Boeing 787 project vice-president and chief engineer Mike Sinnet conceded the change in aircraft technology proved longer and more difficult than expected, but the result is "a fantastic airplane".
"It's a joy to fly, it's a joy to fly on and it's joy to ride on, so we're just really happy with how that has gone," he said.
The US aerospace giant has sold 821 Dreamliners to 56 customers around the world and expects to sell more than 3400 over the next two decades. More than 40 have already rolled off the production line at Everett, near Seattle, and the first 210- to 250-seat 787-8 will be delivered to All Nippon Airways in about two weeks. Production problems will make it more than three years late, but its entry into service will be widely welcomed by airline executives.
The airliner is expected to be about 20 per cent more fuel-efficient per seat than the aircraft it replaces, will cost about 30 per cent less to maintain and has other cost savings in areas such as lower landing costs and reduced training expenses for airlines with other Boeing planes such as the popular 777. Able to cruise at Mach 0.85, it is slightly faster than some of its competitors and is designed to optimise cargo revenue.
The designers have paid unprecedented attention to passenger comfort, with bigger windows providing a better line of sight to the horizon, higher cabin pressure and humidity, better economy seating options, more headroom and a smoother ride.
About 24 per cent of travellers experience respiratory distress after flying 12 hours in a conventional aircraft with a cabin pressure of about 8000 feet, but this drops to to 5-6 per cent at the 6000-foot pressure used by the 787. The air is also cleaner because of a two-stage filtration system designed to remove irritating volatile organic compounds produced by things such as alcohol, hand wipes, deodorant and carpets.
Mr Sinnet said the importance of the windows, which were dimmed electronically rather than using mechanical window shades, had been obvious on test flights involving partial or full interiors. "You can sit down in multiple locations in the cabin, even a full cabin, and still see out the window," he said. "It's a remarkable difference because of the height of that window, what you can see outside without having to bend . . . and without having to move around to see out the window."
Improvements to the 787 derive from a combination of the materials used in its construction -- more than 50 per cent of it, including the fuselage, is carbon composite -- as well as aerodynamic efficiency, improvements to its high-bypass turbofan engines and system architecture.
The Boeing engineer said the flight control system was used in different ways to provide a smoother landing and better flight in cruise mode through a vertical gust suppression system that could dampen frequencies of wind that typically caused motion sickness.
The flight control system also limits roll and yawing in the aircraft as it comes into land. As the plane is approaching for a landing, "there are certain frequencies of (wind) gust that the airplane can tune out" because the pilot hasn't commanded a rolling response to any yawing, Mr Sinnet said.
"So, you see, the control surfaces move to counteract that pitch and roll on approach. We can't dampen out everything, but we can do a fair amount of it, and we consistently have gotten feedback that the airplane is smoother on approach than other airplanes."
The aircraft is the most aerodynamically efficient built by Boeing due to the composite construction, which allows a stiff wing with a high aspect. The use of carbon composites and smaller internal components have allowed a much thinner wing whose camber, uniquely, can be varied when cruising to make it more efficient.
Another advantage of the new technology is that it is quieter inside and outside the aircraft, particularly on the flight deck. "It's really, really remarkable and the flight crews have really loved it," the Boeing executive said.
"And one of the pieces of feedback I typically get from flight crews is that lower flight deck noise has resulted in less flight crew fatigue on long flights. And you typically see flight crews taking their headsets off and putting air traffic control on the speakers on the flight deck rather than having the headsets on, which is a much more comfortable way to fly the airplane."
With the increased use of electric systems, the aircraft is capable of generating 1.45MW of electrical power, meaning it takes less power from the engines and reduces maintenance costs. It is also "e-enabled", a fact Boeing used during flight tests and certification, and tells the plane's owners how it is going.
Boeing has its own control room at its Everett factory, which receives automatic downlinks of an aircraft's health and allows engineers to query the plane and update its software in flight.
The flight deck design includes a standard heads-up display, large-format maps and wide horizon lines. "It has turned out to be a very, very effective way to keep the pilot in the loop and to take advantage of enhanced safety features such as advanced ground (proximity warning), vertical situational awareness on descent, traffic collision and avoidance systems," Mr Sinnet said.
They were all integrated on the same way, but in way that was familiar to 777 pilots, he said.
The higher bypass ratio and no-bleed air architecture and the two engines available for the 787, Rolls-Royce's Trent 1000 and GE's GEnx, have provided at least a 3 per cent improvement in efficiency compared with other engines. The initial test program on Rolls-Royce-powered planes is complete, as is the General Electric certification program, with other extended twin operations and function and reliability testing in progress. Both Rolls-Royce and GE have engine upgrade programs and Mr Sinnet said testing was in progress for both those programs. The Boeing executive said very few changes were needed as a result of the flight-test program.
The biggest problem was a fire in a power board that caused a test plane last year to make an emergency landing in Loredo, Texas. There were some minor aerodynamic changes to things such as the position of the slats at various settings, and a vortex generator was added to the vertical stabiliser to improve rudder effectiveness at very high angles of rudder attack and low speeds. A device was also added to the back of the auxiliary power unit to control fluid drainage, as well as minor changes to brackets and secondary structure.
The changes resulting from the fire involved making the panels more robust against foreign objects such as screws and drill shavings. "We essentially have made the power panels almost impervious to foreign object debris," Mr Sinnet said.
"The way I told the team was I wanted a design where I can take a bucket of drill shavings and pour it into the power panel and not have any bad result come out of it. "And that's essentially what we've got at this point."
Changes were also made to protection algorithms that shut down electrical systems if arcing occurs. The Texas event shut down three of four AC power channels, and even though one was being restored as the plane rolled to a halt Mr Sinnet said the changes would prevent anything not affected by an event from shutting down in response.
The changes were put through their paces during extended twin-engine operations testing and passed with flying colours. "Other than that there weren't any findings in flight testing that I would consider major," Mr Sinnet said. "It was just a lot of conditions we had to get through."
On the question of travelled work -- components reaching Seattle still needing work that should have been done by suppliers elsewhere -- Mr Sinnet said the situation had improved dramatically. Travelled work and the need to redo work has been a major contributor to the delays that have afflicted the new plane, and Boeing still has a separate team working on changes to planes made earlier in the production process.
New York-based Bernstein Research has predicted Boeing will take up to nine months longer than planned to reach a 787 production rate of 10 units monthly, although Boeing has not changed its guidance of late 2013.
However, Mr Sinnet was happy with what was coming through the process. "For the airplanes that are coming in right now, they're coming in a very good condition and our final assembly and delivery is able to move those airplanes through," he said.
There are worries the bigger 787-9, capable of taking about 50 extra passengers and currently going through its critical design review, will enter service later than Boeing's prediction of late 2013. Qantas has ordered 35 of the planes and says it now expects first delivery in 2015 rather than late 2014.
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