Boeing unveiled a speedier and higher-flying version of a concept plane on Tuesday aimed at sharply reducing fuel use thanks to its elongated ultra-light wings.
The so-called Transonic Truss-Braced Wing aircraft boasts a 52-metre wingspan that sits atop the fuselage and is braced from underneath by a truss in a design reminiscent of biplanes from the early years of aviation.
The world's largest planemaker and US space agency NASA have been studying the concept plane for nearly a decade as part of the Subsonic Ultra Green Aircraft Research program. Boeing unveiled a reconfigured model or prototype and artist's rendering at an aerospace conference in San Diego.
Chicago-based Boeing said it tweaked the plane's designs with an optimised truss and a modified wing sweep that allow it to fly at speeds of Mach .8, or about 965 km per hour, slightly faster than previous designs but on par with current passenger jetliners.
Boeing said the jet ideally would reduce fuel burn by 60 per cent compared to an aircraft in 2005, but said it did not have final data to compare the fuel savings to present-day aircraft.
World's biggest planemaker
Meanwhile, figures show Boeing retained its title as the world's largest plane manufacturer in 2018, edging out rival Airbus as both companies kept factories churning late into December to overcome earlier supplier shortfalls.
The US industrial titan also revealed a last-minute flurry of aircraft deals, enabling it to sell more jets than it built in 2018. Boeing netted orders for 893 jetliners last year with a list value of $US143.7 billion ($A200.3 billion), padding its backlog and easing investor concerns that US-China trade tensions and whipsawing oil prices could soften demand for new planes.
For Boeing and Airbus, aerospace's duelling duopolists, year-end order and delivery totals provide bragging rights -- and a first hint of the company earnings reports to be announced over the next month. While Boeing fell shy of its target, Airbus met its twice-lowered delivery goal of 800 jets in 2018, according to preliminary results released Tuesday.
"Although Boeing came in a little short of our delivery estimate for the year, we're talking small numbers," Robert Stallard, analyst with Vertical Research Partners said in a note to clients. "The weighting of deliveries to the fourth quarter should be positive for cash flow, as should the surge in last minute orders and related deposits."
The tallies face special scrutiny this year since both manufacturers worked through the year-end holidays to overcome shortages of engines and other parts that have slowed shipments of their highly profitable single-aisle jets.
Boeing delivered 69 of its 737 airplanes in December to bring total shipments of the narrow-body family, its largest source of profit, to 580. That was less than the 593 deliveries predicted by George Ferguson, an aerospace analyst at Bloomberg Intelligence.
While the "modest shortfall" caused Boeing to miss its goal of delivering a total of 810 to 815 jets for the year, the planemaker closed the gap with higher-than-anticipated shipments of two wide-body models, Stallard said. The tally included 10 of the commercially built 767 aircraft, which were handed over to Boeing's defense division to be converted into KC-46 aerial refuelers for the U.S. Air Force.
The Chicago-based manufacturer landed 218 aircraft orders in December, underscoring the continued strength of the company's wide-body line-up and robust demand for its 737 Max. Despite the negative publicity from a deadly Lion Air crash in Indonesia in October, Boeing sold 194 of the narrow-body aircraft in December. All but 11 of the jets are bound to undisclosed customers, which are often Chinese carriers. Virgin Australia has 40 of the 737 Max planes on order.
The planemaker also recorded 24 wide-body aircraft orders for the month, including four new sales for its jumbo 747-8 freighter. The orders will help extend the life of the hump-backed model nicknamed the "Queen of the Skies," which pioneered a new era of long-range travel when it began flying in 1970.
But Boeing and Airbus will be hard-pressed to extend any sales momentum into 2019 in light of rising interest rates and currency weakness for dollar-denominated airlines, Ferguson said.
"It was a great December," he said in an interview. "As we look to 2019, we don't see the same."