The decision to develop the Airbus A320 around a fly-by-wire flight-control system was "-one of the most difficult I ever made", says the consortium's ex-president Roger Béteille. "Perhaps we were too bold - we had no choice. Either we were going to be first with new technologies or we could not expect to be in the market."

That the A320 saw the light of day as an Airbus project - and that it was launched before the A340 - was the result of protracted negotiations within European aerospace manufacturers as to the form such an aircraft should take and the industry grouping which would build it.

While Europe's aerospace companies had been striving to make a success of the original A300 programme in the early 1970s, studies were quietly being undertaken in parallel to develop a new narrowbodied airliner family to succeed Europe's first-generation jet-powered airliners such as the British Aircraft Corporation (BAC) One-Eleven and Sud Aviation Caravelle. The need for a 150-seater to compete as a replacement for the hugely successful Boeing 737-200 and McDonnell Douglas DC-9 had already seen several different European programmes planned, all of which were stillborn. Airbus, still only a manufacturer of widebodies, remained on the sidelines.

Among the many groups with ideas for a new aircraft were Europlane, with Germany's MBB, the UK's BAC, Sweden's Saab-Scania and CASAof Spain, proposing a rear-engined 180/200-seater, dubbed EUROPLANE. The aircraft was dropped only after it became clear that it was moving too close to the existing A310. Another team, consisting of VFW-Fokker and Dornier in Germany and Hawker-Siddeley in the UK, pursued various 150-seater configurations, while France's Dassault opted for a longer-range version of its Mercure - which led to a Dassault-Aerospatiale-McDonnell Douglas team developing the Advanced Short/ Medium Range Transport. This was also abandoned.

Driven by worries that the chance to compete with the USA would be missed, a new programme was started, involving all the Airbus partner companies, but not Airbus itself. This was the Joint European Transport (JET), which encompassed a family of three aircraft sizes with seating for between 130 and 188 passengers. With power being provided by two wing-mounted CFM International CFM56s and a cruise speed of Mach 0.84, the JET proved to be a forerunner of the A320 family.

According to one Airbus source, the team members eventually "-saw the light", the programme being handed to the consortium, and Airbus' single-aisle (SA) team was formed in Toulouse, headed by ex-JET team leader Derek Brown, in 1980 to spearhead the move into the narrowbodied market. The consortium initially studied a three-aircraft,125- to 180-seat, family dubbed the SA1, SA2 and SA3.

In February 1981, the SA projects were redesignated under "A320" name and, although Airbus focused on the 150-seat SA2 model, the other projects would eventually be undertaken, becoming the A319 and A321.

During 1981, Airbus "-worked closely with Delta Air Lines, which had a specific requirement for a 150-seater, the so-called Delta III requirement," says Airbus vice president strategic planning Adam Brown. As a result, Airbus decided to offer just one fuselage-length, seating 150 passengers in a two-class layout "-so, you could say Delta invented the A320, although it never bought the aircraft",he says.

By now, it was becoming clear that the next Airbus family member would be a single-aisle model - although this resulted in a major disagreement with the German industry, pushed by Lufthansa's preference for a long-range quad-engined widebody. Béteille explains the decision in favour of the shorter-range, aircraft rather than Lufthansa's preferred long-range quad.

"Iwanted the A320 because we were planning to introduce a lot of new technology, including fly-by-wire, which meant that any serious difficulties would be solved more easily if the aircraft were nearer to home," he says.

Now came the decision on the fuselage diameter, Béteille says: "Either we had to use the Boeing section from the 707 and 727 [and later the 737], or do something better." The result was a wider section - 3.7m internal diameter against 3.45m for the Boeings, which, he admits, "...cost us a couple of hundred kilograms".

Efficiency was the name of the game, and the battle to reduce weight never ceased, with Béteille insisting at one point that the aircraft was "unsaleable"because it was "4t too heavy". The weight was subsequently reduced by 3t.

The quest for efficiency was also supported by the move to a digital fly-by-wire system - the A320 being the world's first civil aircraft to be so equipped. "The risk was not too high - after all, we had developed an analogue system for the Concorde and we had worked on several military programmes," Béteille says.

There was never much doubt about the market for the A320, studies suggesting a need for more than 3,000 aircraft over the next decade. Air France confirmed its own intentions by announcing a letter of intent for 25 aircraft at the 1981 Paris air show, followed by Air Inter, British Caledonian, Cyprus Airways and Inex Adria.

The official launch was then delayed for three years, after prolonged difficulties over funding for the $200 million development programme. Total commitments for the A320 at the time of launch in March 1984 stood at 96 from five customers. Probably the most significant single order ever placed for an Airbus came in October 1986, when Northwest Airlines signed an order for up to 100 A320s.

British Aerospace now took responsibility for the entire wing, which was equipped with a gust-alleviation system as part of the fly-by-wire control, improving efficiency in the cruise while reducing passenger discomfort in turbulence.

The fly-by-wire system itself was a complete departure from previous mechanically operated flight-control systems, with the pilot being connected directly to the flying surfaces only through the back-up pitch and yaw controls. The rest is done through the five dual-channel main flight-control computers - three for the spoilers/elevators and two for elevators/ ailerons. Redundancy is provided by making one of the dual channels "active", the operation of which is monitored by the second channel.

A further benefit which, with the development of the Airbus family, is only now beginning to be fully realised, is the ability to design the system to provide similar flying characteristics, whatever the aircraft.

This gives rise to a major Airbus selling point, that pilot qualification for the various fly-by-wire types can be minimised, reducing training costs and increasing the flexibility with which an airline can deploy its aircraft. Eventually, even the 600-to 800-seat A3XX will be given handling characteristics which are familiar to pilots used to flying other Airbus aircraft, again limiting drastically the time taken to convert, even from the smallest aircraft in the range, the A319.

Another major first was the introduction of a sidestick controller, now applied to the entire A319/A320/A321 and A330/A340 family, which removes the traditional control column from in front of the pilot, leaving the space between pilot and control panel clear.

With the A320 Airbus introduced a central fault-display unit in the cockpit along with an all-new six-screen layout giving each pilot two electronic flight instrumentation system displays, two primary flight displays and a pair of electronic centralised aircraft-monitoring displays, derived from those of the A310.

Structurally, the A320 was similar to the A310, although the use of composites was again increased, to a total of 3,900kg throughout the airframe, saving a claimed 800kg per aircraft over an all-metal design.

Meanwhile, the International Aero Engines (IAE) consortium of Rolls-Royce, Pratt &Whitney, Germany's MTU and the Japanese Aero Engines group had developed the IAE V2500 as an alternative engine, bringing R-R onto an Airbus for the first time. IAE suffered initially from development problems but is now well-established on all three versions.

The A320 roll-out, on 14 February, 1987, was marked at Airbus' Toulouse home by a huge ceremony, celebrating around 439 launch commitments, against just 15 for the original A300 back in 1972. The A320 had its first flight on 22 February, 1987, and European certification followed 12 months later. Air France put the first single-aisle Airbus into service in April 1988.

Initial A320s were completed as low-gross-weight -100s, but fairly quickly Airbus introduced the improved -200, equipped with wingtip fences, a wing centre-section fuel tank and higher maximum take-off weight, boosting maximum range to 5,300km (2,865nm).

Developments of the A321 and A319 were the logical next steps. Seen as a competitor to the Boeing 757, the 180-seat A321 was launched in November 1989, with a 6.94m fuselage stretch to the original airframe - one 4.27m section was located in front of the wing, and the second, 2.67m section, behind it.

"There was a big internal debate about what we should do with the [A321's] wing - did we make it bigger to counteract the increased weight and provide better performance, but at extra cost, or did we leave it alone? In the end we took the minimum-change route," says Brown. This saw the incorporation of double-slotted flaps and a revision to the kink in the trailing edge.

Significantly, the A321 was the first Airbus to be funded by the commercial market, with Airbus launch a major Eurolira bond issue in June 1991, which provided an important part of the estimated $480 million required for the development of the aircraft.

Perhaps one of the most significant changes introduced with the A321 was not to the aircraft - but to the production system, which saw final assembly of the type allocated to Daimler-Benz Aerospace (Dasa) Airbus' site at Hamburg, northern Germany.

International Lease Finance (ILFC) had been the first to commit to the A321 in June 1989, with an deal for 16 aircraft, and the type entered service with Alitalia in March 1994. Although the initial version of the A321, designated the -100, lacked the 5,300km-plus range of the A320, Airbus has developed a longer-range version, the -200, which incorporates increased weights and auxiliary fuel tanks.

By 1990, Airbus was re-examining a family member smaller than the A320, which crystallised as the 124-seat A319. "Some of the partners were thinking about doing other things at the bottom end of the market, and it was important that Airbus was kept as one," says Brown. There was a danger that the consensus built up around Airbus was going to fray below 150-seats with partners examining their own projects, and the A319 provided the focus to keep the consortium intact.

"Political and inter-partner differences," mainly over the location of final assembly, saw the go-ahead for the A319 delayed by around a year, but, at the the1993 Paris show, a launch was announced. It was eventually resolved that the A319 would also be assembled in Germany - there is still no decision to shift assembly of the entire single-aisle family (ie the A320) to Hamburg, however.

The A319, which is seven fuselage frames (3.77m) shorter than the A320, was first flown in August 1995, and entered service with Swissair in April 1996. Still to come, launched at this year's Paris air show, is the corporate version, the A319CJ, competing directly with Boeing's Business Jets 737.

Modifications are minimal, allowing "-the aircraft to retain its maximum residual value to customers, since it can be converted back into a passenger aircraft and sold on the market", says Airbus. The interior design accommodates between eight and 50 passengers, and it offers a maximum range of 11,660km. The A319CJ is available from the end of 1999.

A further stretch of the A321, unofficially dubbed the A322, to rival Boeing's extended 757-300 has been studied, but seems unlikely to go ahead. "I don't think there will be a stretch of the A321: it would simply trade range for payload," says Brown.

Source: Flight International