With almost 150 flights and well over 500 hours of test flying behind it, the Airbus A380 very large airliner’s participation at Dubai 2005 marks only its second airshow presence since the maiden flight last April. The program has been boosted this month by visits to airports in Europe and the Asia/Pacific region that will host early scheduled passenger services slated to begin with Singapore Airlines around the end of next year.
This month S/N001 conducted the Asian visits–to Singapore, Kuala Lumpur (Malaysia) and Brisbane, Melbourne and Sydney (Australia). Before departing, the A380 was fitted with three new 70,000-pound-thrust Rolls-Royce Trent 970s as a precaution after slightly high exhaust-gas temperatures were detected on one unit; two others were changed because they were to the same build standard.
With S/N001 having returned to Toulouse from Asia, the second flying A380 (S/N004) has been assigned to fly here in a display that will essentially replicate that flown at the Paris Air Show in June. One very visible difference from the Paris display is that for the first time the A380 is wearing full-dress uniform, resplendent in Emirates Airline livery. The local carrier was the first airline to order the twin-deck, quad-aisle behemoth, which will carry 555 to 656 passengers and will be the world’s largest jetliner when it joins customer airlines at the end of next year.
Airbus has been negotiating compensation with initial customers whose aircraft will be delayed by six to eight months, at least partly because of late definition by airlines of their cabin equipment requirements. Airbus chief operating officer John Leahy has conceded that compensation could cost the manufacturer millions of dollars, but said the arrangements are confidential.
Handling of the new jetliner has exceeded some of the manufacturer’s expectations, while generally coming very close to overall levels of predicted performance.
Airbus has been flying up to 85 hours each month and sometimes twice a day, flight test senior vice-president Fernando Alonso told Aviation International News. As the third of five flying examples joins the program, the A380 is appearing here at the Dubai show with accrued flight time approaching the 500-hour mark, about 20 percent of the way to completion.
S/N001 has demonstrated higher than forecast lift, lower than suggested approach speeds and very favorable stall behavior. Work concentrated on full exploration of the flight envelope, which prepared the way for S/N004 to fly with Airbus being confident of its aerodynamics, even though S/N001 is not absolutely representative of production aircraft.
To ensure adequate margins over the guaranteed performance that a certificated aircraft will offer, Airbus has flown the first A380 at up to 375 knots (compared with an expected 340 knots maximum operating speed) and at Mach 0.96 in support of the planned Mach 0.89 maximum operating Mach number (Mmo).
Low Stall Speeds
But perhaps the most productive work has been in low-speed handling trials. Airbus has now completed its planned tests of low- and high-altitude stalls. By late October, the aircraft had demonstrated about 300 stalls, at speed well below 100 knots.
Low-speed exploration includes runway performance as Airbus investigates the A380’s real, as opposed to computed, coefficient of lift (Cl). Airbus was able to measure the A380’s lowest takeoff speed, or minimum “unstick” velocity (Vmu), earlier in the program than was expected.
The A380 also has undergone a lot of weight-related work, especially as Airbus has measured noise levels. It was flown at a takeoff weight of more than 1.245 million pounds during noise-monitoring operations in Spain–only slightly higher than the nominal maximum takeoff weight of 551 tons. But this was followed by a more impressive touchdown at some 1.2 million pounds (541 tons), compared with the A380’s planned maximum landing weight of 380 tons.
Alonso said Airbus demonstrated behavior at forward and extreme aft center of gravity at both high and low speed. Handling tests, including flutter, were completed in October.
Fuel management is particularly important on the longest A380 flights. For some time the crews were managing the system manually, but Alonso said automatic management has been in use for at least the past two months.
Continued performance testing and propulsion system trials are being conducted on S/N004. S/N002 is earmarked for initial upper- and main-deck cabin development, including internal noise and cold-weather trials.
S/N007, the fourth A380 to fly, will carry flight test instruments for route-proving with customer airlines and exterior-noise trials. The fifth A380 (S/N009) will be the first with General Electric/Pratt & Whitney Engine Alliance GP7200 engines, while one of the earlier machines will be re-engined with GP7200s for route-proving trials.