boeing-747-8-intercontinental
The newest airliner in Boeing's fleet is red, it's orange and it's big. Really big.
Boeing unveiled the 747-8 Intercontinental, its biggest airliner ever, yesterday, and with the glamor of the event behind it, the company faces the ongoing — and difficult — job of certifying two new aircraft and delivering the long-delayed [747-8](http://stag-komodo.wired.com/autopia/tag/747-8/) and [787 Dreamliner](http://stag-komodo.wired.com/autopia/tag/787-dreamliner/) to anxious customers. The two airlines with orders for the 747-8, Lufthansa and Korean Air, were in Seattle for the unveiling along with private customers for the of the business jet version.
The biggest surprise at the Boeing factory was the red, orange and white livery. Boeing says it honors customers "whose cultures recognize these colors as symbols of prosperity and good luck." The color scheme ends Boeing's long streak of blue and white and pays homage and reaches back to the original 747 that first flew in 1969 with a red and white livery.
But a new paint job only goes so far, and the company plans an "aggressive" flight test schedule to finish both the passenger and cargo models of the 747-8. Just under 1,700 hours already have been flown with the [747-8 freighter](http://stag-komodo.wired.com/autopia/2010/02/boeing-747-8-first-flight/) and much of that flight test time will apply to the Intercontinental passenger version. But the flight testing so far hasn't been without issues, including a low frequency vibration in the new wing that led to further delays and a fix that wouldn't have been available on the original 747.
Boeing says the first flight of the Intercontinental will happen in "early spring" with some letting out it is expected by the end of March. As was the case with the freighter version, sitting in left seat will be test pilot Mark Feuerstein. When we sat down with Feuerstein a little over a year ago [in a 747-8 e-cab simulator](http://stag-komodo.wired.com/autopia/2010/01/we-fly-boeings-new-747-8/), he explained that much of flight testing is confirming what the engineers have predicted. But not everything always goes according to the plan.
During [flutter testing](http://stag-komodo.wired.com/autopia/2010/03/a-look-inside-the-brains-of-boeing-flight-test/) at the outer edge of the flight envelope, Feuerstein explains that when they were operating very close to the maximum mach operating speed (MMO), around Mach 0.90, a gentle oscillation could be felt in the cockpit.
"I felt, and the co-pilot felt, like we were very gently," he explains, "just rocking up and down."
Normally, Feuerstein says, when the pilot smacks the control yoke during [flutter testing](http://stag-komodo.wired.com/autopia/2010/03/flutter-testing-aircraft/) the vibration comes and goes right away. But on this particular test the vibration didn't disappear.
"It just lingered, it didn't go away, and that was the key," he says.
The 2.3-Hz vibration was in the wing and it was very gentle, Feuerstein says. Engineers on the ground had them stop the test, and simply reducing power and slowing down made the vibration disappear.
Flight testing on the 747-8 has pushed all the way out to Mach 0.98, according to Feuerstein, "within about seven knots of Mach 1."
The high-speed testing is done at maximum continuous power with the nose of the airplane pointed downhill. Feuerstein says the vibration wasn't as big an issue at the highest [Mach numbers](http://stag-komodo.wired.com/thisdayintech/2010/02/0218ernst-mach-born/), but the predicted buffeting also plays a role at those speeds.
The test that created the vibration was repeated many times in different configurations and it was mainly happening at one particular airspeed, altitude and weight loading, according to Todd Zarfos, vice president of engineering for the 747-8 program.
Zarfos says the vibration occurred in a place where the aircraft would not normally be operated, and was so small it was not a fatigue issue. But in order for the airplane to be certified, it did have to be eliminated.
"For our particular phenomenon," Zelfos says, "the most efficient and quickest answer to it was using the outboard aileron."
The outboard aileron on the new 747-8 is controlled using a fly-by-wire system instead of the direct mechanical linkages that connect the pilot to other flight control surfaces. With the fly-by-wire and a computer in between the pilot and the aileron, a software law was all that was needed to eliminate the problem.
"Modal suppression, we do it all the time, we do it for gust suppression in the tail," Zelfos says of the solution to the vibration. "You use an outboard aileron to basically counteract it out of phase and it dampens it out."
During normal flight the flight control system will automatically cancel out any type of vibration that begins without the pilot ever knowing it is happening. Similar fly-by-wire software fixes are used in many aircraft. In the original 747, which had all mechanical connections, the fix would have required an aerodynamic or structural change.
More than 42 years after that [original 747 first flew](http://stag-komodo.wired.com/thisdayintech/2010/02/0209boeing-747-flies/), the chief engineer on the first jumbo jet in the world was sitting near the stage at the unveiling of the Intercontinental on Sunday. Joe Sutter is 89 years old now and is commonly referred to as the "Father of the 747."
Under a flood of red lights as the crowds of people were inspecting the new 747 up close, Sutter says he never would have predicted that more than 40 years later it would once again be Boeing's newest airplane. But he's happy that his predictions weren't as good as his engineering. Sutter believes making the right decisions in the beginning more than pays off in the long run.
"If you design it right in the beginning, it will last for a long time."
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