After more than two years of delays and speculation about the impact of excess weight on the 787's carbonfibre airframe, Boeing has increased the maximum take-off weight of all three variants and opted to shrink the wing of the 787-9 stretch.
The changes, disclosed in the December 2009 revision of the 787 Airport Compatibility document, identify the MTOW of the baseline 787-8 as 227,900kg (502,000lb) - up 8,400kg from the initially planned 219,500kg - while the 787-9's weight has grown by 2,270kg to 247,400kg. The short-range 787-3 has seen a 5,000kg increase to 170,250kg. The ranges of three 787 variants are not specified on this document.
Boeing says the new weights will be introduced beginning with Airplane 20 and that the initial 219,500kg (484,000lb) MTOW for the first 787-8s delivered remain in effect.
Boeing says the increase "will help us to meet the expectations of our customers".
Another notable development is a third revision to the 787-9's wing, which started its design life with a common wing to the 787-8 at 60.1m (197ft 3in) span. This was later increased to 61.9m, then as high as 63.4m, but has now shrunk back to the same dimensions as the 787-8.
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Programme sources tell ATI and Flightglobal that the decision to decrease the size of the 787-9 wing, which was made in May, was driven by favourable findings on the capability of the 787-8 wing during tests of the break trial of the half-span "-18" test wingbox, and the early static tests.
At last month's Dubai air show, Ethiopian Airlines chief executive Girma Wake said Boeing was trying to "come up with various solutions" to meet contractual range, payload and fuel consumption targets for the 787-9.
Boeing says that keeping the 787-9 wing the same size as the 787-8 is the "best choice to meet our objectives".
The use of the 787-8 gauge wing on the 787-9 is expected to yield significant weight savings for the first Dreamliner derivative due for entry into service with Air New Zealand at the end of 2013. One observer estimates that a common span between the two aircraft could save more than 1,800kg in empty weight, "which would yield almost as much range as the loss in [aerodynamic] efficiency costs".
Meanwhile, Boeing's first 787 test aircraft (ZA001) was last week continuing round-the-clock testing to ensure its readiness for first flight. The long-awaited milestone could come as early as next week. Boeing pushed the Rolls-Royce Trent 1000-powered Dreamliner forward into two to three days of closed-loop final gauntlet simulations on 8 December. Those tests entailed operation of aircraft systems to "fool" the aircraft into thinking it was flying.
Source: Air Transport Intelligence news
