To build airplanes that quickly, Raburn has
replaced the manual method of riveting pieces together with an automated aluminum construction process known as friction-stir welding. The process was first used on rockets, but never tried extensively on aircraft.
Friction-stir welding was invented and patented in 1991 by the Welding Institute in the United Kingdom. Using specialized tooling, a manufacturer first softens without melting two pieces of metal to be joined. A spindle then stirs the two pieces of aluminum together. The plasticized material is transferred from the front of a pin tool to behind it as the tool traverses along the joint. Because the aluminum never melts, friction-stir welding more closely approximates a forging or extrusion process rather than traditional welding.
Eclipse claims that friction-stir welds are two or three times stronger than single-row riveted joints and that the process is 10 times faster than manual riveting, and four times faster than automated riveting. The company says the process will produce very smooth surfaces, thereby further reducing assembly time by cutting the time required to prepare the aircraft for painting.
“We invested about $30 million” to make the welding process applicable to the Eclipse, says Raburn. The company uses custom-made computer numeric control machines that automatically weld the aircraft structure from the inside out, creating an exterior skin just as smooth as composites, says Raburn. “The great and obvious payoff for us is the speed,” says Raburn. “We can weld an entire set of airplane parts in one shift in eight hours that replaces 1,700- to 1,900-man hours and multiple shifts to build the airplane.”
Another computer whiz bringing software sensibilities to the aviation industry is Adam Aircraft CEO George F. “Rick” Adam. Adam ran the Real-Time Computer Center at the Kennedy Space Center during the Apollo program before taking a string of tech jobs that culminated with the chief information officer slot at finance giant Goldman Sachs. He founded Adam Aircraft in 1998, initially to make new-generation piston aircraft, but in 2003 began development of the $2.25 million A700 very light jet. The company expects to have the A700 certified next year and currently has 310 orders for it.
“I was always struck by how little new technology was making its way into airplanes,” says Adam. “If you bought a general aviation airplane, it looked just like it did 40 years ago. That always struck me as really unnatural.”
Adam has a more modest production plan than Eclipse and still thinks composites are the way to go. Both the A700 and A500 piston aircraft are fashioned from carbon fiber composite, and Adam credits this construction with holding down costs as well as providing a lighter aircraft and a more voluminous cabin. (With composite construction, there is no need for ribs, stringers, or any of the other support structures that hold aluminum fuselages together.)
“It is much less expensive to design and tool an airplane in composites than it is in aluminum,” Adam says. “In aluminum, you have to go to a tool-and-die maker, and the typical turnaround is six to nine months.” (Raburn figures differently: It’s cheaper to tool a composite aircraft, but the material is more expensive than aluminum. Raburn is counting on an automatic production line for further savings.)
“We do all of our own tooling in-house,” says Adam, “and we can build a tool in a week. In software, we used to call this ‘rapid prototyping.’ If we make a mistake, we fix it in a couple of days. If a guy in aluminum tooling makes a mistake, it loops back through months and months and months. Time is money. By cutting down the elapsed time, we use less money.”