage compressor rotor blades.