Airbus started operating outsized aircraft in 1974 to support its production sites scattered across Europe, bringing fuselage sections and wings to the final assembly line in Toulouse.

The first type was the Super Guppy, a highly modified Boeing Stratocruiser, with a fleet of four aircraft eventually being operated by subsidiary Airbus Transport International (ATI).

As A320 Family production rates picked up, and the larger A330 and A340 were launched, there was a need for greater capacity, which led to the introduction from 1995 of five Beluga ST aircraft, converted from the A300-600.

By 2013, it was clear that another step needed to be taken and the A330-700L Beluga XL was launched a year later, based on the A330-200 Freighter.

“Advantages of this”, says Bertrand George, head of Beluga XL programme, “were that the airframe had already been reinforced in certain areas and, in these days of composite materials, a traditional metal structure was easier to convert, the latter being important to achieve entry into service of the first aircraft in mid-2019.”

By that time, Airbus will be producing A320 Family aircraft at a rate of 60 per month across its four final assembly lines in Toulouse, Hamburg, Mobile, AL, and Tianjin, as well as at least 10 A350s per month.

George explains that ATI does not function as an airline, it is fully integrated into the production system, delivering items exactly when and where they are needed – the sections of every aircraft built will have accumulated about two flight hours in a Beluga before assembly.

Given the importance of the A350, it was a drawback that the Beluga ST could only take a single wing and one of the design drivers for the XL was that it should accommodate a complete shipset.

In addition, it has to be able to fly into all the airfields currently used by ATI in France (Saint-Nazaire, Nantes, Meaulte), Germany (Hamburg, Bremen), Spain (Getafe, Seville), Turkey (Ankara) and the UK (Broughton) and use all the existing infrastructure, jigs and tools.

The growing scale can be seen from last year’s operations, when the Beluga ST fleet accumulated 10,000 flight hours supporting commercial aircraft and the A400M Grizzly military transport, involving up to five flights a day, six days a week.

George explains that, taking A320 demand as a benchmark, the A330 programme required three times as many flight hours but the A350 requires nine times as many. The XL conversion to an outsized aircraft starts with a partially completed A330-200 Freighter being delivered from the assembly line to the Beluga hangar.

One of the first steps is to remove upper fuselage pieces – the fuselage is built in barrel sections and it is easier to cut a complete barrel than assemble half a barrel.

The Cargo Loading System from Telair is installed at an early stage as it is used to move the jigs that support installation of the large, curved fuselage side panels from Deharde Aerospace in Germany.

The Beluga XL cargo bay is 6m longer than the ST, 1m wider and 0.5m higher. Part of the length increase has been achieved by maintaining the full-width further aft than before. This allows the outsized aircraft to carry a pair of A350 wings.

With such a swollen fuselage, there have been significant aerodynamic changes. The vertical tailplane has been increased by 50 per cent (it and the rear fuselage are manufactured by AERnnova of Spain) and the horizontal tailplanes (from Aciturri of Spain) have been extended and fitted with endplates.

Strakes are fitted on the lower rear fuselage as well. Payload has increased from 47 tonnes to 51 tonnes, performance is essentially the same, M0.69 at 35,00ft, but range has been considerably extended, from 900nm to 2,300nm, meaning it could be used for flights to Mobile.

With this in mind, the crew accommodation has been changed. The ST has two flight deck seats and three jump seats, while the XL has two flight deck seats and one jump seat, plus a courier area aft with four seats, allowing a relief crew to be carried.

This could also be useful for intensive daily operations, says George, where crew hours can come into play. With the first aircraft substantially complete, first flight is scheduled for summer 2018, after which it will be subjected to an intensive test programme ahead of certification in 2H19.

This means the second aircraft will actually be the first to enter service, following completion in 1Q19 and Function & Reliability trials. The remaining three aircraft will arrive at yearly intervals, with the Beluga ST fleet being retired by 2020.

George says the ST fleet will still have around half of its useful life remaining so is likely to remain in service for some time, not necessarily with ATI.