CompositesWorld
Issue link: https://cw.epubxp.com/i/919214
NEWS 29 CompositesWorld.com SIDE STORY Paint color has been the topic of much research at Diamond Aircraft (Weiner Neustadt, Austria). When its DA62 was in development, the company wanted to differentiate the craft in the market by offering a variety of color options. The dark color range, however, was a challenge. On a hot day, the sun can heat a plane's structure while it sits out on the tarmac to more than 70°C, which exceeds the specified limits of many epoxies, including the legacy Hexion epoxy used on the DA40 and DA42. The effect is a possible weakening of the structure that could result in failure during takeoff. It's important to note that such failure would require that the plane experience a 3.6G event while at that elevated temperature, Further, when the plane is in the air, it cools rapidly, so the risk of such a failure is remote. That said, the possibility of such an outcome, although highly unlikely, still must be dealt with from a design and manufacturing perspective. There are two ways to overcome the potential loss of composite structural strength, says David-Alexander Bausek, the company's head of production: Increase the composite laminate thickness by adding plies, or change to a higher temperature resin matrix. However, he notes, increasing thickness adds weight, and "the lighter the aircraft, the better the performance." Changing the resin matrix has its own risks because it requires a change in manufacturing processes to accommodate a different cure profile. Diamond Aircraft chose the latter, which led to the application of Hexion's RIM epoxy system on the DA62, and enabled the company to offer the plane with the desired range of light and dark colors. Diamond Aircraft: Color and aircraft composites Diamond Aircraft Austria The heart of Austria CW's visit required travel to Austria, about an hour south of Vienna, to the small town of Wiener Neustadt (population 44,000), where Diamond Aircraft spans a multi-building campus adjacent to the single-runway Flugplatz Wiener Neustadt Ost (Wiener Neustadt East Airfield). Founded in 1981 as Hoffmann Flug- zeugbau, the fledgling airframer first manufactured the HK36 motorglider. Dries acquired the company in 1991 and, in 1992, bought Diamond Aircraft in London, ON, Canada, then combined the two companies under the name Diamond Aircraft Industries in 1996. Today, the Diamond Canada facility, which focuses on engi- neering and manufacturing, is 60% owned by Christian Dries. In addition, Diamond Aircraft operates two manufacturing facilities in China via joint ventures, one in Pinau and one in Wuhu. Diamond Aircraft's first product was the DV20, a two-seat, single-engine plane, delivered in 1995. A year later, the company rolled out its single-engine DA40 and twin-engine DA42 — planes that eventually put the company on the general aviation map. Today, most of Diamond Aircraft's manufacturing — as many as 150 aircraft per year, depending on portfolio mix — is split evenly between single-engine and twin-engine aircraft, comprising three models: e single-engine, four-seat DA40; the twin-engine, four-seat DA42; and the twin-engine, seven-seat DA62. Diamond Aircraft also makes the DART 450, a civil single-engine, two-seat aerobatic trainer. And, coming this year is its new single-engine, five-seat DA50-V. Composites use, as might be expected, has evolved as aircraft have evolved. e early DA40 composites structures are all glass fiber. e later DA42 structures are a combination of glass and carbon fiber, and the more recent DA62 is all carbon fiber. Compos- ites, as a fraction of each plane's finished weight, are about 30%. Primacy of platform architecture Before the tour commences, CW's guide, Bausek, explains the material and manufacturing philosophy that shapes Diamond Aircraft's composites fabrication operations. Its overriding prin- ciple is that of common platform architecture. For example, the wings of all Diamond Aircraft products are fully interchangeable. Beyond that, the company has a stable of fuselage designs and horizontal flight-surface designs that can be mixed and matched, depending on aircraft type, aircraft size, passenger limit, number of engines and the aircraft's intended use. "For instance, the DA40 and the DA42 have the same fuselage, just a different nose section and a different midsection. is gives us the ability to produce more parts out of the same tool," Bausek points out. He notes that it also limits the mold inventory "and keeps our manufacturing pricing more attractive in terms of cost for the end-user. Also, we have a common part policy. at means we try as much as possible over all aircraft to use common parts." In addition, Diamond Aircraft, on the DA40 and DA42 (but not the twin-engine DA62), uses adhesive bonding only to join composite structures. is is done to minimize the need for drilling that might weaken composite structures, and to save the weight associated with metallic fasteners. is means Diamond Aircraft has become highly adept at bondline verification. FIG. 1 Long-term supplier relationship Olaf Krause, technical account manager, Hexion, and David-Alexander Bausek, the head of production at Diamond Aircraft, discuss a carbon fiber composite wing structure. Hexion has a long history as a supplier of epoxy and onsite technical support to Diamond Aircraft's composites manufacturing operations. Source | Diamond Aircraft