The Paris air show was dominated by airplane and engine orders—enormous numbers of them. But suppliers were generating their own news, including PPG Aerospace’s introduction of a process for making cockpit and cabin windows that the company says saves weight and lightens life-cycle costs.
|Credit: PPG AEROSPACE |
PPG is a leader in a crowded field of aircraft transparency—or window—manufacturers. Its recent innovations include introduction of electrochromic windows on the Boeing 787 that permit passengers and flight attendants to control the amount of sunlight entering the cabin with a twist of a dial while still not completely obscuring views to the outside, a far cry from the all-or-nothing approach of a pull-down shade.
At Le Bourget, PPG revealed an advanced transparency material that another long-time customer, Gulfstream, is launching on passenger windows for its G650 long-range business jet. Called Opticor, the material is laminated to stretched acrylic for Gulfstream to create an outboard surface PPG says resists crazing——minute cracks that typically spread inward from a window’s edge—and maintains optical clarity longer than current surfaces. Opticor has been under development for about four years at PPG’s Glass Business and Discovery Center in Harmarville, near Pittsburgh, and at the company’s Huntsville, Ala., transparency factory.
Anthony Stone, director of new business development, calls Opticor the first major change in transparency plastics for aviation in 50 years, going back to the days when the industry learned how to take basic acrylics, which are still applied in non-pressurized rotor and general aviation aircraft, and stretch them under pressure and heat to attain the strength necessary for pressurized cabins.
Stretched acrylics are formed into windows from flat sheets using heat and vacuum that allow them to be contoured in a single direction. PPG’s new plastics are poured into a mold. “They set up like Jell-O,” says Stone. “Opticor can be cast to shape, so we don’t need a flat sheet and vacuum to shape it.” For airframe designers, this quality should open the possibility of using more complex shapes for windows. The stiffness of Opticor coatings also are less subject to cabin pressurization bulging in cruise, which interferes with an airframe’s aerodynamics, he says.
While its initial application in the G650 is for passenger windows, the new transparency process also is applicable for cockpit panes. The large G650 windows (above) are laminated to stretched acrylic for added stiffness and are assembled with an inboard coated glass panel that can be heated for antifogging.
Stretched acrylic transparencies typically have service lives of 3-4 years, Stone says. Opticor’s are projected to be 7-8 years. Windows deteriorate not because of higher exposure levels to ultraviolet radiation in cruise, but due to factors on the ground. Jet exhaust fumes at airports, cleaning agents, aircraft washes and scratches from foreign objects are what do them in, he says. A big threat to longevity is crazing. If not replaced promptly, crazes will eventually penetrate the window, causing it to depart the airplane.
Besides longer service life, PPG says Opticor is 10% lighter than standard transparencies. The windows also are clearer, although Stone says, “We don’t claim it as an advantage.”
The material’s resistance to burning in both vertical and horizontal tests is a safety bonus. In a fire, it does not produce the toxic chemicals that stretched acrylics do, he says.
PPG has been talking to airframers about the process for several years and has completed tests of the new plastic’s mechanical, optical and thermal characteristics. “We’ve finished the characterization tests and are now in long-term aging effects,” Stone says. “Commercially, we have something that we can deliver.”
Meanwhile, Nordam was making its own window news
There was more window news in Paris. In a new five-year contract, Airbus named the Nordam Transparency Group as its supplier of cabin windows for the A320 family, including its New Engine Option program that led all orders at the show. Nordam will fulfill the “multi-million-dollar” contract with its trademarked Nordex 188 stretched acrylic. The work will require 15 new employees at its Tulsa, Okla., factory and is due to begin Jan. 1, 2012. At peak annual production, 60,000 panes will flow out of Tulsa.
Nordam began working for Airbus 30 years ago providing wing-tip light lenses, which it now makes for A320s, A330s, A340s and the A380. Its first window contract came on the A380. But while that is a big airplane, the A320 contract, especially after the 1,200 order bulge that Airbus has gained with the New Engine Option, is the bigger deal.
“We are happy to say, we are the cabin window provider for the world’s largest aircraft, the A380, and now the world’s fastest-growing aircraft family, the A320,” says Chief Operating Officer Hastings Siegfried.